A new species of the armored catfish genus Pareiorhaphis Miranda Ribeiro ( Siluriformes : Loricariidae ) from the rio Paraguaçu , Bahia State , northeastern Brazil

A new armored catfish species of the genus Pareiorhaphis is described from the middle and upper portions of rio Paraguaçu basin, coastal drainage of Bahia State, northeastern Brazil. The new species is readily distinguished from all its congeners by having two putative autapomorphies: (1) skin fold just posterior to each emergent tooth series of dentary formed by a single enlarged, flattened papilla, and (2) the midline of lower lip immediately behind the dentaries with small patch of distinct papillae arranged in a short median bump. In addition, the shallow caudal peduncle and comparatively lower number of teeth in each dentary also distinguishes the new species from all congeners. The new species is also compared to Pareiorhaphis bahianus, the geographically closest congener.


Introduction
Pareiorhaphis Miranda Ribeiro currently comprises 21 nominal valid species of small to medium-sized suckermouth armored catfishes easily recognized by a series of derived features, including cheeks, opercle, and the exposed lateral process of the cleithrum of adult males covered with hypertrophied odontodes, and the lateroventral portion of preopercle deeply rugose due to the attachment of hypertrophied odontodes (Pereira et al., 2007(Pereira et al., , 2010)).Species of Pareiorhaphis are almost completely restricted to rivers draining the Brazilian Shield, with the exception of P. regani (Giltay), which was described from a tributary of the rio Negro, in the Amazon basin.Although the highest species diversity of the genus has been traditionally attributed to southern drainages, with at least nine species occurring in Santa Catarina State, in the last two decades six new species were revealed to occur in rivers draining a more northeastern portion of the country (e.g., rio Doce, rio Jequitinhonha, and rio São Francisco drainages), and two small coastal rivers of the Espírito Santo State, named Piraquê-Açu and Reis Magos.Up to date, P. bahianus (Gosline) described from Fazenda Almada, Ilhéus, is the only species known to occur in Bahia State and represents the northernmost distribution record of the genus.The type locality of P. bahianus is within the area drained by the rio Almada and this species is recorded from various small coastal rivers located between the rio Pardo and rio de Contas basins (Carvalho & Bockmann, 2007).
Field expeditions over the last eight years in coastal drainages of Bahia State yielded several undescribed species of armored catfishes, revealing an unknown diversity of loricariids in the area.This fact can be exemplified by discoveries of two new species of Hypostomus describe recently (Birindelli et al., 2007;Zanata et al., 2013) and a new species of Pareiorhaphis described herein.

Material and Methods
All morphometric features were taken as pointto-point linear distances with digital calipers under a stereomicroscope, and recorded to the nearest 0.1 mm.Counts and measurements followed Pereira et al. (2007).Nomenclature and counts of body plates follow Schaefer (1997).Standard length (SL) is expressed in millimeters while all other measurements are given as percents of SL, except for subunits of the head, which are presented as percents of the head length (HL).Counts of procurrent caudal-fin rays and vertebrae were made only in cleared and counterstained specimens (c&s) prepared according to Taylor & Van Dyke (1985).Vertebral counts comprise all vertebrae including the five centra modified into the Weberian apparatus and the compound caudal centrum (PU1+U1) was counted as one element.Meristic and morphometric data for comparisons of Pareiorhaphis species in the diagnosis section are from Pereira & Reis (2002), Pereira (2005), Pereira et al. (2007Pereira et al. ( , 2010)), Pereira &Britto (2012), andPereira et al. (2012).Institutional abbreviations are: Museu de Ciências e Tecnologia, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre (MCP); Museu de Zoologia, Universidade de São Paulo, São Paulo (MZUSP); and Universidade Federal da Bahia, Salvador (UFBA).Descriptions of coloration were based on specimens preserved in ethanol and photographs of the freshly collected specimens.In the lists of examined material the museum abbreviation and catalog number come first, followed by the number and SL range of specimens in that lot, the number and SL range of specimens measured for the morphometric comparisons, in parentheses, and locality.
Adult males of Pareiorhaphis are herein defined according to Pereira et al. (2007).The specimens included in the list of material examined are a combination of male, female and immature specimens of both sexes.

Pareiorhaphis lophia, new species
Figs   Dorsal fin origin on vertical line through pelvic-fin origin.Dorsal fin short, reaching three plates behind its base terminus when adpressed.Nuchal plate exposed, not covered by skin.Dorsal-fin spinelet usually absent.Dorsal-fin locking mechanism non-functional.Dorsal-fin spine moderately flexible, followed by seven branched rays.Distal margin of dorsal fin straight.Adipose fin with well-ossified leading spine bearing odontodes.Adipose-fin membrane short or extended slightly beyond adipose-fin spine.Adipose fin preceded by two or three median azygous plates.Pectoral-fin origin situated more dorsally than pelvic-fin origin.Pectoral fin moderate in size, with curved and flattened unbranched ray, covered by minute odontodes in immature males and females.Adult males with first pectoral-fin spine very broad and straight, curved on its base; bearing straight and short hypertrophied odontodes on its entire surface; dorsal surface with discrete dermal flap along its entire length.Pectoral fin I,6; first and second branched rays distinctly longer than spine and subsequent branched rays decreasing gradually in size.Posterior margin of pectoral fin straight, surpassing pelvic-fin origin when adpressed.Pelvic fin i,5, not reaching or just reaching origin of anal fin when adpressed.Pelvic-fin unbranched ray depressed, covered with minute odontodes ventrally and laterally.Well-developed dermal flap on dorsal surface of pelvic-fin unbranched ray; flap of males distinctly higher near fin base, and extending to tip of ray in adult males; flap of females reduced or absent.Anal fin i,5.Caudal-fin posterior margin forked or slightly concave, asymmetrical; lower lobe longer than upper; 14 branched rays.Upper caudal-fin lobe with four and lower lobe with two or three plate-like procurrent rays.Posteriormost procurrent rays elongate.Hypural plate asymmetrical with lower lobe longer than upper.Total vertebral centra 28.
Color in alcohol.Ground color of dorsal surface of head and body light to dark brown; yellowish or whitish pale ventrally (Fig. 1).Cheeks, anterior margin of snout, area between nostrils and orbits, and compound pterotic covered with small, irregularly shaped, light or dark brown blotches.Soft fleshy skin on lateral portion of head well developed and whitish in adult males.Narrow transversal light brown bar extending through middle portion of supraoccipital.Dorsum and most of flank covered by irregularly closelyset darker brown blotches sometimes coalescing.Blotches usually arranged in five inconspicuous transverse saddles, situated between posterior margin of supraoccipital and origin of dorsal fin, behind dorsal-fin spine, posterior portion of dorsal-fin base, at preadipose area, and between adipose and caudal fins.Midlateral region of body with dark brown blotches contrasting with somewhat reticulate light areas.Ventral portion of head and abdomen either completely whitish or pale yellow.Ventral portion of caudal peduncle with numerous small dark blotches more conspicuous in anal-fin pterygiophore covered by skin.Lower surface of head and portion from pelvic-fin insertions to anal-fin origin completely naked, except by plated region around anal fin.
Head broad and moderately depressed.Outline of head round in dorsal view.Interorbital space straight or slightly concave.Three weakly elevated ridges between orbits and snout tip.Median ridge slightly more prominent.Snout convex in lateral profile; snout tip with rounded area of naked skin, devoid of odontodes.Adult males with welldeveloped soft fleshy lobes on lateral portion of head.Soft fleshy area ornamented with short hypertrophied odontodes, approximately perpendicular to body axis (Fig. 1).Eye small, dorsolaterally placed.Iris operculum small or absent in some specimens.Nares ovoid, slightly longer than wide, positioned much closer to anterior margin of orbit than to snout tip.
Oral disk circular.Lips moderately developed, occupying most of ventral surface of head.Upper lip narrow, bearing small rounded papillae.Lower lip wide but not reaching pectoral girdle.Lower lip densely covered by minute papillae.Papillae surrounded by small naked areas, decreasing in size towards edge.Patch of distinct papillae at midline of lower lip immediately behind dentaries, arranged in short median and forming a bump (Fig. 2).Posterior margin of lower lip fringed.Maxillary barbel short, mostly adnate to lower lip and with small free portion distally.Teeth series in both premaxillae and dentaries forming shallow arc with overall angle less than 180 degrees, with mesial ends slightly curved inwards.Teeth slender, asymmetrically bifid, medial cusp slightly curved inwards.Lateral cusp long and pointed, reaching half-length of medial cusp.Distinct skin fold posterior to each emergent tooth series of dentary formed by single enlarged, flattened papilla (Fig. 2).region after posterior margin of anal fin.First thickened rays of dorsal, pectoral, and pelvic fins light brown or grayish.Dorsal and caudal fin branched rays with 2-5 transverse irregular dark bars.Paired fins with diffuse blotches from middle to margin of fin, sometimes arranged in few irregular series.One or two dark brown blotches at adipose-fin spine.

Color in life.
Color pattern of freshly collected specimens light brown to yellowish tan with small and irregular dark spots scattered on dorsal region of head and predorsal area (Fig. 3).Posterior region of body and flank with wide dark brown transversal saddles.Soft fleshy skin on lateral portion of head and first thickened rays of pectoral and pelvic fins yellowish.Markings on caudal fin conspicuous with narrow blotches irregularly arranged on unbranched and branched caudal-fin rays sometimes forming four or five dark brown narrow stripes.Iris golden.
Distribution.The new species is known from middle portion of the rio Paraguaçu and two tributaries of its upper portion (Fig. 4a).Extensive ichthyological collecting efforts through the main coastal rivers across Bahia in recent years failed to yield samples of Pareiorhaphis lophia from outside the rio Paraguaçu drainage, making it possible that the species is endemic to that river basin.
Habitat and ecological notes.The rio Paraguaçu is a blackwater coastal river situated in northeastern Brazil, with headwaters on highlands of central Bahia State.The river stretch in Iaçu, at the period of sampling, was around 60 m wide with rocky platforms exposed on the river borders.The riparian vegetation is represented by a few trees restricted to the river border and the surrounding area is almost completely that is present in females but reduced.In adult males, the thickened first pelvic-fin unbranched ray have developed dermal flap along the entire dorsal surface and distinctly higher near fin base, while in females the dermal flap is reduced.Compared to males, females possess an enlarged, swollen urogenital opening, while males have a small and pointed urogenital papilla.
Comments.The absence of first dorsal-fin spinelet also diagnoses Pareiorhaphis lophia from most of the remaining congeners.However, variation in this feature was noted in the type series.The single specimen of the lot MCP 47712 (64.1 mm SL) has a reduced first dorsal-fin spinelet.Although the absence of dorsal fin-spinelet must be considered diagnostic to Pareiorhaphis lophia, the variation related to this feature deserves mention.
Etymology.The species name lophia is from the Greek Λοϕια, meaning crest, ridge.In allusion to the presence of distinct bump on the lower lip, a diagnostic feature of the new species.A noun in apposition.

Discussion
The most distinctive feature of Pareiorhaphis lophia is the single narrow and transversally flattened papilla, just posterior to each dentary, which easily distinguishes P. lophia from all its congeners.Among the neoplecostomines, the distinctive papilla posterior to each dentary is similar to a series of papillae found in Neoplecostomus.However, the new species fits in the diagnosis of Pareiorhaphis proposed by Pereira et al. (2007) and can be further distinguished from all Neoplecostomus species by the absence of a thoracic shield of small dermal platelets located between the pectoral girdle anthropized mainly by cattle ranching.The specimens were collected at night, on the shallow rocky platforms and inside crevices.Data about the other location on the rio Paraguaçu, situated upstream Itaetê, are not available.The rio Santo Antônio, a blackwater tributary of the upper rio Paraguaçu, is around 20 meters wide and surrounded by riparian forest in the stretch sampled (Fig. 4b).Stretches of rapids and pools alternate, with rocks, loose stones, pebbles, and sand composing the substrate.At that sampling point, the specimens of Pareiorhaphis lophia were hidden among pebbles on the shallow rapids.In the rio Una, a blackwater river, the new species was sampled on narrow stretches around 50 cm deep, just below a waterfall, with fast water current and rocky bottom.The specimens gathered at this locality were hidden in crevices or under large stones.The new species occurs syntopically with the loricariids Hypostomus chrysostiktos Birindelli, Zanata & Lima and H. jaguar Zanata, Sardeiro & Zawadzki.

Sexual dimorphism. The sexual dimorphism of
Pareiorhaphis lophia is characterized mainly by the large soft fleshy lobes restricted to middle portion of the lateral margins of head that extends from anterior margin of nostrils to posterior margin of orbits of adult males.This soft area is ornamented by short hypertrophied odontodes.Odontodes also occur in females and juveniles, but are comparatively much smaller, while soft lobes are absent in females and juveniles.Also, adult males have the unbranched pectoral fin-ray strongly intumescent along its entire length with the dorsal, lateral and ventral faces ornamented with short hypertrophied odontodes, sometimes equal in size to those on head margin, that are absent in females.In addition, fully developed males have a narrow fleshy flap along the entire length of the dorsal margin of the pectoral-fin spine  and the pelvic-fin insertions, present in all Neoplecostomus species.In addition, P. lophia exhibits a single flattened papilla posterior to the dentaries (Fig. 2) whereas two or three series of large papillae are found in most species of Neoplecostomus.Neoplecostomus selenae also possess one or two irregular series of large flattened papillae, just posterior to the dentary (Zawadzki et al., 2008), however, P. lophia is readily distinguished from N. selenae by the presence of well-developed hypertrophied odontodes and soft fleshy skin on the lateral margin of head in adult males (vs.absence in adult males of N. selenae).Furthermore, the new species is also distinct from all congeners in having a small patch of distinct papillae arranged in a short median and slightly more elevated bump (Fig. 2) at the midline of lower lip, immediately behind the dentaries (vs.papillae not elevated in a bump).This feature also occurs in the hypoptopomatine Hisonotus insperatus, which possesses a distinct median series of papillae at the midline of lower lip behind to the dentaries, arranged in a bump (Britski & Garavello, 2003;Martins & Langeani, 2012).Despite of these similar morphology, H. insperatus and P. lophia are relatively distant phylogenetically and these features are likely convergent.
profile almost straight between snout tip and pelvic girdle, slightly elevating posteriorly along anal-fin base, almost straight along caudal peduncle.Dorsal surface of body covered by plates except for narrow naked area around dorsal-fin base.Predorsal plates arranged in three to four series of pairs in some specimens, or without any noticeable arrangement.Five lateral rows of dermal plates covering body, not forming keels; mid-dorsal and mid-ventral series of lateral plates incomplete, terminating four or five plates before caudal fin.Abdomen entirely devoid of plates.First

. 1-3
papillae arranged in a short median bump (vs.papillae not projected in a bump).Moreover, the lower caudal peduncle also distinguishes P. lophia from all remaining Pareiorhaphis species (6.7-7.8 vs. 7.8-14.0%SL),withtheexception of P. proskynita.Furthermore, P. lophia can be distinguished from remaining congeners but P. bahianus, P. cerosus, P. eurycephalus, P. nudulus, P. parmula, P. steindachneri, and P. vestigipinnis by the lower number of dentary teeth(20- 38 vs. 42-120).Pareiorhaphis lophia can be distinguished from P. bahianus, P. cerosus, P. eurycephalus, P. parmula, and P. steindachneri by the usual absence of first dorsal-fin spinelet (vs.spinelet present).The new species can be further distinguished from P. nudulus and P. vestigipinnis by the possession of an adipose fin (vs.adipose fin absent) and the narrower caudal peduncle (4.1-5.3 vs. 5.5-8.7%SL).Description.Counts and measurements in Table1.Small to medium-sized loricariid with standard length of measured specimens 45.5-82.1 mm SL.Head and body moderately depressed.Greatest body width at cleithrum, progressively tapering to end of caudal peduncle.Dorsal profile of body slightly convex, from snout tip to dorsal-fin origin and almost straight from that point to end of adipose fin, then slightly concave to caudal fin.Greatest body depth at dorsalfin origin.Least body depth at shallowest part of caudal peduncle.Trunk and caudal peduncle mostly oval in crosssection, flattened ventrally and more compressed caudally.Lateral-line canal in median series complete, pored tube visible from compound pterotic to caudal-fin base.Ventral

Table 1 .
Morphometric and meristic data of the type series of Pareiorhaphis lophia.Values given as percents of standard length or head length.H = holotype, n = number of specimens, and SD = standard deviation.