Bull. Natl. Mus. Nat. Sci., Ser. A, 33(1), pp. 1–30, March 22, 2007 Digeneans (Trematoda) of Freshwater Fishes from Nagano Prefecture, Central Japan Takeshi Shimazu Nagano Prefectural College, 8–49–7 Miwa, Nagano, 380–8525 Japan E-mail:
[email protected] Abstract Examination of digeneans (Trematoda) parasitizing freshwater fishes collected in Nagano Prefecture, central Japan, revealed that 22 species including two new species occur in this prefecture. Sanguinicola ugui sp. nov. (Sanguinicolidae) is described from the blood vessels of Tribolodon hakonensis (Günther) (Cyprinidae). Azygia rhinogobii sp. nov. (Azygiidae) is described from the stomach of Rhinogobius sp. (Gobiidae, type host) and Gymnogobius urotaenia (Hilgen- dorf) (Gobiidae), and the intestine of T. hakonensis. Phyllodistomum anguilae Long and Wai, 1958, P. mogurndae Yamaguti, 1934, P. parasiluri Yamaguti, 1934 (Gorgoderidae), and Pseudex- orchis major (Hasegawa, 1935) Yamaguti, 1938 (Heterophyidae) are redescribed. The generic di- agnosis of the genus Pseudexorchis Yamaguti, 1938 is amended in part. New host and locality records are provided for 20 known species. An outline of the life cycle of Asymphylodora macro- stoma Ozaki, 1925 (Lissorchiidae) is given. A furcocystocerous cercaria, probably the cercarial stage of A. rhinogobii sp. nov., is briefly described from Sinotaia quadrata histrica (Gould) (Gas- tropoda, Viviparidae). Key words : digenean, parasite, new species, furcocystocercous cercaria, taxonomy, life cycle, freshwater fish, Nagano, Japan. ed considerable