MATTONI Camilo Ivan
congresos y reuniones científicas
Phylogeny and Biogeography of the Family Bothriuridae (Scorpiones)
San Isidro, Buenos Aires, Argentina
Congreso; VII Reunión Argentina de Cladística y Biogeografía; 2007
The scorpion family Bothriuridae comprises ca. 130 species in 13 genera, with a Gondwana distribution in South America (11 genera), southern Africa (one genus) and Australia (one genus). Phylogenetic relationships among the bothriurid genera have been studied previously, but require further investigation in light of recent developments. For example, the monophyly and validity of Brandbergia (Prendini, 2003) was recently questioned, and it was synonymized with Lisposoma (Fet et al., 2004). Some genera, like Bothriurus, have been hypothesized as non monophyletic (Prendini, 2000, 2003), and the validity of one monotypic genera, Brazilobothriurus (Lourenço & Monod, 2000), remains controversial. Recently collected scorpions from Chile show intermediate and/or new characteristics, and are considered possible new genera. The goals of the present study were to (1) test the monophyly of Bothriuridae and determine its phylogenetic placement with respect to other scorpion families; (2) resolve the phylogenetic relationships among and test the monophyly of the bothriurid genera; (3) provide a hypothesis of historical biogeographical events explaining the present distribution of the family in light of the phylogeny. A comprehensive revision of the external and internal morphology was undertaken, which produced 247 characters (50 uninformative) for 49 bothriurid species and 12 outgroups. DNA from 5 loci (12S, 16S, 18S, 28S and COI) for all taxa (except Brandbergia haringtoni and Brazilobothriurus pantanalensis) were sequenced and aligned using Muscle, providing 4266 additional characters (1177 informative). Combined matrix comprises 1373 informative characters. Phylogenetic analyses were conducted and the support for each group calculated for the morphology and the combined matrices using TNT program. The addition of DNA sequences slightly change the results coming from the morphology alone, adding more support to most of the internal branches. The monophyly of Bothriuridae was well supported (Fig. 1), but its placement as sister group of the remaining scorpionoids is contentious. The validity of Brandbergia was confirmed, the genus being placed sister to all other Bothriuridae genera, and it was reinstated. The monophyly of Brachistosternus, and its current division into three subgenera, were supported, and its position as sister group of the remaining bothriurids (excepting Brandbergia, Lisposoma and Thestylus) was established. Bothriurus and Orobothriurus were polyphyletic: three new genera must to be created. Brazilobothrius is placed deeply inside Bothriurus bonariensis clade. Vachonia and Timogenes were sister taxa, placed in a group with part of Bothriurus species (“inermis” group). Tehuankea was closely related to Centromachetes, and Cercophonius+Urophonius clade. Some of the genera presenting the most plesiomorphic characters, Lisposoma, Brandbergia, and Thestylus, display distributions that are congruent with vicariance events associated with the break up of Gondwana. Considering present distribution patterns and phylogeny, the family Bothriuridae is at least 150 million years old. Three historical biogeographical events were important in the evolution of its genera: (1) the break up of Gondwanaland (first Africa, secondarily Australia and South America); (2) development of the high Andes; (3) formation of the arid and semi-arid lands in central-south South America. The most speciose bothriurid genera (e.g. Bothriurus, Brachistosternus) evidently radiated in association with the aridification of southern South America.