Myrrhinidae Bergh 1905

Family Myrrhinidae Bergh, 1905 (Figs 1, 2; Table 4) Bergh 1905: 226. Martynov et al. 2019: 90, 111–2. Diagnosis: Body moderately broad to narrow. Notal edge completely reduced. Cerata in arches or rows, numerous per row. Rhinophores smooth, with swellings or perfoliate. Cleioproctic anus. Masticatory edges of jaws moderately to very strongly denticulated, denticles relatively simple to compound. Radula formula 0.1.0. Central teeth with distinct denticles, sometimes reduced, cusp non-compressed or compressed. Proximal receptaculum seminis. Vas deferens from very long to short, prostate indistinct or distinct. Accessory gland present in some taxa. Massive external permanent penial collar absent. Penis internal, conical, sometimes with internal glands, or massive, papillated, unarmed or armed with stylet. Genera included: Dondice Er. Marcus, 1958, Godiva Macnae, 1954, Hermissenda Bergh, 1879, Nanuca Er. Marcus, 1957, Nemesignis Furfaro and Mariottini, 2021, and Phyllodesmium Ehrenberg, 1831. Remarks: The family Myrrhinidae Bergh, 1905 highlights the paradoxical ‘nature’ of contemporary taxonomy, when at the morphological level the family Myrrhinidae, even though it comprises a relatively few number of genera, represent a heterogenous assemblage, but because it was uncovered as paraphyletic compared to the other Facelinidae, its separation (Martynov et al. 2019) was immediately accepted and did not promote any notable discussion. While we apparently must be satisfied that such a case is ‘allowed’ to exist, it, in reality, clearly reveals the fundamental problem of modern taxonomy, which predominantly relies on the results of molecular phylogenetic analysis without a deep understanding of basic biological facts: that every taxon does not represent merely a branch from the ‘endless phylogenetic tree’, but inevitably is comprised of individual organisms, each in all its ontogenetic complexity, and only these complex individuals interact on one side to make a permanent ‘evolutionary flow’, but on the other side always remain individuals, not merely a part of a human-constructed ‘phylogenetic tree’ (see also: Martynov and Korshunova 2022). That is why the more taxonomy is differentiated, the more it departs from overformalized phylogenetic trees and approaches the true element of any evolutionary process—a dynamic individual with a particular set of characters. A further paradox is that the family Myrrhinidae was uncovered as phylogenetically more related to the family Aeolidiidae than to the rest of Facelinidae, whereas at the morphological level Myrrhinidae is similar to Facelinidae, and not to Aeolidiidae. Therefore, it is perfectly possible in a case when morphologically similar families are mosaically distributed within the superfamily Aeolidioidea using that logic of ‘intermediate morphology’ during pan-synonymization events in another aeolidacean superfamily Flabellinoidea (Gosliner and Griffiths 1981), to lump the family-level diversity of the aeolidioidean superfamily into merely one family, Aeolidiidae / Glaucidae, just because of molecular phylogenetic data (Figs 1, 2). However, the potential synonymy of fine-scale differentiated families, Myrrhinidae and Aeolidiidae, is not discussed, whereas, again, fundamentally similar cases at different levels of the superfamilies Fionoidea and Flabellinoidea are instead the target of highly dismissive synonymy without any morphological basis.