Calyptapis florissantensis Cockerell, 1906

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

Calyptapis florissantensis Cockerell, 1906

Holotype.

Sex unknown. MCZPALE 2008, collections of the Museum of Comparative Zoology (Harvard University, Cambridge, USA). Samuel Hubbard Scudder collection. Type specimen has been located and revised ( Figs 1B , 3B ).

Type strata and locality.

Eocene-Oligocene boundary (i.e., 34.0 Ma), the Florissant shale of Colorado, USA.

Diagnosis.

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

Description.

Integument of body black to dark brown as preserved (taphonomically altered); forewing venation brown to dark brown, membrane hyaline as preserved; forewing length 7.6 mm; maximum width approximately 2.5 mm as preserved; basal vein (1M) faintly arched at base, straight along length, basad 1cu-a by about twice vein width, faintly angled relative to 1Rs; Rs+M originating anteriad, 1Rs about as long as r-rs; pterostigma short, slightly longer than wide, border inside marginal cell slightly concave, prestigma very short, scarcely present, about as long as 2.5-3 times width of 1Rs; marginal cell length 2.2 mm, width 0.5 mm, tapering slightly across its length, free portion of cell subequal to portion bordering submarginal cells, apex rounded and offset from anterior wing margin by about vein width, not appendiculate; 2Rs weakly arched basally, comparatively straight; r-rs about as long as 3Rs; 4Rs slightly longer than 3Rs; three submarginal cells of comparatively similar sizes, albeit third slightly larger than first or second, but slightly shorter than combined lengths of first and second submarginal cells; first submarginal cell length 0.9 mm (as measured from origin of Rs+M to juncture of r-rs and Rs), width 0.4 mm (as measured from Rs+M to pterostigma); second submarginal cell length 0.7 mm (as measured from juncture of Rs+M and M to juncture of Rs and 1rs-m), width 0.4 mm (as measured from midpoint on M between 1m-cu and 1rs-m to juncture of r-rs and Rs); third submarginal cell length 0.9 mm (as measured from juncture of 1rs-m and M to juncture of M and 2rs-m), width 0.6 mm (as measured from juncture of M and 2m-cu to juncture of 2rs-m and Rs); 1rs-m weakly arched; 2rs-m strongly arched distally in posterior half, such that third submarginal cell is greatly bulged distally; 1m-cu distinctly angulate anteriorly near M, entering second submarginal cell slightly before cell’s midlength; 2m-cu weakly and gently arched apically, meeting third submarginal cell near cell’s apex, basad 2rs-m by about 2.5 times vein width; mesosoma length 4.4 mm as preserved; metasoma length 8.8 mm as preserved; total body length 15.2 mm as preserved. Specimen UCM 4415: left lateral view; pro-, meso-, and metasoma preserved, both forewings preserved; parts of right hindleg and foreleg preserved; forewing venation preserved; part of one antenna preserved. Specimen MCZPALE-2008: mesosoma preserved, as well as part of prosoma; right forewing visible. See Cockerell (1906, 1908c) for original description.

Comments.

Calyptapis florissantensis was first described based on a poorly preserved specimen collected by Samuel H. Scudder (MCZPALE 2008), and was first attributed to Eucerini by Cockerell (1906). The well-preserved second specimen (UCM 4415) was described by Cockerell (1908) and this permitted him to attribute both specimens to Bombini . However, he stated that the fossil differed from extant Bombus in the form of the second and third submarginal cells, thus suggesting it to be a member of a genus close to Bombus ( Cockerell 1906, 1908; Zeuner and Manning 1976). Based on the general morphology and forewing shape affinities, Calyptapis is perhaps a stem-group bombine and we consider it as such for the moment, although a cladistic analysis encompassing additional characters is needed for a more definitive clarification of its phylogenetic affinities.

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.