Neoplecostomus selenae, Zawadzki, Cláudio Henrique, Pavanelli, Carla Simone & Langeani, Francisco, 2008

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 : 36-40

Neoplecostomus selenae , n. sp.

Figure 4 ; Table 1

Holotype. MZUSP 51889 [male], 101.7 mm SL, São Paulo State, Ribeirão Grande, Ribeirão das Batéias, upstream from the bridge at Ribeirão Grande to Intervales road, affluent of the Rio Paranapanema, 24 Aug 1997, O.T. Oyakawa and A. Akama.

Paratypes. (same data as the holotype) DZSJRP 7449, 4 [2 m, 2 f], 56.5–95.8 mm SL; MZUSP 51873, 3 [1 m, 2 f], 52.3–66.1 mm SL; MZUSP 52589, 4 [f], 42.8–64.9 mm SL; NUP 3572, 5 [1 m, 4 f (smallest not measured)], 48.0– 84.8 mm SL.

Diagnosis. Neoplecostomus selenae can be distinguished from its congeners, excepting N. yapo , by having enlarged odontodes on distinct swollen skin along snout lateral margins in mature males (vs absent); from N. yapo it differs by having enlarged odontodes along ridges before the eyes in mature males (vs absent). Besides these characteristics, N. selenae is diagnosed from N. corumba and N. yapo by having greater mandibullary width/HL (19.9–21.8 vs 16.3–18.1 and 14.1–15.2, respectively), and greater caudal peduncle depth/ SL (6.7–7.7 vs 6.0–6.5 and 6.0–6.3, respectively); from N. paranensis by having well-developed adipose fin (vs reduced or absent), and greater orbital diameter/HL (12.1–12.7 vs 7.9–12.0); from N. franciscoensis and N. ribeirensis by having well-developed dorsal-fin spinelet, wider than dorsal-fin spine base (vs absent or narrower than dorsal-fin spine base); from N. granosus by having 28–30 lateral line plates (vs 34–43), and greater orbital diameter/HL (12.1–12.7 vs 9.0–11.0); from N. microps by having greater orbital diameter/HL (12.1–12.7 vs 8.0–11.0), and 15–24 dentary teeth (vs 5–12); and from N. variipictus by having smaller snout length/HL (57.4–65.0 vs 66.7–72.0), greater orbital diameter/HL (12.1–12.7 vs 9.1–9.9), 17–24 premaxillary teeth (vs 12–14), and 15–24 dentary teeth (vs 7).

Description. Counts and measurements are presented in Table 1 . Body relatively short and depressed. Greatest width at cleithrum, narrowing to caudal peduncle. Dorsal body profile gently convex, elevating from snout tip to dorsal-fin origin and descending to first caudal-fin procurrent spine. Greatest body depth at dorsalfin origin. Trunk and caudal peduncle dorsally rounded in cross-section; body ventrally flattened to anal-fin origin, flattened to slightly rounded 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 moderately depressed. Head and snout rounded in dorsal view in larger specimens, and slightly obtuse in smaller ones. Interorbital space slightly concave in frontal view. A weak ridge from snout tip to area between nares, sometimes absent, more evident in larger specimens. A weak ridge from middle of snout to superior margin of orbit. Snout gently convex in lateral profile. Mature males with moderately hypertrophied odontodes and swollen skin along lateral margins of snout sides, head anterior portion, and along ridge in front of eye. Eye moderately small (12.1–12.7 of HL), dorsolaterally placed. Lips well developed and rounded. Lower lip relatively small, not reaching pectoral girdle and covered by papillae, wider anteriorly; one or two irregular and conspicuous rows of large and transversally flattened papillae, just posterior to dentary teeth. Maxillary barbel short and coalesced with lower lip, generally with free tip. Teeth long, slender and bicuspid; mesial cusp longer than lateral. Dentary rami forming an angle of approximately 95º.

Dorsal-fin origin slightly posterior to vertical passing through pelvic-fin origin; nuchal plate not covered by skin; dorsal-fin spinelet half-moon shaped 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, surpassing vertical through end of pelvic-fin rays when adpressed. Moderate to well developed and always present adipose fin, generally preceded by one or, rarely, two azygous plates. Pectoral fin with six branched rays and a depressed and inward curved spine (more curved in larger specimens), shorter than longest branched ray, its posterior margin nearly straight, reaching or almost reaching first third pelvic-fin length when adpressed. Pelvic fin with one spine and five branched rays; its posterior margin nearly straight, almost reaching anal-fin origin 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. Caudal fin 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 only ventrally.

Color in alcohol. Ground color of dorsal surface of head and body light brown. Head, dorsum, flanks and fins covered by many coalescent 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 dark bars: the first through supraoccipital, the second at dorsal-fin origin, the third at dorsal-fin end, the fourth at adipose fin, and the last at caudal-peduncle posterior portion. Head usually with two light, short and parallel lines anterior to nares, bordering the naked area on snout tip. Orbital margin lighter, mainly on its superior portion. Small light spot on interorbital space, inconspicuous in some specimens. Few specimens with two small convergent light lines on suppraoccipital posterior region, sometimes joined as a lied V with vertex forward. In some specimens, body lateral portions with a longitudinal line dividing upper darker region from lower lighter one, running just below lateral line. All fins with dark dots forming irregular transverse stripes on rays, except adipose fin which is generally dark on laterals and light on dorsal portion of spine.

Ventral surface of head and body mostly unpigmented, except for some brown, faded, scattered chromatophores on body lateral margins and from pelvic fin to caudal-fin base; upper lip entirely dark, except for its light narrow margin.

Etymology. The specific name, selenae , is in honor to Selena Canhoto Zawadzki, C.H. Zawadzki’s daughter.

Distribution. Neoplecostomus selenae is only known from the type-locality ( Fig. 3 ).

Figures

FIGURE 3. The type localities of N. corumba (dot), N. selenae (lozenge), N. yapo (star), and N. paranensis (triangle).

FIGURE 4. Neoplecostomus selenae, holotype, MZUSP 51889, male, 101.7 mm SL.