Wednesday, January 18, 2017

[Ichthyology • 2017] Hyphessobrycon petricolus • A New Species of Tetra (Characiformes: Characidae) from the rio Madeira basin, Mato Grosso, Brazil

Hyphessobrycon petricolus 
Ohara, Lima & Barros, 2017

A new species of Hyphessobrycon is described from the rio Roosevelt, rio Madeira basin, Mato Grosso State, Brazil. Hyphessobrycon petricolus sp. n. can be distinguished from its congeners by the unique combination of the following features: a well-defined, relatively narrow dark midlateral stripe on body extending from immediately behind posterior margin of opercle to the middle caudal-fin rays, relatively conspicuous humeral blotch, and 16–20 branched anal-fin rays. Comments on the remaining Hyphessobrycon species presenting a conspicuous dark midlateral stripe are presented. 

Keywords: Pisces, Amazon basin, Hyphessobrycon heterorhabdus species-group, Hyphessobrycon cachimbensis, Hyphessobrycon nigricinctus, rio Roosevelt

FIGURE 3. Hyphessobrycon petricolus, paratypes, immediately after capture. 

Sexual dimorphism. Bony hooks on fins, a common dimorphic feature in characids (Malabarba & Weitzman, 2003), were not found in any specimens of Hyphessobrycon petricolus.

Distribution. The new species is so far only known from its type locality, a small tributary of the middle rio Roosevelt, rio Aripuanã drainage, rio Madeira basin, northwestern Mato Grosso State, Brazil (Fig. 4).

Ecological notes. The type locality of Hyphessobrycon petricolus is a small, black water stream 1.5–4 m wide and 0.3–1.5 m deep, with swift water current, and rocky bottom (Fig. 5a), upstream a large waterfall (Fig. 5b). The stream run across a small cerrado-vegetation enclave situated within Amazon forest. Individuals of Hyphessobrycon petricolus were captured near of surface during the night in small groups of 2 to 4 individuals. Other species sampled syntopically were: Aequidens sp., Erythrinus erythrinus, Pyrrhulina sp., Synbranchus sp. and Tatia cf. brunnea

Etymology. The specific name petricolus derives from the Latin petra meaning rock and colus, to abide, to dwell, referring to the occurrence of the species in a rocky-bottomed stream. An adjective.

 Willian M. Ohara, Flávio C T Lima and Bruno S Barros. 2017. Hyphessobrycon petricolus, A New Species of Tetra (Characiformes: Characidae) from the rio Madeira basin, Mato Grosso, Brazil. Zootaxa. 4221(2); 242-250. DOI:  10.11646/zootaxa.4221.2.8

Resumo: Uma espécie nova de Hyphessobrycon é descrita do rio Roosevelt, bacia do rio Madeira, estado do Amazonas, Brasil. Hyphessobrycon petricolus sp. n. pode ser distinguida das suas congêneres pela combinação única das seguintes características: uma bem definida, relativamente estreita faixa médio-lateral escura no corpo estendendo-se de imediatamente após a margem posterior do opérculo aos raios medianos da nadadeira caudal, uma conspícua mancha umeral e 16–20 raios ramificados na nadadeira anal. Comentários sobre as demais espécies de Hyphessobrycon que apresentam uma faixa escura médio-lateral são apresentados.
Palavras chaves: Bacia amazônica, grupo de espécies Hyphessobrycon heterorhabdus, Hyphessobrycon cachimbensis, Hyphessobrycon nigricinctus, rio Roosevelt 

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