Protocheirodon, Vari & Melo & Oliveira, 2016

Vari, Richard P., Melo, Bruno F. & Oliveira, Claudio, 2016, Protocheirodon, a new genus of Characidae (Teleostei: Characiformes) with the redescription of the poorly known Protocheirodon pi, Neotropical Ichthyology 14 (2), No. e 150154, pp. 1-7: 2-3

publication ID 10.1590/1982-0224-20150154

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new genus

Protocheirodon   , new genus

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Type species. Protocheirodon   pi (Vari, 1978).

Diagnosis. Protocheirodon   possesses the four synapomorphies proposed for the Cheirodontinae   by Malabarba (1998): 1) the presence of a pseudotympanum, a hiatus in the body wall musculature lateral to at least a portion of the anterior chamber of the swimbladder; 2) the lack of a dark humeral spot; 3) the possession of pedunculate dentition; and 4) the presence of only a single row of regularly arranged premaxillary teeth. Protocheirodon   differs from all other genera of the Cheirodontinae   and indeed members of the Characiformes   by the unique form of the swimbladder which has a smaller rotund anterior chamber and the posteriorly chamber elaborated into two vertically elongate, side by side, slightly inclined chambers. These modifications yield a unique overall pi (π)-shaped structure (Vari, 1978) ( Fig. 2 View Fig ). This trenchant difference versus other cheirodontins is supplemented by a diagnostic combination of meristic, morphometric and details of pigmentation.

Description. As Protocheirodon   is a monotypic genus, its description corresponds to the redescription of the typespecies, Protocheirodon   pi (Vari, 1978).

Etymology. Proto from Greek prōto, meaning first or earliest form of, in reference to the phylogenetic position of the species as sister to all remaining members of the Cheirodontinae   , and cheirodon   , an allusion to the genus Cheirodon   and subfamily Cheirodontinae   . Gender masculine.