The black-headed conundrum: Species boundaries in Chyphotes (Hymenoptera: Chyphotidae)

Although the taxonomy of Chyphotes (Hymenoptera: Chyphotidae) was revised by Mickel (1967), a great deal of taxonomic confusion remains in this unique group of nocturnal wasps.  One taxonomically challenging group, the C. melaniceps species-group, has a distinct color pattern where the head is black contrasting with the reddish-brown body.  This species-group is in one of the two subgenera, Chyphotes s.s., and includes C. aenigmus Mickel, C. atriceps Mickel, C. calexicensis Bradley, C. incredulus Mickel, C. melaniceps (Blake) and C. sp. nov.  These species, however, are based on minor differences in genitalic structures—differences that would not be considered to denote species in other groups—and have no external morphological differences. This makes distinguishing the species very difficult. Prior to Mickel (1967), authors thought that all of these were a single species (Chyphotes melaniceps (Blake)). Furthermore, their geographical distributions overlap.  These factors lead us to suspect that this "species-group" really contains only a single species.  We investigate this question with a Bayesian analysis of molecular data derived from the mitochondrial cytochrome c oxidase subunit I (COI) and the nuclear gene wingless (wg).  We obtained COI and wg sequences for all six species of black-headed Chyphotes (Chyphotes), five additional species in the subgenus of Chyphotes and two species from the subgenus Pitanta (used for outgroups) were analyzed also.  Unexpectedly, this analysis suggests that these species are, in fact, distinct and the minor differences in genitalic structure represent species-level variation.