Adalaria ultima Martynov & Korshunova 2017, sp. nov.

• Main Authors: Martynov, Alexander, Korshunova, Tatiana
• Format: Other/Unknown Material
• Language: unknown
• Published: 2017
• Subjects: Biodiversity; Taxonomy; Animalia; Mollusca; Gastropoda; Nudibranchia; Onchidorididae; Adalaria; Adalaria ultima; Arctic; Okhotsk; Pacific; okhotsk sea
• Online Access: https://zenodo.org/record/6010359; https://doi.org/10.5281/zenodo.6010359

Adalaria ultima sp. nov. (Figures 1, 3; 5B) http://zoobank.org/urn:lsid:zoobank.org:act:0684148E-3C12-4BEE-9C6D-CB33842EC258 Type Material. Holotype, ZMMU Op-551 (21 mm length), NW Pacific Ocean, Okhotsk Sea, Sakhalinsky Bay, depth 95 m, collector not known, 1985. Paratypes, 2 specimens, ZMMU Op-552, NW Pacific Ocean, Japan Sea, off Moneron Island, depth 40–60 m, collector not known, 29.08.1978. Type locality. Okhotsk Sea, Sakhalinsky Bay. Etymology. This species is named in reference to the remote far eastern range of this species in the north-west Pacific compared to the high latitude Arctic habitat of the related species A. rossica. Ultimus in Latin means far, and is an adjective. Description. External morphology. The length of the preserved holotype is 21 mm and 7 mm wide (Fig. 3 A– B). The lengths of two preserved paratypes are 12 mm and 19.5 mm, their widths 4 mm and 7 mm. The notum is moderately broad, rounded in front and posteriorly. The rhinophores are long and retracted into sheaths with smooth edges, except for several tubercles of various size that are connected to the edge of each sheath. There are 12–19 rhinophoral lamellae. The notum is densely covered with slender, narrow, elongated tubercles. Tubercules are alike all over the notum, narrow and elongated (Fig. 3 A). Larger tubercles are regularly intermingled with smaller ones. The rays of spicules radiating from the bases of tubercles form a sort of network under the surface of the soft notum. The spicules are not conspicuous externally. The gill cavity is absent. Eleven to twelve uni- and bipinnate gills form an almost complete semicircle around the anus, and one tubercle may be present just behind the anus. The large oral veil consists of two pairs of processes: a single, broad trapezoid upper triangular projection that is not medially fused with the hyponotum, and two flattened lobes below (Fig. 3 B). The foot is broad, anteriorly rounded, with no labium. Colour. The living specimens are light yellowish white. The gills and rhinophores are ...