Melittidae

Abstract: Bees, the largest (>16,000 species) and most important radiation of pollinating insects, originated in early to mid-Cretaceous, roughly in synchrony with the angiosperms (flowering plants). Understanding the diversification of the bees and the coevolutionary history of bees and angiosperms requires a well supported phylogeny of bees (as well as angiosperms). We reconstructed a robust phylogeny of bees at the family and subfamily levels using a data set of five genes (4,299 nucleotide sites) plus morphology (109 characters). The molecular data set included protein coding (elongation factor-1α, RNA polymerase II, and LW rhodopsin), as well as ribosomal (28S and 18S) nuclear gene data. Analyses of both the DNA data set and the DNA+morphology data set by parsimony and Bayesian methods yielded a single well supported family-level tree topology that places Melittidae as a paraphyletic group at the base of the phylogeny of bees. This topology (“Melittidae-LT basal”) is significantly better than a previously proposed alternative topology (“Colletidae basal”) based both on likelihood and Bayesian methods. Our results have important implications for understanding the early diversification, historical biogeography, host–plant evolution, and fossil record of bees. The earliest branches of bee phylogeny include lineages that are predominantly host–plant specialists, suggesting that host–plant specificity is an ancestral trait in bees. Our results suggest an African origin for bees, because the earliest branches of the tree include predominantly African lineages. These results also help explain the predominance of Melittidae, Apidae, and Megachilidae among the earliest fossil bees.

Abstract: The long-standing notion of pollination syndromes, which postulates that plants form recognizable groups according to pollinator type, has been challenged recently on the basis of apparent widespread generalization in pollination systems. As a test of the pollination syndrome concept, I examined the pollination biology of a group of 15 orchids that share a recognizable syndrome of floral features that includes yellow-green coloration, oil secretion, pungent scent, shallow flowers, and a September peak in flowering. The orchids occur in sympatry in the Cape Floral Region of South Africa. According to the pollination syndrome concept, the similar floral features of this group indicate a shared pollinator. To test this prediction, I observed pollinators on Pterygodium alatum, P. caffrum, P. catholicum, P. volucris, Corycium orobanchoides, and Disperis bolusiana subsp. bolusiana. They shared a single species of pollinator, the oil-collecting bee, Rediviva peringueyi. Female bees collected oil from the lip appendage using modified front tarsi. The orchids reduce interspecific reproductive interference through differences in pollinarium length or the use of mutually exclusive pollinarium attachment sites on the body of the bee. The results are contrary to the expectation of generalization in pollination systems and suggest that pollinators play an important role in mediating selection on floral traits.

Abstract: Bees are the primary pollinators of angiosperms throughout the world. There are more than 16,000 described species, with broad variation in life history traits such as nesting habitat, diet, and social behavior. Despite their importance as pollinators, the evolution of bee biodiversity is understudied: relationships among the seven families of bees remain controversial, and no empirical global-level reconstruction of historical biogeography has been attempted. Morphological studies have generally suggested that the phylogeny of bees is rooted near the family Colletidae, whereas many molecular studies have suggested a root node near (or within) Melittidae. Previous molecular studies have focused on a relatively small sample of taxa (~150 species) and genes (seven at most). Public databases contain an enormous amount of DNA sequence data that has not been comprehensively analysed in the context of bee evolution. We downloaded, aligned, concatenated, and analysed all available protein-coding nuclear gene DNA sequence data in GenBank as of October, 2011. Our matrix consists of 20 genes, with over 17,000 aligned nucleotide sites, for over 1,300 bee and apoid wasp species, representing over two-thirds of bee genera. Whereas the matrix is large in terms of number of genes and taxa, there is a significant amount of missing data: only ~15% of the matrix is populated with data. The placement of the root as well as relationships between Andrenidae and other bee families remain ambiguous, as several alternative maximum-likelihood estimates fall within the statistically credible set. However, we recover strong bootstrap support for relationships among many families and for their monophyly. Ancestral geographic range reconstruction suggests a likely origin of bees in the southern hemisphere, with Melittidae ancestrally located within Africa, and Halictidae, Colletidae, and Apidae within the New World. Our study affirms the monophyly of each bee family, sister-taxa relationships between Apidae and Megachilidae (the ‘long-tongued bees’), between Colletidae and Stenotritidae, and between Colletidae + Stenotritidae and Halictidae. Our analyses reject a Colletidae-basal hypothesis for family-level relationships and instead support Melittidae as sister to the remaining bees. Southern hemisphere vicariance likely played an important role in early diversification within many bee families.

Abstract: The 173 family-group names for bees (Apoidea: Anthophila) are cataloged in chronological order. For each name the correct author, date, type genus, and combining stem are provided. The following names are considered nomina nuda: Phenacolletini, Ctenioschelini, †Chalicodomopsini, Liphanthini, Austropanurgini, and Hoplitini. The authorship of three names (Tapinotaspidini, Hexepeolini, and Ancyloscelidina) is corrected as each was a nomen nudum when first proposed, but has been subsequently made available by other authors. The following new names are proposed herein: Scraptrinae Ascher and Engel, new subfamily (Colletidae); Neffapini Ascher, new tribe (Andrenidae: Panurginae); Afrodasypodini Engel, new tribe (Melittidae: Dasypodainae), Afrodasypoda Engel, new genus; Hesperapina Ascher and Engel, new subtribe (Melittidae: Dasypodainae); Macrogaleina Engel, new subtribe (Apidae: Xylocopinae); and Ancyloscelidina Engel and Michener, new subtribe (Apidae: Apinae). A hierarchical outline of Apoidea class...