Gymnocorymbus Eigenmann, 1908

Benine, Ricardo C., Melo, Bruno F., Castro, Ricardo M. C. & Oliveira, Claudio, 2015, Taxonomic revision and molecular phylogeny of Gymnocorymbus Eigenmann, 1908 (Teleostei, Characiformes, Characidae), Zootaxa 3956 (1), pp. 1-28 : 10

Gymnocorymbus Eigenmann, 1908

Gymnocorymbus Eigenmann, 1908:93 . Type species: Gymnocorymbus thayeri Eigenmann, 1908 . Type by original designation. Gender: Masculine.

Diagnosis. In addition to the three features described under “Morphological support for monophyly and interrelationships within Gymnocorymbus ”, the combination of the following characters externally discriminate Gymnocorymbus within the Characidae : the predorsal area naked or with an irregular series of scales; the deep body (around 50% in SL); the 7–9 horizontal scale rows between the lateral line and the dorsal-fin origin; the elongate anal fin with iv,31–40 rays; the sheath of 2–6 horizontal rows of scales covering the anal-fin base; a sheath of scales covering the proximal two thirds of the lobes of caudal fin; and the absence of a predorsal spine.

Distribution. Gymnocorymbus is widely distributed in lowlands of the Orinoco, Corantijn, Amazon and Paraguay basins, and in the Rio Gurupi and Rio Parnaíba in northeastern Brazil ( Fig. 9 ). Introduced populations of G. ternetzi occur in marginal lagoons of the Rio Mogi-Guaçu and Rio Grande, tributaries of the upper Rio Paraná and also in the upper Rio Paraíba do Sul in southeastern Brazil ( Fig. 9 ). The reported occurrence of Gymnocorymbus thayeri in Trinidad and Tobago ( Phillip et al. 2013) could not be confirmed due to the impossibility of examine the associated vouchers.

Etymology. Gymnos from Greek, meaning naked; corymbus from Greek, meaning summit. Eigenmann (1908) refered to the smooth predorsal line due to absence of scales and/or the presence of a thick layer of epidermic cells in that area.

Figures

FIGURE 9. Distribution map showing collecting localities of examined specimens of Gymnocorymbus bondi (white circles), G. flaviolimai (red circles), G. ternetzi (blue circles) and G. thayeri (yellow circles). White lines represent country boundaries.