Diagrams of basal sclerites of labium, posterior views of lorum, mentum, and basal part of prementum, extended and arranged in a single plane, and lateral views of same sclerites in more natural position. a, Anthophora occidentalis Cresson (Apidae); b, Melitta leporina (Panzer) (Melittidae); c, Melitturga clavicornis (Latreille) (Andrenidae); d, Panurgus calcaratus (Scopoli) (Andrenidae); e, Pseudopanurgus aethiops (Cresson) (Andrenidae); f, Megandrena enceliae (Cockerell) (Andrenidae); g, Andrena erythrogaster (Ashmead) (Andrenidae); h, Protoxaea gloriosa (Fox) (Andrenidae); i, Lasioglossum calceatum (Scopoli) (Halictidae). Abbreviations used here and in Figure 33-4 are: LA, loral apron; L, lorum; M, mentum; PM, prementum; F, basal fragmentum of prementum; A, basal apodeme of prementum; S, area of lorum lying against shaft of cardo, or in L-T and melittid bees, against apex of cardo. (Only the profiles of unsclerotized mentums or portions of mentums are shown, as dotted lines. Dots represent membrane. Dotted areas above lorums represent the membranous posterior surface of the labiomaxillary tube, extending toward its attachment to the head.) From Michener, 1985a. (source: Michener, 2007)