Andrena sieverti Cockerell, 1906

Andrena sieverti Cockerell, 1906e: 436 [♀]

Andrena lappulae Cockerell, 1906e: 437 [♂‚] [synonymy by Lanham (1993)]

Andrena sieverti var. opacicauda Cockerell, 1936d: 1 [♀]

Notes: Andrena sieverti, A. lappulae, andA. sieverti var. opaciacauda were considered synonyms of a hybrid of A. scurra, A. arabis, and A capricornis by Ribble (1974) and Hurd (1979). After further study of populations in Colorado, Lanham (1993) resurrected A. sieverti, with A. lappulae as a synonymy. Here we are considering the species valid, though elsewhere it, A. lappulae is considered a synonymy of A. scurra, and A. sieverti and A. sieverti var. opaciacauda are considered possible synonyms of A. scurra (Ascher and Pickering 2018); though Lanham (1993) was undecided about the status of A. sieverti var. opaciacauda, we include it as a synonymy.