Mesenchytraeus megachaetus, a new enchytraeid with enlarged ventral chaetae (Annelida, Clitellata) from Changbaishan Mountain, China

摘要

Mesenchytraeus megachaetus, new species, is described from northeast China. It is characterized by possessing enlarged ventral chaetae in segments V-VI (3-4 per bundle); nephridia with solid unlobed postseptale, relatively developed interstitial tissue and near-septal origin of the efferent duct; nephridia occurring in 5 pairs in preclitellar region; seminal vesicle absent, replaced by 5-8 naked "spermatozeugmata" in dorsal region of XI; spermathecae without diverticula and attached entally to esophagus in segment VI; atria tubular (indistinct from vasa deferentia) and without prostate glands; egg sac much developed (extending to XVII-XVIII).