| abstract | One new genus and two new species of chigger mites are described and illustrated from amphibious sea snakes of the Nansei Islands in Japan. Ancoracarus gen. nov. is created for the unique species Ancoracarus hayashii sp. nov., collected from a Japanese sea krait Laticauda semifasciata (Reinwardt, 1837). This mite is characterized by having a palpal setal formula of BN/NNB/6B; more than 7 genualae on each of genu I, II, and III; 2, 2, and 1 tibiala on each of tibia I, II, and III; no mastisetae on legs; elongated tarsala I; unique anchor-like post-humeral setae in the central portion of the dorsal idiosoma; scutum roughly pentagonal with filamentous sensillae that are trifurcate; and anteromedian seta base on the line of the anterolateral seta bases. A. hayashii sp. nov. is also parasitic on the other Japanese sea kraits, L. laticaudata (Linnaeus, 1758) and L. colubrina (Schneider, 1799). Schoutedenichia masunagai sp. nov., found only on L. laticaudata, differs from the previously known species of the genus Schoutedenichia Jadin and Vercammen-Grandjean, 1954 by the shape and size of the scutum, form of sensillae and combination of characters mentioned in the diagnosis. Our description of a new species of Schoutedenichia increases the total number of species in this genus to 3 (S. atollensis, S. nagasakiensis and S. masunagai sp. nov.) in Japan and 10 in Asia. |