Pachylis Lepeletier & Serville, 1825 is one out of 22 genera of Nematopodini Amyot & Serville, 1843, which contains some of the largest species of Coreidae Leach, 1815. With eight species, the genus is characterized by the presence of expansion on antennomeres III and ventrally on metatibiae. Pachylis is sometimes confused with Thasus Stål, 1865, but the metatibial expansions are dorsal and ventral in the latter. Pachylis and Thasus have already been treated as closely related from a taxonomic perspective, although this relationship has never been tested in previous phylogenetic analyses. A phylogeny including seven Pachylis species and four Thasus species is performed here, based on morphological data and under implied weighting. Pachylis laticornis (Fabricius, 1798) is redescribed and P. furvus Brailovsky & Guerrero, 2014 is proposed as its new synonym. The outgroup contains 44 species, 30 out of them representative of other Nematopodini, and 14 species representing other tribes and subfamilies of Coreidae. We recovered Pachylis monophyletic and sister to T. rutilus Brailovsky & Barrera in Brailovsky et al., 1994 with the remaining three species of Thasus recovered sister to the clade of T. rutilus and Pachylis. Here we propose Thasus as a new junior synonym of Pachylis following our phylogenetic results. Our results also indicate Nematopodini, Melucha Amyot & Serville, 1843, and Piezogaster Amyot & Serville, 1843 are not monophyletic, emphasizing the need for further phylogenetic studies including these taxa.
Meropachyinae, leafooted bugs, squash bugs, Western hemisphere, male and female genitalia, new synonym, new combinations