1. Species group of atopus (= Chthonolasius part 1/2)

(Figs 8D, 9D)

Constituent species (1): atopus [e].

Distribution: Restricted to western North America (California).

Identification: Among all Lasius, L. atopus has uniquely elongate scapes and a uniquely slender mesosoma (scapes about as long as anteroposterior head length; metanotum relatively elongate, and mesonotum almost in plane with metanotum). In addition, with dense standing pilosity across the entire body, including appendages. See the definition of this species in Cole (1958).

Notes: This species was previously classified in the former subgenus Chthonolasius; our sequenced specimen represents a new species near L. atopus .