Bombus (Cullumanobombus) trophonius Prokop, Dehon, Michez & Engel, 2017

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 (Cullumanobombus) trophonius Prokop, Dehon, Michez & Engel, 2017

Holotype.

Female. ZD0003 (coll. Bílina mine). Type specimen has been located and revised ( Figs 2A , 3F ).

Type strata and locality.

Lower Miocene (i.e., 20.0 Ma), Clayey Superseam Horizon, Bílina mine, Czech Republic.

Diagnosis.

The fossil has a wing pattern most similar to B. (Cullumanobombus) rufocinctus Cresson (Milliron 1973; Williams et al. 2014). Moreover, both species display a similar combination of 3Rs about as long as r-rs but shorter than 4Rs, a basal vein basad 1cu-a, a vein 2Rs arched posteriorly but not as greatly prolonged proximally as in several other species of Cullumanobombus (e.g., Milliron 1971), and a vein 1m-cu entering second submarginal cell near midpoint. However, the convex pterostigmal border within the marginal cell, less apically narrowed marginal cell, and less arched 2rs-m minimally serve to distinguish the fossil species from B. rufocinctus . See Prokop et al. (2003) and Prokop et al. (2017) for original diagnosis.

Description.

Wings and integument black as preserved; forewing total length 14.6 mm; maximum width 5.10 mm; basal vein weakly arched basally, comparatively straight along length, basad cu-a by about vein width, in line with 1Rs; M+Rs originating anteriad, 1Rs slightly shorter than r-rs; pterostigma short, slightly longer than wide, tapering inside of marginal cell, border inside marginal cell convex, prestigma nearly as long as pterostigma; marginal cell length 5.1 mm, width 1.1 mm, free portion slightly shorter than portion bordering submarginal cells, apex rounded and offset from anterior wing margin by much more than vein width, not appendiculate; 2Rs strongly arched basally and slightly arched outward; r-rs about as long as 3Rs; 4Rs slightly longer than 3Rs; three submarginal cells of approximately same sizes, albeit third slightly larger than first or second; first submarginal cell length 0.9 mm (as measured from origin of M+Rs to juncture of r-rs and Rs), width 1.0 mm (as measured from Rs+M to pterostigma); second submarginal cell length 1.3 mm (as measured from juncture of Rs+M and M to juncture of Rs and 1rs-m), width 0.9 mm (as measured from midpoint on M between 1m-cu and 1rs-m to juncture of r-rs and Rs); third submarginal cell length 1.6 mm (as measured from juncture of 1rs-m and M to juncture of M and 2rs-m), width 1.2 mm (as measured from juncture of M and 2m-cu to juncture of 2rs-m and Rs); 1rs-m straight; 2rs-m arched distally in posterior half; 1m-cu distinctly angulate anteriorly near M, entering second submarginal cell near cell’s midlength; 2m-cu slightly arched apically, meeting third submarginal cell at cell’s apical fifth of length. Hind wing length 9.4 mm, width 2.6 mm. Preserved portion of mesosoma and legs difficult to describe, although portion of metatibial corbicula preserved (basal quarter to third), and sclerites with numerous, long setae. See Prokop et al. (2003) and Prokop et al. (2017) for original description.

Comments.

The specimen was first reported as Bombus sp. in Prokop et al. (2003). Prokop et al. (2017) demonstrated that the fossil clustered within contemporary Cullumanobombus and formally described the species. Although the majority of contemporary species of Cullumanobombus are found in the New World and a few species in the Old World, Hines (2008) estimated that the subgenus originated around 20.0-15.0 Ma in the Palearctic. Our result, as well as that of Prokop et al. (2017), is consistent with Hines (2008) as the fossil specimen was found in the Lower Miocene (i.e., 20.0 Ma) deposits of Bílina Mine in northern Bohemia (Czech Republic).

Figures

Figure 2. Representative fossil bumble bees A Bombus (Cullumanobombus) trophonius (photograph by Jakup Prokop) B B. (Cullumanobombus) randeckensis (photograph by Torsten Wappler) C B. vetustus (photograph by Alexandr P. Rasnitsyn) D B. (Cullumanobombus) pristinus (photograph by Irene Zorn and Monika Brueggeman-Ledolter) E B. (Melanobombus) cerdanyensis (photograph by Thibaut De Meulemeester).

Figure 3. Forewing drawings of the fossil bumble bees studied herein. Some forewings were mirrored to enable comparison across all specimens A Oligobombus cuspidatus (mirrored) B Holotype of Calyptapis florissantensis (mirrored) C C. florissantensis D Bombus (Paraelectrobombus) patriciae (mirrored) E B. (Mendacibombus) beskonakensis F B. (Cullumanobombus) trophonius (mirrored) G B. (Cullumanobombus) randeckensis (mirrored) H B. vetustus I B. (Cullumanobombus) pristinus (mirrored) J B. (Melanobombus) cerdanyensis.