Volume 23 (2018) Issue 1 Pages 13-37
Seven (including six new) species of interstitial hoplonemerteans in the genus Ototyphlonemertes Diesing, 1863 are described from southern Vietnam. The descriptions are based on light microscopic examination of internal structures as well as three methods of molecular species delimitation analyses, i) Automatic Barcode Gap Discovery (ABGD), ii) Poisson Tree Process (PTP), and iii) statistical parsimony, on the basis of ~658-bp cytochrome c oxidase subunit I gene sequences that have been i) newly determined from the Vietnamese specimens and ii) deposited in the public databases for other Ototyphlonemertes species. Three taxa are circumscribed as ‘species groups’ and placed at an infra-subgeneric, supra-specific rank, each represented by O. duplex Bürger, 1895, O. macintoshi Bürger, 1895, and O. parmula Corrêa, 1950. Of the seven Vietnamese species, one is identified as Ototyphlonemertes (species group macintoshi) ani Chernyshev, 2007, which is molecularly confirmed to be distributed from Vietnam (Phu Quoc and Nha Trang) to Japan (Okinawa and Wakayama). The other six are new to science, to which formal taxonomic descriptions are given: these are O. (duplex) chernyshevi sp. nov., O. (duplex) envalli sp. nov., O. (duplex) norenburgi sp. nov., O. (parmula) lei sp. nov., O. (parmula) nakaoae sp. nov., and O. (parmula) tsukagoshii sp. nov.