Hoplitis (Formicapis) robusta ( Nylander 1848 )

Müller, Andreas & Mauss, Volker, 2016, Palaearctic Hoplitis bees of the subgenera Formicapis and Tkalcua (Megachilidae, Osmiini): biology, taxonomy and key to species, Zootaxa 4127 (1), pp. 105-120 : 110-111

Hoplitis (Formicapis) robusta ( Nylander 1848)

Heriades robusta Nylander 1848: 270 . Type material: Lectotype ♀, by designation of Tkalcu (1995), “Helsingfors” ( Finland), Finnish Museum of Natural History, Helsinki. Type species of Formicapis Sladen.

Osmia Rhinoceros Giraud 1861: 464 . Type material: Syntypes ♀♀, “Gastein” ( Austria), Giraud Collection. Synonymy in Schletterer (1889).

Heriades trinacria Morawitz 1869: 41 . Type material: Ƌ, “im Gdowschen Kreise” ( Russia), Zoological Institute, Russian Academy of Sciences, St. Petersburg. Synonymy in Popov (1946).

Formicapis clypeata Sladen 1916: 271 . Type material: Syntypes Ƌ♀, “Aweme, Manitoba and Waterhole, Alberta” ( Canada). Synonymy in Peters (1970).

New records. SWITZERLAND, Grisons: Vals, Riefa-Pradätsch-Riedboda, 1600–2050m, 25.7.2008 (leg. A.

Müller); Medel, Uaul da Vergera, 1600m, 18.6.2013 (leg. R. Neumeyer); Sedrun, Uaul Bugnei, 1700m, 5.7.– 1.8.2013 (leg. A. Müller); St Gallen: Pfäfers, 1420m, 7.7.– 31.7.2013 (leg. H. Martz); Valais: Chandolin/Siders, 2200m, 18.7.1989 (leg. Perraudin); Visperterminen, 2000m, 12.8.2005 (leg. A. Müller); Montana, 15.7.2006 (leg. K. Hirt). AUSTRIA, Carinthia: Oberschachnern SE Heiligenblut, 22.8.1985 (leg. J. Gusenleitner); Ochsenriegel NW Weinebene, Koralpe, 1460m, 25.8.1989 (leg. J. Gusenleitner); Tirol: Zedlach W Matrei, 20.8.1985 (leg. J. Gusenleitner). ITALIA, South Tirol: Wolkenstein, 2.7.1921; Seiser Alp, 2.– 14.7.1971 (leg. H. Wolf); Schnals/ Kurzras, Meran, 2100m, 7.– 10.8.1974 (leg. H. Wolf); Pfossental, 1500–2000m, 27.8.1984 (leg. N. Mohr). MONGOLIA: Khangaur Mountains 5km N Khunt, 20.7.2005 (leg. J. Halada).

Distribution. Boreal zone across Europe (southern half of Finland, Estonia, Latvia, Belarus, European part of Russia), Asia (Asian part of Russia, northern Mongolia, northeasternmost China) and North America (Alaska, Canada) ( Grünwaldt 1939; Elfving 1968; Peters 1970; Romankova 1985; Tkalcu 1995; Prishchepchik 2000; Wu 2006; Ascher & Pickering 2015). In addition, H. robusta is distributed in the Alps ( Italy, Switzerland, Austria) between 1200m and the timberline ( Schwarz et al. 1996; Ebmer 1997, 2001; Amiet et al. 2004; Kopf 2008) and in mountainous regions of the western USA southwards to California and Colorado ( Hurd & Michener 1955). According to Rasmont et al. (1985), H. robusta also occurs in Belgium and Luxembourg, which is certainly erroneous, as well as in France, which is not beyond doubt as no reliable record exists for this country ( Benoist 1931; M. Aubert & G. LeGoff personal communication).

Pollen hosts. Polylectic with a strong preference for Potentilla (Rosaceae) , e.g. P. erecta ( Tab. 1 ). Females collect pollen on flowers of P. erecta by rapidly seesawing their metasomal scopa against the anthers, which they embrace below the mesosoma , while turning their body axis around the flower centre ( Fig. 2 ); simultaneously, they suck nectar from the nectaries at the base of the androecium. The importance of Potentilla as pollen source is apparent by the finding that its pollen constituted 68.1% of the total pollen grain volume and that 18 out of 22 pollen loads analyzed contained Potentilla pollen, 13 of which were pure loads ( Tab. 1 ). Additional pollen sources were Helianthemum (Cistaceae) , Medicago (Fabaceae) , Rubus (Rosaceae) , Cichorioideae (Asteraceae) and Ranunculus (Ranunculaceae) . The fact that the two pollen loads originating from the USA were composed of pollen of the Potentilla type and of Helianthemum , respectively, suggests that North American and European populations of H. robusta exhibit similar host plant preferences. One brood cell provision from Wyoming analysed by Clement & Rust (1975), however, was composed of putative Fabaceae pollen, suggesting that flowers of Fabaceae might locally be important pollen hosts. Flower records: Taraxacum ( Hurd and Michener 1955; Elfving 1968); Anthriscus sylvestris, Geranium palustre, G. sylvaticum , Geum rivale , Leontodon autumnalis , Potentilla anserina, Satureja alpina, Sedum acre, S. aizoon , S. camtschaticum , S. cepaea , S. spurium , Silene viscaria ( Elfving 1968) ; Silene rupestris ( Peters 1970) ; Lotus corniculatus , Potentilla aureola , P. pulcherrima (label records).

Nesting biology. Nesting sites are insect burrows and drilled borings (diameter 4–5mm) in dead wood containing 3–14 linearly arranged brood cells ( Clement & Rust 1975; Frey-Gessner 1880). Some nests contain empty vestibule cells following the last brood cell. Cell partitions are made of chewed leaves, sometimes with small pieces of wood embedded in the leaf matrix. The nest plug varies in thickness from 10mm to 14mm and consists of 8–13 layers of leaf pulp ( Clement & Rust 1975). In one case, a female collected leaf pulp on leaves of Potentilla erecta (A. Müller unpublished).

Figures

FIGURE 1 – 8. 1: Hoplitis robusta, typical habitat in open subalpine forest with large proportion of dead wood (Swiss Alps, Sedrun, Grisons). 2: Hoplitis robusta, pollen collecting female on Potentilla erecta. 3: Hoplitis coreensis, clypeus and mandibles of female. 4: Hoplitis maritima, clypeus and mandibles of female. 5: Hoplitis maritima, tergum 7 of male. 6: Hoplitis excisa, clypeus and mandibles of female. 7: Hoplitis robusta, clypeus and mandibles of female. 8: Hoplitis robusta: tergum 7 of male.