Cladistic analysis of the Neotropical genus Chroaptomus Sharp (Coleoptera: Staphylinidae: Staphylininae)

CHANI POSSE, M.

Trelew, Argentina

Congreso; VI Reunión Argentina de Cladística y Biogeografía; 2006

The Neotropical genus Chroaptomus Sharp belongs to the Philonthina, a very speciose subtribe of Staphylinidae, particularly in the tropics where many genera have not been revised since their original description. Recent studies on Philonthina do not deal with Neotropical fauna, with exception of those genera with representatives in the Neotropics which are only 4 % of about 450 species currently cited for this area. The genus Chroaptomus comprises five species distributed from central Mexico, throughout Central and South America, to northwestern Argentina: Chroaptomus flagrans (Erichson), C. regalis Sharp, C. coelites (Erichson), C. centralis Chani-Posse and C. mexicanus Chani-Posse and Navarrete-Heredia. Its striking sexual dimorphism of the labrum and frontoclypeus is unusual in the subtribe Philonthina and shows great variability among species. Chosen outgroups to root the tree were four representatives within Philonthina: two in the genera Philonthus Stephens, one in Bisnius Stephens, and one in Belonuchus Nordmann. Ten terminal units were included in the cladistic analysis, the five species of Chroaptomus, and the four outgroup taxa. Forty characters were used, from which 31 were derived from the external morphology, eight from male genitalia and one from female genitalia. Ten multistate characters were treated as unordered (non-additive) and given equal weight. Data matrix was analyzed with Nona (Goloboff 1999). The analysis of the data matrix produced three cladograms with 70 steps. The three trees differ only in the placement of outgroups. In all of the three trees, relationships within Chroaptomus are resolved. The monophyly of Chroaptomus is established by nine synapomorphies and high Jacknifying values. Keywords: Neotropical-Staphylinidae-Philonthina-Chroaptomus- sexual dimorphism