Proventricular structure in the bee tribe Augochlorini (Hymenoptera: Halictidae)

Characters of the digestive tract have received little attention in modern phylogenetic analyses regarding relationships among bees, in part because studies on the internal morphology of bees generally concentrate on physiological and behavioural aspects. This paper presents a comparative study of the proventricular structure, analysed with scanning electronic microscopy, in bees of the tribe Augochlorini. Eleven species of Augochlorini were analysed as the ingroup, versus one each of Halictini and Caenohalictini, and two of Crabronidae as outgroups. The presence of a long columnar proventricular fold is an apomorphy for Augochlorini, whereas a proventricular fold with a keel-shaped structure at the moving lip level is an apomorphy for Augochlorina. Together these data corroborate the monophyly of Augochlorini and Augochlorina, respectively.