Probolodus oyakawai

description

Description. Morphometrics of types presented in Table 1. Body moderately compressed and deep, less so in individuals of less than 150 mm SL, greatest body depth within region delimited anteriorly by vertical through insertion of pelvic fin and posteriorly by vertical through origin of dorsal fin. Average body depth variable among population samples, but with broad overlap in ranges among examined samples. Dorsal profile of head distinctly convex from margin of upper lip to vertical through posterior nostril, straight to very slightly convex from latter point to tip of supraoccipital spine. Dorsal profile of body moderately convex from tip of supraoccipital spine to origin of dorsal fin, straight and posteroventrallyslanted along base of dorsal fin, straight to slightly convex from posterior terminus of base of dorsal fin to adipose fin, and slightly concave along caudal peduncle. Broad middorsal ridge present along predorsal region of body, with ridge less obvious anteriorly. Dorsal region of body between posterior terminus of dorsal fin and adipose fin transversely rounded overall, but slightly flattened middorsally in some individuals. Ventral profile of head sligtly convex ante

Taxonomy of Probolodus Eigenmann, 1911 (Characiformes: Characidae) with description of two new species, and comments about the phylogenetic relationships and biogeography of the genus

diagnosis

Diagnosis. Probolodus oyakawai differs from its two congeners, P. heterostomus and P. sazimai (new species) by the following characteristics: the base of the large epural not leaning against the urostyle bone (vs. the base of the large epural in contact, not fused the urostyle) (Fig. 6 a); first and second infraorbitals contacting but not overlapping (vs. relationship with overlapping or leaning against) (Fig. 6 b); posterior portion of the maxilla extended in relation to median portion (vs. posterior portion of the same width than median portion) (Fig. 1 b); anterior extension of nasal reaching the lateral projection of mesethmoid (vs. outpacing the end of the projection of mesethmoid). It may be further separated from P. heterostomus by three attributes: 41 - 43 perforated scales on the lateral line (vs. 45 - 56 perforated scales); 14 - 16 scale series around the caudal peduncle (vs. 18 - 21 scale series around the caudal peduncle); body relatively shorter, with 33 - 34 totals vertebrae (vs. 34 - 35 totals vertebrae).

Taxonomy of Probolodus Eigenmann, 1911 (Characiformes: Characidae) with description of two new species, and comments about the phylogenetic relationships and biogeography of the genus

discussion

Remarks. Probolodus oyakawai has been previously cited as P. heterostomus by various authors who have studied specimens collected in the rio Ribeira de Iguape basin (see synonymy). However, as shown on the item “ Ecological notes ”, P. oyakawai also shows preference by fish scales. Thus, as hypothesized by Sazima (1977), Astyanax fasciatus is not found over the entire range of Probolodus, being probable that in other drainages there is an association with other similar species of Astyanax. In the rio Ribeira de Iguape basin, A. ribeirae is a likely candidate, as Deuterodon iguape, which also have the general appearance of Astyanax (Sazima, 1977; Oyakawa et al., 2006).

Taxonomy of Probolodus Eigenmann, 1911 (Characiformes: Characidae) with description of two new species, and comments about the phylogenetic relationships and biogeography of the genus

distribution

Distribution. Probolodus oyakawai is known to occur in the rio Ribeira de Iguape basin, southeastern Brazil (Fig. 2). Ecological notes. Ctenoid and cycloid fish scales were observed in the stomach contents of three P. oyakawai specimens (MZUSP 53499, 2, 31.7 - 64.3 mm SL; MZUSP 55006, 1, 37.9 mm SL). No other item could be identified, possibly due to their advanced state of decomposition.

Taxonomy of Probolodus Eigenmann, 1911 (Characiformes: Characidae) with description of two new species, and comments about the phylogenetic relationships and biogeography of the genus