Bombus (Melanobombus) cerdanyensis Dehon, De Meulemeester & Engel, 2014

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 (Melanobombus) cerdanyensis Dehon, De Meulemeester & Engel, 2014

Holotype.

Sex unknown. Conserved in the Paleontology department collection, Muséum national d’Histoire naturelle, Paris, France. The fossil consists of a part and counterpart. Type specimen has been located and revised ( Figs 2E , 3I ).

Type strata and locality.

Late Miocene (i.e., 10.0 Ma), lacustrine beds of Cerdanya, Spain.

Diagnosis.

Forewing membrane with alar papillae beyond apical crossveins; membrane infuscate, particularly in area beyond apical crossveins and along anterior borders of radial and marginal cells; pterostigma small, trapezoidal, not larger relative to prestigma and width not much shorter than length; marginal cell longer than distance from apex to forewing tip, tapering in width across its length, with apex acutely rounded and slightly offset from forewing margin; three submarginal cells of approximately same size, anterior borders of second and third submarginal cells subequal; 1m-cu angulate anteriorly, meeting second submarginal cell near midpoint; 2m-cu slightly arched, meeting third submarginal cell in apical fifth; mesotibia five times longer than wide; transector vein visible in the first submarginal cell. See Dehon et al. (2014) for original diagnosis.

Description.

Fossil compressed in apparently dorsal oblique view, with left forewing outstretched; right forewing not preserved; hind wings not preserved; prosoma not preserved; mesosoma and metasoma incomplete and damaged; mid and hind legs preserved, partially overlapping forewing; right profemur length 1.4 m, width 0.8 mm as preserved; left mesofemur length 3.6 mm, width 0.9 mm; mesotibia length 3.0 mm, width 0.6 mm; mesobasitarsus length 3.2 mm, width 0.9 mm; remaining tarsomeres and pretarsal claws well preserved; pretarsal claws apparently not toothed as preserved; right mesofemur length 3.5 mm, width 0.5 mm; mesotibia length 2.0 mm, width 0.4 mm as preserved; left forewing length 13.3 mm, maximum width 4.6 mm; three submarginal cells of similar size; first submarginal cell length 1.5 mm (as measured from origin of Rs+M to juncture of r-rs and Rs), heigth 0.7 mm (as measured from Rs+M to pterostigma); second submarginal cell length 1.5 mm (as measured from juncture of Rs+M and M to juncture of Rs and 1rs-m), height 0.8 mm (as measured from midpoint on M between 1m-cu and 1rs-m to juncture of r-rs and Rs); third submarginal cell length 1.3 mm (as measured from juncture of 1rs-m and M to juncture of M and 2rs-m), height 1.1 mm (as measured from juncture of M and 2m-cu to juncture of 2rs-m and Rs); first medial cell length 3.4 mm (as measured from juncture of M+Cu and Cu to juncture of 1m-cu and M), height 1.2 mm (as measured from juncture of M and Rs+M to midpoint on Cu between M+Cu and 1m-cu); pterostigma length 0.9 mm; marginal cell length 3.4 mm with apex rounded, offset from anterior wing margin, not appendiculate; 1m-cu strongly curved, meeting second submarginal cell near midpoint; 2m-cu slightly arched, meeting third submarginal cell in apical fifth; metasoma width 5.8 mm as preserved; first two segments visible, first segment length 1.8 mm, second segment length 1.2 mm as preserved. See Dehon et al. (2014) for original description.

Comments.

The attribution based on geometric morphometric analysis (i.e., Melanobombus ) is consistent with the timing and geographic origin of the subgenus proposed by Hines (2008). Indeed, the fossil was found in the Upper Miocene (i.e., 10.0 Ma) deposit of La Cerdanya in Spain, while Melanobombus is estimated to have originated between 20.0-15.0 Ma in the Old World. The relative sizes of the prestigma and pterostigma exclude a placement in the Electrobombini (although the presence or absence of a jugal lobe in the hind wing cannot be determined in the holotype). The forewing is apically papillate (as in Bombini ), and the marginal cell is not appendiculate and 1m-cu is strongly angulate together suggesting the species does not belong to the Electrapini or Melikertini (although some melikertines have 1m-cu more angulate, such as Melissites trigona Engel, 1m-cu is always much shorter and not as long as in Bombini or Euglossini ; a long 1m-cu is more plesiomorphic among Corbiculata). Indeed, the forewings of the present fossil are distinctly Bombus -like: presence of papillae, general infuscation of the membrane, three submarginal cells of relatively similar size (albeit the latter character is assuredly plesiomorphic). Based on the specimen morphology and forewing shape affinities, the fossil is likely an extinct species of Melanobombus .

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.