Abstract
A new species of the previously monotypic catfish genus Phreatobius is described from an artificial well in the village of Rio Pardo, located 90 km south of the city of Porto Velho, State of Rondônia, Brazil, in the drainage area of the Rio Branco (Rio Madeira system, Amazon basin). Phreatobius dracunculus n. sp. differs from its only congener, P. cisternarum, by the absence of eyes (vs. present), the lack of dark integumentary pigmentation (vs. faint dark pigment always present), the presence of five pectoral-fin rays (vs. four), ventral procurrent rays 11-13 (vs. 22 to 26), dorsal procurrent rays 29-31 (vs. 42 to 50), fewer vertebrae (52 or 53 vs. 59 to 64) and the larger pseudotympanus. The new species shows all diagnostic characters so far proposed for Phreatobius, including an unusual red coloration in life. The localities of the two species of Phreatobius are approximately 1900 km apart. That, in association with their peculiar and mostly inaccessible habitats, indicates that the genus may be widely distributed in the Amazon basin.
Highlights
The catfish Phreatobius cisternarum is one of the most peculiar members of the Neotropical freshwater fish fauna. It lives mainly in subterranean waters around the mouth of the Amazon river and most specimens so far have been secured from hand-dug wells, with epigean records from leaf litter in the State of Amapá
It is likely that several new populations or new species await discovery in the vast area between the known occurrences of P. cisternarum and P. dracunculus
Phreatobius dracunculus shares all 15 diagnostic characters for Phreatobius proposed by Muriel-Cunha & de Pinna (2005)
Summary
The catfish Phreatobius cisternarum is one of the most peculiar members of the Neotropical freshwater fish fauna. It lives mainly in subterranean waters around the mouth of the Amazon river and most specimens so far have been secured from hand-dug wells, with epigean records from leaf litter in the State of Amapá Many other morphological peculiarities make the species distinctive at a glance from other Neotropical catfishes, such as a paddle-shaped caudal region formed by a caudal-fin extended dorsally and ventrally by numerous large procurrent rays, ventrally confluent with the anal-fin, a strongly prognathous lower jaw, massively hypertrophied jaw muscles and a bright red Shibatta, O.A. et al.: A new subterranean species of Phreatobius coloration in life. Collecting efforts focused on the species yielded more numerous specimens for study, which formed the basis for a redescription of the species (Muriel-Cunha & de Pinna, 2005)
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