Full text
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| Author(s): |
Roberta Leone Masiero
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2006-12-19 |
| Examining board members: |
Hussam El Dine Zaher;
Francisco Luís Franco;
Marcio Roberto Costa Martins
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| Advisor: | Hussam El Dine Zaher |
| Abstract | |
The genus Xenodon, together with five other genera, Erythrolamprus, Liophis, Lystrophis, Waglerophis and Umbrivaga, constitutes the tribe Xenodontini Bonaparte 1845. This tribe is included in the subfamily Xenodontinae, a monophyletic group distributed throughout the South American continent. The phylogenetic proximity among Xenodon, Waglerophis, and Lystrophis has already been pointed out by authors. The synonymy of Waglerophis with Xenodon as well as a sister-group relationship between Lystrophis and the latter have already been proposed. The present study offers a phylogenetic analysis of the genus Xenodon, based on a total of 54 morphological characters derived from cephalic miology and osteology and hemipenial morphology. Representatives of other tribes of the subfamily Xenodontinae as well as taxa representing other Xenodontini genera were included in the data matrix as outgroups for the genera Xenodon, Lystrophis and Waglerophis. Additionally, representatives of the genera Farancia, Heterodon, and Hydrodynastes, of uncertain position within the subfamily or included by some authors in the tribe Xenodontini, were also added to the data matrix in order to test their phylogenetic affinities with the latter. The monophyly of the tribe Xenodontini and of the group composed of the genera Xenodon, Lystrophis, and Waglerophis was corroborated. According to the presented results, both genera Waglerophis and Lystrophis are rooted within a polyphyletic genus Xenodon. Three different possibilities of taxonomic rearrangement for the clade composed of these three genera are as follows: 1) to include the three genera under the name Xenodon; 2) to split the genera in four groups, maintaining the names Xenodon and Lystrophis for monophyletic subgroups of the clade and accommodating X. neuwiedii and X. guentherii in new genera; 3) to keep the name Xenodon for a monophyletic subgroup, create a new genus for Xenodon neuwiedii and another for Xenodon guentheri plus Lystrophis. (AU) | |