Recent observations indicate that a laying season seems to exist, in karstic as well as in phreatic populations. Nevertheless, a single female cannot lay each year, because the reproductive intermolt averages 15-16 months and is always followed by one (9-10 months) or several non-reproductive intermolts. So, the minimum laying rhythm of female St. virei is biennial. The cavernicolous population (St. v. virei) of the Padirac swallow-hole is not a relict, but a colony separated from the main settlement of the alluvial waters of the Dordogne river. On the contrary, it is possible to find, close to each other, karstic and phreatic populations which belong to different subspecies (St. v. hussoni and St. v. boui) and live independently.
Remarques sur la biologie et l'écologie de Stenasellus virei Dollfus (Crustacea Isopoda Asellota des eaux souterraines).
International Journal of Speleology,
Available at: https://scholarcommons.usf.edu/ijs/vol8/iss1/12