Ziminella circapolaris, Korshunova, Tatiana, Martynov, Alexander, Bakken, Torkild, Evertsen, Jussi, Fletcher, Karin, Mudianta, I Wayan, Saito, Hiroshi, Lundin, Kennet, Michael Schroedl, & Picton, Bernard, 2017

Korshunova, Tatiana, Martynov, Alexander, Bakken, Torkild, Evertsen, Jussi, Fletcher, Karin, Mudianta, I Wayan, Saito, Hiroshi, Lundin, Kennet, Michael Schroedl, & Picton, Bernard, 2017, Polyphyly of the traditional family Flabellinidae affects a major group of Nudibranchia: aeolidacean taxonomic reassessment with descriptions of several new families, genera, and species (Mollusca, Gastropoda), ZooKeys 717, pp. 1-139 : 19

Ziminella circapolaris sp. n. Fig. 13

Type material.

Holotype, ZMMU Op-598, 35 mm long (fixed), Arctic Ocean, Franz Josef Land, Wiltona Island, 23.08.2013, depth 18-25 m, collected by O.V. Savinkin. 1 paratype, ZMMU Op-482, 14 mm long (fixed), Arctic Ocean, Franz Josef Land, Northbrook Island, 26.08.2013, depth 18-23 m, collected by O.V. Savinkin. 1 Paratype, ZMMU Op-483, 12 mm long (preserved), Arctic Ocean, Franz Josef Land, Pioneer Island, 17.08.2013, depth 21-23 m, collected by O.V. Savinkin.

Type locality.

Franz Josef Land.

Etymology.

From circa (= near, Latin) and polaris (= polar, Latin) in reference to the proximity of the habitat of the new species (Franz Josef Land) to the North Pole.

Diagnosis.

Continuous notal edge, colour yellowish, cerata reddish-brown, few apical white dots, rachidian tooth with up to ten denticles clearly delineated from central cusp, lateral teeth with numerous denticles (up to 24) which cover whole edges of lateral teeth, receptaculum seminis not evident, penis folded.

Description.

External morphology. Body wide. Foot and tail wide, anterior foot corners short. Rhinophores similar in size to oral tentacles, smooth to slightly wrinkled. Dorsal cerata elongate, thick, continuously attached to well-defined uninterrupted notal edge without forming clusters. Notum narrow but distinct throughout both lateral sides of body. Digestive gland diverticulum fills significant volume of cerata. Anal opening on right side below notal edge close to middle body part. Reproductive openings on right side. Tail long and pointed, extending only a short distance beyond last cerata.

Colour (Fig. 13A, B). Background colour yellowish-white. Digestive gland diverticula reddish-brown. Rhinophores light orange-yellowish. Lateral branches of digestive gland (that shine through lateral dorsum sides) not distinct.

Jaws (Fig. 13E, F). Jaws broad, yellowish in colour. Masticatory processes of jaws covered with several simple denticles.

Radula (Fig. 13 G–J). Radula formula up 26 × 1.1.1 (specimens 20-24 mm in length). Rachidian tooth elongate with strongly protracted, pointed, non-compressed cusp of almost 1/3 of tooth length (Fig. 13G, I). Rachidian tooth bears five to ten lateral denticles. Larger denticles not intermingled with smaller ones. Cusp clearly delineated from the adjacent first lateral denticles. Lateral teeth (Fig. 13H, J) narrowly triangular with 19-24 denticles on internal edge.

Reproductive system (Fig. 13K, L). Diaulic. Hermaphroditic duct leads to long, relatively narrow convoluted ampulla of several whorls. Vas deferens long, without distinct prostate. Penial sheath elongated. Penis folded. Oviduct connects through insemination duct into female gland complex. No distal or proximal receptaculum seminis detected.

Ecology.

Soft bottom with stones 18 to 23 m.

Distribution.

Franz Josef Land.

Remarks.

According to the molecular phylogenetic analysis Ziminella circapolaris sp. n. forms a separate sister clade to Z. salmonacea (Fig. 1). Specimens from the West Atlantic North American coast (type locality of Z. salmonacea ) and Spitzbergen belong to Z. salmonacea , according to molecular data, whereas specimens from Franz Josef Land belong to the separate species Z. circapolaris sp. n. This is concordant with a considerable level of endemism of the nudibranch fauna of Franz Josef Land recently demonstrated for other nudibranch groups ( Martynov and Korshunova 2017). Morphological analysis reveals differences in the denticulation of the lateral teeth between Z. salmonacea and Z. circapolaris sp. n.: in the first species denticulation on the lateral teeth tends to be restricted to the first half of the length of lateral teeth or the teeth can be completely smooth, whereas in the new species denticulation runs up to the very end of the lateral teeth, and the teeth are always denticulated. Kuzirian (1979) studied the radulae of 15 specimens of Z. salmonacea from near the type locality and all of them have considerably smoother lateral teeth than Z. circapolaris sp. n.