Remarks
Established based on four specimens, up to 3.7 mm in length, collected from 19–25 m depth near Wauwermans Islands, Antarctica. With four eyes. The rhynchocoel is “composed of single fibres spaced apart from one another in a partially woven lattice” (Crandall 2010: 2412), a character state that cannot readily be interpreted as decisively homologous with that in Cratenemertea and/or Plectonemertidae. The cerebral organs are large, located behind the pre-cerebral septum, lying beside and beneath the brain, and thus conforming to those in Cratenemertea, but also in Proamphiporus Chernyshev & Polyakova, 2019. The vascular plug is “broad and flat, lying tightly against ventral wall of rhynchocoel” (Crandall 2010: 2421), but one of the original figures (Crandall 2010, fig. 12) depicts it as if there are two vascular plugs, reminiscent of the character state in Oerstediina. The taxonomic placement of the family Cinclidonemertidae Crandall, 2010, the genus Cinclidonemertes Crandall, 2010, and C. mooreae among Monostilifera thus requires further scrutiny.