Topotype-based redescription of the leech Torix tukubana (Hirudinida: Glossiphoniiformes: Glossiphoniidae)

Abstract

A poorly-known proboscidate leech species, Torix tukubana (Oka, 1935), in which the mid-body somites are biannulate dorsally and triannulate ventrally, is redescribed based on new specimens collected from its type locality, Mt. Tsukubasan in Honshu, Japan. The redescription provides the internal digestive and genital organs of T. tukubana for the first time. Our observation reveals that this species possesses equal-sized 1st-6th pairs of crop ceca that are nondiverticulated and tubular ovisacs running alongside the ventral nerve cord. Additionally, phylogenetic analyses using nuclear 18S rRNA, mitochondrial cytochrome c oxidase subunit I, 12S rRNA, tRNALeu, and NADH dehydrogenase subunit 1 markers reveal that T. tukubana is closely related to the Palearctic Hemiclepsis Vejdovský, 1884, in which the mid-body somites are triannulate.