Scientists from Brazil have described a new species of sexually dimorphic loricariid catfish from southeastern Brazil.
The description of the new species, named Pareiorhaphis nasuta by Edson Pereira, Fbio Vieira and Roberto Reis, is published in the latest issue of the journal Neotropical Ichthyology.
Pareiorhaphis nasutus can be distinguished from other members of the genus in having a longer snout.
It is additionally distinguished from most other Pareiorhaphis species, except for P. garbei, P. vestigipinnis, P. cerosus, and P. splendens, in having a smaller eye. Pareiorhaphis nasuta further differs from P. garbei in having bifid teeth, with a small lateral cusp in both dentary and premaxilla, from P. vestigipinnis in having an adipose fin, from P. cerosus in having one to three preadipose azygous plates, and from P. splendens in the longer pelvic-fin spine.
The new species shows marked sexual dimorphism: nuptial males have a slightly thickened pectoral-fin spine with somewhat enlarged odontodes and hypertrophied odontodes on the lateral margins of head, a dermal flap on the dorsal surface of the pelvic-fin spine, and a well-developed fleshy flap along the entire length of the posterodorsal margin of the pectoral-fin spine.
Pareiorhaphis nasuta, named after its elongate snout (from the Latin nasutus, meaning long-nosed), is known only from the upper Doce River drainage, where it has been collected in areas of rapids at streams and rivers amongst the loose rocks making up the substrate.
The water from which the fish has been collected is either clear and transparent, or nearly transparent and slightly black.
Other fish species that have been collected with Pareirhaphis nasuta include Astyanax cf. taeniatus, Hypostomus affinis, Harttia sp., Neoplecostomus sp., Trichomycterus spp., Rhamdia quelen, and Geophagus brasiliensis.
For more information, see the paper: Pereira, EHL, F Vieira and RE Reis (2007) A new species of sexually dimorphic Pareiorhaphis Miranda Ribeiro, 1918 (Siluriformes: Loricariidae) from the rio Doce basin, Brazil. Neotropical Ichthyology 5, pp. 443"448.