Osmia (Hoplosmia) fallax Pérez 1895

Müller, Andreas, 2018, Palaearctic Osmia bees of the subgenus Hoplosmia (Megachilidae, Osmiini): biology, taxonomy and key to species, Zootaxa 4415 (2), pp. 297-329 : 306-307

Osmia (Hoplosmia) fallax Pérez 1895

Osmia fallax Pérez 1895: 13 . Type material: Lectotype ♂, by designation of Tkalců (1974a), “Andalusia” (Spain), Muséum National d’Histoire Naturelle Paris.

Literature records. SPAIN: Granada: Sierra Elvira ( Moreno-Rueda et al. 2008); Malaga ( Tkalců 1974a); Barcelona, Cataluña (Ceballos 1956).

New records. SPAIN: Valencia: Almenara la Llosa, 12 km N Sagunt, 27.4.2001 (leg. E. Scheuchl); 80 km SW Valencia, Muela de Cortes reserv., 14.5.2003 (leg. M. Halada); Alicante: Xixona, 1.5.2000 (leg. E. Scheuchl); Coll de Rates, between Callosa d’en Sarria and Parcent, 520 m, 3.5.2000 (leg. E. Scheuchl); Murcia: Alahama de Murcia, Monte Muela, 29.4.2000 (leg. E. Scheuchl); Pto. de Jumilla, 800 m, 19.5.2003 (leg. M. Halada); 25 km SW Cartagena, 19.5.2003 (leg. M. Halada); Almeria : 50 km W Almeria, Berja , 21.4.2003 (leg. M. Halada); Granada: Polopos, 5.5.1997 (leg. M. Halada). MOROCCO: Fès-Meknès: Ifrane, 15.6.1962 (leg. W. Schläfle); Ifkern, 25 km E Boulemane, 24– 25.5.1995 (leg. M. Halada); Ifrane, 1680 m, 10.6.1996 (leg. P. Rasmont); TUNISIA: Kasserine: 10 km NNW Thelepte, 24.3.2001 (leg. C. Saure).

Distribution. Western and southern Spain, Maghreb ( Morocco, Tunisia).

Pollen hosts. Polylectic with a strong preference for Cistaceae (e.g. Helianthemum ), additional pollen sources include Brassicaceae , Asteraceae ( Asteroideae , Cichorioideae ), Echium (Boraginaceae) and Lamiaceae (based on 13 pollen loads from six different localities in Spain and Morocco). Pollen of Cistaceae constituted 93.6% of the total pollen grain volume and was recorded in all pollen loads, seven of which were pure Cistaceae pollen loads, indicating a very high importance of the flowers of Cistaceae as host plants. Interestingly, the scopal hairs of O. fallax are straight and apically spatulate rather than wavy and apically button-like as in all the other O. ( Hoplosmia ) species, which are most probably all specialized on Asteraceae . This deviating scopal hair shape might be an adaptation to the need of transporting pollen of different sizes and morphologies or might reflect the relaxed selection for wavy hairs to uptake or transport Asteraceae pollen. Furthermore, in both sexes of O. fallax the first and the second segment of the labial palpus are of roughly the same length, which is in sharp contrast to all the other O. ( Hoplosmia ) species, where the first segment is distinctly shorter than the second. This difference might be due to different morphological requirements to suck nectar from the host plants of O. fallax and Asteraceae , respectively.

Nesting biology. The nests are built in empty snail shells (e.g. Sphincterochila candidissima) and contain 1–4 brood cells per shell ( Moreno-Rueda et al. 2008; J. Ortiz-Sanchez personal communication). In southeastern Spain, O. fallax and the cleptoparasitic megachilid bee species Stelis odontopyga Noskiewicz were found at the same localities inhabiting empty snail shells ( Moreno-Rueda et al. 2008), suggesting that S. odontopyga , which is known to develop in nests of O. spinulosa ( Noskiewicz 1925; Blüthgen 1926), might also parasitize O. fallax .