Jorunna daoulasi, 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 daoulasi sp. nov.

Figs 8A-C , 9A , 10A, B

Jorunna ? Jorunna sp. 10: Gosliner et al. 2018: 122.

Rostanga ? Rostanga sp. 4: Nakano 2018: 263.

Type material.

Holotype: In front of the harbor, Koumac, New Caledonia (20°35.3'S, 164°16.4'E), 6 m depth [Koumac 2.1 stn. KR220], 17 Nov 2018, 12 mm long, (MNHN IM-2013-86230).

Other material examined.

In front of the harbor, Koumac, New Caledonia (20°35.3'S, 164°16.4'E), 6 m depth [Koumac 2.1 stn. KR220], 17 Nov 2018, 1 specimen 24 mm long, dissected (MNHN IM-2013-86220). Koumac, New Caledonia (20°35.2'S, 164°16.3'E), 6 m depth [Koumac 2.3 stn. KR886], 21 Nov 2019, 1 specimen 27 mm long, dissected (MNHN IM-2013-86219, isolate JI22) .

Description.

Body oval, narrow, elongate, completely covered with numerous caryophyllidia (Fig. 8A-C ). Branchial and rhinophoral sheaths low, simple, circular; gill composed of nine short, tripinnate branchial leaves, imbricated, arranged upright, with the apices close to each other in the living animal. Rhinophores short, lamellated, with eight or nine lamellae. Body color grey, with a complex network of white lines of different thicknesses; in some specimens some of the lines are very thick and contain darker areas (Fig. 8A ), whereas in others thicker lines form the main network and thinner lines form a secondary network (Fig. 8 ) and in others all lines are approximately the same thickness (Fig. 8B ). Rhinophores and branchial leaves are the same color as the dorsum but the rhinophoral lamellae and in some cases the gill lamellae are white.

Reproductive system (Fig. 9A ) with a long, narrow, curved ampulla that connects with the female gland complex and an elongate prostate. The prostate is as wide as the ampulla but narrows substantially before expanding into the short, curved, narrow deferent duct. The deferent duct is much narrower than the prostate. The penis is unarmed. The vagina is very elongate and wide distally, several times wider than the deferent duct, narrowing considerably proximally and connecting directly to the irregular bursa copulatrix. The oval seminal receptacle also connects to the bursa copulatrix next to the vaginal connection, and the short uterine duct that enters the female gland complex. The bursa copulatrix is ~ 3 × as large as the seminal receptable. A large accessory gland connects to a narrow and convoluted duct that opens into the genital atrium, where a curved, sharp stylet is located.

Radular formula 24 × n.0.n in a 26-mm long specimen (MNHN IM-2013-86220) and 25 × n.0.n in a 27-mm long specimen (MNHN IM-2013-86219). Rachidian teeth absent. Innermost lateral teeth wide, having a short cusp with four or five irregular denticles (Fig. 10A ). Mid-lateral teeth hamate, lacking denticles (Fig. 10A ). The teeth increase in size gradually towards the distal portion of the half-row (Fig. 10B ). Outermost teeth very elongate, longer than mid-lateral teeth, with several elongate apical denticles (Fig. 10B ). No jaws ware observed.

Biology.

Range includes New Caledonia and possibly Papua New Guinea and Japan (see Remarks section below); uncommon, found at ~ 6 m depth on an unidentified grey sponge on which it is highly cryptic. All the specimens were found directly on the sponges while SCUBA diving.

Etymology.

This species is named after Alain Daoulas, outstanding collector and naturalist, who participated in two of the Koumac expeditions, collecting a number of important specimens.

Remarks.

Jorunna daoulasi 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). Specifically, J. daoulasi 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. Finally, in the molecular phylogenetic analyses, J. daoulasi sp. nov. is a member of a well-supported clade containing other members of Jorunna .

Camacho-García and Gosliner (2008) provided a comprehensive revision and illustrations of the valid species of the genus Jorunna , including all the Indo-Pacific taxa described to date. None of the species included in Camacho-García and Gosliner’s (2008) monograph have a similar color pattern and morphology to J. daoulasi sp. nov. Since then, several additional new species have been described from the Atlantic Ocean ( Edmunds 2011; Alvim and Pimenta 2013; Ortea et al. 2014; Ortea and Moro 2016; Neuhaus et al. 2021) and the Indian Ocean ( Tibiriçá et al. 2023), but they are also morphologically and/or genetically different from J. daoulasi sp. nov. The most similar species to J. daoulasi sp. nov. in external morphology are Jorunna sp. 10 from Papua New Guinea illustrated by Gosliner et al. (2018) and Rostanga sp. 4 from Japan illustrated by Nakano (2018), which have a very similar body shape and color and could represent the same species.

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).