A new species of Neoplecostomus Eigenmann & Eigenmann , 1888 ( Siluriformes : Loricariidae : Neoplecostominae ) from the upper rio Paraná basin

Neoplecostomus jaguari, a new neoplecostomine, is described based on material from the rio Jaguari, rio Tietê basin, southeastern Brazil. The new species differs from all congeners by having a conspicuous sexual dimorphism: females with 30-38 teeth in the dentary and 30-39 in the premaxilla, and males with 13-18 and 14-20 teeth, respectively (vs. number of teeth in the dentary and premaxilla approximately equivalent in all other species, except for N. langeanii in the premaxilla); females with larger mandibullary width, 18.5-21.6% HL, males 11.8-15.7% HL (vs. mandibullary width in males and females approximately equivalent); females with teeth longer and thin, males with teeth shorter and robust (vs. teeth similar in other species, except for N. langeanii in the premaxilla). Furthermore the new species is distinguished from all other species from the upper rio Paraná basin by having a lateronasal plate either forming the border of the nostril or posteriorly displaced (vs. lateronasal plate absent). Finally, other useful character includes four to six plates between the frontal and prefrontal, herein called posteronasal plates (vs. one to three in all other species). An identification key to all Neoplecostomus species is provided.


Introduction
Representatives of Neoplecostomus are endemic to the high streams in the Brazilian Cristaline Shield and to date includes 14 valid species distributed in the rio Doce, rio Paraíba do Sul, upper rio Paraná basin, rio Ribeira de Iguape, rio São Francisco, and some other small costal drainages (e.g., Jucu and São Lourenço in the Espírito Santo State).It was first proposed as a subgenus of Plecostomus by Eigenmann & Eigenmann (1888), including the type species Plecostomus microps Steindachner, 1876, from Rio de Janeiro, rio Paraíba do Sul basin, and Hypostomus granosus Valenciennes, 1840, from Cayenne (an error) and Rio de Janeiro.Posteriorly, Eigenmann & Eigenmann (1889) elevated Neoplecostomus to genus, which was latter diagnosed by Langeani, (1990) by having two or three conspicuous rows of enlarged and transversally flattened papillae just posterior to the dentary teeth, larger than those on the remaining portions of the lower lip, and the abdomen covered with conspicuous and small platelets, between insertions of pectoral and pelvic fins, surrounded by naked areas.
A new species of Neoplecostomus from the upper rio Paraná basin 2 Neoplecostomus paranensis Langeani, 1990 until very recently was the unique species described to the upper rio Paraná basin.Zawadzki et al. (2008) proposed three new species to the area: N. corumba, N. selenae, and N. yapo; few years later, Roxo et al. (2012a) described three additional species: N. bandeirante, N. botucatu, and N. langeanii, increasing by almost 100% the total number of known species to the genus and making the upper rio Paraná the richest basin concerning Neoplecostomus diversity.In the present paper, we describe an additional new species to the upper rio Paraná basin, from tributaries of the rio Jaguari, drainage of the rio Tietê, and provide an identification key for the species in the genus.

Material and Methods
Measurements and counts of bilaterally symmetrical characters were made point-to-point with digital calipers, to the nearest 0.1 mm, on the left side of the specimens under a stereomicroscope.Body plate nomenclature follows Schaefer (1997) and Armbruster (2004), and measurements follow Langeani (1990) and Zawadzki et al. (2008).Osteological preparations (c&s) follow Taylor & Van Dyke (1985).Sex determination was based primarily on secondary sexual characters: mature males with a dermal flap on the dorsal surface of the pelvic-fin rays (vs.absent in females) and a conspicuous urogenital papilla posterior to anus (vs.absent in females).The gonads were also observed in the specimens, which were latter cleared and stained.
- Roxo et al., 2012c: 6 (fig.2), 7 (fig.3).Neoplecostomus sp."Casca d'Antas": Lucena et al., 2012: 326 (  Mature males without hypertrophied odontodes and swollen skin along lateral margins of snout and dorsal anterior portion of head.Interorbital space slightly concave in frontal view.Eye moderately small and dorsolaterally placed.Lips well developed and rounded; lower lip almost reaching pectoral girdle and covered by papillae, wider and transversely flattened anteriorlly forming two or three irregular and conspicuous rows, just posterior to dentary teeth.Maxillary barbel short and almost entirely joined to lower lip, with free tip.Teeth long and thin in females and short and robust in males (Fig. 3), bicuspid, mesial cusp longer than lateral; premaxilla with 30-39 teeth in females and 14-20 in males; dentary with 30-38 teeth in females and 13-18 in males.Dentary rami forming an angle of approximately 110°-115°.Dorsal-fin origin posterior to vertical passing through pelvic-fin origin, nuchal plate not covered by skin; dorsal-fin spinelet with same width or wider than dorsal-fin unbranched thick ray base; dorsal-fin locking mechanism absent.Dorsalfin rays ii,7; distal margin straight, surpassing vertical through origin of pelvic fin.Adipose fin moderate to well developed, generally preceded by one azygous plate.Pectoral-fin rays i,6, unbranched thick ray depressed and inward curved, more curved in larger specimens and always shorter than longest branched ray; its distal margin nearly straight, when adpressed reaching first third of pelvic fin.Pelvic-fin rays i,5; distal margin nearly straight, when adpressed reaching or almost reaching anal-fin origin; pelvic-fin unbranched thick ray ventrally flattened; dermal flap on dorsal surface of pelvic-fin rays in males, more commonly along unbranched thick ray and first branched rays.Pectoral and pelvicfin unbranched thick ray with odontodes on lateral and ventral portions.Anal fin rays i,5, posterior margin straight; unbranched thick ray with odontodes lateroventrally.Caudal fin rays i,14,i, bifurcate; lower lobe longer than upper.
Color in alcohol.Head and body light brown to dark in adults, and yellowish to dark brown in juveniles.Head, dorsum and flank with inconspicuous dark blotches, absent in some specimens.Dorsal, pectoral, pelvic, anal, and caudal fins with irregular series of dark bands on branched rays and usually conspicuous blotches in unbranched rays.Juveniles and some adults with five transverse dark bars: first and second inconspicuous, first through supraoccipital, second at dorsal-fin origin; third at dorsal-fin end; fourth at adipose fin; last at posterior portion of caudal peduncle.Head usually with two light, short and parallel lines anterior to nares, bordering naked area on tip of snout; sometimes another stripe between nares, generally absent in young individuals smaller than 50 mm SL.Orbital margin lighter, mainly on superior and posterior portions.Small, usually conspicuous, light spot on interorbital space.
Sexual dimorphism.Males with conspicuous urogenital papilla immediately posterior to anus (vs.absent in females); dermal flap on dorsal surface of the unbranched thick ray and branched pelvic-fin rays, less developed in branched rays (vs.absent in females); males with 14-20 teeth in the premaxilla and 13-18 in the dentary (vs.30-39 and 30-38 in females); females with larger mandibullary width, 18.5-21.6% of the head length (vs.11.8-15.7% in males), and teeth longer and thin in females (vs.shorter and robust in males) (Fig. 3).

Discussion
The wide geographic distribution of taxa such as Neoplecostomus paranensis was reported by Bizerril (1996) as possible cases of species complexes.Neoplecostomus paranensis was until very recently the only species occuring in a wide range in the upper rio Paraná basin; however, a review made by Zawadzki et al. (2008) redescribed N. paranensis and described three new species; latter Roxo et al. (2012a) described three additional species.Those two papers increased by almost 100% the total number of the species in the genus, also suggesting that its diversity may be greater than previously observed.
Morphological character sets which to date proved effective to differentiate species relate to body plates (e.g., N. ribeirensis having a divided canal plate and the spinelet absent or narrower than the dorsal-fin unbranched thick ray, and N. bandeirante having the first plates in the mid-ventral series shorter than the naked area between them), and sexual dimorphism as proposed by Zawadzki et al. (2008) for N. selenae and N. yapo (adult males having large odontodes and swelling of skin on the lateral margins of the snout).Sexual dimorphism was also informative to diagnose Neoplecostomus jaguari, as reported above for some morphological features related to the number and form of teeth and mandibulary width, that until now were never referred to any other species of Neoplecostomus or even Neoplecostominae.Related to this, our analysis have shown that some of these dimorphims also occur in N. langeanii, the putative most related species to N. jaguari; these dimorphisms, however, were not reported in the original description of that species by Roxo et al. (2012a).These features such as the dimorphic ones, as already stated by Roxo et al. (2012a), are more apparent or only present in mature specimens, and consequently samples lacking such specimens, relatively common in ichthyological collections, make identification of species difficult.Distribution.The species is known from the ribeirão do Forja and from córrego Casca d'Antas, both tributaries from the rio Jaguari, sub-basin from the rio Piracicaba-Capivari-Jundiaí, rio Tietê drainage, upper rio Paraná basin (Fig. 4).
Etymology.The specific epithet jaguari is a reference to the rio Jaguari, basin which ribeirão do Forja and the córrego Casca d'Antas belong.The epithet jaguari, from the Tupi Guarani, meaning river of jaguar ('onça').
The upper rio Paraná basin is the second largest basin in the South America, the largest one in the Brazilian Cristaline Shield and, because of that, harbors a larger number of Neoplecostomus species when compared to other basins in the shield.We can, however, suppose a similar situation in those other basins, which also drain large geographic extensions in the area; consequently, material from such other basins is currently being analyzed in more detail in order to reveal putative undiscovered diversity.
Dorsal body surface completely covered by plates, except for naked area around dorsal-fin base.Snout tip without plates and odontodes.Head naked ventrally except by canal plate bearing odontodes directed mesially in front of gill openings.Head wide and moderately depressed.Head and snout slightly obtuse in specimens smaller than 50 mm SL in dorsal view and slightly rounded in specimens larger than 50 mm SL.Abdomen with conspicuous small platelets between pectoral and pelvic-fin insertions, forming thoracic shield surrounded by naked areas.
H. Zawadzki, B. F. Morales & V. S. Ferreira.Diagnosis.Neoplecostomus jaguari can be distinguished from all species of Neoplecostomus by having a conspicuous sexual dimorphism: females with 30-38 teeth in the dentary and 30-39 in the premaxilla, and males with 13-18 and 14-20 teeth respectively (vs.number of teeth in the premaxilla and dentary equivalent in all other species, except for N. langeanii in the premaxilla); females with larger MW, 18.5-21.6%HL, males 11.8-15.7%HL (vs.females and males with MW/HL equivalent in the other species); females with teeth longer and thin, males with teeth shorter and robust (vs.teeth similar in males and females in all other species, except for N. langeanii in the premaxilla).Furthermore the new species is distinguished from all other species from the upper rio Paraná basin by having a lateronasal plate either forming the lateral border of the nostril or posteriorly displaced (vs.lateronasal plate absent).Finally, other useful character includes four to six plates between the frontal and prefrontal, here called posteronasal plates (vs.one to three in all other species).