Phylogenetic analysis of the Tityus clathratus species group and other Tityus groups and subgenera (Scorpiones, Buthidae) based on molecular and morphological characters

Author(s)

Jairo Andres Moreno Gonzalez

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2021-02-10

Examining board members

Ricardo Pinto da Rocha; Oscar Federico Francke Ballvé; Alvaro Eduardo Florez Daza; Camilo Iván Mattoni

• Advisor: Ricardo Pinto da Rocha

Abstract

Among the buthid genera, Tityus is the most species-rich genus (>220 species). Nevertheless, despite its richness, wide distribution, and medical importance, insufficient attention has been paid to the study of its phylogenetic relationships. Our study aimed to test the monophyly of Tityus and its subgenera and species groups, with a special emphasis on the Tityus clathratus species group, using a total evidence approach. To do so, we used 162 phenotypic characters and ~3618 nucleotide base pairs from three mitochondrial (12S, 16S, and COI) and two nuclear (18S and 28S) markers. Also, we included 161 terminals (141 terminals of Tityus/ 88 terminals of the Tityus clathratus species group), representing 58 Tityus species (25% of the genus richness). The other 20 terminals were composed of outgroup buthid genera mainly distributed in South America, and each genus was represented by two species (except for Ananteris). Molecular-only and total evidence matrixes were individually analyzed using maximum likelihood (IQTREE), and maximum parsimony with static homology (TNT) and dynamic homology (POY) for the molecular data. In general, the hypotheses obtained were very similar, independently of the optimality criteria and molecular homology scheme employed. In all the trees: i) Tityus was monophyletic and had two main clades, ii) MesoTityus was a synonym of Tityus, iii) MicroTityus was the sister group of Tityus (except for the MP-SH-TE tree), iii) Tityus (MesoTityus) was monophyletic, and vi) Ananteris was the sister group of the other genera analyzed. Additionally, we observed an increase in the support values in the total evidence dataset analysis compared to the molecular-only dataset analysis, in both optimality criteria. Interestingly, outgroup genera relationships, Tityus (MesoTityus) internal relationships, and the positions of a few terminals of Tityus (Atreus) and Tityus (Tityus) were sensible to the optimality criteria and molecular homology scheme employed. Also, based on our results, we proposed: a new subgenus; three new species groups; a new species of Tityus (MesoTityus): Tityus crypticus sp. n..; two species groups synonyms, and seven species synonyms of the Tityus clathratus species group. In total, 14 Tityus species group were recovered in our analyses. Finally, to allow the taxonomic use of our phylogeny, we proposed an identification key to New World buthid genera and Tityus species groups. This study was the third total evidence analysis ever done in the family Buthidae and the first to focus on Tityus terminals. Nevertheless, additional phylogenetic studies, including more evidence (phenotypic and genotypic) and Tityus terminals, are needed to propose a future comprehensive phylogenetic hypothesis of this diverse Neotropical genus. (AU)

• FAPESP's process: 15/18376-2 - Systematic revision and phylogenetic analysis of Tityus (Archaeotityus) (Scorpiones: Buthidae) based upon morphological and molecular characters
• Grantee: Jairo Andrés Moreno González
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)