Bombus luianus, Zhang, 1990, species inquirenda

Dehon, Manuel, Engel, Michael S., Gerard, Maxence, Aytekin, A. Murat, Ghisbain, Guillaume, Williams, Paul H., Rasmont, Pierre & Michez, Denis, 2019, Morphometric analysis of fossil bumble bees (Hymenoptera, Apidae, Bombini) reveals their taxonomic affinities, ZooKeys 891, pp. 71-118 : 71

" Bombus " luianus Zhang, 1990, species inquirenda

Holotype.

Female. Specimen n°82771. Plate XXXIII-1, fig. 164 from Zhang et al. (1994), plate I-1, 2 from Zhang (1990). The type material from Shanwang was not available for study and we have, therefore, had to base our information on this and the following two species (vide infra) on the original Chinese descriptions, the rather poor original photographs, and the tenuously accurate line drawings in these publications. Accordingly, our evaluation of B. luianus , B. dilectus , and B. anacolus has been considerably hampered.

Type strata and locality.

Middle Miocene (i.e., 17.0-15.2 Ma), deposit of the Shanwang Formation, large lacustrine and lithified deposit, with diatomaceous and tuffaceous mudstone. Located in Linqu County, Shanwang Province, China.

Description.

Taken from Zhang (1990) and Zhang et al. (1994): Prosoma poorly preserved; meso- and metasoma preserved; mesosoma stout, setose, and dark; metasoma dark, reddish-brown near apex, displaying five segments, suboval in shape, little longer than wide, distinctly narrower than mesosoma; forewing membrane brown and transparent, venation dark brown; metatibia widening posteriorly, displaying two strong spurs, outer margin covered with strong coarse setae; metabasitarsus flat, rectangular, truncated at both ends, nearly as wide as distal part of metatibia; tarsomere IV displaying pair of spur-like bristles distally; inner margin of pretarsal claw displaying single tooth at midlength; forewing length approximately 14.0 mm, maximum width approximately 4.5 mm as preserved; basal vein relatively straight and almost in line with cu-a; cu-a almost straight; 1st abscissa of Rs straight; 2nd abscissa of Rs curved anteriorly; r-rs curved; Rs+M straight and shorter than r-rs; 3Rs almost straight and as long as r-rs; 4Rs almost straight and longer than r-rs; marginal cell length approximately 4.0 mm, width 0.8 mm; three submarginal cells; 1rs-m slightly curved apically near midpoint; 2rs-m curved apically in its posterior half; 1m-cu almost straight and reaching M near midpoint between 2nd abscissa of Rs and 1rs-m; 2m-cu slightly curved and reaching M basad to 2rs-m; hind wing length 8.6 mm; total body length approximately 13.0 mm, width approximately 8.0 mm as preserved. The original description and figure do not display a transector vein. See Zhang (1990) and Zhang et al. (1994) for original descriptions.

Comments.

According to Zhang (1990), the fossil species is closely similar to B. (Bombus) tunicatus Smith, 1852 (extant species distributed in Himalaya), but differs from it in that the mesosoma is narrower than the mesosoma, and not so massive as is usual for the genus; the spurs becoming shorter; vein 1m-cu meeting second submarginal cell at midlength; and veins M+Cu and M of hind wing aligned in a straight line. The validity of these features for distinguishing the species remains unclear. Our morphometric study showed a similar shape with the subgenus Melanobombus . It is estimated that Melanobombus originated between the Lower and Middle Miocene, while the fossil was discovered in the Middle Lower Miocene (i.e., 17.0-15.2 Ma) deposits of Shandong, China ( Zhang 1990; Zhang et al. 1994). The results based on geometric morphometric analyses for this species could be wrong, since they were based on Zhang’s drawings and not on a picture or on examination of the holotype. Given this, we consider the fossil as species inquirenda.