Subgenus Prochelostoma
The species listed below were formerly treated as members of the subgenus Ceraheriades Tkalcu (Michener, 2007; Ungricht et al., 2008). However, 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subgenera is no longer justified and Ceraheriades is treated here as a junior synonym of Prochelostoma (A. Müller, unpublished). The subgenus Prochelostoma Robertson occurs both in the Palaearctic and the Nearctic region with 4 and 1 species, respectively.
Species accounts
Chelostoma (Prochelostoma) carinoclypeatum Wu, 1993
1993 Chelostoma carinoclypeatum Wu, Insects of the Hengduan Mountains Region, vol. 2, p. 1392, p. 1419. Type material: Holotype f, “Sichuan: Xiangchen, 3000 m” [China], IZCAS (Beijing); paratypes ff.-Combination Chelostoma (Ceraheriades) carinoclypeatum Wu in Wu (2006: 88).
Distribution-Northern Asia: RC(SW).
Identification-Keys, Descriptions: Wu (2006). Note: Male unknown.
Nesting biology: Unknown.
Flower preferences: Two pollen samples from different localities consisted of pollen of Ranunculaceae (A. Müller, unpublished). This species might thus belong to the subgenus Chelostoma s. str., which contains several Ranunculus oligoleges, rather than to the subgenus Prochelostoma. Additional flower records: Lysimachia (Primulaceae) (Wu, 2006).
Chelostoma (Prochelostoma) longilabrare Wu, 2004
2004 Chelostoma (Ceriheriades) longilabraris Wu, Acta Zootaxonomica Sinica, 29: 535. Type material: Holotype f, “Xizang, Mengkang (29.6°N, 98.5°E), 3250 m”, IZCAS (Beijing).
Distribution-Northern Asia: RC(WP).
Identification-Keys, Descriptions: Wu (2006). Note: Male unknown.
Nesting biology: Unknown.
Flower preferences: One pollen load consisted of Asteraceae pollen of the Aster type and the Taraxacum type (A. Müller, unpublished).
Chelostoma (Prochelostoma) petersi (Tkalcu, 1984)
1984 Archeriades (Ceraheriades) petersi Tkalcu, Annotationes Zoologicae et Botanicae (Bratislava), 158: 5. Type material: Holotype f, “Kina S. Kansu, Sven Hedin Exp. Ctr. Asien” [China], ZMHB (Berlin). Type species of Ceraheriades Tkalcu.-Combination Chelostoma (Ceraheriades) petersi (Tkalcu) in Michener (2000: 439).
1993 Chelostoma lamellum Wu, Insects of the Hengduan Mountains Region, vol. 2, p. 1390, p. 1418. Type material: Holotype m, “Sichuan: Xiangcheng, 3000 m” [China], IZCAS (Beijing); paratypes mm, ff.-Combination Chelostoma (Ceraheriades) lamellum Wu in Wu (2006: 85).-New synonymy based on type material and original description (A. Müller, unpublished).
Distribution-Northern Asia: RC(NO), RC(SW).
Identification-Keys, Descriptions: Wu (2006). Misapplication: Heriades schmiedeknechti in Alfken (1936b: 7) is Chelostoma petersi (Tkalcu).
Nesting biology: Unknown.
Flower preferences: Possibly oligolectic on Philadelphus (Hydrangeaceae) (Sedivy et al., 2008). Additional flower records: Lysimachia (Primulaceae) (Wu, 2006).
Chelostoma (Prochelostoma) sublamellum Wu, 1993
1993 Chelostoma sublamellum Wu, Insects of the Hengduan Mountains region, vol. 2, p. 1391, p. 1418. Type material: Holotype f, “Yunnan: Dêqên, 2500-3180 m” [China], IZCAS (Beijing); paratypes m, f.-Combination Chelostoma (Ceraheriades) sublamellum Wu in Wu (2006: 86).
Distribution-Northern Asia: RC(SW).
Identification-Keys, Descriptions: Wu (2006).
Nesting biology: Unknown.
Flower preferences: Possibly oligolectic on Philadelphus (Hydrangeaceae) (Sedivy et al., 2008). Additional flower records: Lysimachia (Primulaceae) (Wu, 2006).