Metynnis cuiabá

Pavanelli, Orta and Petry, 2009

New species of Metynnis Cope, 1878 (Characiformes: Characidae) from the

rio Paraguay basin, Mato Grosso State, Brazil

Carla S. Pavanelli1,2, Rafaela P. Ota2 and Paulo Petry3

Neotropical Ichthyology, 7(2):141-146, 2009 Copyright © 2009 Sociedade Brasileira de Ictiologia



A new species of Metynnis is described from the rio Cuiabá and rio Manso drainages, in the upper rio Paraguay basin, Mato Grosso State, Brazil. This laterally compressed species, which rarely exceeds 140 mm in SL, is readily distinguished from other members of the genus Metynnis by having 100-110 lateral-line scales, 48-56 rows of scales above the lateral line, 32-36 circumpeduncular scales, 22-24 gill rakers, 38 vertebrae, singular color pattern, and relatively smaller snout, width, and head length.

Uma nova espécie de Metynnis é descrita das drenagens dos rios Cuiabá e Manso, bacia do alto rio Paraguai, Estado do Mato Grosso, Brasil. Essa espécie de corpo comprimido lateralmente, que raramente excede os 140 mm de comprimento padrão, é prontamente diagnosticada dos outros membros do gênero Metynnis por possuir 100-110 escamas na linha lateral, 48-56 séries de escamas acima da linha lateral, 32-36 escamas circumpedunculares, 22-24 rastros branquiais, 38 vértebras, padrão de colorido distinto, e comprimento do focinho, largura e comprimento da cabeça relativamente menores.

The genus Metynnis has a number of species placed in its genus (14). They are closely aligned with the piranhas, indeed they are in the piranha clade according to recent Phylogenetic  study (Orti et al., 2008). Unfortunately, the species was inadvertently transplanted into the Rio Paraná basin when a dam was constructed (Itaipau; Langeani et al., 2007). According to experts today, the upper Rio Paraguay basin contains one of the largest known flood plains in the world. In the floodplain is the Pantanal. This Metynnis species was discovered in the Rio Cuiabá. This river flows  through the Mato Grosso and the Mato Grosso do Sul (Brazilian States).  From there it flows to the Pantanal  into the rio Paraguay very close to the borders of Bolivia and Brazil.

The species was compared with other known types found in this river system, one being Metynnis maculatus (Verissimo et al., 2005). The species was separated from the following species; M. fasciatus, M. guaporensis, M. hypsauchen, M. longipinnis, M. luna and M. orinocensis by several morphometric  measurements including gill rakers count. Other attributes included body markings and fin/scale counts.

The species is sexual dimorphic, with the male having a lobule at the far edge (distal) of the anal fin. Also noted the dorsal fins were not elongated as commonly found in other sexually dimorphic species. The female of the species have a normal straight anal fin edge with the first dorsal fin ray elongated, forming filaments apparently only during breeding period (Pavanelli et al., 2009).

Some recent researchers remain unclear as to what family the Serrasalmins should be placed in. Jégu, 2003 maintains the subfamily Serrasalminae, while others contend it is a distinct family, the Serrasalmidae (e.g. Calcagnotto et al., 2005). According to Freeman et al., (2007) future studies  should include combined genetic data and careful documentation of specimens examined (Pavanelli et al., 2009). According to Dr. William L. Fink, UMMZ,  family or subfamily placement is arbitrary.

Maximum size:

142.5 mm (5.61 in.) SL







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