Neoplecostomus yapo, 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 : 40-42

Neoplecostomus yapo , n. sp.

Figure 5 ; Table 1

Holotype. DZSJRP 6714 [male], 97.4 mm SL, Paraná State, Tibagi, Riacho Fortaleza (Fazenda Santo Amaro), affluent of Rio Yapó , Rio Tibagi basin, 18 February 2002, A.M. Gealh and K. de Geus.

Paratypes. (same data as the holotype) DZSJRP 6194, 6 [3 m, 3 f], 69.3–105.2 mm SL; MZUSP 86211, 7 [5 m, 2 f], 63.8–105.2 mm SL; NUP 3569, 6 [3 m, 3 f], 68.6–106.34 mm SL; NUP 2609, 15 (not measured) [6 m, 9 f], 48.4–109.6 mm SL.

Diagnosis. Neoplecostomus yapo can be diagnosed from its congeners, excepting N. selenae , by having enlarged odontodes and distinct swollen skin along lateral margins of snout in mature males (vs absent); from N. selenae by lacking enlarged odontodes and distinct swollen skin along ridges before eyes (vs present). It can be further distinguished from N. corumba by having greater mandibullary width/HL (14.1–15.2 vs 16.3– 18.1); from N. selenae by having smaller cleithral width/SL (24.1–27.2 vs 27.5–30.2), and smaller caudalpeduncle depth/SL (6.0–6.3 vs 6.7–7.7); from N. paranensis by having well-developed adipose fin (vs illdeveloped or absent), and greater mandibullary width/HL (14.1–15.2 vs 8.4–12.4); from N. espiritosantensis by having greater orbital diameter/HL (11.9–12.9 vs 6.0–9.0), 10–15 premaxillary teeth (vs 19–38), and 08– 12 dentary teeth (vs 15–35); 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 29 lateral-line plates (vs 34–43), smaller caudal-peduncle depth/SL (6.0–6.3 vs 7.0–10.0), greater orbital diameter/HL (11.9– 12.9 vs 9.0–11.0), and 8–12 dentary teeth (vs 11–14); from N. microps by having a greater thoracic length/SL (15.8–17.4 vs 10.0–15.0), greater orbital diameter/HL (11.9–12.9 vs 8.0–11.0), and greater mandibullary width/HL (14.1–15.2 vs 7.0–13.0); and from N. variipictus by having greater head length/SL (28.7–31.9 vs 26.2–26.8), smaller caudal-peduncle depth/SL (6.0–6.3 vs 7.3–7.8), smaller snout length/HL (59.3–65.0 vs 66.7–68.9), and greater orbital diameter/HL (11.9–12.9 vs 9.1–9.9).

Description. Counts and measurements are presented in Table 1 . Body elongated and depressed. Greatest width at cleithrum, narrowing to caudal-fin base. Dorsal body profile gently convex, elevating from snout tip to dorsal-fin origin and descending to first caudal-fin procurrent spine. Greatest body depth between supraoccipital process and dorsal-fin 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 depressed. Head and snout rounded in dorsal view. Interorbital space straight in frontal view. Median ridge slightly rising from snout tip to area between nares or not evident. A ridge from naris to superior margin of orbit. Snout gently convex in lateral profile. Mature male (DZSJRP 6194, 105.5 mm SL) with moderately enlarged odontodes and distinct swollen skin along lateral margins of snout. Eye moderately small (11.9–12.9 of HL), dorsolaterally placed. Lips well developed and rounded. Lower lip almost reaching pectoral girdle and covered with papillae, wider anteriorly; two or three 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 125–130º.

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 or slightly falcate, not reaching vertical through end of pelvic-fin rays when adpressed. Moderate to well developed and always present adipose fin, preceded by azygous plate. Pectoral fin with six branched rays and a depressed and inward curved spine (more pronounced in larger specimens) shorter than longest branched ray, its posterior margin nearly straight, reaching or almost reaching anal-fin insertion when adpressed. Pelvic fin with one spine and five branched rays; its posterior margin nearly straight or slight concave, 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 slight concave. 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 yellowish. Head, dorsum, flanks and fins covered by numerous inconspicuous darker irregular 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 anterior to dorsal fin, 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 or irregular blotch on interorbital space, inconspicuous in some specimens. Few specimens with two small convergent lighter lines on suppraoccipital posterior portion, sometimes joined as a lied V with vertex forward. Body lateral portion frequently with an upper darker region and a lower lighter one, just below lateral line, sometimes very evident.

All fins, except adipose fin, with irregular series of dark dots on rays, sometimes forming irregular, diffused, transverse stripes; adipose fin generally dark on laterals and light on dorsal portion of spine. Ventral surface of head and body mostly unpigmented, except for some brown, faded and scattered chromatophores on lateral margins of body from pelvic fin to caudal-fin base; upper lip dark brown, except for its light narrow margin.

Etymology. The specific name refers to the Rio Yapó , drainage of the type-locality. It is treated as a noun in apposition. The word “ yapo ” in Tupi language means flooded area or marsh.

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

Remarks. One lot of this new species collected at type-locality (NUP 2609) contains various eviscerated paratype specimens neither measured nor counted.

Figures

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

FIGURE 5. Neoplecostomus yapo, holotype, DZSJRP 6714, [male], 97.4 mm SL.