Tetragonopterus bahiensis Steindachner

De Lucena, Carlos Alberto S. & Soares, Helena Gouvea, 2016, Review of species of the Astyanax bimaculatus “ caudal peduncle spot ” subgroup sensu Garutti & Langeani (Characiformes, Characidae) from the rio La Plata and rio São Francisco drainages and coastal systems of southern Brazil and Uruguay, Zootaxa 4072 (1), pp. 101-125 : 120

Notes on Tetragonopterus bahiensis Steindachner

Eigenmann (1921), without examining the syntypes, but considering the area from where the species was described (Bahia, but precise locality is imprecise), places Tetragonopterus bahiensis Steindachner, 1877 as a junior synonym of Astyanax bimaculatus vittatus . Recently, Lima et al. (2003) provisionally considered A. bahiensis in the synonymy of Astyanax bimaculatus Linnaeus. Considering that there is little knowledge on the species, and judging from its taxonomic history, it is plausible to suppose that it can be treated as a species of the Astyanax bimaculatus group. It is for this reason that we include this note. Examination of photographs, radiographs and data obtained from syntypes showed that A. bahiensis is a valid species. The following facts have led us to this conclusion:(1) Steindachner (1877), upon describing the species, mentions the presence of an oval humeral spot, as well as the resemblance of his specimens with Tetragonopterus maculatus Muller & Troschel, 1845 (= Astyanax bimaculatus ). Among the three specimens examined that are part of the syntypic series — NWM 57251 (2 specs.) and NWM 57252 (1 spec.) — in two of them (NWM 57251) the humeral spots are higher than long and not horizontally elongated (vs. the horizontally oval shape characteristically present in the A. bimaculatus group).The humeral region of specimen NWM 57252 is damaged, impeding observation of the shape, or even whether one was present; (2) specimens NWM 57251-1 and NWM 57252 have five cusps on teeth of the external series of the premaxilla (F. Carvalho pers. comm.)(vs. presence of teeth with three cusps in species of the A. bimaculatus group). Garutti & Britski (2000) mentioned that the posteriormost tooth could have four or five cusps in Astyanax altiparanae ; (3) all of the syntypes present two teeth on the maxilla (F. Carvalho pers. comm.) (vs. species of the Astyanax bimaculatus group that have either one tooth on the maxilla, especially those occurring in the Amazon basin and to the north, or teeth absent from this bone, especially those species occurring in drainages of the east and northeast of South America; see Discussion); and (4) the specimens do not present a continuous dark lateral band (present in the Astyanax bimaculatus black lateral stripe subgroup). Due to the facts exposed, we suggest the removal of A. bahiensis from the synonymy of A. bimaculatus and, in consequence, of any subgroup of the species related to this name.