Parastenocarididae, Chappuis, 1940

Wells, J. B. J., 2007, An annotated checklist and keys to the species of Copepoda Harpacticoida (Crustacea), Zootaxa 1568 (1), pp. 1-872 : 597

Family Parastenocarididae

Although seven genera have now been described in this speciose family, the vast majority of the species are still contained in the genus Parastenocaris . Most species have a highly restricted distribution, and many have been recorded only once. The family is in desperate need of a comprehensive phylogenetic study, but this is inhibited by the extreme sexual dimorphism displayed by all species—which provides species­specific characters for males but often not for females—and is made more difficult by the poor quality of the description of many of the species. But Galassi & De Laurentiis (2004) and Corgosinho & Martínez Arbizu (2005) have begun the process.

Caution: Because many of the known species seem to be restricted to single river systems (or part thereof), and much of world remains to be investigated this thoroughly, it can reasonably be predicted that only a small number of the species of this family have been described; Karanovic (2005) estimates the number may reach at least 1000.

Sexual dimorphism is highly developed in this family. Because of this, separate keys are given for males and females.

From the viewpoint of constructing keys for identification, it is unfortunate that most of the characters currently used to define species are male secondary sexual characters.

Females attributed to different species often are difficult to distinguish (a situation aggravated by the lack of detail in descriptions and of precision in illustrations) and in many cases are placed in a particular species purely because of their association with distinctive males in seemingly monospecific samples.

It is very likely, therefore, that these keys will secure a false identification (particularly for specimens from areas where the groundwater fauna is not well known) and it is critical that any identification be checked against the best published descriptions.