Protobombus, Cockerell, 1908

Engel, Michael S. & Davis, Steven R., 2021, New genera of melikertine bees with facial modifications in Baltic amber (Hymenoptera: Apidae), Journal of Melittology 2021 (103), pp. 1-52 : 47

Key to Subgenera of Protobombus

1. Forewing basal vein (1M) proximad 1cu-a ............................................................. 2

—. Forewing basal vein (1M) confluent with 1cu-a ...... Protobombus Cockerell , s.str.

2(1). Forewing with three submarginal cells (1rs-m present) .......................................... ................................................................................... Thnetobombus Engel, n. subgen.

—. Forewing with two submarginal cells (1rs-m absent) ... Sophrobombus Cockerell

Subgenus Protobombus Cockerell , s.str.

The subgenus presently includes four named species, three in Bartonian Baltic amber (Engel, 2001a) and one from the Ypresian of Grube Messel (Wappler & Engel, 2003), along with one undescribed species in Ypresian Cambay amber (Engel et al., 2013).