Pseudovermidae Thiele 1931

Family Pseudovermidae Thiele, 1931 (Figs 1, 2; Table 4) Thiele 1931: 454. Korshunova et al. 2017a: 67, 72, 73, supplementary materials. Martynov et al. 2020: 1, 3, 12–15. Diagnosis: Body narrow, worm-shaped. Notal edge completely reduced. Cerata reduced in a few separate rows. Rhinophores and oral tentacles absent. Anus acleioproctic in anterior part of the body. Masticatory edges of jaws bear a single row of denticles. Radula formula 1.1.1. Central teeth broad, pectinate, cusps not compressed by adjacent lateral denticles. Lateral teeth denticulated, not broadened. Proximal receptaculum seminis. Vas deferens moderately long to short, prostate indistinct or distinct. Supplementary and accessory glands absent. Massive external permanent penial collar absent. Penis internal, narrow, unarmed. Genera included: Pseudovermis Perejaslavtzeva, 1891. Remarks: The family Pseudovermidae is the apex of paedomorphic reduction within the suborder Aeolidacea, when its initially complex ancestral body, driven by evolution in the interstitial environment (see: Flammensbeck et al. 2019, Martynov et al. 2020), was modified into an almost worm-shaped form with completely reduced rhinophores and oral tentacles, and considerably reduced cerata. Despite its dramatically paedomorphic evolution-modified external form, internally Pseudovermidae possess a triserial radula whose general pattern corresponds well to the family Cumanotidae, and together with the robust molecular phylogenetic data (Martynov et al. 2020, present study; Figs 1, 2) allows Pseudovermidae to be firmly placed with Cumanotidae in the same superfamily Cumanotoidea.