Neoplecostomus paranensis Langeani, 1990

Zawadzki, Cláudio Henrique, Pavanelli, Carla Simone & Langeani, Francisco, 2008, Neoplecostomus (Teleostei: Loricariidae) from the upper Rio Paraná basin, Brazil, with description of three new species, Zootaxa 1757, pp. 31-48 : 42-44

Neoplecostomus paranensis Langeani, 1990

Figure 6 ; Table 1

Holotype. MZUSP 38572, male, 72.2 mm SL, São Paulo State, Cajuru, Rio Cubatão, Santa Carlota farm, 13 Apr 1986, Exc. Dept. Zoologia FFCLRP-USP.

Paratypes. MZUSP 10213, 2 [f], 39.4–41.5 mm SL, Minas Gerais State, Carandaí, Rio Carandaí, 7 Sep 1973, H. A. Britski; MZUSP 35397, female, 38.4 mm SL, Minas Gerais State, Fortaleza de Minas, stream affluent of Rio São João, road between Fortaleza de Minas and Perobas, 16 Jan 1986, Z. C. M. Vasconcelos and F. Langeani; MZUSP 35822–35824, 3 [m], 68.3–92.8 mm SL, same data as the holotype; MZUSP 36583, 4 [undetermined], 36.3–62.4 mm SL, same data as the holotype; MZUSP 36625, female, 56.0 mm SL, Brasília, Distrito Federal, Ribeirão Papuda, affluent of Rio São Bartolomeu, Sep 1985, M. Ribeiro et al.

Diagnosis. Neoplecostomus paranensis can be distinguished from its congeners by having adipose fin absent or ill-developed (vs moderate to well developed and always present adipose fin). In addition, N. paranensis can be separated from N. corumba , N. selenae and N. yapo by having smaller mandibullary width/HL (8.4–12.4 vs 14.1–21.8) and from selenae and N. yapo by lacking enlarged odontodes and distinct swollen skin along lateral margins of snout in mature males (vs present); from N. espiritosantensis by possessing 8-15 dentary teeth (vs. 19-38); from N. franciscoensis and N. ribeirensis by having well-developed dorsal-fin spinelet, wider than dorsal-fin spine base (vs absent or narrower); from N. granosus by having 28–30 lateralline plates (vs 34–43); and from N. variipictus by lacking conspicuous roundish dark dots over body and fins (vs present).

Description. Counts and measurements are presented in Table 2. Body elongated and depressed. Greatest width at anterior portion of cleithrum, narrowing to caudal-fin base. Dorsal body profile gently convex, elevating from snout tip to dorsal-fin origin and descending slightly concave from dorsal-fin origin to adipose fin, descending straight from adipose fin to first caudal-fin procurrent spine. Greatest body depth at dorsal-fin origin. Trunk dorsally rounded in cross section; caudal peduncle dorsally rounded to slightly depressed; body ventrally flattened to anal-fin origin, flattened to slightly round to caudal fin. Dorsal body surface completely covered by dermal plates, excepting for a naked area around dorsal-fin base. Snout tip naked. Ventral head surface naked except by a plate bearing odontodes in front of gill openings. Abdomen with conspicuous, small dermal platelets between insertions of pectoral and pelvic fins, forming a thoracic shield surrounded by naked areas.

Head wide and depressed, somewhat triangular in dorsal view. Interorbital space straight in frontal view. Median ridge from snout tip to nares weak or not evident. A weak ridge from middle of snout to superior margin of orbit. Snout convex in lateral profile. Eye moderately small (7.9–12.0 of HL), dorsolaterally placed. Lips roundish and relatively small compared to other species. Lower lip covered by papillae, wider anteriorly, and not reaching horizontal line through opercular-membranes ventral insertion; two irregular and conspicuous rows of large and transversally flattened papillae, just posterior to dentary teeth. Maxillary barbel laterally coalesced with lower lip, with free tip in some specimens. Teeth long, slender and bicuspid; mesial cusp longer than lateral. Dentary rami forming an angle of approximately 130o.

Dorsal-fin origin posterior to vertical passing through pelvic-fin origin; nuchal plate not covered by skin; dorsal-fin spinelet rectangular and wider than dorsal-fin spine base; dorsal-fin locking mechanism absent. Dorsal-fin with spine flexible, followed by seven branched rays; its posterior margin straight or slightly concave, reaching or surpassing vertical through pelvic-fin end when adpressed. Adipose fin absent or ill developed, small, with adipose spine shorter than fin membrane; in some specimens just an azigous plate at adipose fin place. Pectoral fin with six branched rays, and with depressed and inward curved spine (more pronounced in larger specimens), shorter than longest branched ray, its posterior margin nearly straight, reaching or almost reaching half pelvic-fin length when adpressed. Pelvic-fin with one depressed and curved spine and five branched rays; its posterior margin nearly straight, reaching anal-fin insertion when adpressed. Pelvic-fin spine ventrally flattened, with dermal flap on its dorsal surface in males. Anal fin with one flexible spine and five branched rays, its posterior margin straight or slightly concave. Caudal fin moderately bifurcate, lower lobe longer than upper; 14 branched rays. Pectoral and pelvic-fin spines with odontodes on lateral and ventral portions. Anal-fin spine with odontodes laterally and ventrally.

Color in alcohol. Ground color of dorsal surface of head and body yellowish or light brown. Head, dorsum, flanks and fins covered by inconspicuous darker dots or blotches of variable shapes and sizes. Dorsal color pattern, even in mature larger individuals, retains the generic juvenile color pattern of five transverse darker bars: the first, inconspicuous, through supraoccipital, the second at dorsal-fin origin, the third at dorsalfin base end, the fourth at adipose fin, and the last at caudal-peduncle posterior portion. Head usually with two light lines from snout to nares. Orbital margin lighter, mainly on its anterior and superior portion. Small light, sometimes inconspicuous spot on interorbital space. Lateral body portion usually with an upper darker region and a lighter lower one. Ventral surface of head and body mostly unpigmented, excepting some brown, faded and scattered chromatophores on upper lip.

Dorsal fin with irregular dark dots series on rays. Pectoral, pelvic, anal, and caudal fins with dark dots forming irregular transverse stripes on rays; pectoral and pelvic fins also with some scattered small chromatophores along membrane. Adipose fin generally dark laterally and light on spine dorsal portion.

Distribution. Neoplecostomus paranensis occurs in headwater streams of Grande, Paranapanema, Tietê, and Paranaíba rivers in the upper Rio Paraná system (see discussion for details).

Figures

FIGURE 6. Neoplecostomus paranensis, holotype, MZUSP 38572, male, 72.2 mm SL.