Fionidae Gray, 1857

Family Fionidae Gray, 1857 View in CoL

( Figs 1, 2; Table 4)

Gray 1857: 227.

Family Fionidae View in CoL restricted in original sense: Korshunova et al. 2017c: 9, 14, 17, 18.

Diagnosis: Body wide. Notal edge present.Ceratal rows branched, numerous non-elevated cerata per row. Membranaceous fold on ceratal edge in the type genus. Rhinophores smooth. Anus cleioproctic. Masticatory edges of jaws commonly bear single row of simple or compound denticles. Radula formula 0.1.0. Central teeth usually with strong cusp not compressed by adjacent lateral denticles. Distal receptaculum seminis. Vas deferens extremely long, prostate indistinct. Supplementary gland absent. Massive external permanent penial collar absent. Penis internal, extremely long, narrow, unarmed.

Genera included: Fiona Alder and Hancock, 1853 and? Tergiposacca Cella et al., 2016 (temporarily included).

Remarks: Choosing the family ‘Fionidae’ sensu latissimo as the basis for synonymizing the morphologically and molecularly hugely disparate family and genera levels of the superfamily Fionoidea lacks anything approaching even ‘phylogenetic systematics logic’: the family Fionidae proper completely lacks the main apomorphy of the pan-lumping ‘Fionidae’– the supplementary gland. Throughout literature, the special supplementary gland is also inappropriately termed as ‘penial’. This is incorrect, because the supplementary gland can be inserted either to the vas deferens, or to the base of penial sheath, and, at any measure, the supplementary gland is never a completely integral part of the penis, and, therefore, the term ‘penial gland’ should be avoided. The other main external character of the family Fionidae —the distinct notal edge—differs not only from the more related family Trinchesiidae , but also from all other families of the superfamily Fionoidea ( Korshunova et al. 2017a,b,c, 2021, 2022), except for the strongly-reduced notal edge in the family Murmaniidae . Prior to its erroneous synonymization in 2016, for more than 150 years of taxonomic history the family Fionidae has invariably contained only a single, highly peculiar (compared to a majority of related families) genus Fiona ( Gray 1857, Odhner in Franc 1968, Jensen 2000). The genus Tergiposacca , although also lacking a supplementary gland, otherwise is significantly different from Fionidae proper and is included in that family temporarily ( Tables 3, 4).