Two new species of Hypostomus Lacépède ( Teleostei : Loricariidae ) from the upper rio Paraná basin , Central Brazil

Two new species of Hypostomus Lacépède (Teleostei: Loricariidae) from the rio Paranaíba and rio Grande basins, both in the upper rio Paraná basin, central Brazil, are described herein. One of them is distinguished from all congeners, except H. albopunctatus, by having the pectoral-fin spine length equal to or smaller than the pelvic-fin spine. From H. albopunctatus, it is distinguished by having round dark spots (vs. pale) on body and fins. The second species is distinguished from all congeners, except H. multidens and H. ternetzi, by having more than 115 teeth (vs. less than 109) per ramus on dentary and premaxilla. It is distinguished most readily from H. ternetzi by having teeth with two symmetrical (vs. asymmetrical) cusps. It is distinguished from H. multidens by having round dark spots (vs. pale) over body and fins.


Introduction
Hypostomus occurs widely throughout the neotropics and is one of the most speciose genera among siluriforms, comprising about 117 to 130 species.The lower count is according to Ferraris (2007) who recognized Aphanotorulus, Isorineloricaria and Squaliforma as valid genera.The higher count is according to Armbruster (2004) and Armbruster et al. (2007) who synonymized these taxa with Hypostomus.
The upper rio Paraná basin is known as region of endemism for fishes (Britski & Langeani, 1988;Vari, 1988) compared to the remaining portions of the La Plata basin, which also includes rio Iguaçu, lower rio Paraná, rio Paraguay, and rio Uruguay basins.The upper rio Paraná basin has been reported to have 21 species of Hypostomus (Weber, 2003;Jerep et al., 2007).Representatives of the genus are found in almost all aquatic habitats, from large main rivers to small rivulets.Ichthyological surveys by the Núcleo de Pesquisas em Limnologia, Ictiologia e Aqüicultura (Nupélia), of the Universidade Estadual de Maringá, jointly with Furnas Centrais Elétricas, provided five years of monthly ichthyological samples from the rio Corumbá basin, a tributary to rio Paranaíba, in Goiás State, central Brazil.These surveys provided enough material to distinguish two new species of Hypostomus.Both are diagnosed from congeners by color, morphometric and meristic traits, and are described herein.

Material and Methods
All examined specimens were collected during five years of monthly sampling carried out by Nupélia.Institutional abbreviations follow standard ASIH codons listed at http:// www.asih.org/files/codons.pdf, with the addition of NUP for Coleção Ictiológica do Nupélia.Measurements and counts were taken from the left side of the body whenever possible.Body plate nomenclature follows Schaefer (1997), except plates in dorsal series anterior to dorsal spine are referred to as predorsal plates following Oyakawa et al. (2005).Measurements follow Boeseman (1968) modified by Weber (1985), with addition of lower lip width (measured at insertion of maxillary barbels); and lower lip length (taken at midline, from just posterior of dentary rami to distal border of lip).All measurements were taken point to point with digital calipers to the nearest 0.1 mm.Abbreviations used are: HL (head length), SL (standard length), and TL (total length).

Hypostomus denticulatus, new species
Fig. 1 Hypostomus sp. and teeth with two symmetrical cusps (Fig. 2a) vs. two asymmetrical cusps (Fig. 2b).Hypostomus denticulatus is distinguished from H. multidens by having dark (vs.pale) spots over body and fins (Fig. 3).Lips well developed and transversely ellipsoidal.Lower lip reaching or almost reaching transverse line between gill openings, its inner surface covered with numerous small papillae.Maxillary barbel short with free tip.Mouth large.Teeth long, very slender, bicuspid, and curved inward distally; mesial cusp similar in length and form to lateral cusp (Fig. 2a).Five rows of slightly spinulose plates on side of body.Dorsal series of plates starting at vertical through dorsal-fin origin.A weak longitudinal keel begins on first plate of dorsal series and continues until dorsal procurrent caudal-fin plates.Mid-dorsal series of plates without keel or with a very weak keel.Median series bearing lateral line.Mid-ventral series forming longitudinal ridge along first five or six plates.Plates in ventral series right-angled transversely on caudal peduncle, forming a strong keel along lower portion of peduncle.Caudal peduncle roughly triangular in cross section.

Description. Counts and measurements in
Upper and lower lips without scutelets.Ventral surfaces of head and abdomen completely naked in specimens up to 131.2 mm SL; larger specimens with small platelets distributed just anterior to gill opening, in narrow transverse band between gill openings, laterally on abdomen between pectoral and pelvic fins (contacting ventral plates), and anterior to urogenital opening.Preanal plate partially exposed in specimens up to 129.8 mm SL, usually completely covered with skin in larger specimens.Dorsal-fin origin situated two lateral-plate rows anterior to vertical through pelvic-fin origin.Dorsal fin large with flexible spine and seven branched rays; two posteriormost rays reaching or almost reaching adipose-fin origin.Adipose-fin spine straight and well developed.Pectoral fin with moderately inward-curved spine and six branched rays; distal margin straight.Pectoral-fin spine covered with poorly-developed odontodes; odontodes more developed distally in some larger specimens.Pectoral fin inserted on same horizontal plane as pelvic fin such that pectoral spine, when adpressed, lies on top of and reaches to approximately middle of pelvicfin spine.Pelvic fin with flexible and slightly inward-curved spine and five branched rays; distal border straight.Pelvicfin spine flattened ventrally; when adpressed spine tip reaches to about middle of anal-fin spine.Anal fin with flexible spine and four branched rays; spine tip reaching fifth plate posterior to its origin.Caudal fin slightly emarginate, with two longer outer spines and 14 inner branched rays; ventral lobe longer than dorsal lobe.
Color in alcohol.Background color of dorsal and lateral surfaces of head and body beige to light-brown.Head, dorsum, flanks and fins covered by many large dark spots.Dark spots generally merge into short and narrow vermiculations on anterior portion of head, becoming isolated and roundish on pterotic-supracleithrum and more elongate posteriorly.Spots most conspicuous on head and usually fade gradually on trunk towards caudal peduncle.Background color of ventral surfaces of head and body lighter than dorsal portions, except ventral portion of snout uniformly dark brown.Upper and lower lips and ventral surface of head without spots.Abdomen usually without spots or with very faded irregularly spaced dark spots in a few specimens.Ventral surface of caudal peduncle without spots.
Dorsal fin with roundish dark spots only on its base; spots merging distally into bands on interradial membranes paralleling rays.Adipose fin and caudal fin brown.Pectoral fin and pelvic fin with dark spots on spine, rays and interradial membranes.Anal fin with diffuse dark markings.

Distribution and habitat.
Hypostomus denticulatus is known from the rio Corumbá in the vicinity of the Corumbá Reservoir, upper rio Paraná basin, Brazil (Fig. 4).This species was mostly collected in the reservoir of the rio Corumbá just upstream from the dam, and its tributary the rio Areia.Water was turbid, substrates rocky with sand, and riparian vegetation variable and remnant.This species was not found associated with woody debris, and occurs syntopically with H. ancistroides, H. iheringii, H. margaritifer, H. regani, Hypostomus sp., and the second new species described herein.
Etymology.From the Latin denticulus, meaning small teeth, plus -atus, meaning provided with.Diagnosis.Hypostomus heraldoi is distinguished from all congeners, except H. albopunctatus, by having the pectoralfin spine length equal to or smaller than the pelvic-fin spine.From H. albopunctatus, it is distinguished by having roundish dark (vs.pale) spots on body and fins, and generally with more premaxillary teeth, 39-59 per ramus (vs.32-42; see Table 2).out median ridge, and with short and rounded posterior process bordered by partially divided predorsal plate.Lips small and transversely ellipsoid.Lower lip not reaching transverse line between gill openings, its inner surface covered with numerous small papillae.Maxillary barbel very short, largely coalesced with lower lip but with free tip.Mouth moderate.Teeth medium sized, robust, bicuspid, and curved inward distally; inner cusp with elongated crown, about twice length of lateral cusp.Dentary teeth usually not overlapping medially.Dentary ramus forms angle of approximately 140°.

Description. Counts and measurements in
Five rows of slightly spinulose plates on side of body.Predorsal region and all plates in lateral series usually without conspicuous keels.Dorsal series of plates starting at vertical through dorsal-fin origin.Mid-dorsal series interrupted by first plate of dorsal series.Median series bearing lateral line; interrupted by ventrally oriented expansions of plates in mid-dorsal series in region just below dorsal-fin base.Midventral series without keel or with very weak keel restricted to first three plates.Plates in ventral series weakly angled transversely on caudal peduncle; angle more pronounced posteriorly.Caudal peduncle roughly triangular in cross section.
Ventral surface of head mostly covered with minute platelets except beneath lower lip and along outer edge of upper lip.Abdomen covered with minute platelets, even in smaller specimens, except for small naked areas near pectoral and pelvic-fin insertions and surrounding urogenital opening in some specimens.Preanal plate partially exposed.Dorsal-fin origin situated two lateral plates anterior to vertical through pelvic-fin origin.Dorsal fin small with flexible spine and seven branched rays; two posteriormost rays touching second plate anterior to azygous pre-adipose plate.Adipose-fin spine well developed in most specimens, straight or slightly curved inward.Pectoral fin with slightly inwardcurved spine and six branched rays; posterior margin straight.Pectoral-fin spine covered with poorly-developed odontodes; odontodes more developed distally in larger specimens.Pectoral fin inserted on same horizontal plane as pelvic fin such that pectoral spine, when adpressed, lies on top of and reaches between basal one-fourth to one-third of pelvic-fin spine.Pelvic fin with flexible and slightly inward-curved spine and five branched rays; distal margin straight.Pelvic-fin spine slightly flattened ventrally; when adpressed, tip reaches to distal one-third of anal-fin spine.Anal fin with flexible spine and four branched rays; spine tip reachs to sixth plate poste-rior to its origin.Caudal fin slightly forked, with two outer spines and 14 inner branched rays; ventral lobe longer than dorsal lobe.
Color in alcohol.Background color of dorsal and lateral surfaces of head and trunk brown and covered by darker spots.Spots closely to moderately spaced, and slightly faded in some specimens.Dark spots smaller, more compact and numerous on head, becoming slightly larger, and more dispersed posteriorly.Background color of ventral surfaces of head and body lighter than superior portions.Upper lip uniformly dark except for lighter border.Spots on ventral surface of head and body present but vary in conspicuousness among specimens.Ventral spots roundish and isolated in some specimens; spots merged into vermiculations in others.Caudal peduncle region with very faded dark spots ventrally.Dorsal, pectoral, pelvic and caudal fins with roundish dark spots on spines and rays; spots weakly aligned to form five to seven transverse bands.Dorsal fin sometimes with dark spots merging to form irregular bands on interradial membranes paralleling rays.Adipose fin spotless or with irregular dark spots.Anal fin with dark spots generally merged into two or three transverse bands.

Distribution and habitat.
Hypostomus heraldoi is known from the rio Corumbá and rio Grande drainages, upper rio Paraná basin (Fig. 4).The Corumbá Reservoir and its tributary rio Pirapitinga are the main sites where H. heraldoi was collected.The water was turbid, substrates rocky with sand, and riparian vegetation variable and remnant.This species was not found associated with woody debris, and, like H. denticulatus, occurs syntopically with H. ancistroides, H. iheringii, H. margaritifer, H. regani and Hypostomus sp.
Etymology.Hypostomus heraldoi is named in honor of Heraldo Antônio Britski, MZUSP (Museu de Zoologia da Universidade de São Paulo), for his extensive contributions to our knowledge of neotropical fish diversity.

Discussion
Hypostomus denticulatus is morphologically very similar to H. iheringii (Regan), H. latirostris (Regan), H. ternetzi (Boulenger) and H. multidens Jerep, Shibatta & Zawadzki, sharing with these species characters such as a wide jaw, deep caudal peduncle, conspicuous keel on supraoccipital process and predorsal plates, and abdominal plates restricted to anterior portion of the abdomen with extensive naked areas surrounding pelvic-fin insertion.Hypostomus ternetzi and H. cf.iheringii (= Hypostomus sp. 2 sensu Zawadzki et al., 2005) share a unique allozyme pattern among 11 species of Hypostomus examined from the upper Paraná basin.This pattern corroborates their similarities in external morphology, and both species were placed in the H. ternetzi group by Zawadzki et al. (2005).Hypostomus multidens and H. denticulatus also seem to fit this group.Hypostomus multidens exhibits some Hypostomus heraldoi is morphologically very similar to H. albopunctatus from the rio Piracicaba basin despite having black spots instead of pale ones.Hypostomus albopunctatus was up to now the only species of Hypostomus having the pectoral-fin spine equal to or shorter than the pelvic-fin spine.Zawadzki (2001) found an allele at locus Pgm-A diagnosing H. heraldoi (= Hypostomus sp. 1) from six other species of Hypostomus in the rio Corumbá basin.Later, Zawadzki et al. (2005) found this same allele diagnostic of H. albopunctatus among ten Hypostomus species from the Itaipu Reservoir.Thus, genetic data and external morphology suggest that these two species are related, yet clearly distinguished by color pattern and to a lesser degree by the number of premaxillary teeth (i.e., 39-59 per ramus in H. heraldoi vs. 32-42 in H. albopunctatus).
Each of the two new species described herein show a color pattern opposite to that of its morphologically most similar species.This suggests that some genetic trigger may influence speciation events in some Hypostomus by inversion of the color pattern.The precise phylogenetic placement of both new species is beyond the scope of this paper.Further morphological and molecular studies will be necessary to confirm sister relationships between species with inverted color patterns.
The Corumbá dam has dramatically changed the lotic environment of the rio Corumbá to a lentic one, and the extent to which these modifications affect fish populations is still unknown.Although the lower stretches of the rio Paraná have been extensively surveyed, H. denticulatus and H. heraldoi have never been collected outside the rio Grande and rio Paranaíba basins, and are probably endemic to these watersheds.The rio Paranaíba supports a number of endemic fishes and its isolation from the remaining Paraná basin is attributed to a series of rapids and canyons downstream its mouth that apparently represent barriers to free dispersal (Pavanelli & Britski, 1999).

Table 1 .
Morphometric data and counts for Hypostomus denticulatus and H. heraldoi from the upper rio Paraná basin, Brazil.Means are presented for measurements, and modes for counts.SD = standard deviation.

Table 2 .
Frequency of premaxillary teeth in Hypostomus albopunctatus and H. heraldoi.traits of the H. ternetzi group, but differs by having light (vs.dark) spots on body and fins, and symmetrical (vs.asymmetrical) bicuspid teeth.Hypostomus denticulatus also has teeth with two symmetrical cusps, but has large dark spots on body and fins as do the other members of the H. ternetzi group. morphological