Classification of the genera that belong to the families Enchytraeidae Vejdovsky, 1879 and Propappidae Coates, 1986 (Annelida: Clitellata: Tubificidae)

To date, there is limited information on the taxonomic composition of enchytraeids in Japan. In this study, keys to and diagnoses for the genera of Enchytraeidae and Propappidae have been provided. The keys cover 25 terrestrial, marine, and freshwater genera that have been recorded and are potentially distributed in Japan, and some local or dubious genera were excluded. The major diagnostic characters used in the keys were as follows: 1. shape of the prostomium; 2. presence/ absence and location of dorsal pores; 3. shape and numerical pattern of chaetae; 4. shape and distribution of nephridia; 5. location of the dorsal blood vessel origin; 6. shape of the chloragocytes; 7. abrupt/gradual transition of the esophagus into the intestine, 8. presence/absence, shape, and position, and size of the esophageal appendages; 9. quantity, size, shape, and texture of the coelomocytes; 10. shape of the male funnel; 11. shape of the spermatheca and its attachment (or not) to the esophagus; 12. presence/absence, size, and shape of the testis sacs or seminal vesicles. In addition, the characters of each genus have been described.