Description of a new species of Pareiorhaphis ( Loricariidae : Neoplecostominae ) from the rio Jequitinhonha basin , Minas Gerais , eastern Brazil

A new species of the loricariid genus Pareiorhaphis is described based on specimens from several tributaries of the upper and middle rio Jequitinhonha basin, Minas Gerais State, eastern Brazil. The new species increases the number of known species of Pareiorhaphis to 25 and, at the same time, represents the second member of the subfamily Neoplecostominae reported from the rio Jequitinhonha basin. The new species is diagnosed from all remaining congeners by a putative autapomorphic feature related to the color pattern: a well-defined, dark brown stripe on the median series of lateral plates that extends along the flank from the posterior margin of compound pterotic to the caudal-fin base. The shallow caudal peduncle and the comparatively larger number of dentary teeth also distinguish the new species from most congeners. The new species is also compared to Pareiorhaphis stephanus, a syntopic congener with similar traits.


Introduction
Pareiorhaphis Miranda Ribeiro comprises a distinctive assemblage of loricariid catfishes with 25 known species, including the new taxon described in this report.Species of this genus exhibit a significant variation in body size, color pattern, nature of the pectoral girdle covering, shape of the head, and other morphometric and meristic traits.However, a common pattern related to the sexually dimorphic attributes associated with adult males is shared by all species of the genus and diagnoses Pareiorhaphis among all other neoplecostomines, namely the hypertrophied odontodes that cover most of the cheek, opercle, and exposed lateral process of the cleithrum (Pereira et al., 2007(Pereira et al., , 2010)).The type locality of the new species is located in the rio Itacambiruçu, one of the main tributaries of the rio Jequitinhonha, a coastal drainage included in the Northeastern Mata Atlântica freshwater ecoregion (Abell et al., 2008), which harbors high levels of fish endemism (Camelier, Zanata, 2014).In addition, no other neoplecostomine have been reported in that basin since Oliveira, Oyakawa (1999) described Pareiorhaphis stephanus from the ribeirão das Pedras, a headwater tributary to the rio Jequitinhonha basin near Diamantina, 2 e170007 [2] Minas Gerais State.Recently, however, a possible second species of Pareiorhaphis has been identified based on DNA barcode comparison and since its genetic distance from P. stephanus was higher than 2% (namely 5.79%), it was considered a candidate new species by Pugedo et al. (2016), what was confirmed with the present morphometric analysis.Various ichthyological surveys conducted by the authors in tributaries to upper and middle portions of the rio Jequitinhonha basin during the last few years, have produced good series of that distinct, undescribed species of Pareiorhaphis, which is formally described in the present paper.

Material and Methods
Specimens examined belong to the American Museum of Natural History, New York (AMNH); Academy of Natural Sciences of Drexel University, Philadelphia (ANSP); Auburn University Museum, Auburn (AUM); Laboratório de Ictiologia de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto (LIRP); Museu de Ciências Naturais, Pontifícia Universidade Católica de Minas Gerais, Belo Horizonte (MCNIP); Museu de Ciências e Tecnologia, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre (MCP); Museu Nacional, Rio de Janeiro (MNRJ); and Museu de Zoologia da Universidade Estadual de Londrina, Londrina (MZUEL).Comparative material of Pareiorhaphis species is listed in Pereira et al. (2012), with the addition of Pareiorhaphis lophia in Pereira, Zanata (2014), P. proskynita in Pereira, Britto (2012), P. garapia in Pereira et al. (2015), P. vetula in Pereira et al. (2016), and P. stephanus below.The subfamily Neoplecostominae is used herein in the sense of Pereira, Reis (2017).Counts and measurements were taken according to Pereira et al. (2007).Counts of procurrent caudal-fin rays and vertebrae were made in two cleared and counterstained specimens (c&s) prepared according to Taylor, Van Dyke (1985).Vertebral counts include five centra in the Weberian Apparatus and the fused ural + preural centra, which was counted as one element.Nomenclature and counts for body plates follow Schaefer (1997).Morphometric features were obtained with digital calipers to the nearest 0.1 mm and were made from point to point under a stereomicroscope.Standard length (SL) is expressed in millimeters while all other measurements are given as percent of standard length or head length (HL).In the list of examined material, 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.Conservation status of the new species was evaluated according the categories and criteria of the International Union for Conservation of Nature (IUCN, 2016).The Extent of Occurrence (EOO) was calculated by the minimum convex polygon method, using the software Google Earth Pro.

Diagnosis.
Pareiorhaphis lineata can be diagnosed from all congeners by a putative autapomorphy, the possession of a dark brown stripe on the median series of lateral plates that extends along the flank from the posterior margin of compound pterotic to the caudal-fin base (vs.no dark stripe on flank).In addition, P. lineata can be distinguished from all other congeners, except P. stephanus, by having the entire margin of the head ornamented with hypertrophied odontodes in adult males (vs.hypertrophied odontodes on the cheeks only).From the remaining species, except P. garbei and P. stephanus, it is distinguished by a longer dorsal fin, whose posterior margin reaches the middle or distinctly beyond the middle of the anal fin when adpressed in adult males (vs. a short dorsal fin, whose posterior margin does not reach to or slightly surpasses the anal-fin origin).
The shallower caudal peduncle (7.9-9.0 vs. 9.1-14.0%SL) also distinguishes Head broad and moderately depressed, rounded in dorsal view; widened in adult males.Interorbital space flat to slightly concave.Three weak elevations between orbits and snout tip; one median from snout tip to area between nostrils and two in front of orbits.Elevations ornamented with many short hypertrophied odontodes directed upward in adult males.Snout tip with small ovoid area of naked skin; covered by short hypertrophied odontodes in fully developed adult males.Adult males with well-developed soft fleshy lobes extending along lateral and sometimes anterior portions of head.Eye small, dorsolaterally placed; iris operculum small or unnoticeable.Nares ovoid, slightly longer than wide, positioned much closer to anterior margin of orbit than to snout tip.Narrow area of naked skin in front of nostril, between mesial margin of infraorbitals 1 and 2 and prenasal plates.Oral disk oval; lips well developed, occupying most of ventral surface of head.Lower lip wide and long, not reaching pectoral girdle, upper lip narrow.Lower lip densely covered by minute papillae.Papillae surrounded by small naked areas, decreasing in size towards edge and absent near lip margin.Margin of lower lip slightly fringed.Maxillary barbel short, mostly adnate to lower lip and with small free portion distally.Teeth series in both premaxilla and dentary forming shallow arc with overall angle of approximately 130-140 degrees, with mesial ends slightly curved inwards.Teeth slender, asymmetrically bifid, medial cusp slightly curved inwards.Lateral cusp small and pointed, never reaching half-length of medial cusp in unworn teeth.
Dorsal-fin posterior margin straight to slightly concave; usually not contacting preadipose azygous plates when adpressed, sometimes contacting first preadipose plates in adult males.Nuchal plate exposed, not covered by skin.Dorsal-fin spinelet oval-shaped, varying from slightly wider than base to usually narrower than base of dorsal-fin spine, sometimes divided into two small platelets, or absent.Dorsal-fin locking mechanism non-functional.Dorsal-fin spine moderately flexible, followed by seven branched rays.Adipose fin with well-ossified leading spine bearing odontodes.Adipose-fin membrane short or extended slightly beyond adipose-fin spine.Adipose fin preceded by 1-5 (usually 2-3) median preadipose azygous plates.Pectoral-fin origin situated slightly dorsal to pelvic-fin origin.Pectoral fin moderate in size, with spine slightly curved and flattened, covered by minute odontodes in females, immature males, and juveniles.Adult males with pectoral-fin spine very broad, bearing straight and short hypertrophied odontodes over entire outer surface.Pectoral fin with six branched rays, first and second longer than spine.Subsequent branched rays decrease gradually in size, last ray half length of first one.Distal margin of pectoral fin approximately straight.Tip of adpressed pectoral fin almost reaching or reaching to mid-length of pelvic-fin unbranched ray.Pelvic fin with one unbranched and five branched rays, not reaching or just reaching to origin of anal fin when adpressed.Pelvic-fin unbranched ray depressed, covered with minute odontodes ventrally and laterally.Dermal flap on its dorsal surface present and well developed, extending to ray tip in adult males; absent in females.Anal fin short with one unbranched and five branched rays; passing vertical at adiposefin origin when adpressed.Caudal fin with 14 branched rays, posterior margin slightly forked; ventral lobe distinctly longer than dorsal .Dorsal caudal-fin lobe with 4-5 and ventral lobe with 3-5 plate-like procurrent rays, posteriormost elongate.Odontodes on principal and procurrent rays small and irregularly arranged.Hypural plate asymmetrical with ventral lobe longer than dorsal.Total vertebral centra 29.

Color in alcohol.
Overall background color of dorsal and lateral surface of head and trunk pale yellow to light brown, sometimes brownish gray.Flank with conspicuous dark brown stripe from compound pterotic to caudal fin on median series of lateral plates, distinctly contrasting with lighter color of mid-ventral and ventral series of plates (Fig. 1).Scattered dark blotches and dark saddles common to other species, absent in P. lineata.Ventral surface of head and abdomen yellowish or whitish pale or with small dark grey spots scattered on lateral portion of abdomen and caudal peduncle.Dorsal fin with 3-4 inconspicuous dark blotches on spine and branched rays; interradial membrane darkened.Paired fins darkened anteriorly and pale yellow posteriorly.Caudal fin with rays and interradial membrane gray.
Color in life.Similar to color in alcohol but contrast between dark brown longitudinal stripe and lighter mid-ventral and ventral series of plates more conspicuous.Lateral portion of snout between eye and fleshy lobe on cheek darkened.Distal margin of caudal fin chestnut brown (Fig. 2).Sexual dimorphism.Pareiorhaphis lineata shares with all members of the genus the remarkable morphological modifications already known to occur in adult males of Pareiorhaphis.Some of those attributes in the new species are especially developed, as the fleshy lobes that extend along the entire margin of the head and that are ornamented with short emerging hypertrophied odontodes, both of which are absent in females; by a thickened pectoral-fin spine strongly intumescent along its entire length with dorsal, lateral, and ventral surfaces ornamented with short hypertrophied odontodes, sometimes equal in size to those on head margin, that are absent in females; and by the skin fold on the dorsal surface of the unbranched pelvic-fin ray that extends to the ray tip and is slightly higher near the fin base, whereas the skin fold is absent or very reduced in females.Other examples of secondary sexual dimorphism of adult males include distinct keels of the ventral series of lateral plates; three weak elevations between the orbits and the snout tip that are covered with many short hypertrophied odontodes directed upward; dorsal-fin posterior margin that sometimes contacts the first preadipose plate; and possession of a much broader head than females.Compared to males, females possess an enlarged, swollen urogenital opening, while males have small and pointed urogenital papillae.

Geographical distribution. Upper and middle rio
Jequitinhonha basin in the state of Minas Gerais, Brazil (Fig. 3).Etymology.The species name Pareiorhaphis lineata is from the Latin linea, meaning line or stripe, in reference to the dark stripe on the flank, which is distinctive of this species.An adjective.
Conservation status.Pareiorhaphis lineata is broadly distributed in the upper and middle rio Jequitinhonha basin (Fig. 3), being relatively frequent and abundant.Its Extent of Occurrence (EOO) was estimated at approximately 24,500 km 2 .The lower reach of the rio Itacambiruçu, the second main tributary to the rio Jequitinhonha, has been compromised by the Irapé dam reservoir.Now a series of small dams are planned for the upper and middle reaches of that river, which may substantially reduce suitable habitats for this species.Despite a variety of threats such 8 e170007 [8] as contamination by domestic sewage, species introduction (mainly Serrasalmus brandtii from the rio São Francisco), mining, damming, and deforestation, with the subsequent river siltation, were observed in portions of the area of distribution, no specific threats were detected, and Pareiorhaphis lineata should be categorized as Least Concern (LC) according to IUCN criteria (IUCN, 2016).

Discussion
Pareiorhaphis lineata was included as a member of Pareiorhaphis by sharing the several synapomorphies disclosed by Pereira, Reis (2017) for the genus, which include the remarkable morphological attributes known to occur in adult males of all congeners, as already discussed by Pereira et al. (2007) -the thickened pectoral-fin spine, fleshy lobes on the cheeks, and hypertrophied odontodes on the dorsal surface of the pectoral-fin spine and on the lateral margins of the head.
There are several similarities regarding the general color pattern of most species of Pareiorhaphis.Often, the dorsal surface of body and head is grayish to dark brown, the ventral surface is light brown to yellowish white, with the skin of the abdomen white to pale yellow.In addition, the dorsum and flanks are covered by distinct to inconspicuous dark blotches that form irregular transverse saddle-like marks, from the predorsal area to the end of the caudal peduncle.Of the 25 species of Pareiorhaphis only four diverge from that general color pattern: P. stomias, with the dorsal surface of the head and dorsum covered by many small, distinct black dots, more concentrated on the head (Pereira, Reis, 2002); P. proskynita, which has a singular color pattern among all species of Pareiorhaphis, with conspicuous dark brown blotches irregularly scattered over a yellowish tan background on the head, dorsum, and flanks (Pereira, Britto, 2012); P. vetula, with irregular and inconspicuous scattered dark brown blotches not forming saddles on the head, dorsum, or flanks (Pereira et al., 2016); and P. lineata, which is diagnosed from all remaining congeners by a putative autapomorphic feature related to the color pattern that is so far unknown among other Pareiorhaphis, a welldefined, dark brown stripe on the median series of lateral plates that extends along the flank from the posterior margin of the compound pterotic to the caudal-fin base, over a pale yellow or light brown background, further on the absence of saddle-like marks on the dorsum.
Pareiorhaphis stephanus is the single other neoplecostomine known to occur in the rio Jequitinhonha basin (Oliveira, Oyakawa, 1999), where they occur sympatrically and syntopically.The two species share some morphological traits, including a ventral caudalfin lobe that is longer than the dorsal lobe, hypertrophied odontodes that are distributed along the entire margin of the head, and aspects of the color pattern.Despite possessing morphological traits similar to P. stephanus, the size of the hypertrophied odontodes of P. lineata differs significantly.
Adult males of P. lineata have the largest hypertrophied odontodes on the head and pectoral-fin spine that are always shorter than one orbital diameter, while larger hypertrophied odontodes are always longer than one orbital diameter in P. stephanus (Fig. 5).In addition, adult males of P. lineata have a rounded pectoral fin-spine in cross-section and the greatest body width is located at the posterior portion of cheek, while in P. stephanus, the pectoral-fin spine is dorsoventrally flattened and the greatest body width is at the lateral margin of the cleithrum (Figs. 5 and 6).Regarding to color pattern, P. lineata possesses the well-defined, dark brown stripe on the median series of lateral plates that extends along the flanks, and has no saddle-like marks on the dorsum (Figs.1,2,6).By contrast, P. stephanus has dark brown blotches forming the typical saddle-like marks of many Pareiorhaphis species that are sometimes laterally united to form a diffuse and inconspicuous stripe on the flank (Figs. 5,6).Regarding immature males, females, and juveniles, which are more frequently collected, the new species can be easily distinguished by the color pattern, by the head being wider than the cleithrum, by the smaller eye diameter , and by the larger snout (60.8-66.5% vs. 55.5-60.8%HL).
The particular color pattern of a longitudinal stripe observed in Pareiorhaphis lineata is shared with Euryochus thysanos, an unrelated neoplecostomine that inhabits the contiguous river basins of the rio Doce, rio Mucuri, rio São Mateus, and small coastal drainages in eastern Brazil.Although the color pattern is superficially similar in the two species, E. thysanos is easily distinguished from P. lineata by lacking the attributes found in adult males of Pareiorhaphis, such as odontodes along the head margins and broad pectoral-fin spine, and was also shown to be not closely related to Pareiorhaphis (Pereira, Reis, 2017).

Fig. 3 .
Fig. 3. Distribution of Pareiorhaphis lineata in eastern Brazil.Red dots = paratypes; star = type-locality; yellow dots = non-type specimens.Each symbol may represent more than one lot or locality.Ecological notes.Pareiorhaphis lineata was captured in habitats with medium to strong water current and substrate composed of smooth bedrock, large boulders, and cobbles, in addition to small amounts of gravel and sand, usually in low depth (< 0.5 m).No individuals were captured in sand bottomed stretches, such as beaches or pools.Rocks were sometimes covered by weeds (Podostemaceae).Rivers where specimens were collected are 0.3-4.5 m deep and 1.7-55 m wide, with banks covered by shrub
Morphometric and meristic data of Pareiorhaphis lineata.Values are given as percents of standard length or head length.H = holotype, n = number of specimens, and SD = standard deviation.