Oligobombus cuspidatus Antropov, 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

Oligobombus cuspidatus Antropov, 2014

Holotype.

Sex unknown. NHMUK In.17349 (part and counterpart), Smith collection of the Natural History Museum (NHM, London, UK). Type specimen has been located and revised ( Figs 1A , 3A ).

Type strata and locality.

Late Eocene (i.e., 36.0 Ma), Insect Bed of the Bembridge Marls from the Isle of Wight, UK.

Diagnosis.

Owing to monotypy, the diagnosis for the species is identical to that of the genus (vide supra).

Description.

Part consists in middle and apical parts of right forewing; counterpart consists of middle part of right forewing; forewing distal membrane papillate; complete venation preserved; total forewing length 13.3 mm, maximum width 4.0 mm as preserved; basal vein length 2.3 mm, relatively straight and basad cu-a; cu-a length 0.3 mm; marginal cell length 4.0 mm, width 0.9 mm, apex roundly truncate; prestigma 0.2 mm; pterostigma length 0.8 mm; 1st abscissa of Rs straight; 2nd abscissa of Rs almost straight; 3Rs length approximately same as r-rs; 4Rs slightly longer than 3Rs; M+Rs length 1.2 mm; three submarginal cells; first submarginal cell length 1.5 mm (as measured from origin of Rs+M to juncture of r-rs and Rs), width 0.6 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 0.7 mm (as measured from midpoint on M between 1m-cu and 1rs-m to juncture of r-rs and Rs); third submarginal cell length 1.4 mm (as measured from juncture of 1rs-m and M to juncture of M and 2rs-m), width 1.0 mm (as measured from juncture of M and 2m-cu to juncture of 2rs-m and Rs); 1rs-m straight; 2rs-m posterior half curved apically; 1m-cu anterior half curved apically, reaching M approximately at midpoint between 2nd abscissa of Rs and 1rs-m; 2m-cu basad 2rs-m. See Antropov et al. (2014) for original description.

Comments.

There is only one specimen, the holotype NHMUK In.17349, consisting of a part and counterpart. Antropov et al. (2014) described the specimen and considered it as possibly a member of Bombini . According to the original author, the forewing shape displays mixed features of Bombini , Electrapini , Electrobombini , Euglossini , and Melikertini (e.g., the forewing distal membrane being papillate is characteristic of Bombini , Electrobombini , and Euglossini , the shape of vein Rs displays mixed features reminiscent of the corbiculate tribes Bombini , Electrobombini , Electrapini (i.e., Thaumastobombus Engel, 2001), Euglossini , and Melikertini (i.e., Melikertes Engel, 1998 and Succinapis Engel, 2001), the submarginal cells are reminiscent of Electrapini , Electrobombini , and Euglossini , 1m-cu is reminiscent of Electrapini and Electrobombini , 2m-cu is reminiscent of Electrapini , Euglossini , and Melikertini ). All in all, the specimen has a forewing venation with features that can be found in different extinct and extant tribes of Corbiculata, but that taken together do not occur in any of them. According to the Antropov et al. (2014), the fossil forewing venation is generally similar to extant species of Bombini , but the lack of features from the pro-, meso-, and metasoma prevents identification of its exact taxonomic affinities. Based on the general morphology and forewing shape affinities, Oligobombus is perhaps a stem-group bombine and we consider it as such for the moment. Further material and additional characters, ideally analyzed in a cladistic framework, are needed to corroborate this placement, or the species could have phylogenetic affinities with Electrobombini or Electrapini .

Figures

Figure 1. Representative fossil bumble bees A Oligobombus cuspidatus (photograph by Antropov et al. (2014)) B Holotype of Calyptapis florissantensis (photograph by Manuel Dehon) C C. florissantensis (photograph by Talia S. Karim) D Bombus (Paraelectrobombus) patriciae (photograph by Gaelle Doitteau) E B. (Mendacibombus) beskonakensis (photograph by Gaelle Doitteau).

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.