First report of two North American branchiobdellidans (Annelida: Clitellata) or crayfish worms on Signal crayfish in Europe with a discussion of similar introductions into Japan

Two species of North American branchiobdellidans, Cambarincola gracilis Robinson, 1954 and Cambarincola okadai Yamaguchi, 1933, have been reported in Europe for the first time. These branchiobdellidans together with Xirogoniton victoriensis Gelder and Hall, 1990 were found on signal crayfish, Pacifastacus leniusculus (Dana, 1852), collected from the Lot and Tarn River drainages in southern France. Specimens of X. victoriensis were also reported on the same host in the Mayenne River drainage in northeastern France. Brief morphological descriptions of the three alien branchiobdellidan species are given. These introductions are briefly discussed and compared with similar alien ectosymbiotic associations found in Japan.