Molecular Phylogeny of the Genus Nipponnemertes (Nemertea: Monostilifera: Cratenemertidae) and Descriptions of 10 New Species, With Notes on Small Body Size in a Newly Discovered Clade

Nemerteans, or ribbon worms, have been reported from intertidal to hadal depths, often showing bathymetrically wide distribution in genus levels. Although current nemertean systematics practices require provide DNA sequences and infer phylogenetic relationships with suitable molecular markers, previous on nemerteans are mostly biased toward shallow-water species. Members the Nipponnemertes occur worldwide, tropical polar waters bathyal waters. Molecular studies scarce for genus; only six species of 18 were subject phylogeny. Thus, is one candidate that needs be assessed by genetic approaches. In this study, we performed analyses using 59 specimens 23 based partial two mitochondrial (16S rRNA cytochrome c oxidase subunit I) three nuclear gene markers (18S rRNA, 28S histone H3). Our extensive sampling Northwest Pacific significantly updated fauna region four 17 We herein establish 10 new an list concisely summarizing all congeners known world. tree indicated major lineages within (herein referred as “Clade A, B, C”), each presumably characterized combination morphological characters head region. Clade A are: pulchra (Johnston, 1837), ogumai (Yamaoka, 1947), several unidentified congeners, having demarcated without cephalic patches; members B crypta sp. nov., jambio neonilae ojimaorum C ganahai kozaensis lactea notoensis ornata sugashimaensis forms collected off Jogashima (Japan) Guam (USA), non-demarcated lacking patches. Furthermore, discuss evolution remarkably small body size retained among C.