Systematic status of Plectroctena mandibularis Smith and P. conjugata Santschi (Hymenoptera: Formicidae: Ponerini)

Abstract

Plectroctena mandibularis Smith is the type species of Plectroctena F. Smith. Because there has been some doubt about its distinctness from P. conjugata, several techniques were used to assess the systematic status of the two species. Most crucially, several colony series contained workers of both phenotypes, and where these series included queens or males, the distinguishing feature of these specimens was not consistently related to those of the workers. Queens, males and workers did not manifest qualitative differences between the taxa, and morphological variation was continuous between the two. The putative morphological basis (funicular index) for distinguishing workers of the taxa arose from allometric variation. Putatively diagnostic colour variation in males was related to latitude, but no simple pattern of morphological variation could be correlated with geographical distribution. Plectroctena conjugata is therefore considered a junior synonym of P. mandibularis