Systematics of Lamontichthys Miranda-Ribeiro (Siluriformes: Loricariidae), with the description of two new species

The taxonomic revision of the genus Lamontichthys Miranda-Ribeiro, based on the examination of 164 specimens of different river drainages throughout the Amazon basin, revealed the presence of six species of which two are new. Lamontichthys filamentosus occurs in the upper and middle portions of the rio Amazonas basin; L . llanero in the río Orinoco basin; L . maracaibero in the lago Maracaibo basin; and L . stibaros in the upper río Amazonas basin. Lamontichthys avacanoeiro , new species, occurs in the upper rio Tocantins basin; and L . parakana , new species, in the lower rio Tocantins basin. The new species represent a considerable extension in the so far known distribution of the genus. A parsimony analysis, including 87 osteological and external morphological characters from Lamontichthys and related taxa (total of 16), resulted in three most parsimonious trees with 194 steps (CI = 0.73 and RI = 0.78). The hypothesis of monophyly of Lamontichthys is corroborated and supported by six derived characters. Within Lamontichthys two monophyletic assemblages are recognized, one includes L . avacanoeiro and L . stibaros , the other includes L . maracaibero and the clade formed by L . filamentosus and L . llanero . The relationships of Lamontichthys parakana , a species that was not included in the phylogenetic analysis is discussed. The monophyly and relationships of the monotypic genus Pterosturisoma microps are also discussed. quais duas são novas. Lamontichthys filamentosus ocorre na bacia do alto e médio rio Amazonas; L . llanero , na bacia do rio Orinoco; L . maracaibero , na bacia do lago Maracaibo; e L . stibaros , na bacia do alto rio Amazonas. Lamontichthys avacanoeiro , espécie nova, ocorre na bacia do alto rio Tocantins e L . parakana , espécie nova, na bacia do baixo rio Tocantins. As novas espécies representam uma considerável ampliação da distribuição geográfica do gênero. Uma análise de parcimônia, incluindo 87 caracteres osteológicos e de morfologia externa de 16 táxons, incluindo Lamontichthys e grupos relacionados, resultou em três cladogramas mais parcimoniosos com 194 passos (CI = 0.73 and RI = 0.78). A hipótese de monofiletismo de Lamontichthys é corroborada e sustentada por seis sinapomorfias. Entre as espécies de Lamontichthys , dois grupos monofiléticos são reconhecidos, um incluindo L . avacanoeiro e L . stibaros e outro L . maracaibero e um clado formado por L . filamentosus e L . llanero . A relação de Lamontichthys parakana com as demais espécies do gênero é discutida, apesar da espécie não ter sido incluída na análise filogenética. O monofiletismo e as relações do gênero monotípico Pterosturisoma microps são também discutidos.


Introduction
Species of armored catfishes of the genus Lamontichthys Miranda-Ribeiro, comprise small to medium fishes, reaching approximately 20 cm in standard length, and occur in the northern and central regions of South America in the rio Solimões-Amazonas, rio Tocantins, and río Orinoco river basins and in the lago Maracaibo drainage. They inhabit the bottom of rapid flowing streams, but currently very little is known about the biology of the species of Lamontichthys in their natural habitats (Taphorn & Lilyestrom, 1984). As most other catfishes, they have the body completely covered with dermal plates, a ventral sucker-like mouth and jaws provided with very small teeth that are used to scrape the substrate. In addition to having the dorsal and ventral most principal caudal-fin rays elongated, a common feature among loricariids, a few species of Lamontichthys possess the pectoral-fin spine and/or the dorsal-fin spine prolonged into a filament that may far exceed the body length, and large specimens sometimes possess a well developed hunch, dorsally on the head.
The taxonomic history of Lamontichthys is relatively recent and the genus currently includes five nominal species, four of which are considered as valid (Ferraris Jr., 2003. The genus was first proposed by Miranda-Ribeiro (1939: 12) to include Harttia filamentosa LaMonte, from the rio Juruá, a tributary of the right margin of rio Solimões. Subsequently, Boeseman (1971: 6) considered Lamontichthys a junior synonym of Parasturisoma Miranda-Ribeiro. Isbrücker & Nijssen (1978b) examined the holotype of the type-species of Parasturisoma (Loricaria brevirostris Eigenmann & Eigenmann) and concluded that it is a member of the genus Sturisoma Swainson. The authors also diagnosed Lamontichthys based on the presence of seven branched pectoral-fin rays (vs. six in the remaining genera of the Loricariinae; Isbrücker & Nijssen, 1976), described L. stibaros, based on two specimens from Ecuador, and redescribed Lamontichthys filamentosus (LaMonte). Harttia filamentissima Eigenmann & Allen was provisionally considered by Isbrücker & Nijssen (1978b) as a junior synonym of Lamontichthys filamentosus. Although those authors observed variation in a few meristic and morphometric characters of L. filamentosus, the small number of specimens available for study at that time (only 15), precluded a more detailed evaluation of the meaning of such variation. More recently, Taphorn & Lilyestrom (1984) described two new species of Lamontichthys, L. maracaibero and L. llanero, from the lago Maracaibo drainage and the río Orinoco basin respectively, extending considerably the known distribution of the genus to the north and increasing to four the number of valid species in the genus.
No additional taxonomic studies of Lamontichthys were carried out subsequently to that of Taphorn & Lilyestrom (1984). Recently, examination of material deposited in various collections revealed that species of Lamontichthys are more widely distributed than previously recorded and in addition there are two additional undescribed species in the genus. Current knowledge about the species level taxonomy and hypotheses of phylogenetic relationships of Lamontichthys derived from the studies mentioned above provide an appropriate framework for a more detailed study focusing on the systematics of Lamontichthys.
The main objectives of the present study are to: 1) describe two new species of Lamontichthys and provide new diagnosis for all valid species; 2) update information about the geographic distribution of the recognized species; 3) evaluate the hypothesis of monophyly of Lamontichthys; 4) propose a hypothesis of phylogenetic relationships among the species of Lamontichthys.

Material and Methods
Species accounts. The taxonomic section of this study was based on the analysis of meristic and morphometric characters, color pattern, and external morphological features, of 164 specimens of Lamontichthys. Counts and measurements were made on the left side of specimens, except when the structure being measured or counted was recognizably abnormal or damaged, in which case corresponding data were taken from the right side.
Measurements were taken point to point with digital calipers. Counts were done with the help of a stereomicroscope. Counts and measurements follow Boeseman (1971Boeseman ( , 1976, Isbrücker & Nijssen (1978a) and Taphorn & Lilyestrom (1984) with some modifications and with the inclusion of additional data as follows: dentary length: from the lateral to the medial tips of the dentary; caudal-peduncle depth: measured at the vertical through the anterior border of the last dorsal plate; length of branched dorsal-fin ray: measured from base to tip of first branched dorsal-fin ray; length of branched pectoral-fin ray: measured from base to tip of first branched pectoral-fin ray; caudal peduncle depth: measured at the anterior border of the penultimate postdorsal plate, which corresponds to the narrower point of the caudal peduncle.
Counts of body plates follow Schaefer (1997) and Reis & Pereira (2000) except as follows: lateroventral thoracic plates: number of plates between the last pectoral-fin ray and the unbranched pelvic-fin ray, and only those in contact with the lateral plates of the mid-ventral series; ventral thoracic plates: number of plates in the largest oblique row located between the contralateral series of lateroventral thoracic plates (Fig. 1).
According to Reis & Pereira (2000: 1030, counts of coalescing plates refer to the number of plates in the midventral series in which the two keels are very close. In Lamontichthys, these two keels are not very evident, but through examination of cleared and stained specimens it was observed that the point in which the two keels meet is always coincident with the last plate of the mid-ventral series. In the specimens in alcohol, although the three series of lateral plates are not easily visualized, it is possible to distinguish the last plate of the mid-ventral series paired with the lateral plate of the median series. These two plates possess canals of the lateral sensory system. The last plate of the median series is triangular and situated on the base of the caudal-fin.
Roman numerals designate unbranched rays; uppercase roman numerals designate fin-spines. Lamontichthys filamentosus possesses the dorsal and pectoral-fin spines and L. llanero the dorsal-fin spine prolonged into long filaments that are often damaged. Therefore, in order to compare variation in dorsal and pectoral-fin lengths of all Lamontichthys species we chose to take this measurement from the base to the tip of the first branched fin ray.
The terms "tooth" and "odontods" follow Ørvig (1977), who considers tooth as dental units which are situated on the jaws and pharyngeal plates and odontods are dental units which occupy positions anywhere else in the dermal skeleton. Dentition terminology follows Schaefer (1987) and Müller & Weber (1992).
Meristic and morphometric characters were summarized using the program SYSTAT 10.0. Samples from proximate localities were first compared and grouped in one larger sample when no differences were detected. This was done successively until all samples were included in the analysis. Counts and measurements are presented in tables. Subunits of the head are given as proportions of head length (HL). Head length and measurements of body subunits are given as proportions of standard length (SL). In the "Material examined" section of each species account, lots are grouped by country and within each country, by state or department, followed by institutional abbreviation, catalog number, number of specimens in the lot, number of cleared and stained (cs) specimens when present, their range of standard lengths, and specific locality data. Institutional abbreviations follow Leviton et al. (1985) and Leviton & Gibbs (1988) except for Universidade Federal do Rio de Janeiro, Rio de Janeiro (UFRJ).
Formal descriptions are provided only for the new species. Redescriptions of Lamontichthys filamentosus, L. llanero, L. maracaibero, and L. stibaros are not presented since their original descriptions or more recent redescriptions provide information to unambiguously diagnose each species (LaMonte, 1935;Isbrücker & Nijssen, 1978b;Taphorn & Lilyestrom, 1984). For these species we provide a synonymy list; diagnosis, geographical distribution, general remarks, and a list of examined material.
Osteological characters were not included in the species diagnoses due to the lack of cleared and stained specimens of all species for comparison.
Phylogenetic procedures. The phylogenetic study of Lamontichthys was based on the examination of 87 morphological characters, both osteological and from external morphology, in 16 taxa that include five species of Lamontichthys and representatives of nine genera of the Loricariinae proposed as more closely related to Lamontichthys (Boeseman, 1971;Isbrücker, 1978Isbrücker, , 1980Rapp Py-Daniel, 1997) plus one species of Hypostomus and one of Neoplecostomus. Rapp Py- Daniel's (1997) unpublished study comprises the most recent and detailed cladistic analysis of the Loricariinae and provided the basis for selection of taxa and characters for the phylogenetic analysis carried out in the present study. For this reason and with the consent of the author, in the "Description of characters" section, Rapp Py-Daniel (1997), is credited for all characters or character states that were originally proposed in that study. Many characters were redefined after examination and reinterpretation of data available in the literature, and others were proposed for this just time in the present study. Specimens for osteological study were cleared and counterstained for cartilage and bone using a modification of the method outlined by Taylor & Van Dyke (1985). Cleared and stained specimens were dissected under a stereomicroscope using ophthalmologic instruments. Drawings were made by the first author with the aid of a camera lucida connected to a stereomicroscope. Unless noted in the figure legend, illustrations in lateral view are always oriented with the anterior side to the left, regardless of the side of the specimen used to prepare the illustration, and those in dorsal or ventralview with anterior side to top.
Osteological terminology follows Lundberg & Baskin (1969) and Schaefer (1987). Vertebral counts follow Schaefer (1997: 27), in considering each of the five vertebrae of the "Weberian apparatus" all fused in loricariids, and the vertebra that is incorporated in the hypural plate, as separate elements. Precaudal vertebrae refer to those anterior to the vertebra articulated with the first anal-fin pterygiophore, and caudal vertebrae are those posterior to the latter vertebra.
One of the new species diagnosed in this study, Lamontichthys parakana, was not included in the phylogenetic analysis due to the reduced number of specimens available which did not allow the preparation of cleared and stained material for the examination of osteological characters. For this species only the external The monophyly of Lamontichthys and the phylogenetic relationships among its species were inferred using the cladistic methodology first proposed by Hennig (1950Hennig ( , 1966 and subsequently discussed by various authors. Detailed explanations about the principles of the cladistic method and its operational aspects are available in Nelson & Platnick (1981), Wiley (1981), Wiley et al. (1991), Swofford et al. (1996) and Amorim (2002). Parsimony analysis was employed to generate hypothesis of phylogenetic relationships and character state transformations using NONA (Goloboff, 1999) associated with Winclada ver. 1.00.08 (Nixon, 2002). The heuristic search was performed with 1000 replications (mult*1000), keeping five trees in each replication (hold/5), and a multiple tree bisectionreconnection (TBR) + TBR search strategy. The cladograms were rooted on Neoplecostomus ribeirensis.
The most parsimonious hypotheses generated by the analysis were summarized in a strict consensus cladogram. No specific optimization method, i.e. accelerated transformation optimization (ACCTRAN), or delayed transformation optimization (DELTRAN) was used to optimize characters on the resulting cladograms (i.e. in the list of synapomorphies, ambiguous characters are listed separately from the unambiguous characters).
This study is focused on the evaluation of the monophyly of Lamontichthys and the phylogenetic relationships among its species. Characters pertaining to the question of phylogenetic relationships among other genera of the Loricariinae were included with the objective of providing a framework on which to study the relationships within Lamontichthys. Therefore, the scheme of relationships among outgroups that resulted from the present analysis should not be regarded as an attempt to propose a hypothesis of relationships among these taxa. In order to do that, we would have to survey a much larger number of characters and taxa. Discussion of character optimization, polarity and proposed synapomorphies are only provided for the portion of the cladogram pertinent to the question of monophyly of Lamontichthys and intrageneric relationships.
Cleared and stained specimens are indicated by "cs" and those in alcohol are indicated by "alc". Species name is followed by institutional catalog number, number of specimens in the lot, their range of standard lengths and specific locality data.
Geographic distribution. South American drainages including the upper and central portions of rio Solimões-Amazonas, the drainages of río Ucayali, río Marañon and río Napo, the upper regions of rio Purus and rio Juruá, rio Madeira and rio Tocantins basins. It also occurs in the middle and upper río Orinoco basin, and in the lago Maracaibo drainage (Fig. 2).
Key to the species of Lamontichthys 1. Teeth with short cusps (Fig. 3b) . 15-18 lateral plates in the mid-ventral series; more than one plate from base of last pelvic-fin ray to anterior margin of anus (Fig. 1); 6-10 lateroventral thoracic plates in specimens larger than 100 mm SL (Fig. 1)  The "x" indicates interorbital distance and "y" indicates distance from orbit to exposed border of cleithrum.
3. Pectoral-fin spine prolonged into a long filament in specimens larger than 60 mm SL; head width 97.4-111.1% HL; interorbital distance equal to distance from orbit to exposed margin of cleithrum (rarely shorter) (Fig. 6) Lamontichthys avacanoeiro can be further distinguished from L. filamentosus, L. llanero, and L. maracaibero by the anterior tip of the snout with an oval shaped area without plates (vs. tip of snout totally covered with plates or, with only a very small area lacking plates), and by the teeth with long cusps (vs. short) (Fig. 3). Lamontichthys avacanoeiro can be further distinguished from L. filamentosus and L. llanero by the lower lip semi-oval shaped (vs. semicircular) (Fig. 9). Lamontichthys avacanoeiro also differs from L. maracaibero in having more than one plate between the base of the last pelvic-fin ray and the anterior margin of the anus (vs. one plate) (Figs. 1 and 5) and in the greater abdominal length in specimens larger than 150 mm , vs. 14.1-16.3% SL [n = 5]). Lamontichthys avacanoeiro can be distinguished from L. parakana by the more posterior location of the anal-fin origin (at the vertical through the distal tip of the last dorsal-fin ray, vs. anterior to that point), by the shorter unbranched anal-fin ray , and by the smaller orbital diameter  in specimens larger than 70 mm SL.
Description. Morphometric and meristic data presented in Table 1. Largest specimen 159.9 mm SL. Head and trunk totally covered with plates. Body depressed, deeper at vertical through dorsal-fin origin, gradually more depressed posteriorly to caudal-fin base and, anteriorly, to snout tip. Head ellipse shaped in dorsal view. Dorsal profile of head slightly convex. Dorsal profile of body straight from posterior tip of supraoccipital to dorsal-fin origin, posteroventrally slanted from latter point to vertical through tip of longest anal fin ray, straight from that point to caudal-fin base. Largest body width at cleithrum, gradually narrower posteriorly to 20 th to 21 st lateral plate of median series, more abruptly posteriorly into caudal-fin base. Caudal peduncle long, narrow and very depressed. Ventral profile of body and head straight from snout tip to base of caudal fin. Pectoral-fin origin at vertical through posterior margin of orbit. Dorsal-fin origin immediately anterior to vertical through pelvic-fin origin. Analfin origin at or slightly posterior to vertical through distal tip of last dorsal-fin ray.
Eyes located dorsally, anterior to vertical through pectoralfin origin. Interorbital distance shorter or equal to distance from orbit to exposed borders of cleithrum. Mouth ventral, upper and lower lips semi-oval shaped. Lower lip extending short of vertical through anterior margin of orbit and covered with small papillae on ventral surface and along its border. Dorsal surface of lower lip smooth. Upper lip narrower than lower lip, its ventral surface (internal) with small papillae and dorsal surface (external) with small, round plates covered with odontods. Maxillary barbel inconspicuous, united by membrane to lateral border of lower lip.
Teeth setiform, long, hook-shaped and bicuspid. Tooth cusps long, flattened and unequal, with round tips, darker than rest of tooth. Median cusp slightly longer and broader Three horizontal keels along trunk, on lateral plates, converging from plate 5 to 15 or 16, continuing as a single keel posteriorly. Lower keel more evident, upper keel less evident. Last lateral plate of median series small and triangular, with one diminutive plate on each side of its base, located between two other plates of similar shape (one upper and other lower), above caudal-fin base. Lateral plates of median series, 31 to 34. Lateroventral thoracic plates 6 to 9 in specimens larger than 50 mm SL. Ventral thoracic plates, small, lozenge shaped, irregularly arranged in oblique rows; longest row with 8 to 10 plates delimited by ventrolateral thoracic plates. Region of abdomen anterior to anus covered with small, lozenge-shaped plates followed by three large polygonal plates, and the anal plate larger and bordering anterior margin of anus.
Pectoral-and dorsal-fin spines, unbranched pelvic-and anal-fin rays not projecting as long filaments. Unbranched caudal-fin rays projecting as long filaments. Branched caudalfin rays gradually longer toward dorsal and ventral unbranched rays. Dorsal most branched caudal-fin ray longer than ventral most ray. Unbranched pelvic-fin ray reaching to vertical through second ventral plate, located posterior to base of last anal-fin ray, unbranched anal-fin ray reaching to vertical through seventh ventral plate, located posterior to the base of last anal-fin ray. Dorsal-fin rays II,7; pectoral-fin rays I,7; pelvic-fin rays i,5; anal-fin rays i,5; caudal-fin rays i,12,i.

Color in alcohol.
Ground coloration of head and body of adults and juveniles varying between brown and yellow. Ventral region of head and body lighter, uniformly yellow. Dorsal region of upper lip dark brown. Straight unpigmented median stripe from base of last anal-fin ray to base of unbranched lower caudal-fin ray. Fins and dorsal region of body and head with dark brown and yellow spots. One dark brown, longitudinal band extending from base of dorsal fin to base of caudal fin.
Etymology. The species name, avacanoeiro, is in reference to the Avá-canoeiros, inhabitants from the upper rio Tocantins basin. Avá-canoeiros, an American group that historically inhabited the area of the upper rio Tocantins, drainage from which the examined specimens of the species in this study originated.
Diagnosis. Specimens of Lamontichthys filamentosus larger than 60 mm SL are distinguished from all congeners by having the pectoral-fin spine extending into a very long filament that may exceed four times the length of the first branched pectoralfin ray (vs. not extending into a long filament in the remaining species of Lamontichthys) (Fig. 10). The pectoral-fin filament is very fragile, breaks off easily, and it is frequently damaged in preserved specimens.
Lamontichthys filamentosus is further distinguished from all other Lamontichthys species, except L. llanero, by having the dorsal-fin spine prolonged into a long filament that may reach the posterior margin of the caudal fin (vs. dorsal-fin spine not extending into a long filament) and by the lower lip  Lamontichthys filamentosus is further distinguished from L. llanero by having a broader head .
Lamontichthys filamentosus is distinguished from L. maracaibero, L. stibaros, and L. parakana by having fewer lateral plates on the mid-ventral series (14 to 18, vs. 18 to 20). The presence of more than one plate between the base of the innermost pelvic-fin ray and the anterior margin of the anus further distinguishes Lamontichthys filamentosus from L. maracaibero, which has only one plate ( Figs. 1 and 5).
Lamontichthys filamentosus is further distinguished from L. stibaros, L. avacanoeiro, and L. parakana by having the anterior portion of the snout almost totally covered with plates (vs. anterior portion of the snout with a large nude area lacking plates) and by the teeth with short cusps (vs. long) (Fig. 3). The longer first branched dorsal-fin ray further distinguishes Lamontichthys filamentosus from L. avacanoeiro (27.8-39.9%, vs. 20.5-26.0% SL). Morphometric and meristic data are presented in Table 1.
Comments. Specimens smaller than 80 mm SL differ from adults in having various poorly defined transversal bands on the back, between the base of the last dorsal-fin ray and the base of the caudal fin.
Fins of specimens from the upper rio Madeira (FMNH 107021, 1, 119.6 mm SL), upper rio Juruá (MZUSP 50379 and 50497, 3, 158.3-172.5 mm SL) and one specimen from upper rio Purus basin (MCP 28834, 154.9 mm SL) have gray and light brown small spots, forming short transversal bands more evident on the pectoral-fin spine and unbranched pelvic-fin ray. In addition, the specimens from the upper rio Madeira basin (FMNH 107021) and upper rio Purus basin (MCP 28834) also have the head relatively larger than the other specimens of similar size (18. 2-19.3%, vs. 16.5-18,0% SL, n = 13, 119.4-172.5 mm SL). Isbrücker & Nijssen (1978b) previously reported on the variation of color pattern in specimens of L. filamentosus from the río Chapare, upper rio Madeira basin in Bolivia, and suggested that those specimens could represent a distinct subspecies or species. Although some differences were observed in specimens from the upper rio Juruá, rio Purus and rio Madeira basins, the reduced (n = 6) number of specimens from these localities do not allow to infer if these differences are significant, and we therefore chose to conservatively assign them to L. filamentosus.
Although the holotype of Harttia filamentissima Eigenmann & Allen (1942: 211) was not examined, information from the literature and photographs (available at www.calacademy.org) allowed us to confirm the synonymy of this species with L. filamentosus, previously proposed by Isbrücker & Nijssen (1978b). Lamontichthys llanero has the interorbital distance larger (n = 36) and only rarely equal (n = 2) to the distance from the orbit to the exposed border of the cleithrum. All other species of Lamontichthys possess the interorbital distance shorter or equal to the distance from the orbit to the exposed border of the cleithrum (Fig. 6). The presence of two plates between the base of the last pelvic-fin ray and the anterior border of the anus (vs. one) (Figs. 1 and 5), and 7 to 10 lateroventral thoracic plates in specimens larger than 50 mm SL (vs. 5 to 6) further distinguishes L. llanero from L. maracaibero. Specimens of Lamontichthys llanero larger than 70 mm SL further differs from L. stibaros, L. avacanoeiro, and L. parakana; in having the snout entirely covered with plates or with only a round inconspicuous area lacking plates at its anterior tip (vs. with a large oval area lacking plates), and teeth with short cusps (vs. long) (Fig. 3). Lamontichthys llanero further differs from L. avacanoeiro in the longer first branched dorsal-fin ray, in specimens larger than 50 mm SL (30.9-40.5%, vs. 21.9-26.0% SL). Morphometric and meristic data are presented in Table 2.

Geographic distribution. Río Orinoco basin (Fig. 2).
Comments. Lamontichthys llanero has been collected near the margins of rivers varying from less than 10 m until 1 km of width, in areas with muddy waters, and sand or mud in the bottom (F. Provenzano, pers. comm.). (

Diagnosis.
Lamontichthys maracaibero differs from all congeners in the presence of a single plate (vs. two plates) between the pelvic-fin base and the anterior margin of the anus (Figs. 1 and 5). Specimens of L. maracaibero larger than 150 mm SL possess a deeper body at the predorsal region (14.0-15.1%, n = 6, vs. 11.5-13.5%, n = 26) relative to the other species of Lamontichthys (except for L. parakana for which specimens larger than 150 mm SL were not available for comparison), forming a hump between the head and the dorsal-fin origin. Lamontichthys maracaibero is further distinguished from L. filamentosus and L. llanero by the semi-oval shape of the lower lip (vs. semicircular) (Fig. 9); and from L. llanero by the reduced number of lateroventral thoracic plates in specimens smaller than 50 mm SL (5 to 6 plates, vs. 7 to 10), and from L. stibaros, L. avacanoeiro, and L. parakana by having the snout totally covered with plates at its anterior tip (vs. presence of an area lacking plates) and by the teeth with short cusps (vs. long) (Fig. 3). The specimens of Lamontichthys maracaibero larger than 100 mm SL also differs from L. stibaros, L. avacanoeiro, and L. parakana in the relatively shorter head (16.7-17.8%, vs. 19.8-23.0% SL) and shorter dentary (14.8-19.1%, vs. 18.4-23.4% HL). Morphometric and meristic data are presented in Table 2.

Diagnosis.
Lamontichthys parakana differs from all other species of the genus in the more anterior position of the analfin (anal-fin origin situated anterior to the vertical through the distal tip of the last dorsal-fin ray, vs. anal-fin originating posteriorly).
Lamontichthys parakana further differs from the other species of Lamontichthys, except L. avacanoeiro and L. stibaros, in the lack of plates on the anterior tip of the snout (vs. snout entirely covered with plates or with an inconspicuous naked area), in the teeth with long cusps (vs. short) (Fig. 3), and in the longer dentary in specimens larger than 50 mm SL (20.1-22.6%, vs. 11.5-19.1% HL).
The semi-oval shaped lower lip further distinguishes Lamontichthys parakana from L. filamentosus and L. llanero that have the lower lip semicircular shaped (Fig. 9).
Lamontichthys parakana also differs from L. avacanoeiro in the longer length of the first branched dorsal-fin ray (26.4-31.0%, vs. 20.5-26.7% SL). Table 3. Largest specimen 119.0 mm SL (n = 3). Head and trunk totally covered with plates. Body depressed, deeper at vertical through dorsal-fin origin, gradually more depressed posteriorly, to caudal-fin base and anteriorly, to snout tip. Head ellipse shaped in dorsal view, with slight prominence at anterior tip. Dorsal profile of head slightly convex. Dorsal profile of body slightly convex from posterior tip of supraoccipital to dorsal-fin origin, posteroventrally slanted from latter point to vertical through tip of last anal fin ray, straight to caudal-fin base. Largest body width at cleithrum, gradually narrower to 18 th to 19 th lateral plate of median series more abruptly so posteriorly, into base of caudal-fin. Caudal peduncle long, narrow and very depressed. Ventral profile of head and body straight from snout tip into base of caudal-fin. Pectoral-fin origin at vertical through posterior border of orbit. Dorsal-fin origin immediately anterior of vertical through pelvic-fin origin. Base of last anal-fin ray at vertical through distal tip of last dorsal-fin ray.

Description. Morphometric and meristic data presented in
Eyes located dorsally, anterior to vertical through pectoralfin origin. Interorbital distance shorter or equal to distance from orbit to exposed borders of cleithrum. Mouth ventral.
Upper and lower lip semi-oval shaped. Lower lip extending short of vertical through anteriormost margin of orbit, covered with small papillae on ventral surface and along its border. Dorsal surface of lower lip smooth. Upper lip narrower, with small papillae on ventral surface (internal) and with small round plates covered with odontods on dorsal surface (external). Maxillary barbel inconspicuous, united by membrane to lateral border of lower lip.
Teeth setiform, long, hook-shaped and bicuspid. Tooth cusps long, flattened and unequal, with round tips, darker than rest of tooth. Median cusp slightly longer and broader than lateral cusp. Number of jaw teeth increasing with growth. Number of premaxillary teeth approximately 16% greater than number of dentary teeth. Emergent teeth placed in two irregularly arranged rows; teeth gradually smaller laterally. Replacement teeth oriented at 90 degrees relative to emergent teeth and covered with skin.
Anteroventral tip of snout without plates, with distinguishable naked portion, approximately oval shaped, Three inconspicuous horizontal keels along body, from plates 6 to 14 or 16. Last plate of median lateral series diminutive and triangular, located on caudal-fin base, between two slightly larger plates of similar shape (one upper and one lower, upper plate slightly larger than lower plate). Lateral plates of median series, 32-33. Small ventral thoracic plates lozenge shaped, arranged in irregular, oblique rows. Longest row with 7 to 8 plates delimited by lateroventral thoracic plates. Region of abdomen anterior to anus covered with small, lozenge shaped plates, followed by one larger plate that form anterior border of anus.
Pectoral-and dorsal-fin spines, unbranched pelvic-and anal-fin rays not projecting into long filaments. Unbranched caudal-fin rays of both specimens damaged, except lower unbranched caudal-fin ray from one specimen which projects as long filament. Branched caudal-fin rays gradually longer toward upper and lower unbranched rays. Dorsal most branched caudal-fin ray slightly longer than ventral most ray. Unbranched pelvic-fin ray reaching vertical through anterior border of first ventral plate posterior to base of anal fin. Unbranched anal-fin ray reaching eighth ventral plate posterior to base of anal fin.

Color in alcohol.
Coloration of paratype faded, uniform yellow. Color pattern based only on holotype. Ground coloration of head and body brown or yellow. Ventral region of head and body lighter, uniform yellow. Dorsal region of upper lip dark brown. Straight unpigmented median stripe from last anal-fin ray to base of unbranched lower caudal-fin ray. Dorsal region of body with three longitudinal, dark brown bands extending from base of dorsal fin to base of caudal fin. Two of these bands extending ventrally to cover lateral plates. Third band extending along dorsal midline of body, from dorsal-fin base to caudal-fin base. Bands gradually narrower posteriorly. A transversal, dark brown band between bases of pectoral-fins, with anterior margin at posterior tip of supraoccipital. Dorsal portion of head dark brown with slightly lighter areas. All fin rays with dark brown pigmentation. Anterior half of dorsalfin dark brown, remaining of fin hyaline. Paired fins and analfin dark brown. Caudal-fin base and three upper most and

Diagnosis.
Lamontichthys stibaros differs from all other species of the genus, with the exception of L. avacanoeiro and L. parakana, in the lack of plates on the anterior tip of the snout (vs. anterior portion of snout totally covered with plates or with an inconspicuous naked area), in the teeth with long cusps (vs. short) (Fig. 3), and in the lower lip semi-oval shaped (vs. semicircular) (Fig. 3). Lamontichthys stibaros differs from L. avacanoeiro and L. parakana in the longer first branched dorsal-fin ray (29.7-36.8%, vs. 22.6-31.0% SL), in specimens larger than 70 mm SL. It further differs from L. avacanoeiro in the longer first branched pectoral-fin ray (21.7-25.1%, vs. 19.2-22.0% SL) and from L. parakana in the narrower head (89.1-101.4%, vs. 101.3-106.1% HL).
The presence of 19 to 20 lateral plates along the mid-ventral series (vs. 14 to 18) and the longer dentary (18.6-23.2%, vs. 11.5-17.3% HL) in specimens larger then 70 mm SL also distinguishes L. stibaros from L. filamentosus and L. llanero. Lamontichthys stibaros differs from L. maracaibero in having more than one plate between the base of the last pelvic-fin ray and the anterior border of the anus (vs. one plate) (Figs. 1 and 5) and in the uniform color pattern of the fins (vs. with brown and gray spots). Morphometric and meristic data are presented in Table 3.

Description of characters and phylogenetic analysis
Characters and their respective states analyzed in this study are grouped according to the region of the body with which they are associated. (1) present (CI = 100; RI = 100).
The mesethmoid of loricariids varies considerably in shape but usually its posterior portion is relatively elongate, narrow, and cylindrical. The lateral projections (cornuas) at the anterior tip of the ossification may be extremely reduced or absent (Schaefer, 1990: 175;1998: 394) and the median anteroventral portion is usually thin and lacks a groove or cavity.
Uniquely among taxa examined, the mesethmoid of L. filamentosus, L. llanero, and L. maracaibero possesses an anteroventral depression (Fig. 15a). A strong, anteriorly directed ligament attaches to this groove and is, apparently, connected to plates on the snout tip.
A thick layer of tissue, strongly adhered to the anterior tip of the mesethmoid, which may be covered by plates, is present in all taxa examined except Farlowella and Pseudoloricaria. This feature was previously described by Rapp Py-Daniel (1997: character 8).
The ventral surface of the mesethmoid of astroblepids and loricariids possesses a vertical process on the median longitudinal line close to the premaxillae and is referred to as the mesethmo-premaxillary articular condyle or mesthmoid disk (Schaefer, 1987: 5;1998: 384). Ligaments that sustain the premaxillae are inserted on this process and enable their ample mobility (Schaefer, 1987).
In Lamontichthys, Harttia, Hypostomus, Neoplecostomus, Pterosturisoma, and Sturisomatichthys, the mesethmoid disk is robust, circular in lateral view and with the margins of the disk much broader than the central portion ( Figs. 15 and 16a). In the two conditions considered as derived, the mesethmoid disk is more delicate (Fig. 16b-c). In Farlowella and Sturisoma, although the disk is also approximately circular in lateral view it is laminar shaped. In Loricaria, Pseudoloricaria, and Rineloricaria, the mesethmoid disk is also laminar shaped, but the lamina is thin and rectangular to triangular in lateral view, similar to a keel.
In Loricariids the vomer is elongate with reduced lateral wings, and is sutured anteriorly to the mesethmoid and posteriorly to the parasphenoid (Schaefer, 1987: 5). The anterior portion varies in shape and the posterior portion is tapered at the end, forming an elongate tip (Rapp Py-Daniel, 1997: character 9).
In Lamontichthys, Harttia, Neoplecostomus, and Sturisomatichthys the vomer has a thick anterior portion, with very short anterior prolongations (Fig. 15). In the derived condition, present in Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisoma the anterior portion of the vomer is elongate, and has one or two long and narrow prolongations (Fig. 16b-c). Schaefer (1987: 5;1997a: 23) observed a similar condition in Hypostomus plecostomus (Hypostominae) and in Otocinclus (Hypoptopomatinae). The lateral ethmoid in loricariids encapsulates the nasal organ from below (Howes, 1983;Schaefer, 1991). Anteriorly, the lateral ethmoid has a concave face, with cartilage, that articulates with the autopalatine. Posteriorly, the lateral (vertical), ventral (horizontal) and medial (vertical) walls of the capsule are open only dorsally. The meeting of these walls shape part of the anterior border of the orbit.
Pterosturisoma microps possesses the dorsal border of the nasal fossa circular, while in the other taxa the border is oval. This condition was not codified in the present analysis, however it may be tentatively proposed as autapomorphic for this species.
Among the Siluriformes, only in the family Loricariidae the ventral surface of the lateral ethmoid contacts the dorsal border of the metapterygoid (Schaefer, 1987). In Lamontichthys, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys this contact is limited to the posterior portion of the dorsal border of the metapterygoid, which articulates with the lateral ethmoid by processes present on both ossifications, a condition shared with Neoplecostomus and most loricariids (Fig. 18a). In the derived condition, Farlowella and Hypostomus possess an additional contact characterized by a short suture in the anterior portion of the metapterygoid (Fig. 18c). In Loricaria, Pseudoloricaria, and Rineloricaria, the dorsal border of the metapterygoid contacts the lateral ethmoid by an interdigitating type of contact (Fig. 18b). Schaefer (1991: 7;1998: 394) reported the presence of a vertical lamina in the lateral ethmoid contacting the metapterygoid in various loricariids (Ancistrinae, most Hypoptopomatinae, Hypostominae, most Loricariinae, and Neoplecostomus), however, he did not describe variation in the type of contact between these structures.
Located lateral to the supraoccipital, the sphenotic forms the dorsoposterior portion of the orbit in the majority of the Loricariidae and bears part of the temporal laterosensory canal (Schaefer, 1987: 6). The sphenotic of loricariids is usually square-shaped with one long lateral process. Schaefer (1987: 6) considered the lateral process of the sphenotic in loricariids as homologous to the prominent "lateral spine" representative of the Siluriformes in general. However, Howes (1983: 95) considered that the lateral spine present in the sphenotic of primitive Teleostei is absent in Siluriformes, including the Diplomystidae (Arratia, 1987: 92), Scoloplacidae (Schaefer, 1990: 180) and the Loricariidae.
Astroblepids and many loricariids possess a long lateral process of variable width on the sphenotic (Armbruster, 2004: 26), while other loricariids possess a relatively short and wide or inconspicuous process. Variation in the size of this process is accompanied by several degrees of participation of the sphenotic in the margin of the orbit.
Lamontichthys, Farlowella, Harttia, Loricaria, Pseudoloricaria, Rineloricaria, and Sturisomatichthys possess a long sphenotic process of variable width, a condition shared with other loricariids such as Hypostomus and Neoplecostomus (Fig. 19). In this condition, the sphenotic contributes with 1/5 or more to the dorsoposterior margin of the orbit.
Sturisoma possesses a short and wide lateral process, and the sphenotic contributes with approximately 1/5 of the border of the orbit, and in Pterosturisoma this process is much shorter and the sphenotic has little or no contribution to the margin of the orbit (Fig. 20).
Observation of this character is better accomplished with the sphenotic separate from the rest of the neurocranium.

9.
Orbital notch in sphenotic: (0) absent; (1) present (CI = 100; RI = 100). The orbital notch is formed by an anteroventral laminar expansion of the sphenotic, in the region where the sphenotic forms the posterior margin of the orbit, and its presence is considered derived within loricariids and proposed as autapomorphic for the tribe Loricariini (Boeseman, 1971: 17).
In the Astroblepidae and Loricariidae the anterior and posterior ceratohyals possess a ventral laminar expansion along their posterior borders, forming an angle of approximately 90º with the remaining of the hyoid arch (anterohyal of Schaefer, 1987: 12). Schaefer & Lauder (1986) discussed various specializations in the musculature and osteology of the hyoid arch in the Astroblepidae and Loricariidae associated with the life-style of members of these families. These fishes continue to respire while maintaining the suck pressure of the oral disk (Alexander, 1965: 136). In addition, the ceratohyal of the Loricariidae possesses expansions forming a broad surface for the attachment of the associated musculature (Schaefer & Lauder, 1986: 500).
The ventral expansion of the posterior border of the anterior ceratohyal varies among loricariids. In Farlowella, Hypostomus, Loricaria, Neoplecostomus, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisomatichthys the laminar expansion widens abruptly in the lateral portion of the bone.
In Lamontichthys (except L. avacanoeiro), Harttia, and Sturisoma, the ventral expansion of the anterior ceratohyal is relatively narrow overall, and it widens gradually along the extension of the bone (Fig. 21). Although in L. avacanoeiro the ventral expansion of the anterior ceratohyal also widens gradually along the extension of the bone the ossification is relatively broad, distinctly wider than the expansion in the other species of Lamontichthys.
Loricariids possess five pairs of hypobranchials, the first pair is ossified and the others cartilaginous (Schaefer, 1987: 12). The first hypobranchial in loricariids is usually stickshaped and slightly wider in the medial tip. However, some loricariids possess a derived condition, wherein the lateral portion of the first hypobranchial is considerably broader than the medial portion resulting in a fan-shaped ossification (Armbruster, 2004: 11). In the present study, a fan shaped first hypobranquial was observed only in Loricaria and Pseudoloricaria. In the other loricariids examined, including Lamontichthys, the first hypobranchial is stick-shaped, gradually widening towards the lateral margin (Fig. 22).

13.
Shape of lower pharyngeal plate: (0) stick-shaped, slightly expanded; (1) triangular; (2) approximately rectangular, with posterior border parallel to anterior border, medial and lateral borders of similar length; (3) quadrangular, medial and lateral borders parallel, medial border approximately same length of posterior border and slightly longer than lateral border; (4) trapezoidal, medial and lateral borders almost parallel, medial border larger than the posterior border and at least twice larger than the lateral border (CI = 100; RI = 100).
The fifth ceratobranchial in the Otophysi is modified into a plate-like ossification with teeth, and within the Loricariidae there is wide variation in the shape of the pharyngeal plate (Schaefer, 1987: 12). The fifth ceratobranchial in Neoplecostomus is a somewhat broad ossification with a narrow dorsal end, a condition considered plesiomorphic for the Siluriformes (Fig. 23; Arratia, 1987: 41). Armbruster (2004: 9) characterized the shape of the lower pharyngeal plate of most Loricariinae as widened at least anteriorly to form a hatchetlike structure. In the present study, four different conditions may be further distinguished regarding the lower pharyngeal of the Loricariinae.   pharyngeal plate approximately triangular and little expanded. In Harttia this structure is also little expanded, however it is somewhat rectangular-shaped, with the posterior border parallel to anterior border and medial and lateral borders of similar length (Fig. 24a).
The lower pharyngeal plate is considerably enlarged in Lamontichthys and Sturisoma. In Sturisoma the lower pharyngeal plate is approximately quadrangular, the medial and lateral borders are parallel, and the medial border has approximately the same length of the posterior border and is slightly longer than the lateral border (Fig. 24b). In Lamontichthys, the lower pharyngeal plate is approximately trapezoidal, with the medial border larger than the posterior border and, at least, twice as large as the lateral border (Fig.  25a).
The posterior border of the first epibranchial in Lamontichthys has a long triangular laminar expansion that is projected medially (Fig. 26a). In the other Loricariinae examined, this projection is absent or relatively short. Farlowella, Harttia, Loricaria, and Rineloricaria do not possess any projection in the posterior border of this bone (Fig. 26c), and Pseudoloricaria, Pterosturisoma, Sturisoma, and Sturisomatichthys possess a short laminar projection (Fig. 26b). Schaefer (1987: 12) described the presence of a posterior process in the first epibranchial for Hypostomus plecostomus, and the condition of this species was coded as 1 in the present study.
The third epibranchial in the majority of the Loricariidae possesses an uncinate process with varying degrees of development (Rapp Py-Daniel, 1997: character 75). When present, the process arises from the posteromedial border of the epibranchial, and extends into the medial portion of the brachial arches. A small dorsolateral process is present in the third epibranchial of Hypostomus plecostomus (Schaefer, 1987: 14) and Harttia loricariformis (Fig. 27).
The Siluriformes possess a single pair of upper pharyngeal plates, connected to the fourth pharyngobranchial (Fink & Fink, 1981: 323). Teeth arranged in various patterns on the upper pharyngeal plate make contact with the dorsal surface of the fifth ceratobranchial, or lower pharyngeal plate.
The upper pharyngeal plate of Lamontichthys, Harttia, Pterosturisoma, and Sturisomatichthys possess a robust ventral surface and a dorsal laminar projection (Fig. 28a). Teeth are located on the ventral surface, which is triangular shaped with a narrow anterior portion. The upper pharyngeal plate of Neoplecostomus and other loricariids, such as Acestridium discus, lacks a dorsal laminar projection and the ventral surface is drop-shaped with a slightly narrow anterior portion, and completely covered by teeth (Figs. 23 and 28c).
The upper pharyngeal plate of Sturisoma is laminar and triangular shaped, and differs considerably from other examined taxa in having the teeth in a small folded area on the posterior border of the plate and along the medial border (Fig. 25b). This condition is proposed as autapomorphic for Sturisoma. The ventral surface, which usually has teeth in other taxa, is covered by branchial filaments, while the dorsal surface is smooth.
Loricaria, Pseudoloricaria, and Rineloricaria possess a relatively large pharyngeal plate, slightly convex, circular to quadrangular shaped with teeth distributed on the entire ventral face (Fig. 28b). Schaefer (1991: 12;1998: 396) described the general condition of the upper pharyngeal plates in the Loricariidae, as plane, relatively large and wedge-shaped. Members of the Hypoptopomatinae (Otothyris, Pseudotothyris, and Schizolecis) alternatively have a small, compact and rounded upper pharyngeal tooth plate. Armbruster (2004: 12) described two distintict conditions of this plate in the Loricariidae. In the present study four different conditions regarding the shape of the upper pharyngeal plate among examined specimens of Loricariidae were observed.
Loricariids commonly possess only conical teeth on the upper and lower pharyngeal plates. However, many members of the Loricariini possess both conical and molariform teeth in both plates (Rapp Py-Daniel 1997: character 90; Armbruster, 2004: 9), a condition observed in Loricaria among examined taxa.

Jaws and dentition
The Loricariidae surpasses all other Loricarioidea in the high diversity of shapes and sizes of jaws and teeth, probably a consequence of the adaptation to different kinds of microhabitats and substrates explored by these fishes. Associated with the variation of jaws and teeth, there are several other specializations in the feeding mechanisms and in the hyoid apparatus (Schaefer & Lauder, 1986: 504).
The palatine in loricariids is narrow and cylindrical. Anteriorly there is a cartilaginous tip that articulates with the maxilla and posteriorly there is an articular surface for the lateral ethmoid (Arratia, 1990: 209). Medial to this latter articular surface is a ventral posterior process, extremely reduced in loricariids in comparison to other Siluriformes ( Fig. 15a; Schaefer, 1987: 10;Schaefer, 1997: 25;Reis, 1998: 124). Lamontichthys avacanoeiro and Loricaria, in contrast, possess a long posterior process compared to other loricariids (Fig. 15b). In these two species, the posterior process of the palatine extends ventrally beyond the anterior condyle of the lateral ethmoid. In other loricariids, the posterior process fails to reach the condyle of the lateral ethmoid.
According to Schaefer (1990: 185), in loricariids, one of the two subdivisions of the extensor tentaculi muscle inserts on the posterior process of the palatine.
In loricariids, the palatine is usually a cylindrical bone lacking lateral edges (Schaefer, 1997: fig. 12e;Armbruster, 2004: 17). In a few taxa there is a flange projecting from the lateral border of the bone that is already present early in ontogeny (Arratia, 1990: 209). In many members of the Loricariini the flange extends along the entire lateral margin of the autopalatine, a condition observed in Pseudoloricaria and Rineloricaria. In Loricaria, exclusively, the flange is somewhat shorter extending along 2/3 of the lateral margin of the autopalatine (Rapp Py-Daniel, 1997: character 23).
The palatine splint is an ossification of questionable homology that occurs in the Astroblepidae, Scoloplacidae, Loricariidae, some Trichomycteridae and Callichthyidae (Schaefer, 1987: 10;1997: 25;Reis, 1998: 124). In loricariids the ossification is thin, elongate and straight with a wide anterior tip, and contacts the anterior cartilage of the autopalatine (Fig. 29). Posteriorly, it extends parallel to the autopalatine, and reaches the lateral ethmoid.
The palatal splint is present in all examined taxa except Farlowella, Loricaria, and Pseudoloricaria.
The premaxilla and dentary in the Loricariidae are distinctly cup-shaped anteriorly and contain several rows of teeth (Schaefer, 1987: 11;1997: 25). The relative length of the cup-shaped region of the premaxilla compared to that of the dentary varies among examined taxa. Lamontichthys avacanoeiro, L. maracaibero, L. stibaros, Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys have these regions of similar length (Fig. 29), a condition shared with Hypostomus and Neoplecostomus.
Loricaria, Pseudoloricaria, and Rineloricaria have the cup-shaped region of the premaxilla distinctly shorter than that of the dentary. In contrast, L. filamentosus and L. llanero have the cup-shaped region of the premaxilla distinctly longer than that of the dentary.
Lamontichthys parakana, not included in this analysis, has the cup-shaped region of the premaxilla only slightly longer than that of the dentary (state 0).
The dentary of most siluriforms possesses a well developed and conspicuous coronoid process for insertion of the adductor muscles (Schaefer, 1987). The coronoid process in loricariids, when present, is usually strong and concave posteriorly (Howes, 1983). In Farlowella, Pterosturisoma, Sturisoma, and Sturisomatichthys the coronoid process is large and has a small heavily ossified and robust area along its posterior margin (Fig. 30), a condition shared with Hypostomus and Neoplecostomus. Three derived conditions of the coronoid process were observed among examined taxa. Lamontichthys also possesses a large coronoid process, but in this genus the robust area is more developed and occupies almost the entire posterior region of the coronoid process (Fig. 31b). Species of Harttia possess a relatively small coronoid process (Fig.  31a), and Loricaria, Pseudoloricaria, and Rineloricaria lack a coronoid process in the dentary.
As detailed under the previous character, the dentary of many loricariids possesses a posteroventral lamina of bone that overlaps the anguloarticular. The geniohyoideus muscle inserts on this lamina and provides high mobility of the dentary and of the hyoid arch (Schaefer & Lauder, 1986: 499). In Lamontichthys, Hypostomus, Neoplecostomus, Pseudoloricaria, Pterosturisoma, Sturisoma, Sturisomatichthys, and Rineloricaria the muscle is inserted directly on the posteroventral lamina of the dentary. In Harttia there is a small laminar process located at the anterior portion of the posteroventral lamina of the dentary onto which the geniohyoideus muscle is inserted (Fig. 31a). Farlowella possesses a similar process, which is instead situated posteriorly on the posteroventral lamina of the dentary.
Pseudoloricaria and Loricaria, that lack the posteroventral lamina of the dentary (character 24), were not coded for this character.

26.
Shape of maxillary teeth: (0) teeth delicate, long and narrow, tooth cusp forming angle of approximately 90° with longer axis of tooth and ventrally directed; (1) teeth robust, relatively short and wide, tooth cusp forming an angle of approximately 180° with the longer axis of tooth and medially directed (CI = 100; RI = 100).
Loricariid fishes are primarily herbivorous, benthic algae scrapers and greatly exceeds all other loricarioides in the arrangement, number, shape and size of teeth (Schaefer &   Lauder, 1986). The most common pattern of dentition in the family, present in Lamontichthys, Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys, is that of delicate, long and narrow setiform teeth, bicuspid and strongly curved ( Fig. 32a; Isbrücker, 1981;Schaefer, 1987;Müller & Weber, 1992). The cusps, when observed from a lateral view, form an angle of approximately 90° with the longer axis of the tooth.
In contrast, Loricaria, Pseudoloricaria, and Rineloricaria possess relatively strong, short and wide teeth, with only a gentle curvature (Fig. 32b). In addition, the tooth cusps form an angle of approximately 180° with the longer axis of the tooth.
Bicuspid teeth are present in the families Scoloplacidae, Loricariidae and Astroblepidae, but only members of the Loricariidae possess asymmetric cusps (Schaefer, 1990: 185). In the most common condition found in loricariids, the main cusp is longer and wider than the lateral cusp (Müller & Weber, 1992). Although differences in cusp size have not been utilized in phylogenetic analysis of loricariids, Isbrücker & Nijssen (1978b: 70) illustrated teeth of representatives of the Loricariinae, in which it is possible to clearly distinguish between short and long cusps.
Lamontichthys stibaros, L. avacanoeiro, Harttia, and Sturisomatichthys share with Hypostomus and Neoplecostomus teeth with long cusps (Fig. 3a). Hypostomus and Neoplecostomus have teeth with the main cusp twice as large and wide than the lateral cusp. Harttia has teeth with the main cusp twice as large and only slightly broader than the lateral cusp, and the remaing species of Lamontichthys have teeth with cusps of similar size, or with the main cusp only slightly longer and wider than the lateral cusp. The latter condition is also present in L. parakana, a species not included in the analysis. The variation in cusp size is relatively continuous among taxa and therefore it was not coded as distinct character states.
Loricaria, Pseudoloricaria, and Rineloricaria were not coded for this character due to their distinct tooth morphology (character 26).
The number of teeth in each premaxilla or dentary in loricariids is higly variable and Boeseman (1971: 10) was the first author to propose groupings within the Loricariinae based on variation on the number of jaw teeth. Among the nonloricariine Loricariidae, Schaefer (1997: 109) considered the presence of 12 to 18 teeth in each jaw as plesiomorphic for the Hypoptopomatinae. Garavello et al. (1998) showed that variation in the number of teeth could be used to diagnose species of the genus Otothyris.
Lamontichthys, Harttia, and Sturisomatichthys possess between 50 and 100 teeth in each premaxilla or dentary. Farlowella, Pterosturisoma, and Sturisoma possess between 20 and 50 teeth in each premaxilla or dentary, a condition shared with Hypostomus and Neoplecostomus. In Loricaria, Pseudoloricaria, and Rineloricaria the number of jaw teeth rarely reaches 20.
There is a slight difference between the number of teeth in the premaxilla and in the dentary of loricariids. However, such difference is included within the range of variation of the states defined for this character. The number of teeth in the premaxilla and dentary of loricariids increases with growth. In the present study only adult specimens were considered for this character. The hyomandibula of loricariids is a relatively large, square shaped bone. The posterior border is usually straight, with a crest for the insertion of the adductor mandibulae muscle (Schaefer, 1987: 8). In Lamontichthys and in the outgroups Farlowella, Harttia, Loricaria, Neoplecostomus, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisomatichthys, the crest is in direct contact with the pterotic-supracleithrum. In Hypostomus and Sturisoma the hyomandibula extends posteriorly to this crest, and the contact with the pterotic-supracleithrum is made via this posterior projection.

30.
Contribution of pterotic-supracleithrum to hyomandibulacranium articulation: (0) wide, as large as contribution of prootic; (1) short, less than contribution of prootic; (2) absent, with exclusive participation of prootic (CI = 100; RI = 100). Schaefer (1997: 104) proposed that a contribution of the pterotic-supracleithrum and of the prootic in the hyomandibula-cranium articulation is plesiomorphic for the Loricariidae and this condition is present in Neoplecostomus, the Loricariinae, Ancistrinae, many Hypostominae, and in the tribe Otothyrini (Hypoptopomatinae). However, that author did not indicate the degree of participation of each ossification to this articulation and proposed that the lack of contribution of the prootic to the hyomandibula-cranium articulation in members of the Hypostominae and in the tribe Hypoptopomatini (Hypoptopomatinae) as a derived condition. The lack of contribution of the prootic to the hyomandibulacranium articulation reported for some loricariids (Armbruster, 2004: 13) was not observed in taxa examined in the present study.
Three different conditions regarding the contribution of the pterotic-supracleithrum to the hyomandibula-cranium articulation occur among examined taxa. Lamontichthys, Harttia, Hypostomus, and Neoplecostomus possess an equivalent contribution of the prootic and pteroticsupracleithrum to the facet of the hyomandibula-cranium articulation (Fig. 33a). Farlowella, Pterosturisoma, Sturisoma, and Sturisomatichthys possess a smaller contribution of the pterotic-supracleithrum to the facet of the hyomandibulacranium articulation relative to that of the prootic (Fig. 33b). In Loricaria, Pseudoloricaria, and Rineloricaria, the pterotic-supracleithrum is excluded from this articulation, and only the prootic connects to the hyomandibula. Although in Farlowella, the contribution of the pterotic-supracleithrum to the hyomandibula-cranium articulation is particularly small, the ossification is still present in the facet of the hyomandibula and that species was therefore coded as having state 1.
Most Siluriformes including loricariids possess a crest on the hyomandibula, where the levator arcus palatini muscle is inserted (Arratia, 1987;Armbruster, 2004: 15). This muscle originates in the sphenotic, and connects the hyomandibula with the lateral border of the skull (Howes, 1983). The levator arcus palatini muscle is extremely reduced in Farlowella, Hypostomus, Loricaria, and Neoplecostomus, and it is absent in some species of the latter genus (Howes, 1983: 322). In the Hypoptopomatinae the reduction of this muscle is directly proportional to the reduction of the extension of the hyomandibular crest (Schaefer, 1991: 10) Among the Loricariinae, Lamontichthys, Farlowella, Harttia, Pseudoloricaria, Rineloricaria, Sturisoma, and Sturisomatichthys possess the lateral face of the hyomandibula with a very narrow crest, while in Loricaria and Pterosturisoma the crest is absent (Fig. 34).
In the single specimen of L. stibaros examined (FMNH 84111, 62.4 mm SL) the hyomandibula crest does not cross the entire extension of the hyomandibula. The single specimen of L. maracaibero examined (MCNG 3593, 83.8 mm SL) possesses a complete crest, a condition present in the other species of the genus examined in the present study, all represented by larger specimens. Arratia (1987) reported that juveniles of Diplomystes possess a rudimental crest, while in the adult it is well developed, except in the adult of D. camposensis. The lack of both juveniles and adults of all species of Lamontichthys in the present study did not allow comparison of the degree of development of the crest of the homandibula within the genus. Therfore, only the presence or absence of the crest on the lateral face of the hyomandibula was considered in the present study.
The preopercle of loricariids is usually an elongate ossification, with the anterior and posterior tips narrower, and it bears a branch of the laterosensory canal (Schaefer, 1991: 11). The anterior portion of the dorsal border of the preopercle of loricariids is sutured with the quadrate and the posterior portion is sutured with the hyomandibula. The posterior portion of the ventral border of the preopercle in some Loricariinae has a ventral process that articulates with a bony plate (Rapp Py-Daniel, 1997: character 53), which bears a branch of the laterosensory canal ("canal-bearing plate" of Schaefer, 1987: 22). This process occurs in Lamontichthys, and in the outgroups Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys (Fig. 29). On the other hand in Loricaria, Pseudoloricaria, and Rineloricaria the ventral process of the preopercle is absent or inconspicuous, a condition that also occurs in Hypostomus and Neoplecostomus. 33. Exposed region on posterodorsal portion of preopercle: (0) present; (1) absent, totally covered by skin (CI = 33; RI = 60).
Lamontichthys, Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys possess the canal-bearing cheek plate located ventrally on the head (Fig. 1), while in Rineloricaria, Loricaria, and Pseudoloricaria it occupies the lateral region of the head. In Neoplecostomus, part of the canal-bearing cheek plate occupies the lateral region of the head and part the ventral region.
The laterosensory canal on the canal-bearing cheek plate of loricariids (see plate in Fig. 1), commonly travels anteriorly from the posterolateral to the anterolateral portion, running close to the lateral margin of the cheek-plate (Rapp Py-Daniel, 1997: character 161). This condition occurs in Lamontichthys, Farlowella, Harttia, Pterosturisoma, and Sturisomatichthys among examined members of the subfamily Loricariinae. A different condition occurs in Hypostomus, Loricaria, Pseudoloricaria, and Rineloricaria, in which the laterosensory canal is directed laterally and travels along the median line of the cheek plate, from its dorsal to its ventral border. In Sturisoma, the laterosensory canal travels from the posterolateral portion of the cheek plate, running anteromedially to reach the anterolateral portion.
The plesiomorphic condition for the Siluriformes is to have a continuous and complete laterosensory canal on the body, that extends near to or lateral to the hypural plate, is partially included in ossicles, and gives off numerous short tubules that open in the skin by diminutive pores (Arratia & Huaquin, 1995: 90).
According to Schaefer (1991: 20), in Neoplecostomus, some Hypoptopomatinae, and in the majority of the other loricariids the lateral line is complete and extends from the pterotic-supracleithrum, posteriorly to the last lateral plate of the median series on the base of the caudal-fin. Schaefer (1991: 20) and Armbruster (2004: 23) reported that the lateral line of Callichthyidae, Astroblepidae and many loricariids (Hypoptopomatinae, Neoplecostomus, and some members of the other loricariid subfamilies) terminates anteriorly to the hypural plate, while in some Hypostominae, Ancistrinae and many Loricariinae it terminates lateral to the hypural plate. Armbruster (2004: 75) proposed the presence of laterosensory canal on the elongate plate posterior to the hypural plate as synapomorphic for the Loricariinae.
In Lamontichthys filamentosus, L. llanero, L. maracaibero, L. stibaros, Farlowella, Harttia, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys, the posterior border of infraorbital 2 contacts the anterior border of infraorbital 3 along its entire extension, and there is no plate between these two ossifications (Fig. 20). In the derived condition, present in L. avacanoeiro and L. parakana, there is a plate that lacks a laterosensory canal that is situated between infraorbitals 2 and 3, and restricts the contact between these two ossifications (Fig. 36).
The Siluriformes, in general, possess the Baudelot´s ligament ossified, arising from a small process of the supracleithrum and inserting directly on the basioccipital (Chardon, 1968: 190;Fink & Fink, 1981: 335). Lamontichthys, Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys possess a ventral and lateral prolongation of the posterior portion of the basioccipital that is in contact with Baudelot's ligament. In Loricaria, Pseudoloricaria, and Rineloricaria, a ventral prolongation of the posterior border of the exoccipital is situated between the basioccipital and the Baudelot's ligament (Fig. 37). These different conditions were previously described by Rapp Py-Daniel (1997: character 18).
Members of the subfamily Loricariinae have a flange projecting from the dorsolateral side of the seventh precaudal vertebra that extends dorsally along the side of the neural spine. In all examined members of the Loricariinae except Lamontichthys avacanoeiro, the flange is directed anteriorly (Fig. 38a). In L. avacanoeiro, this flange is directed posteriorly. Members of the Loricariidae in general seem to lack a lateral flange on the seventh precaudal vertebra (Fig. 38b).
Pterosturisoma possesses the hemal spine of the last precaudal vertebra considerably elongate and narrow distally, with a length of approximately twice that of the corresponding vertebral centrum (Fig. 39). In Neoplecostomus and in the great majority of the Loricariinae (Lamontichthys, Farlowella, Harttia, Loricaria, Pseudoloricaria, Rineloricaria, Sturisoma, and Sturisomatichthys) this spine is considerably shorter, its length equal or less than the length of the corresponding vertebral centrum (Figs. 40 and 41).
In Hypostomus, the hemal spine of the first caudal vertebra is very short and only its distal posterior tip is split to receive the first anal-fin pterygiophore. The bifid hemal spine of the first caudal vertebra in Neoplecostomus is longer, its length approximately 1/2 of the corresponding vertebral width (Fig.  41). In members of the Loricariinae there is a further elongation   of this structure and in Lamontichthys, Farlowella, Harttia, Loricaria, Pseudoloricaria, Rineloricaria, Sturisoma, and Sturisomatichthys, the bifid hemal spine of the first caudal vertebra is as long as the corresponding vertebral width (Fig.  40).
In Pterosturisoma two very long contralateral projections originate from the proximal region of the hemal spine (Fig. 39). It is not clear whether these processess are homologous to the bifid hemal spines or represent distinct structures (Rapp Py-Daniel, 1997: 64) and this species was therefore coded as "?".
Neoplecostomus and members of the Loricariinae possess completely expanded hemal spines ranging from the fifth, sixth or seventh caudal vertebrae (vertebrae 20 to 23), to the last body vertebra (Figs. 39-41). According to Schaefer (1987: 17), in Hypostomus plecostomus the hemal spines are completely expanded along their length in all caudal vertebrae (posterior to vertebrae 14), a condition observed in the specimens of Hypostomus examined in the present study.
Members of the Loricariinae possess ventrally directed  bilateral projections on the proximal portion of the hemal spines, as well as dorsally directed bilateral projections on the proximal portion of the neural spines, a feature previously described by Rapp Py-Daniel (1997: 106) as a synapomorphy for Loricariinae. These projections are strong and narrow, their length not exceeding one third of the vertebral width ( Figs. 39 and 40). The two anterior most pairs of these projections usually do not contact the body plates, while the more posterior ones possess the distal tips firmly sutured to these plates. The dorsally directed bilateral projections are present from vertebrae 9 to 11, and the ventrally directed bilateral projections, from approximately vertebrae 13 to 15.

44.
Orientation of ventrally directed bilateral projections on second caudal vertebra: (0) ventral to slightly anteriorly or posteriorly directed; (1) distinctly posteriorly directed; (2) distinctly anteriorly directed (CI = 66; RI = 66). The ventrally directed bilateral projections of the second caudal vertebra of the majority of the Loricariinae are directed ventrally or only slightly anterior or posterior and their distal tips lack any type of contact with the body plates. In Harttia the ventrally directed bilateral projections of the second caudal vertebra are directed posteriorly and their distal tips also lack any type of contact with the body plates (Fig. 42a). Lamontichthys llanero has the ventrally directed bilateral projections of the second caudal vertebra anteriorly directed and the distal tips are strongly sutured to the hemal spine of the first caudal vertebra (Fig. 42b).
This character does not apply to Hypostomus and Neoplecostomus because these taxa lack ventrally directed bilateral projections.
The ventrally directed bilateral projections of the third caudal vertebra of the majority of Loricariinae (except Harttia loricariformis) possess their distal tips pointed and lacking any type of contact with the ventral plates (Fig. 39). In Harttia loricariformis, the distal tips of these projections are strongly  attached to the ventral plates of the body (Fig. 42a).
Hypostomus and Neoplecostomus were not coded for this character due to lack of bilateral projections on the vertebrae of these taxa.
The hemal spine of the second preural centrum in all examined taxa extends posteriorly as a process along the ventral margin of the hypural plate (Fig. 43).
In all members of the Loricariinae this process is short not extending beyond half the length of the hypural plate. Alternatively, in Hypostomus and Neoplecostomus this process is long almost reaching the vertical through the posterior margin of the hypural plate.
Harttia, Hypostomus, and Neoplecostomus among examined taxa possess cartilage on the posterior tip of the hemal spine of the second preural centrum. This feature was previously reported in members of the Astroblepidae, Ancistrinae, Hypoptopomatinae, Hypostominae, and Neoplecostominae, and in Harttia among the Loricariinae by Rapp-Py Daniel (1997: character 135).
Three different conditions of the relative length of the neural spine of the second preural centrum were described by Rapp Py-Daniel (1997: character 134) for the Loricariidae. Among examined taxa, Hypostomus possess an elongate neural spine of the second preural centrum that extends parallel to the dorsal border of the hypural plate to the vertical through its posterodorsal tip (Fig. 43c). In all other examined taxa the neural spine of the second preural centrum is shorter. In Lamontichthys, Harttia, Neoplecostomus, Pterosturisoma, Sturisoma, and Sturisomatichthys, the neural spine of the second preural centrum reaches the vertical through 1/2 to 3/4 length of the hypural plate (Fig. 43). In Farlowella, Loricaria, Pseudoloricaria, and Rineloricaria the neural spine of the second preural centrum reaches the vertical through 1/3 the length of the hypural plate.
According to Alexander (1965: 142), one of the main modifications along the evolution of the Siluriformes was the depression of the body in adaptation to a bottom-feeding habit.
One extreme of this modification occurs in the Loricariidae, whose members have the ventral surface of the body very flat. In addition, the caudal peduncle of loricariids is slightly depressed, though still cylindrical in overall shape. The subfamily Loricariinae and the genera Acestridium, Niobichthys, and Oxyropsis (Hypoptopomatinae) possess the caudal peduncle extremely depressed. Schaefer (1987: 20) hypothesized a depressed caudal peduncle to be a synapomorphy for the subfamily Loricariinae. This feature has been used to diagnose the Loricariinae since the original recognition of this taxon (Bonaparte, 1831;Eigenmann & Eigenmann, 1890).
The majority of the Siluriformes possess the first element of the dorsal-fin (often termed the spinelet, Schaefer, 1987: 17) shaped as a strong, short, and spine-like element that acts as a locking system for the second much longer dorsal-fin spine (Alexander, 1965), a condition observed in Hypostomus, among examined taxa. The spinelet is variably reduced or lost in several memberos of the Loricariidae (Schaefer, 1987: 18;Armbruster, 2004: 33).
The second element of the dorsal-fin in the Siluriformes is usually modified into a defensive spine (Reed, 1924), and the proximal end of this spine articulates with a dorsal condyle of the second pterygiophore ( Fig. 45a; Schaefer, 1987: 23), a condition observed in Hypostomus, among examined taxa.
The dorsal-fin pterygiophores of the majority of loricariids possess transverse processes, which provide support for the dermal body plates. Usually, the processes of the anterior most pterygiophores are long, and decrease in size posteriorly (Schaefer, 1991: 18). The number of dorsal-fin pterygiophores bearing transverse processes varies within the Loricariidae (Armbruster, 2004: 33). Variations pertaining to the dorsal-fin pterygiophores observed in the present study are discussed under characters 54 to 59.
The first and the second dorsal-fin pterygiophores of loricariids possess a pair of relatively long transverse processes, involved in the support of the nuchal plate and first rays of the dorsal-fin (Schaefer, 1991: 18). In Neoplecostomus these processes are of similar length, and in the other loricariid examined, the lateral processes of the first dorsal-fin pterygiophore are shorter than those of the second. This character was previously described by Rapp-Py Daniel (1997: character 120).
Different types of orientation of the lateral process of the second dorsal-fin pterygiophore were described for the Loricariidae by Rapp Py-Daniel (1997: character 118). The condition in which the lateral process of the second dorsalfin pterygiophore is directed anterolaterally along its entire extension occurs in Lamontichthys, Pterosturisoma, Sturisoma, and Sturisomatichthys (Fig. 46a). The lateral process of the second dorsal-fin pterygiophore directed anterolaterally at its proximal portion and anteriorly at its distal portion occurs in Loricaria, Pseudoloricaria, and Rineloricaria (Fig. 46b). The lateral process of second dorsalfin pterygiophore directed lateral at its proximal portion and anterolateral at its distal portion occurs in Farlowella, Harttia, Hypostomus, and Neoplecostomus (Fig. 46c).
In the majority of the loricariids examined (with the exception of Neoplecostomus) the lateral processes of the third and fourth dorsal-fin pterygiophores are long and contact the ventral surface of the dorsal body plates (Fig. 44). According to Schaefer (1991: 18) Neoplecostomus lacks transverse processess on the third and fourth pterygiophores, however, two very short processes are present in the specimen of N. ribeirensis examined in the present study and they fail to reach the dorsal plates.
The majority of the Loricariinae examined possess a transverse process on the fifth dorsal-fin pterygiophore (Fig.  44). Sturisomatichthys lacks these processes, a condition that also occurs in Hypostomus and Neoplecostomus.
The connecting bone or lateral bone (Bailey & Baskin, 1976;Schaefer, 1987: 26) is a laminar ossification located between the parapophysis of the sixth vertebra and the first or second dorsal-fin pterygiophore that is present in many loricariids, the Astroblepidae and the Scoloplacidae and occurs as an unossified tendon in callichthyids (Schaefer, 1990: 193;Armbruster, 2004: 32).
The majority of the Siluriformes, including the more basal taxa, have eight or more branched rays in the pectoral-fin (de Pinna, 1996: 37). However, in the Loricariidae there is a reduction of this number to five to seven rays. Neoplecostomus, the Hypostominae, the Ancistrinae and the majority of the members of the Loricariinae and Hypoptopomatinae possess six branched rays in the pectoralfin (Schaefer, 1987(Schaefer, , 1998. Schaefer (1998: 399) considered the presence of seven branched rays in the pectoral-fin as a derived condition within the Hypoptopomatinae. Among the Loricariinae, all species of Lamontichthys (including L. parakana), Harttia leiopleura, and Rineloricaria daraha (Rapp Py Daniel & Fichberg, 2008) possess seven branched rays, while some species of Farlowella possess only five (Boeseman, 1971). The presence of seven branched rays in the pectoral-fin was originally proposed as a diagnostic character for Lamontichthys by Isbrücker & Nijssen (1976, 1978b.
The cleithrum and coracoid in loricariids articulate with their counterparts by means of interdigitating sutures along their symphyses, the extension of which is variable, a feature previously observed by Rapp-Py Daniel (1997: character 142).
In Lamontichthys, Harttia, Farlowella, Hypostomus, Neoplecostomus, Pterosturisoma, Sturisoma, and Sturisomatichthys, the length of the symphysis of the cleithrum is approximately equal to twice as short as the coracoid symphysis (Fig. 47). Alternatively, in Loricaria, Pseudoloricaria, and Rineloricaria, the symphysis of the cleithrum is twice as long as the coracoid symphysis.
The ventral surface of the pectoral girdle of loricariids possesses a fossa between the cleithrum and coracoid, termed the abductor fossa or arrector fossa that lodges the arrector ventralis profundus and arrector ventralis superficialis muscles, responsible for the movement of the pectoral fin (Schaefer, 1987: 24;1991: 18).
In Lamontichthys avacanoeiro, L. parakana (the latter species not included in the analysis), Harttia, Hypostomus, and Neoplecostomus, there is no bony lamina covering the fossa, resulting in a complete exposure of the arrector fossa (Fig. 48a).
A third condition of this character was proposed by Schaefer (1987: 24;1991: 18;1998: 397) as synapomorphic for the Hypoptopomatinae a taxon not included in the present study.
Although Lamontichthys avacanoeiro and L. parakana lack a bony lamina in the ventrolateral portion of the coracoid, these two species possess a thin bony plate, covered by odontods, embedded in the skin and firmly attached to the coracoid in the same position as the osseous lamina in the other taxa. These two species were coded as "0". each process close to each other or connected by ligaments (uninformative).
In the Loricariidae each basipterygium possess a pair of anterior processes, one internal and one lateral (Schaefer, 1987: 19) or anteromesial and anterolateral processes, respectively (Armbruster, 2004: 37). Different types of contact between the anteromesial processes of the basipterygia occur among examined taxa.
In members of the subfamily Loricariinae, the contralateral anteromesial processes are either not in contact, or contact each other only at their distal tips (Fig. 49a, b). The remaining loricariids possess additional regions of contact and in Neoplecostomus they are in contact along their entire medial margins (Fig. 49c).
In Lamontichthys stibaros, the distal tips of the anteromesial processes are connected by ligaments.
Harttia possesses the anteromesial processes of the basipterygium medially directed, a condition previously reported by Rapp Py-Daniel (1997: character 152) for the genus.
In loricariids, the anterolateral process of the basipterygium possesses two laminar expansions for the attachment of the arrector dorsalis muscles (external process ridge of Shelden, 1937). One of these expansions is oriented ventral or ventrolaterally, and the other dorsal or dorsolaterally. Rapp Py-Daniel (1997: character 155) previously reported differences in the relative width of these laminar expansions in the Loricariinae.
In Lamontichthys, Farlowella, Harttia, Pterosturisoma, Sturisoma, and Sturisomatichthys both expansions are well developed and of similar widths. In Loricaria, Pseudoloricaria, and Rineloricaria, the dorsal expansion is considerably narrower than the ventral. Hypostomus and Neoplecostomus have the dorsal expansion of the anterolateral process of the basipterygium considerably wider than the ventral.
The lateropterygium is a bony structure that is connected with the lateral margin of the basipterygium dorsal to the insertion of the pelvic-fin rays, and is present in the Astroblepidae and Loricariidae (Shelden, 1937;Howes, 1983: 336). Armbruster (2004: 39) observed variation in the form of the lateropterygium among loricariids. Due to the difficulty in coding the variation observed in the format of the lateropterygium in the taxa examined in this study, such variation was coded in terms of differences in the relative size of the structure.
Neoplecostomus and Hypostomus possess a relatively  (1) in contact anteriorly and posteriorly at midline, with a small foramen in between; (2) not in contact, with distal tip of large lateropterygium, its size approximately twice the length of that structure in Lamontichthys and Harttia (coded as having a medium sized lateropterygium) (Fig. 49). In the latter two genera the lateropterygium is twice the size of that structure in Farlowella, Loricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys, taxa with a considerably small lateropterygium. Howes (1983: 336) proposed that the lack of a lateropterygium is derived in the subfamily Loricariinae, a condition herein observed in Pseudoloricaria.

Anal-fin
The anal-fin in the majority of loricariids is formed by one relatively large anterior unbranched ray, followed by four branched rays, all supported by five pterygiophores. The anal-fin pterygiophores have the proximal and medial radials fused, with only the distal radial present as a separate element (Schaefer, 1987: 18).
Neoplecostomus possesses the first anal-fin pterygiophore completely covered by skin, lacking any exposed surface and Hypostomus possesses only one small exposed area. In all examined taxa of the Loricariinae the first anal-fin pterygiophore has a relatively large exposed area that supports dermal plates.
The articulation of the first anal-fin pterygiophore with the vertebral column in all examined taxa of the Loricariinae is on centra 12, 13 or 14. In Farlowella, Loricaria, Sturisomatichthys, Pseudoloricaria, Pterosturisoma, Rineloricaria, and Sturisoma, the articulation is on centra 12 or 13 and in Lamontichthys and Harttia the articulation is slightly posterior, on centra 13 or 14. In both cases, most often, the articulation is on centrum 13.
In the Astroblepidae and Callichthyidae, the articulation of the first anal-fin pterygiophore with the vertebral column is on centra 17, 18 or 19 and in the Loricariidae it varies from centra 13 to 17 (Schaefer, 1987: 25). Within loricariids, in the Hypostominae and Ancistrinae the articulation varies from centra 14 to 17, while in the Hypoptopomatinae and Loricariinae on centrum 13. This latter condition was proposed by that author as synapomorphic for the family Loricariidae.
The anal-fin pterygiophores of the majority of loricariids are expanded along the anteroposterior axis. The degree of separation among the proximal region of the first three analfin pterygiophores varies among taxa, and three distinct conditions were defined by Rapp Py-Daniel (1997: character 122). Hypostomus has the proximal tips of the first three analfin pterygiophores relatively separate from each other (Schaefer, 1987: fig. 11a). In Harttia, Loricaria, Neoplecostomus, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys, the proximal regions of the first three anal-fin pterygiophores are less separate, but are not in contact, while in Lamontichthys and Farlowella the proximal tips of the first three anal-fin pterygiophores are in (or almost) in contact .
In the Loricariidae, the five hypurals and the uroneural are fused forming the "hypural plate", the parahypural is fused to hypurals 1 and 2; the uroneural and/or the epural are fused to hypurals 3, 4 and 5.
Within the Loricariidae there is variation in the shape of the posterior border of the hypural elements (Schaefer, 1987: 25). Neoplecostomus possesses a vertical posterior border with symmetric caudal lobes. In the Loricariinae the caudal fin-lobes are also symmetric, however the posterior border is "V" shaped due to the more posteriorly elongate median portion of the hypural plate. This condition was proposed by Schaefer (1987: 25) as synapomorphic for the subfamily Loricariinae.
Asymmetric caudal lobes occur in most loricariids including members of the Hypostominae (Schaefer, 1987: 25), represented in this study by Hypostomus.
The hypurapophyses are projections on the parahypural and first and second hypurals of the caudal-fin skeleton of the Siluriformes, which serve as the insertion site for muscles involved in the movement of the caudal-fin rays (Schaefer, 1987: 17). Loricariids possess hypurapophysis type C (Lundberg & Baskin, 1969: 14), the most common among the Siluriformes in which the primary hypurapophysis is continuous with a secondary hypurapophysis on hypurals 1 and 2.
In the present study, four different conditions regarding shape of the hypurapophysis are recognized. Neoplecostomus and many loricariids possess a short and robust hypurapophysis, triangular to approximately quadrateshaped. Within the Loricariinae, Harttia possesses a robust hypurapophysis, relatively wide and keel-shaped, and in Lamontichthys, Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys, the structures are broad, laminar and wingshaped (Figs. 43 and 50).
In loricariids in general, the hypurapophysis is short and does not project anteriorly to the second preural centrum. However, in all taxa of the Loricariinae examined the hypurapophysis extends anteriorly to the second preural centrum (Figs. 43 and 50).
The ventral surface of the hypurapophysis of Lamontichthys avacanoeiro possesses a narrow ossified process posteroventrally oriented, probably serving as an additional site for the attachment of the caudal-fin musculature ( Fig. 50; Schaefer, 1987: 17). There are no reports of any process on the hypurapophysis of other Siluriformes.
The Siluriformes primitively possess a single epural, relatively large, separate from the dorsal hypurals (Lundberg & Baskin, 1969: 11). Among loricariids, this condition occurs in the Neoplecostominae, Hypoptopomatinae, and some Hypostominae, while in the Loricariinae and many Hypostominae there is a tendency of fusion of the epural to hypurals or reduction in epural size (Fig. 43;Schaefer, 1987: 17). Rapp Py-Daniel (1997: character 127) previously reported variation on the relative size of the epural in the Loricariinae.
The hypural plate of loricariids possesses a notch at its posterior median border, demarcating the separation between the upper and lower lobes (Schaefer, 1987: 17). There is a wide degree of variation in the extent of this notch in the family, including taxa that lack the notch. In the plesiomorphic condition for loricariids, present in Neoplecostomus, there is a deep notch in the hypural plate ( Fig. 43b; Schaefer, 1991: 16).
Loricaria, Pseudoloricaria, and Rineloricaria possess two broad apophyses (Fig. 50). Schaefer (1987: 15, fig. 10) did not mention any apophysis on the second preural centrum of Hypostomus plecostomus, however, in the present study a single narrow apophysis was observed in the caudal skeleton of a specimen of Hypostomus examined (Fig. 43c).
The adipose fin, located between the dorsal-fin and the caudal-fin, is common among the Siluriformes. However, many Loricariidae lack this structure, such as the Loricariinae, members of the Hypoptopomatinae, Neoplecostominae and most of Rhinelepini (Armbruster, 2004: 31).
Many loricariids possess a groove on the snout, extending longitudinally, from the anteriormost point of each nostril until the anteroventral border of the snout. The posterior portion of this groove runs between dermal plates or on the plates, and possess odontods along its margins. In Lamontichthys, Farlowella, Loricaria, Pterosturisoma, Rineloricaria, Sturisoma, and Sturisomatichthys the anterior region of the groove is similar to the posterior region (Fig. 51).
In Harttia, Hypostomus, and Neoplecostomus, the anterior portion of this groove is formed by a distinct fold in the skin that runs on the plates (Fig. 52). Pseudoloricaria lacks a groove on the snout.

80.
Surface of snout tip: (0) without plates, with thick layer of soft connective tissue covered by papillae; (1) without plates, with thick layer of soft connective tissue without papillae; (2) with plates on thick layer of soft connective tissue; (3) with plates, without thick layer of soft connective tissue (CI = 60; RI = 66).
The snout of the majority of the loricariids may be completely covered by plates, or the plates may be absent exposing a thick layer of soft connective tissue attached to the anterior tip of the mesethmoid (Schaefer, 1991: 20;Armbruster, 2004: 43).
Harttia, Hypostomus, Neoplecostomus, Rineloricaria, and Sturisoma lack plates on the snout tip and the soft connective tissue that is exposed possesses numerous, diminute and delicate papillae. Lamontichthys stibaros and L. avacanoeiro also lack plates on the snout tip but the soft connective tissue exposed lacks papillae. Lamontichthys parakana (not included in the analysis) also possesses this latter condition.
The second preural centrum of the Siluriformes in general lack lateral bony projections (apophyses) but Rapp Py-Daniel (1997: character 130) reported the presence of one or two apophyses, on both sides of the second preural centrum in many loricariids. These apophyses are longitudinal, flangelike, and extend along the lateral portion of the vertebral centrum. The second preural centrum of Harttia, Neoplecostomus, Sturisoma, and Sturisomatichthys lack any apophyses (Fig. 43a, b). Farlowella and Pterosturisoma possess two narrow apophyses, and Lamontichthys, more evident in adults. In juveniles of L. filamentosus the plates on the snout tip are not developed.
Although Farlowella has the snout tip covered by plates, it lacks the thick layer of soft connective tissue underneath the plates.
The majority of the Siluriformes possess lips without specializations. However, the Astroblepidae and the Loricariidae possess the lips modified into a sucking disk (Howes, 1983: 309;Armbruster, 2004: 42). The internal surface of the upper lip of loricariids is covered by papillae, but the external surface may have dermal plates.
Although the species of Harttia possess a few diminutive plates on the anterior border of the snout, these plates do not cover the external surface of the upper lip.
Many loricariids possess a projection inside the mouth, on the median transversal line, behind the symphysis of the premaxillae. Armbruster (2004: 39) reported this structure as either absent or very small in Astroblepus, Lithogenes, and most loricariids. In the present study the presence of a small central buccal papillae and the absence of this structure were coded as different states. In Harttia and Lamontichthys (including L. parakana) this structure is relatively small and similar to the other papillae present in the mouth of loricariids (Fig. 9). Farlowella, Loricaria, Pseudoloricaria, Pterosturisoma, Sturisoma, and Sturisomatichthys share with Hypostomus a relatively large, tongue-like central bucal papillae, with a wide basal portion.

83.
Odontods on lateral plates of median series: (0) covering all plate, similar to odontods of other body plates; (1) covering all plate, slightly longer on posterior border of plates; (2) long and restricted to posterior portion of plate; (3) covering all plate with one or two rows of odontods increasing in length and width along the median portion of each plate (CI = 75; RI = 75).
Members of the Loricariidae possess the body plates, fin rays, skull bones, opercular series and pectoral and pelvic girdles covered by odontods (Howes, 1983: 309).  The odontods of the lateral plates of the median series in Hypostomus and Neoplecostomus cover all plate and have similar morphology and size as the odontods of the remaining of body. The odontods of the lateral plates of the median series of the body in members of the Loricariinae examined in the present study are rather, more developed than the odontods of the remaining of the body. In Lamontichthys, Farlowella, and Harttia, the odontods cover all plate and are slightly larger on the posterior margin of the plate forming an inconspicuous keel along the median series of plates ( Fig.  53a; state 1). The odontods of the lateral plates of the median series of Loricaria, Pseudoloricaria, Rineloricaria, and Sturisoma also cover all plate but instead, have one or two rows of odontods increasing in length and width along the median portion of each plate (Fig. 53b). In Pterosturisoma the odontods are restricted to the posterior portion of each lateral plate of the median series, although they may be absent in a few plates along the median series (Fig. 53c).
The differences in size and distribution of the odontods on the lateral plates of the median series (states 1, 2 and 3) together with those on the mid-ventral series result in longitudinal keels of various degrees of development.

84.
Predorsal plates between posterior tip of supraoccipital and nuchal plate: (0) three or more small plates not aligned along the midline; (1) two pairs of large plates, fused in the midline; (2) three pairs of large plates, fused in the midline; (3) six or more pairs of large plates, fused in the midline (CI = 60; RI = 0).
In the Loricariinae the predorsal plates are typically paired, large and fused in the median line of the body, while in Neoplecostomus these plates are relatively small and are not aligned in the median line of the body. Lamontichthys, Harttia, Pseudoloricaria, Pterosturisoma, and Rineloricaria possess only two paired predorsal plates. In the derived conditions, there is an increase of the number of predorsal plates. Loricaria, Sturisoma, and Sturisomatichthys possess three paired predorsal plates, while Farlowella possesses six paired predorsal plates (Fig. 54). According to Boeseman (1971: 16), members of the Loricariinae possess two plates between the supraoccipital and the nuchal plate, with a greater number in Farlowella (6-8) and Sturisoma (2-3).
Lamontichthys, Harttia, Loricaria, Pterosturisoma, Pseudoloricaria, Rineloricaria, Sturisoma, and Sturisomatichthys possess two predorsal plates on the body in the region between the sixth and the seventh vertebra (Fig.  38). In Farlowella, there is a reduction of this number, and only a single plate is present in this region, a condition also present in Acestridium discus (Hypoptopomatinae).
Loricariids have plates on the base of the caudal-fin, posterior to the last row of plates of the caudal peduncle (Schaefer, 1987: 25). In the Loricariinae, there are usually 3-5 supracaudal plates on each side, horizontally elongate and joined by conective tissue to the lateral region of the caudal- fin. In other loricariids these plates are short and numerous (six or more plates) (Fig. 35). Schaefer (1987: 25) proposed the presence of elongate plates on the base of the caudal-fin as synapomorphic for the subfamily Loricariinae, but did not refer to the number of plates.
Many members of the Loricariinae possess the unbranched caudal-fin rays projecting as long filaments. There are few reports about the presence of long filaments in the other fins probably because it is a fragile structure and commonly damaged in specimens, and/or because there are relatively few taxa with long filaments in the unbranched fin-ray. Many members of the Loricariinae possess the pectoral-fin spine forming only a short filament, however L. filamentosus and Pterosturisoma possess elongate filaments. Isbrücker & Nijssen (1974) considered the presence of a long filament in the dorsal-fin as diagnostic for Planiloricaria. Species of Sturisoma and Loricaria also possess this feature. Among the loricariids included in the present analysis, L. filamentosus and L. llanero possess the dorsal-fin spine projecting as a long filament sometimes longer than the standard length of the specimens.
Phylogenetic reconstruction. The parsimony analysis, including 87 osteological and external morphology characters of Lamontichthys and related groups (Table 4), resulted in three most parsimonious cladograms with 194 steps, consistency index of 0.73 and retention index of 0.78 (Fig. 55). The cladograms differ only in the hypothesized phylogenetic relationships of two outgroup taxa Pterosturisoma and Sturisoma. The list of synapomorphies that support hypothesis of the monophyly of Lamontichthys and relationships among its species are detailed below.  The clade formed by L. avacanoeiro and L. stibaros is supported by one exclusive derived character (character 80). Although L. parakana was not included in the phylogenetic analysis, the presence of I, 7 pectoral-fin rays (character 60) clearly diagnose the species as a member of Lamontichthys.

Monophyly of Lamontichthys
Within Lamontichthys, L. parakana shares with L. avacanoeiro the presence of one plate without a laterosensorial canal between infraorbital 2 and 3 (character 37), a condition present only in these two species among all taxa examined in this study; and the lack of an osseous lamina in the ventrolateral region of the coracoid, covering the lateral portion of the abductor fossa of the pectoral girdle (character 62), a feature present in these two species and Harttia among examined loricariines. Therefore, it is tentatively proposed that L. parakana is more closely related to L. avacanoeiro.
Comments on Pterosturisoma microps. The genus Pterosturisoma was described by Isbrücker & Nijssen (1978b) on the basis of the examination of type-specimens of Harttia microps Eigenmann & Allen (1942: 211) from Peru, in the upper rio Amazonas basin. In that study, the authors pointed out the similarity of this species with the then known species of Lamontichthys, both in the general appearance of the body and in the presence of the filamentous extension of the pectoral-fin spine. However, Pterosturisoma differs from Lamontichthys in the presence of six branched pectoral-fin rays (vs. seven in Lamontichthys), the more developed pores of the lateral line, the narrow dorsal region of the cleithrum (vs. wide), and the horizontal flattening of the predorsal plates.
Two autapomorphies are herein proposed for Pterosturisoma microps: 1) the lack of a crest on the lateral surface of hyomandibula for the insertion of the levator arcus palatini muscle (independently acquired in Loricaria) (character 31, 0>1); 2) the elongate and narrow distal portion of the hemal spine of the last precaudal vertebra (character 40, 1>2). Isbrücker & Nijssen (1978b) included Pterosturisoma in the tribe Harttiini based on the presence of the lateropterygium, a well developed palatine splint, and large maxillae.

Comments on the patterns of geographic distribution of
Lamontichthys. Up to the present, Lamontichthys filamentosus was recorded for the upper rio Amazonas basin. In the present study, the known distribution range of the species is extended eastwards to the middle Amazon basin (rio Amazonas-Solimões between the mouths of rio Purus and rio Madeira) (Fig. 2). Lamontichthys stibaros also occurs in the upper rio Amazonas and is found in sympatry with L. filamentosus in the drainages of río Ucayali and río Marañon. All other species of Lamontichthys have allopatric distributions. Two of them occur in Venezuela, L. llanero in the upper portions of tributaries of the rio Orinoco, and L. maracaibero, in the lago Maracaibo system. The two remaining species of Lamontichthys, described in the present study, occur in the Brazilian drainage of rio Tocantins and represent a considerable extension of the known distribution range of the genus. Lamontichthys avacanoeiro occurs in various localities in the upper portions of that river basin and L. parakana is known only from the type locality in the lower rio Tocantins, below Tucuruí Dam (Fig. 2).
Based on the available information on the distribution of Lamontichthys (Western Amazon, rio Orinoco, and lago Maracaibo), Lima & Ribeiro (in press) characterized the distribution of the genus as clearly presenting a foreland distribution pattern, in which a foreland basin is defined as elongated, tectonically imposed lowlands, located between uplands areas of the Andean chain in the west, and the Brazilian Shield in the East. Lima & Ribeiro (in press) also commented on the fact that many fish taxa that has a lowland distribution pattern in the western-central Amazon basin also occur in the rio Tocantins system. Therefore, it is interesting to note that the two new species of Lamontichthys described herein also occur within that river drainage.