Within this genus, a single species has been described to date: Aeropyrum pernix bacilliform virus 1 (APBV1).

[2] The name is derived from the Latin word clava, meaning cudgel, and referring to the thick, stick-like nature of the virus.

The structure of the APBV1 virion has been solved by cryo-electron microscopy to near-atomic resolution, revealing how the helical particle is built from an alpha-helical major capsid protein with a unique structural fold.

[4] Virions are highly thermostable and remain infectious after incubation at 100 °C for 3 hours.

The genome contains 14 open reading frames, none of which share similarity with sequences in public databases.