Niphargus sp.1

New records: L.129—Nessonvaux, basement (9.2.2002, MD); L.148—Rhieux, underground brook (8.3.2002, MD).

Specimens from two localities (Fig. 6) exhibit a peculiar morphology and differ from all other known species. The specimens are rather large (> 15 mm), extremely slender, with relatively large gnathopods, narrow bases of pereopods V–VII, two retinacles on the pleopods and a setose telson (Fig. 7). Particularly distinct is the setal pattern of telson, strongly setose but completely lacking robust setae. Abundant thin setae were observed also in the telson of some populations of N. schellenbergi (see Karaman 1934), but the putative new species differs from the latter in the lower number of hooks in the retinacles. Despite its morphological distinctness, its separate status needs to be confirmed also with molecular delimitation methods. Sequencing in our analyses failed, and additional specimens need to be collected for formal description.