Chaetonotus (Captochaetus) arethusae Balsamo & Todaro, 1995

Localities: Pond with Nymphaea sp., Bergianska Trädgården, Stockholm (N 59º 22’ 07’’; E 18º 02’ 41’’), June 19, 2008.

Material: 1 specimen.

FL, 32 µm; AL, 22 µm; MD, 9 µm; DS 12 x 14 µm; DSp, 22 µm.

Large species, 252–340 µm in total body length (Balsamo & Todaro 1995). Five-lobed head. Hypostomium large, approximately 20 µm in width, shaped as a concave transverse bar. Dorsal sensory bristles present, posterior pair emerging from double-keeled scales. Dorsal surface covered by pentagonal scales, with posterior incisions. Scales bear simple spines. In the posterior dorsal trunk region scales with shorter spines.

The Swedish specimen, an adult in parthenogenetic phase, was in bad condition, but diagnostic features such as shape of scales and spines and the hypostomium could be recorded.

Previously reported from Italy (Balsamo & Todaro 1995).