Translator Disclaimer
3 September 2009 Redescription of the Pez Graso, Rhizosomichthys totae (Trichomycteridae), of Lago de Tota, Colombia, and Aspects of Cranial Osteology Revealed by Microtomography
Scott A. Schaefer, Luis Fernández
Author Affiliations +

Rhizosomichthys totae, the Pez Grasso, greasefish, or runcho of Lago de Tota, Colombia, is known from ten specimens and thought to be extinct. The species is unique among trichomycterids in possessing remarkable rings of extensive adipose tissues surrounding the body. Although its internal anatomy is poorly known, diagnosis of Rhizosomichthys totae and taxonomic status within Trichomycteridae have not been questioned. Non-destructive reconstruction of the osteology of one paratype based on computed microtomography, combined with broad character surveys of representatives of other trichomycterid genera, formed the basis for a redescription of R. totae and revealed the presence of four additional autapomorphies involving features of the cranium, autopalatine, and branchiostegal rays. This evidence further confirms the membership of Rhizosomichthys within the putatively non-monophyletic subfamily Trichomycterinae. We evaluate in R. totae the characters serving to diagnose the genera presently included in the Trichomycterinae.

Rhizosomichthys totae, el Pez Grasso, bagre gordo, o runcho del Lago de Tota, Colombia, es conocido de diez ejemplares y se piensa extinto. La especie es única entre los tricomictéridos en poseer marcados anillos de abundante tejido adiposo rodeando el cuerpo. Aunque su anatomía interna es conocida pobremente, la diagnosis de Rhizosomichthys totae y el estatus taxonómico no ha sido cuestionado dentro de Trichomycteridae. Reconstrucción osteológica no destructiva de un paratipo basado en microtomografía computada, combinada con un amplia búsqueda de caracteres en representantes de otros géneros de tricomictéridos, constituye la base para la redescripción de R. totae y revela la presencia de cuatro autopomorfías adicionales involucrando rasgos del cráneo, autopalatino, y radios branquiostegos. Esta evidencia además lo confirma como miembro de Rhizosomichthys dentro de la no monofilética subfamilia Trichomycterinae. En R. totae evaluamos los caracteres que sirven para diagnosis del género, actualmente incluido en los Trichomycterinae.

2009 by the American Society of Ichthyologists and Herpetologists
Scott A. Schaefer and Luis Fernández "Redescription of the Pez Graso, Rhizosomichthys totae (Trichomycteridae), of Lago de Tota, Colombia, and Aspects of Cranial Osteology Revealed by Microtomography," Copeia 2009(3), 510-522, (3 September 2009).
Received: 7 October 2008; Accepted: 1 March 2009; Published: 3 September 2009

Get copyright permission
Back to Top