Abstract
Ituglanis mambai, new species, is described from a cave in the Mambaí karst area, State of Goiás, Central Brazil. The new species distinguishes from epigean and cave congeners by the combination of the following characteristics: posterior supraoccipital fontanel absent; pectoral-fin rays usually i,7; six pleural ribs; total vertebrae 37-38 behind Weberian apparatus; shorter predorsal length (65.1-70.8% SL); shorter caudal peduncle length (8.4-11.9% SL); shorter dorsal-fin base length (7.7-11.3% SL); wider interobital width (29.2-36.5% HL); larger mouth width (43.4-64.0% HL); intermediate between epigean and other cave Ituglanis species as regards to both eyes (diameter varying from 0.5 to1.0 mm in adults, 7.8-10.1 % HL) and pigmentation, composed by irregular light brown spots along the body. The latter indicate the troglobitic status for I. mambai. In addition, this species has the maxillae with a discrete medial-posterior projection; fronto-lacrimal one half-length of the maxillae and pointed backwards; posterior process of palatine half its length, with a tenuous medial concavity; 14 dorsal and 12 ventral procurrent rays. In the natural habitat, I. mambai displayed cryptobiotic habits, trying to hide in the graveled bottom or under boulders when disturbed, apparently showing a negative response to light. It was observed a preference to slow-moving waters. Recent flood marks were observed in the stream conduit in March/April 2007 (end of the rainy season) when less individuals were observed on 300 m of the subterranean stream compared to September 2004 (end of the dry season).
Highlights
Brazil has a remarkable subterranean ichthyofauna, similar to few other countries or geographically comparable karst areas, such as Mexico, China and the southeastern Asia
Nearly 21 species of Brazilian subterranean fishes are known to present reduction of eyes and pigmentation at least at some degree beyond that observed in their epigean congeners, suggesting a troglobitic status for these fishes, and this number is increasing every year (Trajano, 1997; Bichuette & Trajano, 2003; Trajano & Bichuette, 2004)
Costa & Bockmann (1993) erected the genus Ituglanis to include nine species previously placed in Trichomycterus, based on three autapomorphies
Summary
Brazil has a remarkable subterranean ichthyofauna, similar to few other countries or geographically comparable karst areas, such as Mexico, China and the southeastern Asia. The Mambaí karst area, upper rio Tocantins basin, State of Goiás is located to south of the São Domingos area The latter is distinguished by its subterranean ichthyofauna, rich in both troglomorphic and non-troglomorphic species. After an epigean reach, each stream enters into a cave through a sinkhole, cross hundreds of meters (the largest cave in the region, Gruna da Tarimba, is approximately 7 km long) through subterranean conduits, and emerges to the surface through a resurgence. This area lies in the Cerrado (the savannah-like Brazilian vegetation) domain and is characterized by a tropical semi-humid climate with 4-5 dry mo/yr (Nimer, 1979).
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