Evolution and Diversity of Stingless Bees

Abstract

Stingless bees (Meliponini) belong to the corbiculate bees, a monophyletic group of bees characterised, among other things, by their particular pollen-carrying structures (“pollen baskets” or corbiculae) on the hind legs (Chap. 1; Fig. 1.1) (Michener 2007). The evolution of the concave pollen baskets allowed corbiculate bees to transport large amounts of pollen and especially resin in an efficient way (Martins et al. 2014). Three other tribes belong to the corbiculate bees, the highly eusocial honey bees (Apini), the primitively eusocial bumble bees (Bombini), and the mostly solitary orchid bees (Euglossini) (Grimaldi and Engel 2005; Michener 2007). The term higher eusocial (sometimes also advanced eusocial or superorganismal) is often used to refer to species with morphologically distinct queen and worker castes (Michener 1974, 2007; Danforth et al. 2013; Boomsma and Gawne 2018). Occasionally, a perennial colony lifestyle (Michener 2007) or extensive food exchange among the adults (Michener 1974) is mentioned as defining features of highly eusocial colonies. In primitively eusocial colonies, queens and workers appear morphologically similar and can be distinguished mainly by their size (Michener 1974, 2007; Danforth et al. 2013). Stingless bees can be distinguished from the other corbiculate bees by a number of morphological traits, including a reduced forewing venation, the penicillum, the absence of an auricle (pollen press), the presence of a jugal lobe in the hind wing, and the reduced sting (Figs. 1.1 and 1.3) (see Michener 2007 for details).