Pachypops Gill 1861

Lilian Casatti, 2002, Taxonomy of the South American genus Pachypops Gill 1861 (Teleostei: Perciformes: Sciaenidae), with the description of a new species., Zootaxa 26, pp. 1-20: 2-4

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Pachypops Gill 1861


Genus Pachypops Gill 1861  ZBK 

Type species. Micropogon trifilis Mueller and Troschel 1848  ZBK  : 622 (by original designation).

Diagnosis. Distinguished from the two other known South American freshwater sciaenid genera ( Pachyurus  ZBK  and Plagioscion  ZBK  ) by the following combination of characters: mouth inferior, presence of three mental barbels, the swimbladder with a pair log posterior branches projecting from shorter paired anterior appendages (Fig. 1), and presence of the expanded haemal spine on the first caudal vertebra (Fig. 2). Gender masculine.

Comments. According to Sasaki (1989), Pachypops  ZBK  is characterized phylogenetically by its swimbladder with a pair of anterior appendages (see Fig. 1), the possession of an unpored median barbel, and the possession of a pair of mental barbels. An unpublished phylogenetic study of South American freshwater sciaenids done by the author of the present paper reveals that the species of Pachypops  ZBK  share not only those synapomorphies listed by Sasaki (1989) but also an expanded haemal spine on the first caudal vertebra (see Fig. 2). These four synapomorphies are assumed to be homoplastic with other perciforms in the final most parsimonious phylogeny.

Jordan and Eigenmann (1889: 413) assigned Pachyurus adspersus Steindachner 1879  ZBK  to the genus Pachypops  ZBK  . However, despite bearing three mental barbels and six mental pores, P. adspersus  ZBK  lacks the expanded haemal spine and the appendages on the swimbladder, which occur in Pachypops  ZBK  . Casatti (2001) considered P. adspersus  ZBK  a member of Pachyurus  ZBK  as originally proposed by Steindachner. An expanded haemal spine on the first caudal vertebra is also present in some other examined perciforms (the haemulid Haemulon steindachneri  , the polynemid Polydactylus virginicus  , and the sciaenids Dendrophysa russelli  , Kathala axillaris  , and Plagioscion auratus  , pers. obser.) but it is interpreted as having been independently derived in these taxa.

Based on the barbel morphology Pachypops cevegei Cervigon 1982  ZBK  is not a species of Pachypops  ZBK  , but instead a species of Micropogonias  ZBK  . Therefore, of six nominal species of Pachypops  ZBK  according to previous authors, two ( Pachypops adspersus  and Pachypops cevegei  ZBK  ) are not assignable to the genus. The remaining nominal species are discussed below under “Comments” for Pachypops fourcroi  and Pachypops trifilis  .

Key to Species of Pachypops  ZBK 

1 Brown spots present on sides of body, body depth 4.3 or more in SL ............ ............................................. Pachypops pigmaeus  ZBK  n. sp. (Rio Machado and Madeira basins and upper Rio Branco, Brazil)

- Spots absent on sides of body, body depth less than 4.1 in SL ................ 2

2 Dark longitudinal stripes present on sides of body, horizontal eye diameter from 3.0 to 3.7 in HL ..... Pachypops trifilis  (Rivers of Guyana and Rio Amazonas basin)

- Longitudinal stripes absent on sides of body, horizontal eye diameter from 2.4 to 3.1 into HL ............................................ Pachypops fourcroi  (Amazonas, Essequibo, Corantijn, Approuague and Orinoco basins)