Taxonomic revision and cladistic analysis of Acrochaeta Wiedemann, 1830 (Stratiomyidae: Sarginae), with comments on monophyly of Merosargus Loew, 1855

Author(s)

Diego Aguilar Fachin

• 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: 2014-04-03

Examining board members

Dalton de Souza Amorim; Julio Cesar Rodrigues Fontenelle; Carlos José Einicker Lamas

• Advisor: Dalton de Souza Amorim

Abstract

Among the twelve subfamilies of Stratiomyidae, the Sarginae include 22 genera and 562 described species worldwide, of which 267 are Neotropical. There is still not a cladistic analysis for the subfamily or to the genera. Most of the Sarginae genera are poorly delimited, with diagnosis based mainly on plesiomorphies. The Acrochaeta falls into this situation, because many species of Merosargus have been identified as Acrochaeta due to the presence of elongated antenna and the similar color pattern of scutum between species of both genera. In addition, there is taxonomic and morphological inaccuracy in descriptions of species of Acrochaeta and Merosargus, and lack of illustrations of male and female genitalias of the species, information that could be useful in the delimitation of the genera. This study, hence, makes a taxonomic revision and a cladistic analysis of the genus Acrochaeta, aiming to define the genus from phylogenetic perspective. The Acrochaeta now includes 15 species (seven described and eigth new species). In this study, three Acrochaeta species were transferred to Merosargus: M. chalconota comb. nov, M. longiventris comb. nov. and M. picta comb. nov. Another was moved to Chrysochlorina (Chrysochlorininae): C. elegans comb. nov. In addition, M. convexifrons were moved to Acrochaeta: A. convexifrons comb. nov. The genera Acrochaeta and all previously described species were redescribed, and the new species were described. An identification key to species of the genus is provided. A cladistic analysis is performed, 45 terminal taxa and 63 morphological characters, resulting in four most parsimonious trees (equal weighting). Problems of homology, the position of species in the topology, character evolution and robustness of clades are discussed based on the strict consensus phylogeny. The monophyly of Acrochaeta was recovered by characters of head, thorax and abdomen. An inner clade in the genus was recovered, especially based on characters of the male genitalia. Furthermore, a wide selection of outgroups allowed preliminary results on the non-monophyly of Merosargus, because some of its species being closer to Acrochaeta and Himantigera than a clade that includes the type-species of the genus, Merosargus obscurus. (AU)

• FAPESP's process: 11/14472-6 - Taxonomic revision and phylogenetic analysis of genus Acrochaeta Wiedemann, 1830 (Diptera: Stratiomyidae: Sarginae)
• Grantee: Diego Aguilar Fachin
• Support Opportunities: Scholarships in Brazil - Master