Não informado

Author(s)

Alessio Datovo da Silva

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC)
• Defense date: 2006-10-02

Examining board members

Flávio Alicino Bockmann; Marcelo Rodrigues de Carvalho; Roberto Esser dos Reis

• Advisor: Flávio Alicino Bockmann

Abstract

Nematogenyidae is composed of a single species endemic to Central Chile; Trichomycteridae, its sister group, is the second most diversified family of Loricarioidea, and has a broad distribution throughout the Neotropical Region. These families form the most basal clade of the Loricarioidea and are therefore of great importance to understand its intrarrelationships and the relationships between it and remaining siluriforms. However, several of these questions remain to be satisfactorily resolved, especially within the Trichomycteridae. Several factors contribute to this problematic situation, among which is the poor state of knowledge of a number of morphological systems, such as their myology. A comparative study of myology, guided by cladistic methodology, has not been attempted for any large catfish group. The present dissertation is an attempt to solve these problems by means of a new approach based on the scrutiny of cephalic myology, mainly of the Nematogenyidae and Trichomycteridae. This study presents a detailed descriptive component allied to a rigorous cladistic analyses of myological characters of the cephalic region of the Nematogenyidae and Trichomycteridae. Concerning the descriptive part of this study, four new muscles were discovered and several modifications in the cephalic muscles within the examined groups were observed. The new characters sampled, mainly from the myological study, added valuable information to the cladograms of these families. The use of these features, along with a review of most characters employed in the literature, strongly corroborated some previous arrangements and produced a new hypotheses on the relationships within the Trichomycteridae. Nematogenyidae was confirmed as the sister group of Trichomycteridae. Copionodontinae and Trichogeninae are the basal successive sister groups of the remaining Trichomycteridae. The non-monophyletic nature of the Trichomycterinae was supported as in previous studies. Pareiodon was removed from the Stegophilinae and the subfamily Pareodontinae should be resurrected for it. (AU)