Jorunna hervei, Innabi & Stout & Valdés, 2023

Innabi, Julie, Stout, Carla C. & Valdes, Angel, 2023, Seven new " cryptic " species of Discodorididae (Mollusca, Gastropoda, Nudibranchia) from New Caledonia, ZooKeys 1152, pp. 45-95 : 45

Jorunna hervei sp. nov.

Figs 8D-F , 9B , 10C-E

Type material.

Holotype: Pandop, Koumac, New Caledonia (20°34.9'S, 164°16.5'E), 7 m depth [Koumac 2.1 stn. KR868, rock, sponges, algae including Halimeda ], 26 Sep 2018, 1 specimen 24 mm long (MNHN IM-2013-86225, isolate JI47)

Other material examined.

Koumac , New Caledonia (20°35.6'S, 164°16.3'E), 3 m depth [Koumac 2.1 stn. KR230], 28 Sep 2018, 1 specimen 11 mm long (MNHN IM-2013-86221). Koumac, New Caledonia (20°35.1'S, 164°16.3'E), 3 m depth [Koumac 2.1 stn. KR231], 29 Sep 2018, 1 specimen 21 mm long, dissected (MNHN IM-2013-86222). Koumac, New Caledonia (20°35.1'S, 164°16.2'E), 8 m depth [Koumac 2.1 stn. KR410, sponge bottom], 29 Sep 2018, 1 specimen 14 mm long (MNHN IM-2013-86223). Pandop Point Reef, Koumac, New Caledonia (20°35.2'S, 164°16.3'E), 6 m depth [Koumac 2.1 stn. KR859, sandy-muddy bottom with sponges, Caulerpa ], 17 Sep 2018, 1 specimen 25 mm long, dissected (MNHN IM-2013-86226, isolate JI48); 1 specimen 14 mm long (MNHN IM-2013-86227). Pointe de Pandop, Koumac, New Caledonia (20°34.9'S, 164°16.5'E), 7 m depth [Koumac 2.1 stn. KR868, rock, sponges, algae including Halimeda ], 26 Sep 2018, 1 specimen 22 mm long (MNHN IM-2013-86224). Koumac, New Caledonia (20°32.9'S, 164°16.8'E), 5 m depth [Koumac 2.3 stn. KR917], 19 Nov 2019, 1 specimen 16 mm long (MNHN IM-2013-86228) .

Description.

Body oval, flattened, completely covered with numerous caryophyllidia (Fig. 8D-F ). Branchial and rhinophoral sheaths low, simple, circular; gill composed of nine short, tripinnate branchial leaves, slightly imbricated, arranged fully upright in the living animal. Rhinophores short, lamellated with elongate apices, seven or eight lamellae. Body color variable from pale brown to grey, with numerous irregular dark patches, surrounded by white pigment (Fig. 8E ). Rhinophores and branchial leaves are the same color as the dorsum.

Reproductive system (Fig. 9B ) with an elongate, curved ampulla that connects with the female gland complex and an elongate prostate with a single fold. The prostate is as wide as the ampulla but narrows substantially into a long tube before expanding slightly into the short, curved, narrow deferent duct. The penis is unarmed. The vagina is narrow, as wide as the deferent duct, and very elongate, connecting directly to the oval bursa copulatrix. The oval seminal receptacle also connects to the bursa copulatrix next to the vaginal connection, and the long uterine duct that enters the female gland complex. The bursa copulatrix is many times larger than the seminal receptacle. A large accessory gland connects to a wide duct that opens into the genital atrium, where a sharp, curved stylet is located.

Radular formula 24 × n.0.n, in a 21-mm long specimen (MNHN IM-2013-86222), 28 × n.0.n in a 22-mm long specimen (MNHN IM-2013-86224), and 30 × n.0.n in a 25-mm long specimen (MNHN IM-2013-86226). Rachidian teeth absent. Inner and mid-lateral teeth hamate, having a long cusp and lacking denticles (Fig. 10C-E ). Innermost teeth smaller than mid-laterals (Fig. 10C ). The teeth increase in size gradually towards the medial portion of the half-row (Fig. 10D ). Outermost teeth very elongate, longer than mid-lateral teeth, increasing in size gradually, and hamate (Fig. 10E ). No jaws were observed.

Biology.

The pale brown egg mass is a highly coiled ribbon with ca. seven tightly packed whorls with a wavy upper edge (Fig. 8E ). Eggs are ~ 105 µm in diameter. The geographic range includes New Caledonia and could be an endemic species; uncommon, found at 3-8 m depth on an unidentified brownish grey sponge on which is highly cryptic. All the specimens were collected directly from the sponges while SCUBA diving.

Etymology.

This species is named after Jean-François Hervé, pioneer in the study of the sea slugs of New Caledonia and excellent collector; he participated in two of the Koumac expeditions, finding numerous specimens.

Remarks.

As in the case of Jorunna daoulasi sp. nov., Jorunna hervei sp. nov. is placed in the genus Jorunna because it fits morphologically within the diagnoses of the genus provided by Valdés and Gosliner (2001) and Camacho-García and Gosliner (2008). Jorunna hervei sp. nov. has a soft mantle covered with long caryophyllidia, the radular teeth are hamate, and the reproductive system has an accessory gland and a copulatory stylet, all of which are characteristics of Jorunna . Furthermore, in the molecular phylogenetic analyses, Jorunna hervei sp. nov. is sister to J. daoulasi sp. nov. as well as a member of a well-supported clade containing other members of Jorunna .

Jorunna hervei sp. nov. differs from Jorunna daoulasi sp. nov. in several regards. Externally, J. hervei sp. nov. is less elongate than J. daoulasi sp. nov. and lacks the network of white pigment; instead it has numerous irregular dark patches, in some specimens surrounded by white pigment. The reproductive system of J. hervei sp. nov. is similar to that of J. daoulasi sp. nov., but the accessory gland is comparatively smaller, the bursa copulatrix is much larger in comparison to the seminal receptable, and the deferent duct is shorter in comparison to the vagina. The main anatomical difference between these two species is the radular morphology, while Jorunna hervei sp. nov. has inner and mid-lateral teeth hamate, having a long cusp and lacking denticles, in J. daoulasi sp. nov. the innermost lateral teeth are wide, having a short cusp with four or five irregular denticles. Finally, the ABGD analysis recovered J. hervei sp. nov. and J. daoulasi sp. nov. as distinct species.

Jorunna liviae Tibiriçá, Strömvoll & Cervera, 2023 recently described from Mozambique ( Tibiriçá et al. 2023) is sister to J. hervei sp. nov. and is morphologically similar but differs in several important respects. First of all, the species delimitation analysis recovered J. hervei sp. nov. and Jorunna liviae as different species. Additionally, the body of J. liviae appears to be narrower and more elongate than that of J. hervei sp. nov. More importantly, the outermost radular teeth of J. liviae contain multiple elongate denticles, which are absent in all specimens examined of J. hervei sp. nov. Also, the prostate of J. liviae is flattened, whereas the prostate of J. hervei sp. nov. is tubular an elongate, and the accessory gland appears to be comparatively much larger in J. liviae than in J. hervei sp. nov. although is it variable in size ( Tibiriçá et al. 2023). Finally, the eggs of J. liviae are white, whereas they are pale brown in J. hervei sp. nov. It is clear that these two species are similar but distinct.

A review of the literature does not reveal any other species morphologically similar to J. hervei sp. nov. Rostanga sp. 7 in Gosliner et al. (2018) has some superficial resemblance but there are some obvious differences, including the background color, grey in J. hervei , pink in Rostanga sp. 7, and the egg mass, having one or two loosely packed whorls with ochre, large eggs in Rostanga sp. 7, versus seven tightly packed whorls with pale brown eggs in J. hervei .

Figures

Figure 8. Photographs of live animals of the genus Jorunna Bergh, 1876 A-C Jorunna daoulasi sp. nov., MNHN IM- 2013 - 86219 on black background (A), MNHN IM- 2013 - 86220 in situ (B), Holotype (MNHN IM- 2013 - 86230) in situ (C) D-F Jorunna hervei sp. nov., MNHN IM- 2013 - 86228 on black background (D), MNHN IM- 2013 - 86224 and Holotype MNHN IM- 2013 - 86225 in situ with egg mass (E), MNHN IM- 2013 - 86226 in situ with egg mass (F).

Figure 9. Drawings of the reproductive systems of specimens of the genus Jorunna Bergh, 1876 A Jorunna daoulasi sp. nov., MNHN IM- 2013 - 86219 B Jorunna hervei sp. nov., MNHN IM- 2013 - 86226. Abbreviations: ag, accessory gland; am, ampulla; bc, bursa copulatrix; dd, deferent duct; fg, female gland complex; pr, prostate; sr, seminal receptacle; st, stylet; vg, vagina.

Figure 10. SEM of the radula of specimens of the genus Jorunna Bergh, 1876 A, B Jorunna daoulasi sp. nov., MNHN IM- 2013 - 86220, innermost teeth (A), outer lateral teeth (B) C-E Jorunna hervei sp. nov., MNHN IM- 2013 - 86224, innermost teeth (C), mid-lateral teeth (D), outer lateral teeth (E).