Serrapinnus heterodon ( Eigenmann, 1915 )

Ota, Renata Rúbia, Deprá, Gabriel de Carvalho, Graça, Weferson Júnio da & Pavanelli, Carla Simone, 2018, Peixes da planície de inundação do alto rio Paraná e áreas adjacentes: revised, annotated and updated, Neotropical Ichthyology 16 (2), pp. 1-111 : 37

Serrapinnus heterodon ( Eigenmann, 1915)

Fig. 10

Body elongated; greatest body depth contained 3.3 to 4.0 and caudal peduncle depth 8.6 to 10.5 times in SL; head length 4.1 to 4.4, predorsal distance 1.9 to 2.0 and caudal peduncle length 5.0 to 6.4 in SL; snout length 2.8 to 3.2, horizontal orbital diameter 2.8 to 3.2 and least interorbital width 3.0 to 3.5 in HL. Mouth terminal; premaxilla with 5 or 6, dentary with 4-8 teeth with expanded tips, and maxilla with 1 to 3 teeth. Lateral line completely pored, with 32-36 pored scales; longitudinal series with 32-36 scales; transverse series above lateral line with 6 scale rows and below with 3-4 scale rows. Dorsal fin with 11, pectoral fin with 10-12, pelvic fin with 8, anal fin with 19-22 and caudal fin with 19 rays. Ground color whitish; dark-brown longitudinal stripe on flank, from pseudotympanum to caudal peduncle; black oval, horizontally elongated, blotch on posterior portion of caudal peduncle and caudal-fin base, not extended to median caudal-fin rays.

Maximum standard length. 30.9 mm.

Biological data. Feeding habit omnivorous; total spawning, and spawning period during rainy season ( Gonçalves et al., 2011).

Distribution. Upper rio Paraná and rio São Francisco basins, and coastal drainages of the Rio Grande do Norte State, Northeastern Brazil.

Remarks. Some specimens of Serrapinnus heterodon were identified as Odontostilbe sp. (now as O. avanhandava ) by Graça, Pavanelli (2007). Both species occur in the upper rio Paraná floodplain, where S. heterodon has been captured since 2008 by the Nupélia staff. Serrapinnus heterodon can be distinguished by having the dentary teeth with three wide central cusps of same size and two small lateral ones, caudal peduncle blotch oval-shaped, reaching median caudal-fin rays, and mature males with a ventrally arched caudal peduncle (one of the synapomorphies for the genus, according to Malabarba, 1998) (vs. dentary teeth slender and pointed, with one central cusp longer than the four lateral ones, caudal peduncle blotch rounded, not reaching the median caudal-fin rays, and mature males not having the caudal peduncle arched, in Odontostilbe avanhandava ). The confusion between the specimens of the upper rio Paraná floodplain can be associated with the completely pored lateral line. This character is common in Odontostilbe , whereas the number of pored scales is reduced in Serrapinnus . The only exception in Serrapinnus is found in S. heterodon , which has a completely pored lateral line.

Figures

Fig. 10. a. Aphyocheirodon hemigrammus, NUP 13774, 36.3 mm SL, lagoa do Bilunga, tributary of the rio Paraná, Taquarussu, State of Mato Grosso do Sul. b. Odontostilbe avanhandava, NUP 1517, 40.0 mm SL, canal do Meio (ilha Porto Rico), Porto Rico, State of Paraná. c. Serrapinus calliurus, NUP 17494, lagoa do Guaraná, tributary of the rio Baía, Taquarussu (top, female, 24.1 mm SL; bottom, male, 21.4 mm SL). d. Serrapinnus heterodon, NUP 17495, lagoa do Guaraná, tributary of the rio Baía, Taquarussu, State of Mato Grosso do Sul (top, female, 32.5 mm SL; bottom, male, 30.1 mm SL). e. Serrapinnus notomelas, 31.8 mm SL, fresh specimen, uncat. f. Serrapinnus sp. 1, NUP 3283, lagoa do Bilunga, Taquarussu, State of Mato Grosso do Sul (top, female, 28.7 mm SL; bottom, male, 28.2 mm SL). g. Serrapinnus sp. 2, NUP 17045, 33.5 mm SL, córrego Itauna, Alto Paraíso, State of Paraná.