Serrapinnus lucindai Jerep & Malabarba, 2014

Malabarba, Luiz R. & Jerep, Fernando C., 2014, Review of the species of the genus Serrapinnus Malabarba, 1998 (Teleostei: Characidae: Cheirodontinae) from the rio Tocantins-Araguaia basin, with description of three new species, Zootaxa 3847 (1), pp. 57-79 : 64-67

Serrapinnus lucindai Jerep & Malabarba n. sp.

Figs. 2c–d , 4b , 5b , 6 , 7

Holotype. UFRGS 19198 , 21 , 1 mm SL, Município de Piranhas, tributary of rio Piranhas , between Piranhas and Bom Jardim de Goiás, 16°21’43.3”S 51°55’10.2972”W, 7 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep.

Paratypes. All from Brazil, rio Tocantins-Araguaia basin. Goiás State: UFRGS 12029 , 14 , 14.7–29.6 mm SL, Município de Aragarças , córrego Capivara , between Aragarças and Jussara, 15°54’34.5”S 52°5’34.6”W, 5 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. UFRGS 16444 , 7 , 22.5–26.3 mm SL, Município de Jussara , tributary of rio Claro , 15°58’0.0”S 50°48’59.7”W, 6 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. UFRGS 16445 , 35 , 15.3–25.2 mm SL, collected with holotype. Tocantins State: UFRJ 2128, (3, 19.6–22.8 mm SL), Ilha do Bananal , Fazenda Canguçu , margin of rio Javares , 17 Feb 1994, W. Costa, G. Brasil & C. Campinha. UNT 4135 , 3 , 18.3–22.5 mm SL, Município de Brejinho de Nazar , córrego Sussuarana , 15 Feb 2002, NEAMB-UFT. UNT 4136 , 2 , 21.3–21.4 mm SL, Município de Guara , córrego Barreiro , 20 Oct 2000, NEAMB-UFT. UNT 4137 , 1 , 20.0 mm SL, Município de Lageado , rio Tocantins , close to UHE Lageado , rio Tocantins bottleneck, 27 Jan 2000, NEAMB-UFT. UNT 4745 , 1 , 25.3 mm SL, Município de Paraná , córrego Lageado , 7 Aug 2000, NEAMB-UFT. UNT 4759 , 5 , 16.1–19.7 mm SL, Município de Peixe , Fazenda Água Branca , lagoa Dionísio , 11 Sep 2001, NEAMB-UFT. UNT 6630 , 4 , 17.7–18.9 mm SL, Município de Tocantinópolis , córrego Santana , 29 Jun 2000, NEAMB-UFT. UNT 6927 , 1 , 21.7 mm SL, Município de Porto Nacional , rio Tocantins , 8 Oct 2002, NEAMB-UFT. UNT 7328 , (1, 25.6 mm SL), Município de Porto Nacional , Fazenda Don Augusto , rio das Éguas, 19 Sep 2002, NEAMB-UFT. Mato Grosso State: MCP 40302, 44 , 10.7–27.9 mm SL, Município de Porto Alegre do Norte , rio Xavantino 16 km south of Porto Alegre do Norte in highway BR 158 , 11°01’30’’S 51°38’47’’W, 27 Oct 2005, J. P. Silva. UFRGS 12020 , 7 , 23.5–24.7 mm SL, Mato Grosso, Município de Pontal do Araguaia , stream tributary of rio das Garças, 15°54’27.9”S 52°15’51”W, 8 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. UFRJ 1260, 58, 15.9–34.5 mm SL, (22, 22.1–34.5 mm SL, 4c&s 24.8–25.4 mm SL), creek 13 km west of rio das Mortes, left margin, between Água Boa and Cocalinho, 20 Feb 1993, W. Costa, C. Bore, R. Cunha & C. Muratori .

Diagnosis. Serrapinnus lucindai is primarily distinguished from its congeners by the 17 to 19 ventral procurrent caudal-fin rays (vs. less than 17). Furthermore, the species can also be diagnosed from the remaining species of the genus by the presence of anal-fin hooks on the first unbranched and five branched rays of mature males (vs. anal-fin hooks on at least the anterior six branched rays on the remaining species of the genus), the absence of a continuous mid-lateral black stripe extending from the opercular region to the caudal-peduncle spot (vs. presence of a stripe in S. sterbai ), the presence of 9 to 11 cusps on the premaxillary teeth (vs. 5 in S. microdon and S. potiguar , 7 in S. aster , 7 to 9 in S. calliurus , S. heterodon , S. kriegi , S. micropterus , S. notomelas and S. piaba , and 10 to 12 in S. gracilis and S. littoris ), the dentary teeth without expanded cusps forming a sharp cutting edge and the incomplete lateral line (vs. dentary teeth with expanded cusps forming a sharp cutting edge and complete lateral line in S. heterodon ), the hyaline dorsal fin (vs. fin with a proximal black blotch in S. notomelas ), and an absence of a black spot in the posteroventral region of the abdomen (vs. the presence of a black spot in that region in S. kriegi ).

Description. Morphometric data in Table 2. Body elongated and compressed. Greatest body depth at dorsal-fin origin. Dorsal profile of head strongly convex from tip of snout to vertical through anterior margin of anterior nares; gently convex from that point to base of supraoccipital process, then straight to slightly concave along length of supraoccipital process. Predorsal profile convex. Profile straight to slightly convex along dorsal-fin base. Dorsal profile from last dorsal-fin ray insertion to adipose fin slightly convex in immatures and females, deeply convex in adult males with ventrally arched caudal peduncle. Dorsal profile straight to slightly concave from end of adiposefin base to anteriormost dorsal procurrent caudal-fin ray. Ventral profile of head convex along anterior region of lower jaw, gently convex from that point to pelvic-fin insertion. Ventral region straight to slightly concave from pelvic-fin insertion to anal-fin origin in immatures and females, deeply concave in mature males. Anal-fin base slightly concave in immatures and females; conspicuously convex in mature males along anterior region supporting hypertrophied anal-fin rays and then straight posteriorly. Ventral profile of caudal-peduncle slightly concave in immatures and females, convex in mature males due to hypertrophied procurrent caudal-fin rays extending ventrally through muscle and skin. Caudal peduncle slightly longer than deep; ventrally arched in alcohol preserved mature males. Posterior margin of opercle sinusoidal with upper portion concave and lower portion convex. Mouth terminal; mouth slit on horizontal through middle of pupil. Maxilla angled posteroventrally; posterior tip falling short of vertical through anterior border of eye and horizontal through ventral border of eye. All teeth multicuspidate, pedunculate, compressed and distally expanded ( Fig. 7 ). Premaxillary teeth 4(4), with 9 to 11 cusps; central cusp slightly longer and wider than lateral cusps. Two (3) or 3(1) maxillary teeth with 5 to 11 cusps. Large dentary teeth 4(2) or 5(2) with 7 to 9 cusps, followed by one (4) tooth with 5 cusps, and 1 to 3 smaller teeth with 1 to 3 cusps. Small lateral cusp of dentary teeth overlapping adjacent tooth cusps, other than on posterior teeth. All dentary tooth cusps pointed upward or slightly recurved towards interior of mouth.

Dorsal-fin rays ii,9*(31). Dorsal-fin origin slightly anterior to vertical through midlength of SL. First unbranched dorsal-fin ray about half length of second unbranched dorsal-fin ray. Second unbranched dorsal-fin ray longest in fin; branched rays slightly decreasing in size posteriorly. Adipose-fin origin on vertical through base of last anal-fin ray in females and posterior to that point in males. Anal-fin origin posterior to vertical through base of last dorsal-fin ray. Anal-fin rays iii*-iv,17*(2), 18(9), 19(13), 20(5) or 21(2). Distal border of anal-fin concave; last unbranched and anterior 5–8 branched rays longer than posterior rays. Tip of longest ray of depressed anal-fin of mature males falling short vertical through base of last anal-fin ray. Males with acute, elongate, retrorse hooks on distal half of anal-fin rays. Hooks posterolaterally arranged on last unbranched to 4 th or 5 th, rarely 7 th* (2) branched rays ( Fig. 4b ). Two or three unpaired hooks per ray segment of each contralateral lepidotrichia. Hooks generally located on posterior margin of posterior branches of anal-fin rays. Hook bearing anal-fin ray segments and branches progressively fused in course of maturation of males. Mature males with hypertrophied soft whitish tissue on interradial membrane anterior to anal-fin hooks. Pectoral-fin rays i,9*(19) or 10(12). Tip of pectoral fin falling short of pelvic-fin origin in immatures and females, but extending beyond that point in mature males. Pelvic-fin rays i,6(3) or 7*(28). Pelvic-fin origin slightly anterior to dorsal-fin origin. Longest pelvic-fin ray falling short of anal-fin origin in immatures and females, but extending beyond that point in adult males. Males with one or two acute elongate and ventral-medially placed hooks per segment of lepidotrichia on branched pelvic-fin rays. One specimen with hook on unbranched pelvic-fin ray. Adult males with hypertrophied soft whitish tissue anterior to hooks on ventral surface of pelvic-fin. Principal caudal-fin rays 18(1), 19*(29) or 20(1). Procurrent caudal-fin rays: dorsal 12(1), 13(1), 14(1) or 15(1); ventral 17(1), 18(2) or 19(1). Adult males with ventral procurrent caudal-fin rays hypertrophied, typically fused to each other and distal tips extending through ventral muscles and skin of caudal-peduncle ( Figs. 2c , 6 ). Hypertrophied ventral procurrent caudal-fin rays elongated, rod-shaped, straight, proximally acute and round to flat distally.

Scales cycloid; similar in size over all of body. Lateral line partially pored with 8*(13), 9(13) or 10(5) pored scales and 31(6), 32*(12), 33(7) or 34(6) in lateral-line scale series. Predorsal series in regular row 10(3), 11*(21) or 12(7). Scale rows between lateral line and dorsal-fin origin 5*(27) or 6(4). Scale rows between lateral line and pelvic-fin origin 4*(28) or 5(3). Scale rows around caudal peduncle 12(5), 13(11) or 14*(15). Axillary scale on pelvic-fin base extending posteriorly for one or two scales. Scales along anal-fin base 9(1), 10(3), 11(15), 12(7), 13(3) or 14(1).

Counts based on four clear and stained specimens: Supraneurals 4(4); abdominal vertebrae 15(2) or 16(2); caudal vertebrae 17(2) or 18(2).

Color in alcohol. Overall ground coloration of body pale yellow; darker dorsally from head to end of caudal peduncle. Body with faint dark, rarely silver, midlateral stripe. Longitudinal stripe extending from region slightly anterior to vertical through dorsal-fin origin to light pigmented area preceding caudal spot. Scale series above longitudinal line with higher concentration of darker chromatophores. Abdominal region ventral to longitudinal line lighter. Caudal spot rounded and black, preceded by lightly pigmented area and situated over posterior portion of caudal peduncle and base of central portion of caudal fin, not reaching dorsal or ventral margins of caudal peduncle. Fins mostly hyaline with scattered, sparse dark chromatophores. Dorsal fin with higher concentration of dark chromatophores along unbranched and first branched rays. Adipose fin with few sparse dark chromatophores. Caudal fin with dark chromatophores along fin rays, except for clear areas at base of each caudal-fin lobe. Humeral region with triangular, dark area resulting from pseudotympanum within musculature ( Fig. 6 ).

Sexual dimorphism. Mature males of S. lucindai have caudal peduncle ventrally arched, as in other species of Serrapinnus . Males also have hooks on the pelvic and anal-fin rays. The hook bearing anal-fin rays are hypertrophied, expanded in the sagittal plane, and commonly have the ray segments fused. The ventral procurrent caudal-fin rays of mature males are hypertrophied and extend ventrally beyond caudal peduncle muscle and skin ( Figs. 2c–d , 4b , 6 ).

Distribution. Serrapinnus lucindai is distributed in several tributaries of the rio Tocantins-Araguaia basin ( Fig. 5b ).

Etymology. The species name lucindai is in honor to the Brazilian ichthyologist Paulo Henrique Franco Lucinda (UNT), in recognition of his contribution to the taxonomy of Neotropical freshwater fish, mainly those of the rio Tocantins basin.

Figures

FIGURE 2. Ventral procurrent caudal-fin rays of species of Serrapinnus from the rio Tocantins-Araguaia basin. (a) Serrapinnus aster, male, UFRGS 12023, 26.9 mm SL; (b) S. aster, female, UFRGS 12023, 35.7 mm SL; (c) S. lucindai, male, UFRJ 1260, 24.9 mm SL; (d) S. lucindai, female, UFRJ 1260, 25.9 mm SL; (e) S. sterbai, male, UFRGS 16447, 28.7 mm SL; (f) S. sterbai, female, UFRGS 16447, 29.6 mm SL; (g) S. tocantinensis, male, MCP 40417, 31.6 mm SL; (h) S. tocantinensis, female, MCP 40417, 33.4 mm SL. Lateral view, anterior to left. Scale bar = 1 mm.

FIGURE 4. Anal fin of mature males of the species of Serrapinnus from rio Tocantins-Araguaia basin showing hypertrophied anal-fin rays and hooks shape and distribution. (a) Serrapinnus aster, male, UFRGS 12023, 26.9 mm SL; (b) S. lucindai, male, UFRJ 1260, 24.9 mm SL; (c) S. sterbai, male, UFRGS 16447, 29.7 mm SL; (d) S. tocantinensis, male, MCP 40417, 31.6 mm SL. Lateral view, anterior to left. Arrow head pointing to ligaments connecting approximately midlength of posterior face of proximal segment of lepidotrichia to proximal anterior face of lepidotrichia of the subsequent ray. Scale bar = 1 mm.

FIGURE 5. Geographic distribution of the species (a) Serrapinnus aster (black stars; white star in black dot = type locality), (b) S. lucindai (black triangles; white triangle in black dot = type locality), (c) S. sterbai (black dots) and (d) S. tocantinensis (black lozenges; white lozenge in black dot = type locality) in rio Tocantins-Araguaia basins. Some symbols represent more than one locality.

FIGURE 6. Serrapinnus lucindai (a) holotype, male, UFRGS 19198, 21.1 mm, córrego Fundo, tributary of rio das Garças, Município de Barra do Garças, Mato Grosso, Brazil; (b) paratype, female, UFRGS 16445, 20.1 mm SL, same data as holotype.

FIGURE 7. Serrapinnus lucindai, UFRJ 1260, 25.1 mm SL; Scanning Electron Microscopy images showing (a) left side premaxilla; (b) maxilla; (c) dentary, and (d) detail of the dentary teeth.