Phylogeny of the Corynura group, an endemic southern South American clade sister to all other Augochlorini bees (Hymenoptera: Halictidae), and a revision of Corynura

Abstract

Corynura Spinola, Callistochlora Michener and Halictillus Moure are the only taxa of Augochlorini endemic to southern South America. They are phylogenetically close, comprising a clade sister to all other augochlorines, which are mainly distributed in tropical America. Corynura and Callistochlora are common bees in Chile and the Argentinean Patagonia, while Halictillus inhabits also central Argentina and southern Brazil. A phylogenetic parsimony analysis of 93 morphological characters coded for 25 species supports the monophyly of each of the three taxa, of the clade formed by them, and their sister relationship to the remaining Augochlorini genera. Our analyses suggest Callistochlora as sister to Hallictillus + Corynura. Callistochlora, which has been treated as a subgenus of Corynura, is elevated to genus level. The study of the gradulus of the sterna, a structure usually ignored in morphological analysis, helped in the resolution of the group. A revision of Corynura is presented. We recognize 19 valid species, of which five are described as new: C. callaina sp.n., C. challhuacoensis sp.n., C. condita sp.n., C. luisae sp.n., and C. nahuelita sp.n. The males of C. apicata Sichel, C. patagonica Cockerell and C. spadiciventris Alfken are described for the first time. The following are new synonyms: Rhopalictus callicladurus Cockerell syn.n. is a junior synonym of C. ampliata (Alfken); Halictus analis Herbst syn.n. and C. heterochlora Alfken syn.n. are junior synonyms of C. bruchiana (Schrottky); Rhopalictus corinogaster chiloeensis Cockerell syn.n. is a junior synonym of C. corinogaster (Spinola); R. chloronotus Cockerell syn.n. and R. melanocladus Cockerell syn.n. are junior synonyms of C. herbsti (Alfken). Neotypes are designated to stabilize the usage of three names: Halictus apicatus Sichel, Halictus bruchianus Schrottky, and Corynura gayi Spinola. Lectotypes are designated for six names: Halictus (Corynura) atrovirens Herbst, Halictus analis Herbst, Halictus (Corynura) herbsti Alfken, Halictus spinolae Friese, Corynura lepida Alfken, and Corynura spadiciventris Alfken. Diagnoses, comments on the type specimens, floral associations, notes on variation within species, images, distributional data and a key to the species are provided.