Cordylancistrus santarosensis (Siluriformes: Loricariidae), a new species with unique snout deplatation from the RÃ*o Santa Rosa, Ecuador

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Cordylancistrus santarosensis (Siluriformes: Loricariidae), a new species with unique snout deplatation from the RÃ*o Santa Rosa, Ecuador

MILTON TAN1 & JONATHAN W. ARMBRUSTER1
1 Department of Biological Sciences, Auburn University, 331 Funchess, Auburn, AL 36849, USA, Telephone: (334) 844–9261, FAX: (334) 844-9234, e-mail: (MT) miltontan@auburn.edu; (JWA) armbrjw@ auburn.edu


Abstract
Cordylancistrus santarosensis is described based on five specimens from the RÃ*o Santa Rosa, Ecuador. This species can
be distinguished from all other members of the Chaetostoma group by having plates on the tip of the snout (except for a
central region at the extreme anterior edge), but lacking plates laterally on the head. This snout plating condition is intermediate
between the fully plated snout of other Cordylancistrus and the unplated snout of Chaetostoma.
Keywords: Ancistrini, suckermouth armoured catfish, Ecuador, South America, Neotropics

Introduction
Cordylancistrus is a genus of loricariid catfish that includes fish similar to Chaetostoma Tschudi. Cordylancistruswas first described as a monotypic genus by Isbrücker (1980), with Cordylancistrus torbesensis (Schultz) as the type species. Pérez and Provenzano (1996) described a second species to the genus, Co. perijae. Isbrücker (2001) expanded the genus with three additional species: Co. daguae (Eigenmann), Co. platycephalus (Boulenger), andCo. platyrhynchus (Fowler). Armbruster (2004) found no characters that supported the monophyly of Cordylancistrus, but found that Cordylancistrus was part of a monophyletic group along with Chaetostoma, DolichancistrusIsbrücker, and Leptoancistrus Meek and Hildebrand. Additionally, Co. platyrhynchus was moved to Chaetostomabecause it only differs from other Chaetostoma by the presence of snout plates (vs. unplated snout) (Armbruster 2004). Provenzano and Milani (2006) tentatively placed Ch. platyrhyncha back into Cordylancistrus and described a new species, Cordylancistrus nephelion. Armbruster (2008) found that Cordylancistrus, excluding Ch. platyrhyncha, was still polyphyletic.
With the exclusion of Chaetostoma platyrhyncha from Cordylancistrus, Co. platycephalus is the only species in the genus found in Ecuador, and is known from cis-Andean streams. Cordylancistrus santarosensis is described here from specimens collected in the trans-Andean RÃ*o Santa Rosa (Gulf of Guayaquil drainage) in southern Ecuador. This new species differs from all other Cordylancistrus by its unique snout plate distribution. It is superficially similar in external morphology to Chaetostoma platyrhyncha, but these two species can be distinguished by meristics and morphometrics as well as the snout deplatation of Co. santarosensis.

pdf-Datei: https://www.mapress.com/zootaxa/2012/f/zt03243p058.pdf

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