[2][3] The genus was revised by Everard Britton in 1940,[4] and most recently by Michael Butcher in 1984,[5] with several species added by Peter Johns in 2003.

Species are distinguished by their patterns of setae, grooves, and punctures, and features of the male genitalia, as much as by size as shape.

[5] Holcaspis adults are most commonly found in summer (November to March), but some have been trapped over winter, suggesting they live two years or more like other long-lived carabids.

[9] Species of Holcaspis tend to occur in the drier eastern areas of New Zealand, particularly in the South Island.

[10] As a consequence, several species of Holcaspis are listed as critically endangered by the New Zealand Department of Conservation: H. abdita, H. bathana, H. bidentella, and H.