Abstract
A recent taxonomy of Retropinna (Woods 1968: N.Z. Jl mar. Freshwat. Res. 2: 398–425) is based on the conclusion that variation in four taxonomic characters is related largely to environmental factors. Thus Woods treated all existing New Zealand species in the Retropinna retropinna complex as synonyms of R. retropinna (Richardson). Analysis of Woods’ data casts some doubt on the validity of this argument.