[1][2] Many species are endemic to small ranges, perhaps due to the family's tendency to evolve tolerance for cold (isolating populations in mountain valleys) and winglessness (inhibiting dispersal).

[2] Nymphs of small winter stoneflies typically have very elongated and slender bodies, similar to those of Leuctridae.

[2] The family Capniidae is often considered to be monotypic as to subfamily,[clarification needed] with the Capniinae being inserted at that rank.

However, this is rather pointless;[clarification needed] in any case, the phylogeny, systematics, and taxonomy of the small winter stoneflies are highly confused.

Three new or resurrected genera have recently been created, partially or wholly, from some of its species: Arsapnia, Sierracapnia, and Zwicknia.