09 November, 2011

A PhD thesis with a major analysis of Rhopalurus

Humberto Yoji Yamaguti has presented a PhD thesis with a major analysis and revision of the South American genus Rhopalurus Thorell, 1876 (Buthidae). The thesis is published in Portuguese, which I can not read, but based on the English abstract the author concludes that the genus should be split into four genera (Rhopalurus, Heteroctenus, new genus A and new genus B). Several species are synonymized. See abstract for details.

NB! Please note that the taxonomic decision made in this thesis are not formally valid as a thesis is not considered published according to the ICZN code (Fet, Kovarik, Teruel, personal communications). I expect Yamaguti will publish his interesting results in scientific journals in the near future, making them formally valid.

A relationship hypothesis is proposed for the genus Rhopalurus Thorell, 1876 (Scorpiones: Buthidae). The genus has 19 valid species and two valid subspecies, and is diagnosed mainly by the presence of an stridulatory apparatus and by the expansion of the metassomal segments. The monophyly of Rhopalurus was never tested within a phylogenetic analysis, neither was the useness of those characters to support the genus. The analysis was made with 14 spp of Rhopalurus and 17 spp from other six Buthidae genera. We have used five genes (18S, 28S, 12S, 16S, and COI) and 86 morphological characters in a total evidence analysis, through parsimony and direct optimization. The genus Rhopalurus is paraphyletic and divided in four genera, here described: Rhopalurus, Heteroctenus (revalidation), gên. nov. A, and gên, nov. B. Synonymies: R. amazonicus and R. crassicauda paruensis with R. crassicauda, R. virkkii with H. abudi, R. acromelas with gên. nov. B agamemnon, R. pintoi kourouensis with gên. nov. B pintoi. Some of the South American genera (Rhopalurus, Physoctonus, and gên. nov. B) relate the Brazilian northeast with the north of South America, and the found patterns suggest allopatric speciation within these genera. The Heteroctenus patterns suggest dispersion from North America to the Greater Antilles, with later speciation events in each island. We also discuss a putative populational structure of gên. nov. B rochae. The presence of the stridulatory apparatus doesn't gather the former species of the genus. Furthermore, a detailed study reveals the existence of three different morphological types. Based on the obtained phylogeny, we related each one of these types with the genera where they occur (Rhopalurus, Heteroctenus, and gên. nov. B).

Yamaguti HY. Analise filogenetica e biogeografica do genero Rhopalurus Thorell, 1876 (Arachnida: Scorpiones: Buthidae) [These de Doctorat]. Sao Paulo: Universidad de Sao Paulo; 2011. [Free fulltext]

Thanks to Carlos Turiel, Jacek Szubert and Rolando Teruel for informing me about this thesis!

Family Buthidae

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