Phylogeny of the ‘broadheaded discocephalines’ (Hemiptera, Pentatomidae, Discocephalini)

Dicocephalini include a group of fourteen genera known as “broadheaded discocephalines” (BD). Cladistic analyses in Pentatomidae published so far are based exclusively on the external morphology of adults. Here a cladistic analysis BD genera was made using morphological characters of adults and eggs. Character polarization followed the outgroup method; data matrix included 20 species (ingroup: one of each of 14 genera of BD; outgroup: five non-BD genera, and Lincus (Ochlerini) used for character polarization and rooting of cladograms) and 70 characters, two of these from eggs. Eggs were obtained for nine species after dissection of dried females, cleaned and analyzed by scanning electron microscopy. Analyses were conducted on the software TNT using heuristic searches with equal character weights and under implied weighting, both with and without characters of eggs. Absolute and relative Bremer supports were calculated for each of the four analytical schemes. Analyses with equal character weights recovered the same topology and similar support values, with an extra synapomorphy when the characters of eggs were included. Analyses under implied weighting also recovered the same topology and similar support values, though with the resolution of the only polytomy found after the analyses with equal character weights. The characters of eggs proved to be informative. We suggest their future use on phylogenetic studies of Pentatomidae, and their extraction from dried females when fresh eggs are not available. Broadheaded discocephalines form a paraphyletic group regardless the analytical scheme adopted. However, BD can be considered monophyletic with the inclusion of Parvamima and Dryptocephala.