Palaearctic Osmiine Bees

Exposed brood cell of Hoplitis (Hoplitis) loti (Morawitz, 1867) on the surface of a rock; the cell consists of small pebbles cemented together with mud. Foto A. Müller.

Phylogeny

In a recent molecular phylogenetic study based on three nuclear genes and 95 osmiine bee species (Praz et al., 2008b), the core osmiine genera were found to form a well-supported monophyletic group (Figure 1). However, three small genera, Noteriades, Afroheriades and Pseudoheriades, which were formerly included in the Osmiini (Michener, 2007), do not appear to belong within this clade. The phylogenetic position of the genera Ochreriades and Bekilia remains unsolved. Depending on the analysis, Ochreriades turned out to be either sister to the Osmiini or sister to the clade Megachilini+Anthidiini+Osmiini. Bekilia was not included in the analysis. It is a monotypic genus with uncertain affinities due to the lost type material and may belong to the Anthidiini close to Afrostelis rather than to the Osmiini (Griswold & Michener, 1998; Michener, 2007).

Classification

The molecular phylogeny of Praz et al. (2008b) results in four taxonomic changes in comparison to the classification of Michener (2007): the former genera Stenosmia and Hoplosmia are reduced to subgeneric rank in Hoplitis and Osmia, respectively, Micreriades is recognized as a subgenus of Hoplitis, and the subgenus Nasutosmia is transferred from Hoplitis to Osmia. It further enables a clearer suprageneric subdivision of the Osmiini than that suggested by Michener (2007): the genus Chelostoma clearly emerged as the sister group of all other osmiine bees (Figure 1) and thus deserves the same rank as the Heriades group and the Osmia group, often recognized as subtribes Heriadina and Osmiina, respectively (Engel, 2005; Ungricht et al., 2008).

New suprageneric grouping of the Osmiini (Praz et al., 2008b):

Chelostoma group

Chelostoma Latreille

Heriades group

Heriades Spinola

Hofferia Tkalcu

Othinosmia Michener

Protosmia Ducke

Stenoheriades Tkalcu

Xeroheriades Griswold

Osmia group

Ashmeadiella Cockerell

Atoposmia Cockerell

Haetosmia Popov

Hoplitis (including Stenosmia) Klug

Osmia (including Hoplosmia) Panzer

Wainia Tkalcu

A recent phylogenetic analysis of the genus Chelostoma on a worldwide scale (Sedivy et al. 2008) revealed a close relationship between the North American Chelostoma (Prochelostoma) philadelphi and the eastern Palaearctic Chelostoma (Ceraheriades) petersi (= lamellum) with respect to morphology, DNA sequences and flower preferences. Thus, their inclusion in two different subgenera is no longer justified and Ceraheriades is treated here as a junior synonym of Prochelostoma (A. Müller, unpublished).

Hoplitis oxypyga, the only representative of the subgenus Exanthocopa, was known so far only in the male sex. Recently, females of this rare North African species were detected (A. Müller, unpublished). The females are morphologically so close to the females of Hoplitis (Anthocopa) bisulca that they can hardly be distinguished. Therefore, the subgenus Exanthocopa is synonymized here with the subgenus Anthocopa (A. Müller, unpublished).

Figure 1: Parsimony bootstrap consensus tree of the osmiine bees. All nodes with less than 50% bootstrap support were collapsed. After Praz et al., Molecular Phylogenetics and Evolution, 49, 185-197, 2008. With permission from Elsevier (http://www.sciencedirect.com/science/journal/10557903).