Glaucidae Gray, 1827

Family Glaucidae Gray, 1827 View in CoL

( Figs 1, 2; Table 4)

Gray 1827: pl. 3, figs 21, 22.

Korshunova et al. 2017a: supplementary materials.

Diagnosis: Body broad. Notal edge completely reduced. Cerata on extremely enlarged stalks, numerous per row. Ceratal rows simple and arched. Rhinophores smooth. Anus cleioproctic. Masticatory edges of jaws moderately denticulated with single row of irregular, blunted, or partly sharpened denticles. Radula formula 0.1.0. Central teeth with non-compressed cusp. Distal and proximal receptaculum seminis or only proximal receptaculum. Vas deferens moderately to considerably long, prostate indistinct. Accessory gland absent. Massive external permanent penial collar absent. Penis internal, broad, armed with stylet or unarmed.

Genera included: Glaucus Forster, 1777 and Glaucilla Bergh, 1861 .

Remarks: The genus Glaucus Forster, 1777 represents one of the oldest, and at the same time one of the most aberrant, taxa not only within the superfamily Aeolidioidea , but also within whole suborder Aeolidacea , because of its highly modified body form adapted to a specific pleistonic habitat ( Colin et al. 2024). The remarkable nomenclatural coincidence that the family Glaucidae Gray, 1827 was established ( Gray 1827) in the same year as the family Aeolidiidae Gray, 1827 (with the stem-genus bearing name Aeolidia Cuvier, 1798 ), makes a very unfortunate case for the supporters of pan-lumping systems in Nudibranchia because the most aberrant family Glaucidae (with the name Glaucus older than the stem-genus name Aeolidia ), would become the super-lumped family ‘Glaucidae’ (Rudman 1980), which would encompass all the possible morphological and molecular diversity of the suborder Aeolidacea [see Martynov et al. (2019) and present study, Synopsis, Remarks to the superfamily Fionoidea , and detailed explanations in Discussion]. Therefore, to avoid that action, which would obviously immediately and profoundly dismiss all suborder morphological and molecular diversity (present study, Synopsis above and below; Figs 1, 2), fine-scale differentiated taxonomy must be employed at family and genera levels not only occasionally, as for some unsubstantiated reason within the superfamily Aeolidioidea and, particularly, for the family Facelinidae (see Synopsis below) only, but consistently to all superfamilies and families of the suborder Aeolidacea , as thoroughly explained in the present study (see Synopsis and Figs 1, 2).