Cookidrilus pocosinus sp. n. A Anterior region of the body B caudal region with pygidium C chaetae D chaetal gland behind ventral bundle of chaetae E clitellum F spermathecal and male pores in front of and behind ventral chaetae of segment X G atrium H atrial ampulla showing apical junction of vasa deferentia I atrial ampulla showing junction of prostatic cell clusters J basal junction of vas deferens to atrial ampulla K detail of atrial duct and protruded penis L third spermatheca behind the female segment. A, D, J, K, L histological sections, other photographs from stained whole mounts or dissected specimens.