Serrapinnus tocantinensis Malabarba & Jerep, 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 : 71-75

Serrapinnus tocantinensis Malabarba & Jerep n. sp.

Figs. 2g –h , 4d , 5d , 10 , 11

Holotype. UFRGS 16442 , 32.5 mm SL, male, Brazil, Mato Grosso, Município de Barra do Garças, córrego Fundo , tributary of rio das Garças, 16°52’40.5’’S 52°18’15.1’’W, 8 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep.

Paratypes. All from Brazil, rio Tocantins-Araguaia basin. Goiás State: MCP 19987, 3 , 33.5 –37.0 mm SL, rio Tocantins, 3 km down on Serra da Mesa Dam , Município de Minaçú , 13°50’51’’S 48°16’60’’W, 6 Nov 1996, C. A. S. Lucena & J. F. P. Silva. MCP 19988, 8 , 28.5–37.3 mm SL (6, 34.8–37.5 mm SL), rio Tocantins, at porto do Rubão , Município de Minaçú , 13°44’31’’S 48°8’29’’W, 7 Nov 1996, C. A. S. Lucena & J. F. P. Silva. MCP 42175, 1 , 25.0 mm SL, headwaters of córrego Salobrona , tributary of rio Claro , Município de Montes Claros de Goiás, 16°02’38’’S 51°22’11’’W, 5 Jun 2007, G. A. Pereira. MCP 42269, 2 , 24.8–31.6 mm SL, córrego Salobrona , tributary of rio Claro , Município de Montes Claros de Goiás, 15°56’19’’S 51°20’58’’W, 5 Jun 2007, G. A. Pereira. MCP 42360, 6 , 16.0– 29.4 mm SL, córrego Varginha , tributary of rio Claro , Município de Montes Claros de Goiás, 15°57’52’’S 51°18’40’’W, 5 Jun 2007, G. A. Pereira. MZUSP 4826 , 33 , 14.1–32.6 mm SL, rio Araguaia , Município de Aruan , 15–19 Sep 1966, Exc. DZ. MZUSP 40362 , 27 , 23.6–29.8 mm SL, 4c&s, 26.0– 30.1 mm SL (6, 26.6–29.9 mm SL), marginal lagoon of riacho Seco , close to bridge on highway GO 447, Município de Galheiros , 14 Jan 1989, J. C. Oliveira & W. Costa. MZUSP 40378 , 36 , 13.2–21.8 mm SL, rio Macacos (also Macaquinhos), tributary at right margin of rio Paraná, Fazenda Fortaleza , Município de Flores de Goiás, 10 Sep 1988, J. C. Oliveira & W. Costa. MZUSP 40497 , 12 , 14.3–21.9 mm SL, rio Paraná, waterfall at Fazenda Olho d`Água, Município de Flores de Goiás, 12 Sep 1988, J. C. de Oliveira & W. J. M. Costa. MZUSP 40547 , 5 , 17.9–22.2 mm SL, rio Prata , bridge on highway GO 112, Município de Iaciara , 14 Sep 1988, J. C. Oliveira & W. J. M. Costa. MZUSP 40704 , 4 , 31.1–34.2 mm SL, rio Bezerra , tributary at right margin of rio Paraná, Município de Flores de Goiás, 22 Sep 1988, J. C. Oliveira & W. Costa. MZUSP 40858 , 6 , 20.9 –26.0 mm SL, rio Paraná, between rio Macaco and rio Bezerra, Município de Monte Alegre de Goiás, Sep 1988, J. C. Oliveira & W. Costa. UFRGS 12021 , 7 , 27.9–31.3 mm SL, same data as holotype. UFRGS 12028 , 20 , 14.1–26.3 mm SL, rio das Almas, between Aragarças and Jussara, Município de Aragarças, 15°52’2.4’’S 51°38’57.7’’W, 6 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. UFRGS 12035 , 5 , 26.8–32.8 mm SL, stream tributary of rio Claro , between Aragarças and Jussara, Município de Aragarças, 15°52’10.8’’S 51°32’56.6’’W, 6 Feb 2010, V. A. Bertaco, F. R. Carvalho & F. C. Jerep. Tocantins State: MZUSP 115013 , 2 , 26.5–27.3 mm SL, temporary pond on rio Paraná and rio Bezerra confluence, Município de Arraias , 11 Jan 1989, J. C. Oliveira & W. Costa. UFRJ 1708, 24, 20.8–29.8 mm SL, tributary of rio Verde , 50 km from São Miguel do Araguaia , 28 Aug 1993, W. Costa, E. Vicente, M. Britto, F. Autran & R. D`Arrigo. UNT 4143 , 2 , 25.1–25.2 mm SL, Lagoa Dionísio, Fazenda Água Branca, Município de Peixe , 11 March 2000, NEAMB-UFT. UNT 4265 , 18 , 20.0– 26.8 mm SL, Lagoa Maranhão, Fazenda Traçada, Município de Paraná, 18 Nov 1998, NEAMB. UNT 4757 , 30 , 16.7–27.2 mm SL, Lagoa Água Branca at Fazenda Água Branca, Município de Peixe , 21 Aug 2001, NEAMB-UFT. UNT 7321 , 20 , 18.2–26.1 mm SL, rio Tocantins, Fazenda Traçada, Município de Paraná, 10 May 2000, NEAMB-UFT. Mato Grosso State: MCP 34172, (4, 29.2–31.7 mm SL), córrego Barreiro, tributary of rio São João on road to Vila Berrante, ribeirão Cascalheira 12°57’39’’S 51°40’56’’W, 28 Jul 2003, T. Carvalho & G. Carvalho. MCP 40417, 58 , 19.2–36.2 mm SL (8, 32.5–36.1 mm SL, 3c&s, 30.6–33.4 mm SL), stream on highway BR158 , 61 km south of Porto Alegre do Norte , 11°22’28’’S 51°39’42’’W, 28 October 2005, J. F. P. Silva. MCP 40473, (4, 25.9–30.3 mm SL), córrego Pium, 22 km south of Posto da Mata , on highway BR158 between Posto da Mata and Al Brasil, 11°53’58’’S 51°39’26’’W, 29 Oct 2005, J. F. P. Silva. MCP 40263, 89 , 16.1–25.4 mm SL, rio Crisostomo on highway BR158 between Vila Rica and Confresa, Município de Vila Rica, 10°14’33’’S 51°10’08’’W, 26 Oct 2005, J. F. P. Silva. MCP 44522, 62 , 9.4–20.4 mm SL, ribeirão São Marcos on highway BR158 between Confresa and Vila Rica, Município de Vila Rica, 10°06’05’’S 51°06’00’’W, 23 Apr 2006, J. F. P. Silva & L. Cotrim. MCP 44526, 32 , 9.8 –19.0 mm SL, ribeirão Santana 30 km north of Vila Rica on highway BR158 , Município de Vila Rica , 09°49’11’’S 51°03’21’’W, 23 Apr 2006, J. F. P. Silva & L. Cotrim. MCP 44527, 21 , 15.8–23.1 mm SL, rio Crisostomo on highway BR158 between Vila Rica and Confresa, 10°14’33’’S 51°10’08’’W, 22 Apr 2006, J. F. P. Silva & L. Cotrim. MCP 44530, 8 , 10.6–19.1 mm SL, rio Tapirapé , Município de Porto Alegre do Norte , 10°51’00’’S 51°37’00’’W, 22 Apr 2006, J. F. P. Silva & L. Cotrim. MCP 44532, 3 , 11.1–28.8 mm SL, rio Preto on highway BR158 , 72 km south of Porto Alegre do Norte , 11°27’47’’S 51°40’42’’W, 21 Apr 2006, J. F. P. Silva & L. Cotrim. MCP 44534, 20 , 18.6–30.1 mm SL, rio Paciguara 2 km north of Confresa on highway BR158 , Município de Confresa , 10°37’34’’S 51°32’51’’W, 22 Apr 2006, J. F. P. Silva & L. Cotrim. MCP 44535, 10 , 9.5–22.6 mm SL, rio Xavantinho 16 km South of Porto Alegre do Norte, 11°01’30’’S 51°38’47’’W, 21 Apr 2006, J. F. P. Silva & L. Cotrim. Par State: INPA 20976 , 32 , 27.9–36.4 mm SL (8, 30.6–35.1 mm SL), Igarapé Canoal, Município de Breu Branco , 12 Nov 1981, equipe de Ictiologia INPA. INPA 20977 , (6, 28.3–34.4 mm SL), Igarapé tributary of rio Sossego , Município de Parauapebas , Cana Carajás, 14 Mar 2002, G. Mendes. INPA 20978 , 13 , 18.4–32.7 mm SL (4, 29.1–31.7 mm SL), Igarapé tributary of rio Sossego , Município de Parauapebas , Cana dos Carajás, 14 Mar 2002, G. M. Santos. INPA 20979 , 7 , 24.5–35.3 mm SL, Igarapé Bacuri, 6 Jul 1982, equipe de Ictiologia INPA. INPA 20984 , 20 , 31.5–36.8 mm SL (5, 32.2–36.5 mm SL), Igarapé Bacuri, 26 Nov 1981, Eq. Ictiologia INPA. INPA 20986 , 27 , 32.4–39.8 mm SL (7, 35.0– 39.7mm SL, 3c&s, 34.3–35.0 mm SL), Igarapé Bacuri, close to DNER, 26 Nov 1981, equipe de Ictiologia INPA. MCP 24199, 8 , 28.9–32.8 mm SL, Igarapé Cinzento, tributary on left margin of rio Itacaiúnas , 05°51’1’’S 50°32’7’’W, Jul 1997, P. S. Pompeu. MZUSP 4936 , 188 , 11.4–34.6 mm SL, tributary of rio Araguaia , highway Belém-Brasilia, 30 km North of Gurupi, 31 May 1966, Expedition DZUSP. MZUSP 18144 , 30 , 21.8–29.4 mm SL, lagoon in front of Jatobal, 17 Sep 1970, EPA. Distrito Federal: USNM 292213 , 1 , 33.8 mm SL, rio Maranhão, about 35 km north of Brasília , 15°30’S 47°50’W, 14 Nov 1984, W. C. Starnes, M. Ribeiro, R. Mendonça, et al.

Diagnosis. Serrapinnus tocantinensis can be diagnosed from its congeners by the elongation of the unbranched dorsal and pelvic-fin rays into filaments in mature males. Furthermore S. tocantinensis can be distinguished from S. sterbai by the absence of a continuous mid-lateral black stripe extending from the opercular region to the caudalpeduncle spot, and from the remaining species of the genus by the presence of 9 to 11 cusps in 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 ), dentary teeth without expanded cusps forming a sharp cutting edge (vs. dentary teeth with expanded cusps forming a sharp cutting edge in S. heterodon ), hyaline dorsal fin (vs. with a proximal black blotch in S. notomelas ), and the absence of a black spot on the posteroventral region of the abdomen (vs. the presence of a black spot in that region in S. kriegi ).

Description. Morphometric data presented in Table 4. Body elongated and compressed. Greatest body depth at dorsal-fin origin. Snout anteriorly rounded in lateral profile. Dorsal profile of head gently convex from vertical through posterior margin of posterior nares to base of supraoccipital spine, then straight to slightly concave to tip of supraoccipital spine. Predorsal profile slightly convex between tip of supraoccipital spine and dorsal-fin origin. Straight to slightly convex along dorsal-fin base. Dorsal profile from insertion of last dorsal-fin ray to adipose fin slightly convex in immatures and females; deeply convex in mature males with ventrally arched caudal peduncle. Dorsal profile straight to slightly concave from adipose-fin base to most anterior dorsal procurrent caudal-fin ray. Distal tip of lower jaw convex. Ventral profile of head straight to gently convex along ventral profile lower jaw to vertical through posterior margin of eye; convex from that point to pelvic-fin origin. Ventral region from pelvic-fin insertion to anal-fin origin slightly concave to straight in immature and females; deeply concave in mature males. Anal-fin base slightly concave in immature and females; distinctly convex anteriorly and straight posteriorly in mature males. Ventral profile of caudal-peduncle slightly concave in females; distinctly convex in mature males due to hypertrophied procurrent caudal-fin rays extending ventrally through muscles and skin ( Figs. 2g –h , 10 ). Caudal peduncle slightly longer than deep; ventrally arched in alcohol preserved mature males. Head anteriorly tapered in lateral view. Posterior margin of opercle sinusoidal with upper portion concave and lower portion convex. Mouth terminal, mouth slit just below horizontal through middle of pupil. Maxilla angled posteroventrally; posterior tip reaching vertical through anterior border of orbit and horizontal through ventral border of orbit. All teeth multicuspidate, pedunculate, compressed and expanded distally ( Fig. 11 ). Premaxillary teeth 5(5) with 9 to 11 cusps; central cusp slightly longer and wider than lateral cusps. Two (4) maxillary teeth with 7 to 9 cusps. Dentary teeth 6(1), 7(2) or 8(3) with 7 to 9 cusps, rarely followed by one smaller tricuspid teeth. Lateral small cusps of dentary teeth overlapping adjacent tooth cusps; overlap usually not present on posterior teeth. All dentary tooth cusps dorsally pointed or slightly recurved towards interior of mouth.

Dorsal-fin rays ii,8(2), 9*(65). Dorsal-fin origin slightly anterior to vertical through midlength of standard length. First unbranched dorsal-fin ray about one-half length of second unbranched dorsal-fin ray. Second unbranched dorsal-fin ray longest in fin with branched rays slightly decreasing in size posteriorly. Second unbranched dorsal-fin ray elongated into small filament in mature males. Adipose-fin origin slightly anterior to vertical through base of last anal-fin ray in females and slightly posterior to that point in males. Anal-fin origin posterior to vertical through base of last dorsal-fin ray. Anal-fin rays iii–iv,15*(1), 17(2), 18(19), 19(33), 20(10) or 21(1). Distal border of anal-fin concave; last unbranched and anterior 5–6 first branched rays longest; ray length abruptly decreasing after sixth ray with remaining rays decreasing in size to end of anal fin. Distal tip of longest anal-fin ray of mature males reaching to vertical through base of last anal-fin ray; sometimes reaching ventral procurrent caudal-fin rays when caudal peduncle deeply arched. Males with acute, elongate, retrorse hooks on distal half of anal-fin rays; hooks posterolaterally arranged on last unbranched to 11 th or 17 th branched rays. Two or 3 unpaired hooks per ray segment of each contralateral lepidotrichia ( Fig. 4d ). Hooks generally situated on posterior margin of posterior ray branches. Hook bearing ray segments and branches progressively fused during maturation of males. Mature males with hypertrophied soft whitish tissue on interradial membrane anterior to analfin hooks. Pectoral-fin rays i,9*(18), 10(36) or 11(13). Pectoral-fin ray reaching pelvic-fin origin in immatures and females, but extending beyond that point in adult males. Pelvic-fin rays i,6(2) or 7*(65). Pelvic-fin origin slightly anterior to vertical through dorsal-fin origin. Pelvic fin falling short of anal-fin origin in immature and females; extending far beyond that point in adult males. Males with one or two acute, elongate, ventral-medially situated hook per lepidotrichia segment on all pelvic-fin rays. Adult males with hypertrophied soft whitish tissue anterior to hooks on ventral surface of pelvic fin. Principal caudal-fin rays 17(2) or 19*(65). Procurrent caudal-fin rays: dorsal 12(2), 13(1) or 15(3); ventral 12(1), 13(2) or 14(3). Adult males with ventral procurrent caudal-fin rays hypertrophied, commonly fused, with distal tips extending beyond muscles and skin of caudal-peduncle. Hypertrophied ventral procurrent caudal-fin rays elongated, rod-shaped, anteriorly bent, proximally acute and slightly expanded distally ( Fig. 2g ).

Scales cycloid; similar in size over all body. Lateral line partially pored with 8(1), 11(5), 12(2), 14(7), 15(4), 16(2), 17(6), 18(2), 19(2), 20(2), 21(1), 23(1), 32(5), 33(7), 34(11), 35*(7) or 36(2) pored scales. Scales in lateralline series 31(3), 32(9), 33(22), 34(16), 35*(15) or 36(2). Predorsal series in regular row 8(1), 9*(9), 10(34) or 11(23). Scale rows between lateral line and dorsal-fin origin 5(49) or *6(18). Scale rows between lateral line and pelvic-fin origin 4*(64) or 5(3). Scale rows around caudal peduncle 12(3), 13(24), 14*(36) or 15(4). Axillary scale on pelvic fin base extending posteriorly one or two scales. Scales along anal-fin base 9(4), 10(12), 11(24), 12(14), 13(6), 14(2), 15*(3) or 17(1).

Counts based on six clear and stained specimens: supraneurals 4(4) or 5(2); abdominal vertebrae 15(5) or 16(1); caudal vertebrae 19(4) or 20(2).

Color in alcohol. Overall ground coloration of body pale yellow, darker dorsally from head to caudal peduncle. Body with faint dark, sometimes silver, midlateral stripe usually forming black line along middle longitudinal body axis. Longitudinal stripe extending from region slightly anterior to vertical through dorsal-fin origin to caudal spot. Scale series above longitudinal line with darker chromatophores mostly on posterior border of scales, resulting in faint reticulated pattern. Abdominal region ventral to longitudinal line more lightly colored and without pigmentation. Caudal spot rounded, black, situated over posterior of caudal peduncle and base of middle caudal-fin rays, but falling short of upper or lower margin of peduncle. Fins mostly hyaline with scattered, sparse, dark chromatophores. Adipose fin unpigmented. Caudal fin with dark chromatophores along fin rays, except for clear areas on base of each caudal-fin lobe. Humeral region with triangular, dark area due to pseudotympanum in musculature ( Fig. 10 ).

Sexual dimorphism. Mature males of S. tocantinensis have hooks on the pelvic and anal-fin rays. The caudal peduncle is ventrally arched, as commonly observed in species of Serrapinnus . The hook bearing anal-fin rays are hypertrophied, expanded in the sagittal plane, and sometimes have fused ray segments. Adult males also have the last unbranched dorsal-fin ray and the first pelvic-fin ray elongated, sometimes in a short filament. The ventral procurrent caudal-fin rays are hypertrophied in mature males, and extend ventrally through the caudal peduncle muscles and skin ( Figs. 2g –h , 4d , 10 ).

Distribution. Serrapinnus tocantinensis is distributed throughout the rio Tocantins-Araguaia basin, from the upper to the lower portions of the system ( Fig. 5d ).

Etymology. The species name, tocantinensis , refers to the restricted geographic distribution of the species to the rio Tocantins-Araguaia basin. A noun in apposition.

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 10. Serrapinnus tocantinensis, (a) holotype, male, UFRGS 16442, 32.5 mm SL, córrego Fundo, tributary of rio das Garças, Município de Barra do Garças, Mato Grosso, Brazil; (b) paratype, female, UFRGS 12021, 29.9 mm SL, same data as holotype.

FIGURE 11. Serrapinnus tocantinensis, INPA 20986, 36.2 mm SL; Scanning Electron Microscopy images showing (a) right side premaxilla; (b) maxilla; (c) dentary, and (d) detail of dentary teeth.