Polyphyly of the traditional family Flabellinidae affects a major group of Nudibranchia: aeolidacean taxonomic reassessment with descriptions of several new families, genera, and species (Mollusca, Gastropoda) Author Korshunova, Tatiana Author Martynov, Alexander Author Bakken, Torkild Author Evertsen, Jussi Author Fletcher, Karin Author Mudianta, I Wayan Author Saito, Hiroshi Author Lundin, Kennet Author Michael Schroedl, Author Picton, Bernard text ZooKeys 2017 717 1 139 http://dx.doi.org/10.3897/zookeys.717.21885 journal article http://dx.doi.org/10.3897/zookeys.717.21885 1313-2970-717-1 C19B43B1B3214CB1B1B2A246CEAC56BC C19B43B1B3214CB1B1B2A246CEAC56BC Piseinotecus Er. Marcus, 1955 Figs 2, 34 Type species. Piseinotecus divae Er. Marcus, 1955. Diagnosis. Body narrow. Notal ridge fully reduced. Cerata on low compound stalks. Rhinophores smooth, similar in size to oral tentacles. Anterior foot corners present. Anus pleuroproctic. Rachidian teeth with non-compressed cusp and distinct denticles. Lateral teeth absent. Proximal receptaculum seminis. Short vas deferens with distinct prostate. Penis conical. Species included. Piseinotecus divae Er. Marcus, 1955 (original description in Marcus 1955 ), Piseinotecus (?) sphaeriferus (Schmekel, 1965) (original description in Schmekel 1965 ). Remarks. The genus Piseinotecus is commonly considered to belong to a separate family Piseinotecidae Edmunds, 1970 because of the presence of a uniserial radula instead of the triserial radula common for traditional Flabellinidae . However, external features, including the presence of compound ceratal stalks in the type species of the genus Piseinotecus , P. divae , and the other species (e.g., P. sphaeriferus ) suggest a relationship to Flabellina . Preliminary data suggest that this genus is deeply nested within the traditional family Flabellinidae ( Gosliner et al. 2007 ; Tamsouri et al. 2014 ). This is confirmed by our analysis (Figs 1, 2) and therefore we have considered Piseinotecus a genus within the family Flabellinidae s. str., after removal of the families Coryphellidae , Paracoryphellidae , and others. While this paper was under review an analysis was published ( Furfaro et al. 2017 ) that at least some species previously considered within the genus Piseinotecus (i.e., " P. " gabinierei and " P. " gaditanus) actually possess a triserial radula and thus must be firmly included into the family Flabellinidae in its restricted sense. There are more undescribed species of the putative genus Piseinotecus that appear within some clades which are not closely related, e.g., Flabellinopsidae fam. n. (see above) (Fig. 2). Because of that and also since there are no molecular data for the type species P. divae , the validity and monophyly of this genus still needs to be confirmed. Therefore, until molecular data on the type species P. divae becomes available, we consider the genus Piseinotecus only tentatively as belonging to the family Flabellinidae s. str. According to the first description ( Marcus 1955 ) P. divae has no distinct oral glands but has rather strong cusp of rachidian tooth. These features contradict to the diagnosis of the family Flabellinidae s. str. but still need to be confirmed by novel material. Since the Mediterranean " P. " gabinierei is closely related to Paraflabellina ishitana (Fig. 1) we include " P. " gabinierei into the genus Paraflabellina (see above). Another species " P. " gaditanus is nested within Calmella clade and therefore assigned to that genus. Whether the triserial radula has been overlooked in the type species P. divae or not is currently unclear. Therefore Piseinotecus is not synonymised in the present study with any existing genera, but awaits assignment until more data becomes available. In addition, based on the morphological data we do not include species without ceratal stalks in the genus Piseinotecus or species with more disparate ceratal and radular morphology, such as " Piseinotecus " gonja Edmunds, 1970 and " Piseinotecus " minipapilla Edmunds, 2015 ( Edmunds 1970 , 2015 ).