Phylogeny and Classification

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.


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. Gonzalez et al. (2012) reached a similar conclusion for Noteriades being a member of the Megachilini rather than the Osmiini. 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).


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).

The species of the subgenus Tergosmia and and the only species of the subgenus OzbekosmiaOsmia avosetta, share many morphological characteristics (Warncke, 1988b). In addition, the construction of their brood cells is unique in that the cells are composed of two layers of flower petals that sandwich a thin middle layer of mud (Rozen et al., 2010). Furthermore, all Tergosmia species as well as Osmia avosetta exhibit a strong or exclusive preference for Fabaceae as pollen hosts (see species accounts on this website). For these reasons, we propose to merge the subgenera Tergosmia and Ozbekosmia into one subgenus Tergosmia comb. nov. (A. Müller, unpublished).

A recent study (Sedivy et al., 2013c) proposed to unite all Hoplitis species of the subgenera Annosmia, Bytinskia, Coloplitis and Hoplitis (the “Annosmia-Hoplitis group”) in a single subgenus Hoplitis because i) Annosmia is polyphyletic in its current circumscription, ii) the cleptoparasitic Bytinskia species have evolved from the same lineage as their Annosmia hosts, iii) the most basal clade of Hoplitis is morphologically and biologically intermediate between Annosmia and Hoplitis, and iv) Coloplitis is morphologically very close to Annosmia. An alternative solution to eliminate the polyphyly of Annosmia would be the establishment of a monotypic subgenus for the most basal species of the Annosmia-Hoplitis group, Hoplitis bassana, which, however, appears unjustified owing to the morphological similarity of H. bassana with Annosmia. Merging all four subgenera into a single large subgenus results in a monophylectic taxon, which is morphologically distinctive due to a conspicuous yellowish membrane below the lateral extremity of the labrum that is present in all species.

The same study (Sedivy et al., 2013c) proposed to merge all Hoplitis species of the subgenera Alcidamea, Cyrtosmia, Dasyosmia, Megalosmia, Monumetha and Prionohoplitis (the “Alcidamea” group) into a single subgenus Alcidamea for the following reasons: i) Alcidamea is clearly polyphyletic in its current circumscription with all the other subgenera emerging from within this subgenus, and ii) the monophyly of Prionohoplitis is not supported. Uniting all six subgenera of the Alcidamea group results in a phylogenetically strongly supported clade, which, however, is characterized by only a few morphological characters such as the shape of the female clypus and the shapes of the male sterna 4-7.

Sedivy et al. (2013c) also proposed to unite all Hoplitis species of the exclusively nearctic subgenera Acrosmia, Hoplitina, Penteriades and Proteriades (the “Proteriades group”) in a single subgenus Proteriades because i) neither Proteriades nor Hoplitina appear to be monophyletic taxa, ii) the distinction between the Hoplitis subgenera Penteriades and Acrosmia based on the presence or absence of hooked hairs on the female proboscis is not justified as two of the five Acrosmia species also possess such hooked hairs, and iii) the four subgenera closely resemble each other morphologically, especially in the female sex. Merging all four subgenera of the Proteriades group into a single large subgenus results in a morphologically and biologically well characterized taxon, whose monophyly is strongly supported by numerous morphological characters.

A recent study (Haider et al., 2013) on the phylogeny and floral hosts of Osmia bees of the subgenera Monosmia, Osmia and Orientosmia revealed paraphyly of the largest subgenus Osmia. Given this paraphyly in conjunction with the pronounced morphological resemblance among the species of all three subgenera, the authors propose to to merge Monosmia (1 species), Osmia (25 species) and Orientosmia (3 species) into one single large subgenus Osmia.

Based on a new molecular phylogeny of the bee genus Osmia with emphasis on North American Melanosmia, Rightmyer et al. (2013) erected a new Nearctic subgenus of Osmia, Hapsidosmia, for a single species formerly treated as a member of the subgenus Melanosmia. Furthermore, they synonymized the two Nearctic subgenera Mystacosmia and Acanthosmioides under Melanosmia. This study also clarified the phylogenetic relationships among the different subgenera of Osmia, e.g. Osmia (Erythrosmia) is newly supported as sister to Osmia (Tergosmia).

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 (