Cladistic analysis and biogeography of Brachystethus Laporte (Heteroptera, Pentatomidae, Edessinae)

Abstract

In this paper, Brachystethus Laporte, 1832 is analyzed cladistically, using 21 characters and 15 taxa, including as outgroups, in a first analysis, the genera Neotibilis Grazia & Barcellos, 1994, Edessa Fabricius, 1803, Olbia Stål, 1862, Peromatus Amyot & Serville, 1843, and Pantochlora Stål, 1870. Further, these edessine genera were included in the ingroup, without any changes in the only resulting cladogram. The monophyly of Brachystethus is supported by four synapomorphies: metasternal carina partially bifurcated, pygophore with blade-like processes, anterior margin of gonocoxites 9 deeply concave medially, and a mesial thickening on gonapophyses 9. Brachystethus shares with Edessa, Olbia, Pantochlora, and Peromatus four synapomorphies: loss of subcallous margin on pronotum, mesosternal carina lower than metasternal carina, phallus with a short vesica, and presence of a beak-like projection on the thickening of vaginal intima. Based on the cladogram, the transferal of Brachystethus to Edessinae is here proposed. Biogeographical analysis has shown congruence between the distributional pattern of the clade formed by B. rubromaculatus Dallas, 1851, B. signoreti Stål, 1872, B. cribrus (Fabricius, 1781), and Brachystethus sp. nov. A, and vicariant events on Neotropical region, in the late Cretaceous.

Revision of Brachystethus (Heteroptera, Pentatomidae, Edessinae)

“…A cladistic analysis of Brachystethus (BARCELLOS & GRAZIA, 2003) supported the monophyly of the genus and also of Edessinae. Brachystethus shares with Edessa Fabricius, 1803, Olbia Stål, 1862, Pantochlora Stål, 1870 and Peromatus Amyot & Serville, 1843 the mesosternal carina not elevated, phallus with a short vesica and presence of a ventral, beak-like projection in the thickening of vaginal intima.…”

“…Brachystethus rubromaculatus is the sister group of the clade formed by B. signoreti, B. cribrus and B. schuhi, sharing with these species the fourth antennal segment medially swollen, the metasternal carina strongly elevated anteriorly and the little projected lobes of dorsal rim of pygophore (BARCELLOS & GRAZIA, 2003). It can be easily distinguished by the most frequent color pattern, dorsally black, with rounded red spots and venter black, with 1 + 1 spots extending from the anterior margin of fourth sternite until anterior margin of seventh.…”

“…Brachystethus signoreti is the sister group of the clade composed by B. cribrus and B. schuhi, sharing the homoplastic character of color pattern of legs, apex of femora and base of tibiae yellowish (BARCELLOS & GRAZIA, 2003). It can be distinguished from these species by the absence of calli on the corium and from B. cribrus, especially, by the color of venter, lacking yellow spots.…”

“…Brachystethus cribrus is the sister species of B. schuhi, sharing a homoplastic character, presence of yellowish calli on corium (BARCELLOS & GRAZIA, 2003). Brachystethus cribrus is separated from all other congeners by autapomorphic characters: abdomen with yellow spots and genital cup processes widely visible dorsally.…”

“…Brachystethus schuhi shares with its sister species B. cribrus the yellowish callus on corium, but can be distinguished by the following characters: venter uniformly castaneous, dark-castaneous coxae and genital cup processes moderately visible dorsally. Brachystethus schuhi is also closely related to B. signoreti and B. rubromaculatus (BARCELLOS & GRAZIA, 2003), being distinguished from the the former by the callus on corium and male genitalia, and from the latter by the yellowish apex of femora and base of tibiae. Iheringia (Figs.…”