Andrena allosa Warncke, 1975

Praz, Christophe, Mueller, Andreas & Genoud, David, 2019, Hidden diversity in European bees: Andrenaamieti sp. n., a new Alpine bee species related to Andrenabicolor (Fabricius, 1775) (Hymenoptera, Apoidea, Andrenidae), Alpine Entomology 3, pp. 11-38 : 15-16

Andrena allosa Warncke, 1975 Figs 14, 18, 23, 25, 28, 32, 35, 43, 45, 49, 54.

Andrena allosa Warncke 1975a: 311, ♀, "Allos, Basses-Alpes" [France]. Holotype ♀, OLML, paratypes ♀♀.

Material examined.

Type material: holotype female of A. allosa (Fig. 18); additional material: 57 females, 2 males from various localities in France and Switzerland (Suppl. material 1).

Distribution.

Western Alps from "Alpes Maritimes" in Southeastern France to Western Switzerland (Fig. 3); possibly Northern Spain and Pyrenees (see note below). A mention from northeastern Italy on the map presented in Gusenleitner and Schwarz (2002: 967) was based on a misidentified specimen of A. amieti sp. n. from "Monte Baldo" (OLML).

Notes.

We examined one specimen from Spain labelled as follows: "P. Leon Las Senales , 4,875 10.v-12.vi.1967 I & E Yarrow BM 1967-352" (OLML), which agrees with A. allosa in the sculpture of the terga and in its vestiture, but which has a shorter malar space, the clypeus that is not flattened apically as well as shorter mouthparts. This specimen appears to be superficially similar to the sequenced female collected at Larrau, in the “Pyrenées Atlantiques" department in France (number 1293; Fig. 1), which was 0.73% divergent from Alpine specimens of A. allosa . For now, we consider these two specimens to belong to A. allosa in spite of the lack of the most conspicuous diagnostic characters of this species, namely the long malar space and the flattened clypeus.

Phenology.

Andrena allosa has only one generation per year from the end of March (one isolated record) to the end of June (Fig. 4).

Habitat.

We found Andrena allosa in various subalpine and alpine grasslands from 1370 m to slightly above the tree line at around 2100 m (Fig. 4), often in close proximity to stands of Crocus albiflorus (Fig. 9). Nesting sites are unknown.

Pollen host preferences.

Andrena allosa collected the pollen on eight plant families (Table 3) but had a pronounced affinity for the pollen of Crocus ( Iridaceae ), which contributed 62.4% to the total pollen grain volume and was recorded in 20 out of 24 scopal loads. This finding is supported by field observations at five different localities in the Swiss and French Alps, where several females of A. allosa simultaneously harvested pollen on Crocus (Fig. 14). Numerous females were observed to collect the pollen from Crocus flowers late in the season, at a time when blooming Crocus were restricted to small patches where snow had remained particularly long. Because of the particularly short blooming period of Crocus , this observation suggests that A. allosa females may locate short-lived stands of Crocus throughout their flying season.