Tergipedidae Bergh, 1889

Family Tergipedidae Bergh, 1889 View in CoL

( Figs 1, 2; Table 4)

Subfam Tergipedinae Bergh 1889: 209–11 , part.

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

Korshunova et al. 2017a: 67–78, supplementary materials.

Diagnosis: Body narrow. Notal edge completely reduced. Ceratal rows simple. Single non-elevated cerata per row. Rhinophores smooth. Anus acleioproctic. Masticatory edges of jaws commonly bear single row of simple sharpened denticles. Radula formula 0.1.0. Central teeth with strong cusp not compressed by adjacent lateral denticles. Distal receptaculum seminis. Vas deferens short, prostate indistinct. Supplementary gland present, inserts into penis. Massive external permanent penial collar absent. Penis internal, narrow, armed.

Genera included: Tergipes Cuvier, 1805 .

Remarks: After the obvious morphological heterogeneity and molecularly strong inconsistences of the previous ‘pan-lumping agent’, the genus Cuthona proper was explicitly described [see illustrative history in Korshunova et al. (2021)]. Similarly, by restricting actual natural evolutionary patterns with ad hoc, human-based proposals (see details in: Korshunova et al. 2022), a new super-lumping ‘strategy’ has been invented, completely flattening the highly heterogenous and molecularly highly disparate ‘genus Tenellia sensu latissimo ’ ( Gosliner et al. 2018) to include almost all the diversity of the currently fine-scale differentiated family Trinchesiidae (see Synopsis below). In this respect, it was first argued, using morphological arguments ( Martynov 1992a, 2006a, Miller 2004) more than 30 years ago and currently with extensive molecular phylogenetic data ( Korshunova et al. 2017 a,c, 2018, 2021, 2022), that if a ‘pan-lumping’ concept should dismiss nearly all the diversity of the superfamily Fionoidea , it must choose as its super-lumped group not ‘ Cuthona Alder and Hancock, 1855 ’, nor ‘ Tenellia Costa, 1866’ but the oldest genus, Tergipes Cuvier, 1805 .

This is particularly true for the pan-lumped genus ‘Tenellia’ where the genus Tenellia proper [restricted to only a few species close to the type genus Tenellia adspersa (Nordmann, 1845) , see Korshunova et al. (2022) within the family Trinchesiidae ], which is superficially, and evidently convergently, externally similar to Tergipes (which is placed in a distantly related molecular phylogenetic clade, Figs 1, 2) acquired a reduced, strongly paedomorphic external appearance, but at the level of the reproductive system demonstrates the similar presence of a penial stylet (although of a different pattern) and insertion of the supplementary gland into the penis (the latter feature is not one that is indicative at the family-level, since it is present in several very different families of the superfamily Fionoidea , see Synopsis above and below). Therefore, if, as evidence ad absurdum to apply the flawed logic of pan-synonymization ( Gosliner et al. 2018, Kim et al. 2024) the oldest -‘somewhat’ similar genus to Tenellia Costa, 1866— Tergipes Cuvier, 1805 must be chosen to be truly consistent in the persistent attempts to disregard the many family and genera levels of the superfamily Fionoidea . As we have shown, these attempts contradict true natural, evolutionary-fuelled morphological and molecular diversity ( Figs 1, 2). An example of these attempts is illustrated by the problematic genus Rubramoena Cella et al., 2016 with a somewhat unsettled phylogenetic position (but commonly part of the family Trinchesiidae ), and morphology that does not principally differ from members of the family Trinchesiidae ( Korshunova et al. 2017a –c). However, Rubramoena has not been synonymized either with Tergipes or with ‘Tenellia’, yet, for inexplicable reasons, the morphologically distinct genus Zelentia Korshunova et al., 2017 , with a robust phylogenetic position as sister to a majority of the genera of Trinchesiidae ( Fig. 5A), has been incorrectly synonymyzed with the super-lumped ‘ Tenellia sensu latissimo ’ ( Kim et al. 2024) . Thus, there is no consistency about which taxa are ‘synonymized’ and which are ‘not synonymized’, and clearly personal bias was the guiding principle, rather than scientific results, when making taxonomic decisions in the latter case. Otherwise, the family Tergipedidae in its current restricted sense (see: Korshunova et al. 2017c) well represents a highly coherent morphological and molecular fine-scale taxonomic family-level unit, whose phylogenetic placement suggests several independent acquisitions of highly reduced, paedomorphic morphology within the superfamily Fionoidea ( Figs 1, 2; Tables 3, 4). Sea also Remarks under the family Facelinidae to clearly show a preconception-based taxonomic arrangement in Aeolidacea , where the separation of many families and genera are allowed in the superfamily Aeolidioidea , whereas within the superfamilies Fionoidea and Flabellinoidea (particularly, within the family Coryphellidae )—separation of many families and genera are denied for completely unsubstantiated reasons (see Synopsis below and Discussion).