Descrição de quatro novas espécies de Belostoma Latreille, 1807 e análise cladística do grupo B. plebejum sensu Nieser, 1975 (Insecta: Heteroptera: Belostomatidae)

Abstract

Belostoma plebejum species group sensu Nieser comprises seven extant small species of giant water bugs, currently reported from Honduras to southern South America. The main goals of this thesis were to conduct a cladistic analysis to test the monophyly of B. plebejum species group and to develop a phylogenetic hypothesis for the group. During the study of the specimens, four new species of the group were discovered and described, being employed as components of the ingroup in the analysis. The prosternal keel, axillary sclerites, and male genitalia structures are similar between two species from Amazonas, Brazil, while the other two species, one from Minas Gerais, Brazil and another from Mato Grosso, Brazil, are similar to B. plebejum (Stal) in the body shape and male genitalia structures. A key to species of B. plebejum group was included. Features based on the study of axillary sclerites and the hemelytra-locking mechanisms (the knoband-socket system) were used for the first time. Putative homology hypotheses were coded as 48 characters for 31 terminal taxons, including 14 outgroups from B. denticolle sensu Lauck species group, B. minor sensu Lauck species group, and B. oxyurum sensu Lauck species group. ln order to test procedures as weighting and ordering of characters, ten parsimony analyses of this data set were performed, each with different inclusion or exclusion, weighting and ordering of characters. There was no strong support for monophyly of B. micantulum, which appeared as paraphyletic or polyphyletic m the analysis; the species should be redefined in order to correspond to a monophyletic assemblage.