Boreantrops pollex, Kits, Joel H. & Marshall, Stephen A., 2015

Kits, Joel H. & Marshall, Stephen A., 2015, A revision of Boreantrops Kits & Marshall (Diptera: Sphaeroceridae: Archiborborinae), Zootaxa 3915 (3), pp. 301-355 : 334

Boreantrops emarginatus group

This group of 12 species includes most of the remaining species in the genus. Members of the group are characterized by the structure of the male epandrium, which extends medially between the anal opening and the cerci (the cerci are immediately below the anal opening in the B. mexicanus group). In some species, these extensions of the epandrium are not fused medially, creating a keyhole-shaped anal opening.

Some of the species in this group are readily identifiable based on external characters. Others require examination of the male internal genitalia for separation. For example, B. pollex sp. nov. and B. punctipennis sp. nov. form a distinctive species pair in the group but are only distinguished from each other based on male genitalic characters. As well, a group consisting of B. boliviensis sp. nov., B. calceata , B. challabamba sp. nov., B. subemarginatus sp. nov., B. wayqecha sp. nov., and B. zamora sp. nov. have only subtle external differences and are best separated based on male internal genitalia.