Thursday, November 5, 2015

A new catfish: Pareiorhaphis garapia

The suckermouth armored catfish family (Loricariidae) has about 800 known species and is a taxonomically very difficult group. So difficult that a numbering system was invented that helped registering putative new species waiting for a sufficient taxonomic treatment. The system is by no means based on any scientific system. As a result specific L-number (after the family name) classifications do not guarantee discrete species, multiple L numbers have been given to different populations of the same species. To add to the confusion, sometimes a single L-number may actually be used for multiple species. 

This new species occurs in Southern Brazil and was named after the stream where it occurs and the waterfall which marks the known limit of its distribution.

For the experts: Pareiorhaphis garapia, new species, is described based on specimens collected in the headwaters of the Arroio Garapiá, Rio Maquiné basin, a coastal drainage of Rio Grande do Sul State, southern Brazil. The new species is distinguished from all other Pareiorhaphis species in having the nuchal plate covered by thick skin, the exposed posterior process of the cleithrum comparatively narrow, and the last segment of the preopercular ramus of the latero-sensory canal reduced to an ossified tubule. The absence of a dorsal-fin spinelet, the reduced number of plates in the dorsal and mid-dorsal series of lateral plates, and morphometric traits also distinguish the new species from its congeners. The restricted geographic distribution of P. garapia, endemic to a headwater stream of the Rio Maquiné basin, and the syntopic occurrence of P. nudulus are discussed.

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