New Molecular Phylogenetic Evidence Confirms Independent Origin of Coxal Combs in the Families of the 'Cydnoid' Complex (Hemiptera: Heteroptera: Pentatomoidea).

Simple Summary: Four families (Cydnidae, Parastrachiidae, Thaumastellidae, and Thyreocoridae) in the superfamily Pentatomoidea are morphologically defined by a similar body outline and the presence of a series of stout setae on the distal margin of the coxae. These structures, called coxal combs, are thought to protect the coxal–trochanteral articulation from damage caused by soil and sand particles and have not been observed in other true bugs (Hemiptera: Heteroptera). Therefore, they have been consistently considered a synapomorphy for these four families. However, their independent origin in these families has been suggested by nuclear ribosomal DNA sequence analysis (28S rDNA and 18S rDNA). This study investigated whether the analysis of mitochondrial 16S ribosomal DNA sequences would confirm these results. In addition, we examined whether any group of species possessing the coxal combs could be considered a well-supported independent monophylum. Coxal combs, found only in members of the 'cydnoid' complex (comprising four families: Cydnidae, Parastrachiidae, Thaumastellidae, and Thyreocoridae) within the superfamily Pentatomoidea, have long been regarded as a character confirming their close evolutionary relationship. However, many studies have demonstrated that these four families are phylogenetically distant. Others have been treated as subfamilies of the broadly defined Cydnidae, with the coxal combs as the only character linking them. This is the first study on the origin of coxal combs in species of all families and subfamilies that represent the broadly conceived Cydnidae (69 species in 39 genera). Moreover, this study presents the first 16S rDNA gene sequences providing a basis for such analyses. The analyses included DNA sequences of 62 species in 34 genera of Cydnidae sensu stricto, three species in two genera of Thyreocoridae, two species in two genera of Parastrachiidae, and two species in one genus of Thaumastellidae. The sequence analysis in the family Cydnidae covered 35 species representing 19 genera of the subfamily Cydninae, 16 species in eight genera of the subfamily Sehirinae, five species in two genera of Amnestinae, three species in three genera of Garsauriinae, two species in one genus of Cephalocteinae, and one species of Amaurocorinae. The results of our study demonstrate the independent origin of coxal combs in taxa of the 'cydnoid' complex within the superfamily Pentatomoidea. They confirm the polyphyly not only of the entire 'cydnoid' complex but also of the family Cydnidae itself. [ABSTRACT FROM AUTHOR]