Palaearctic Osmiine Bees

Osmia (Hemiosmia) argyropyga was reported to nest in old brood cells of Megachile (Chalicodoma) pyrenaica Lepeletier (Grandi, 1962), which was assumed to be erroneous in a recent publication (Müller, Zootaxa, 4778, 201-236, 2020) as such a behaviour strongly deviates from the nesting biology of the closely related and morphologically very similar species O. balearica and O. uncicornis. This assumption is now supported by observations made by David Genoud, who observed a female of O. argyropyga nesting in a self-excavated burrow in loose soil in southern France. The record of O. argyropyga from Emilia-Romagna (Italy) given by Grandi (1962) is thus most probably also erroneous.

In two recent publications, the nesting biology of Osmia (Melanosmia) laticeps (Theunert, Beiträge zur Naturkunde Niedersachsens, 72, 53-71, 2019) and Osmia (Melanosmia) uncinata (Müller et al., Alpine Entomology, 4, 157-171, 2020) are described. The first species nests in insect burrows in dead wood, whereas the second constructs its brood cells within self-excavated short burrows in the bark of living trees and dead stumps of Pinus sylvestris or – more rarely – Larix decidua (see species accounts for details).

In three recent publications, the nesting biology of Hoplitis (Alcidamea) princeps (Ivanov & Fateryga, Entomological Review, 98, 995-1005, 2018), Osmia (Erythrosmia) andrenoides (Müller & Richter, Entomo Helvetica, 12, 69-79, 2019) and Osmia (Melanosmia) nigriventris (Müller et al., Alpine Entomology, 3, 105-119, 2019) is described. The first species nests in self excavated short burrows in loose soil, the second species colonizes empty snail shells as nesting sites and the third species tunnels out burrows in the bark of larch and pine (see species accounts for details).

Wainia (Caposmia) sexsignata, which occurs in southern Morocco and northern Western Sahara, nests in empty snail shells as reported in a recent publication in the Journal of Hymenoptera Research, 65, 61-89, 2018 (see species account for details). As several Afrotropical Wainia (Caposmia) species also use snail shells as nesting site, snail shell nesting appears to be a subgeneric trait of Wainia (Caposmia).

Hoplitis mucida was considered to consist of two subspecies with H. mucida mucida (Dours 1873) ranging from northwestern Africa to Israel and Jordan and H. mucida stecki (Frey-Gessner 1908) occurring in southwestern Europe and Sicily. As described in a recent publication (Journal of Hymenoptera Research, 60, 99-109, 2017), the nesting biology of the two subspecies strikingly differs. In North Africa, females construct fully exposed, cake-like nests of mud on the flat surface of rocks and stones containing 8–12 vertically oriented brood cells, rendering these nests unique among osmiine bees regarding both nesting site and nest architecture. In contrast, in Europe females build their few-celled mud nests inside small rock cavities. This discrepancy in the nesting biology is paralleled by considerable morphological differences between the two subspecies suggestive of a long geographical isolation. Due to these biological and morphological differences, the European subspecies H. mucida stecki was elevated to species rank by the authors of the publication mentioned above.

The nesting biology of the rare European osmiine bee species Osmia pilicornis was still unknown. The recent discovery of several nests in Germany and Austria by Prosi et al. (2016) revealed that this species has a unique nesting behaviour among the osmiine bees: the females gnaw their nests with the aid of specialized mandibles in dead branches, which lie on the ground and are partly hidden under vegetation. Recently, Lemoine (2016) also discovered a nest in northern France, which was built in a branch of Populus; in contrast to his statement in the article that a preexisting beetle burrow served as nesting site, the female bee actually tunnelled out the nest by herself (personal communication by G. Lemoine) supporting the findings of Prosi et al. (2016). For details on nesting site and nest architecture see the species account on the Palaearctic osmiine bee website.

In a recently published paper, Müller (2015c) describes nest architecture and flower preferences of the boreoalpine Hoplitis (Alcidamea) tuberculata. The nest architecture of H. tuberculata is unique among Palaearctic osmiine bees. However, it corresponds to that of three North American species closely related to H. tuberculata. For details see the species account on the Palaearctic osmiine bee website.

In a recently published paper, Rozen et al. (2015) describe the nesting biology, flower preferences and larval morphology of Ochreriades fasciatus, a rare bee species restricted in its distribution to the Levant. For details see the species account on the Palaearctic osmiine bee website.

The biology of the two Hoplitis species of the subgenus Tkalcua was entirely unknown so far. On their excursion to Fuerteventura in spring 2015, V. Mauss and A. Müller detected nests of H. (Tkalcua) zandeni in empty snail shells. For details see the species account on the Palaearctic osmiine bee website.

G. Le Goff discovered the hitherto unknown nests of Hoplitis (Anthocopa) zaianorum and Hoplitis (Hoplitis) tenuiserrata in southern Morocco in spring 2013. For details see the species accounts on the Palaearctic osmiine bee website.