A new species of the Neoplecostomine catfish Pareiorhaphis ( Siluriformes : Loricariidae ) from the Coastal basins of Espírito Santo , Eastern Brazil

Pareiorhaphis ruschii, new species, is the first neoplecostomine catfish of the genus Pareiorhaphis described based on material from tributaries to the rio Piraquê-Açu and rio Reis Magos, both small coastal drainages in the State of Espírito Santo, eastern Brazil. The new species is promptly diagnosed from all its congeners by features related to the morphology of the lower lip margin, number of preadipose azygous plates, size and shape of the pectoral-fin spine, and caudal-fin skeleton. Additionally, sexual dimorphism of the new species is marked by hypertrophied odontodes on the lateral margins of head slightly directed forward in adult males.


Introduction
The first six species of what is currently known as Pareiorhaphis were described from 1907 to 1951, from a geographic area that encompasses most of the current geographic range of Pareiorhaphis.Such an area spans from the coastal rio Tubarão in southern Santa Catarina State to small coastal drainages near Ilheus Municipality in Bahia State, the species being P. cameroni (Steindachner, 1907), P. garbei (Ihering, 1911), P. steindachneri (Miranda Ribeiro, 1918), P. regani (Giltay, 1936), P. bahianus (Gosline, 1947), and P. cerosus (Miranda Ribeiro, 1951).With the exception of Pareiorhaphis regani from the rio Curicuriari of the upper rio Negro in the Amazon, a possibly wrong locality (see Pereira & Reis, 2002), those species inhabit small coastal drainages in a rather patchy distribution.After an interval of more than 40 years, the completion of such distribution in small coastal drainages continued through the descriptions of P. splendens (Bizerril, 1995), P. nudulus (Reis & Pereira, 1999), and P. azygolechis, P. hypselurus, and P. stomias by Pereira & Reis (2002), all from the coastal rivers of Santa Catarina and Paraná States, and P. stephanus (Oliveira & Oyakawa, 1999), from the upper rio Jequitinhonha, a large coastal river in Minas Gerais State.
The first species described from the large rivers draining the Brazilian Shield towards the west was Pareiorhaphis vestigipinnis (Pereira & Reis, 1992), from the upper rio Canoas in southern Santa Catarina.Other species from large rivers on the Brazilian Shield were described in subsequent years: P. mutuca (Oliveira & Oyakawa, 1999) from the upper rio das Velhas in the São Francisco basin, and P. eurycephalus, form the upper rio Canoas, and P. hystrix, from the upper Uruguay and Taquari basins in Rio Grande do Sul State, by Pereira & Reis (2002), thus extending the southern end of the distribution of the genus a few hundred kilometers.
In more recent years, Pareiorhaphis parmula was described (Pereira, 2005) from the upper rio Iguaçu, and P. nasuta and P. scutula by Pereira et al. (2007Pereira et al. ( , 2010)), from the upper rio Doce in Minas Gerais State, comprising the first records of a Pareiorhaphis species in such river basins.In the present paper we describe another species of Pareiorhaphis from the coastal rivers Piraquê-Açu and Reis Magos, two small coastal rivers of the Espírito Santo State.Even with the description of the twentieth species in Pareiorhaphis, the distribution of the genus on the Brazilian coastal drainages and rivers draining the Brazilian Shield is rather patchy and the knowledge of the actual diversity of the genus is still being established.

Material and Methods
Comparative data from all Pareiorhaphis species were taken directly from the type specimens (see comparative material).Counts and measurements were taken as described by Pereira et al. (2007).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 include five centra in the Weberian Apparatus and the fused pre-ural centrum.Nomenclature and counts for body plates follow Schaefer (1997) All morphometric features were measured with digital calipers to the nearest 0.1 mm and were made from point to point under a stereomicroscope.Standard length is expressed in millimeters while all other measurements are given as percents of standard length, except for subunits of the head, which are presented as percents of the head length.Descriptions of coloration were based on specimens preserved in ethanol.In the lists 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.
Adult males of Pareiorhaphis are herein defined as specimens having distinctive modifications that involve the shape of the pectoral-fin spine, hypertrophied odontodes along the head margins, and fleshy lobes on the lateral margins of head, although not necessarily in reproductive maturity.The other specimens included in the list of material examined are a combination of females, young males, and immature specimens of both sexes.

Diagnosis.
Pareiorhaphis ruschii differs from all congeners except P. azygolechis, in having the lower lip margin densely fringed (Fig. 1; vs. smooth or just slightly fringed).The new species can be further distinguished from all other Pareiorhaphis species but P. garbei and P. azygolechis in having a series of six to ten (usually seven to nine) small median, preadipose azygous plates, forming a low postdorsal ridge between the dorsal and the adipose fins (Fig. 2, vs. none to five preadipose plates).
Pareiorhaphis ruschii is further distinguished from all remaining species except P. calmoni, P. bahianus, P. nudulus, P. hypselurus, and P. stomias by having the pectoral-fin spine very long and straight, reaching the distal third of the pelvic fin when adpressed in adult males (Fig. 1, vs. spine short and curved and maximally reaching half of the pelvic-fin length).It is also differentiated from most species, except P. eurycephalus, P. hypselurus, P. stomias, and P. stephanus by having the hypural plate asymmetrical with the lower lobe longer than the upper (Fig. 3, vs. hypural plate approximately symmetrical).Head broad and moderately depressed.Outline of head round in dorsal view; adult males more slender anteriorly.Interorbital space straight or slightly concave.Three weakly elevated ridges between orbits and snout tip.Outer ridges from middle of snout to upper margins of orbits slightly more prominent.Ridges ornamented with many short hypertrophied odontodes directed upward in adult males.Odontodes straight, conical and pointed distally, densely covering these ridges and making this area somewhat hispid (Fig. 4).Snout convex in lateral profile; snout tip with small ovoid area of naked skin.Adult males with slender soft fleshy lobes extending along lateral portion of head.Soft fleshy area ornamented with hypertrophied odontodes; larger odontodes bent anteriorly (Fig. 4).Eye small, dorsolaterally placed; orbital diameter 12.2-16.1%HL.Iris operculum absent or very small.Nares ovoid, slightly longer than wide, positioned much closer to anterior margin of orbit than to snout tip.Lips well developed, occupying most of ventral surface of head.Lower lip wide and long but 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 but then increasing again to become slightly larger than those in central region of lip.Margin of lower lip densely fringed.Maxillary barbel short and united to lip by membrane basally, free distally.Teeth series in both premaxillae and dentaries with mesial ends slightly curved inwards.Teeth slender, asymmetrically bifid, medial cusp slightly curved inwards.Lateral cusp small and pointed, reaching or almost reaching half-length of medial cusp.

Description. Counts and proportional measurements in
Dorsal fin originating on vertical line passing through pelvicfin origin.Dorsal fin short, usually not contacting preadipose azygous plates when adpressed, sometimes contacting in adult males.Nuchal plate exposed, not covered by skin.Dorsal-fin spinelet present but dorsal-fin locking mechanism nonfunctional.Dorsal-fin spinelet transversely oval-shaped, as wide or slightly wider than base of dorsal-fin spine.Dorsal-fin spine moderately flexible, followed by seven branched rays.Adipose fin with well-ossified leading spine bearing odontodes.Adiposefin membrane short or extended slightly beyond adipose-fin spine.Adipose fin preceded by six to ten (usually seven to nine)   transverse irregular dark bars.One yellowish blotch on both upper and lowermost caudal fin rays in some specimens.
Distribution.Known from the upper reaches of the rio Piraquê-Açu and rio Reis Magos in Espírito Santo State, Brazil (Fig. 5).Only specimens from the rio Piraquê-Açu basin were included as paratypes in order to maintain the entire type series from a single river basin.
Habitat and ecological notes.The rio Reis Magos and rio Piraquê-Açu are both costal basins of the Espírito Santo State of Brazil.
The headwaters of the córrego Lombardia, where most specimens of Pareiorhaphis ruschii were collected, is a shallow creek (0.5 m depth and approximately 4 to 5 m wide) that crosses the Augusto Ruschi Biologic Reserve.The type material was collected immediately downstream from the reserve limit, where the river was still well preserved.A few hundred meters downstream there are Eucalyptus plantations and the river is highly impacted.

Sexual dimorphism. Mature males possess the remarkable morphological modifications already known to occur in other
Pareiorhaphis species, a skin fold on the dorsal surface of the unbranched pelvic-fin ray, a thickened pectoral-fin spine, fleshy lobes on the lateral margins of head, and hypertrophied odontodes emerging from those fleshy lobes and on the pectoral-fin rays.When compared to males, females posses an enlarged, swollen urogenital opening, while males have a small and pointed urogenital papilla.
Etymology.Species name is given in honor of the late eminent Brazilian naturalist Augusto Ruschi in recognition for his outstanding contributions to the knowledge of Atlantic Forest hummingbirds and his unweary efforts to create the conservation area Reserva Biológica Augusto Ruschi, where now Pareiorhaphis ruschii is preserved.

Discussion
Among Pareiorhaphis it is not unusual to find species that share the relatively common sexually dimorphic features of a skin fold on the dorsal surface of the unbranched pelvic-fin ray, the thickened pectoral-fin spine, fleshy lobes on the lateral margins of head, and hypertrophied odontodes on the dorsal surface of the pectoral-fin spine and on the lateral margins of the head.All these features were found in adult males of Pareiorhaphis ruschii.However one of the most diagnostic features used to distinguish P. ruschii from all other congeners is related to the shape, size, and covering of the pectoral-fin spine of adult males.Despite of similar patterns on sexual dimorphism observed in Pareiorhaphis species that are also characterized by thickened pectoral-fin spine, a clear interspecific variation on morphology of the pectoral-fin spine in adult males of Pareiorhaphis can be detected and revealed three distinct conditions.The first condition associated with the size while the second and third with the shape and ornamentation of the pectoral spine.
The length of the pectoral-fin spine is a sexually dimorphic feature in some Pareiorhaphis species.Most species have the pectoral-fin spine short, its posterior tip just reaching to or not reaching the origin of the pelvic fin when adpressed to the body.However, adult males of P. bahianus, P. cameroni, P. hypselurus, P. nudulus, and P. stomias have the pectoral fin surpassing half length of pelvic fin when adpressed.This condition also was observed in adult males of the new species which, however, is clearly differentiated from all previous species by having six to ten small preadipose azygous plate (vs.none to five).In addition, P. hypselurus, P. nudulus, and P. stomias shared the possession of four branched anal-fin rays while P. ruschii shares the plesiomorphic condition for loricariids of having five branched anal-fin rays.Pareiorhaphis ruschii can be further distinguished from P. cameroni and P. bahianus by having the pelvic-fin unbranched ray clearly wider than the pectoral-fin spine in ventral view (vs.pectoralfin spine slightly wider than pelvic-fin unbranched ray).
Generally adult males of Pareiorhaphis species have the pectoral-fin spine strongly ossified and slightly to strongly intumesced, making the spine thicker than that of females or immature males.Pareiorhaphis ruschii has the pectoral-fin spine with a singular condition, where the distal half is more strongly intumesced making the spine club-shaped.Three species among Pareiorhaphis, P. cameroni, P. parmula, and P. vestigipinnis share a similar condition, however P. ruschii is distinguished from the previous species by having the lower lip margin densely fringed (Fig. 1; vs. smooth or just slightly fringed).In addition, P. ruschii can be further distinguished from P. cameroni by having small platelets or few odontodes embedded on each side of the abdomen just posterior to the gill opening (vs.abdomen totally naked in P. cameroni).From P. parmula it is further distinguished by the smaller number of lateral plates in the median series (25-28 vs. 28-31 in P. parmula).Finally, it is also distinguished from P. vestigipinnis by having a well-developed adipose fin (vs.adipose fin absent in P. vestigipinnis).
A greater development of hypertrophied odontodes on the pectoral-fin spine is a feature shared by most adult males of Pareiorhaphis species.Contrary to this condition, in adult males of P. azygolechis, P. steindachneri, P. regani, P. cerosus, and P. mutuca, however, the pectoral-fin spine is not covered by hypertrophied odontodes and the odontodes present on the spine are not distinct from those on the dorsal region of the head and trunk, and the pectoral-fin spines has no dimorphic modifications on their coverings.On the other hand, adult males of P. ruschii and most other species of the genus possess the pectoral-fin spine bearing many hypertrophied odontodes (Fig. 1).In addition, there is a variation in the type of the covering of the pectoral-fin spine.With the exception of P. hystrix, P. parmula, and P. vestigipinnis, where the hyperthrophied odontodes do not cover the entire length of the spine or are not arranged in a clear pattern, in remaining congeners the pectoralfin spine of adult males bear hypertrophied odontodes from the base to the tip, covering the entire length of the spine.Although the odontodes show different degrees of development within the group the hypertrophied odontodes are approximately uniform in each species and show a relatively uniform ornamentation on the ray.Despite P. ruschii shares a similar condition on the covering to the pectoral-fin spine it is distinguished from all other Pareiorhaphis species by having the odontodes on the distal portion distinctly longer than those covering the remainder of the spine (vs.odontodes approximately equal in size on the entire length of the ray).In addition to the characters presented by Pereira et al. (2007: 445) the features of hypertrophied odontodes described above are not shared by any other neoplecostomine genera and are also useful to distinguish Pareiorhaphis species from Isbrueckerichthys, Kronichthys, Neoplecostomus, and Pareiorhina.

Table 1 .
Small to medium-sized loricariid with standard length of measured specimens 51.7-96.7 mm SL.Body stout, 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 dorsal-fin origin.Least body depth at shallowest part of caudal peduncle.Trunk and caudal peduncle mostly oval in cross-section, flattened ventrally and more compressed caudally.Lateral-line canal in median series complete, pored tube visible from compound pterotic to caudal-fin base.Ventral profile almost straight between snout tip and pelvic girdle, slightly

Table 1 .
Morphometric and meristic data of Pareiorhaphis ruschii.Values are given as percents of standard length or head length.H = holotype, n = number of specimens, and SD = Standard Deviation.Pectoral-fin origin situated more dorsally than pelvic-fin origin.Pectoral fin moderate in size, with spine distinctly straight and flattened, covered by minute odontodes in females, immature males and juveniles.Adult males with pectoral-fin spine very long and straight, tip reaching beyond half length of pelvic fin when adpressed; broadening from insertion to tip, bearing few straight, short hypertrophied odontodes on entire outer face.Pectoral fin with six branched rays, first and second as long as spine.Subsequent branched rays decrease gradually in size, last ray half length of first one.Posterior margin of pectoral fin straight, surpassing mid-length of pelvic fin when adpressed.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 long with one unbranched and five branched rays; passing vertical at adiposefin origin when adpressed.Caudal fin forked or slightly concave; upper and lower lobes approximately equal in size, or lower lobe slightly longer than upper; 14 branched rays.Upper caudal-fin lobe with six and lower lobe with four or five plate-like procurrent rays, posteriormost elongate.Odontodes on principal and procurrent rays small and irregularly arranged.Hypural plate asymmetrical with lower lobe longer than upper.Total vertebral centra 29-30.