Abstract

Most Japanese records and descriptions of the family Lumbriculidae are from the work of H. Yamaguchi, who described 6 endemic species and one genus, in addition to reporting the cosmopolitan Lumbriculus variegatus (Müller, 1774). Yamaguchi's work focused largely on the northern island of Hokkaido; since then, only one new Japanese lumbriculid genus and species has been described, also from Hokkaido. Recent collections from Honshu Island include several species not recorded in earlier literature, and here we report 4 new species of Lumbriculidae, plus a range extension of the Korean Lamprortus orientalis Rodriguez, 1994. Of the new species, only Styloscolex (Styloscolex) tazawaensis can be confidently assigned to an accepted genus using current morphological diagnoses. Styloscolex (Neoscolex) tatsukoae n. sp. is provisionally assigned to that Asian genus and subgenus based on the prosoporous male duct, spermathecae in the preatrial segment, and penial sheath—despite differing from congeners in having a single, median atrium in X, and single spermatheca in IX. Two additional species are here attributed to a new genus, Honshudrilus, which is distinguished by a combination of characters: spermathecae 2 or more segments anterior to the male pores, non-functional anterior male ducts (with loss of anterior testes), elongate-petiolate atria, penes formed by extruding the atrial duct lining, and spermathecal ducts with vestibules.