Sclerodoris faninozi, 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

Sclerodoris faninozi sp. nov.

Figs 14E , 15D-F , 16G-I

Type material.

Holotype: Koumac, New Caledonia (20°33.7'S, 164°11.2'E), 0 m depth [Koumac 2.3 stn. KB518, blocks of dead coral on the margin of the fringing reef flat of the lagoon island], 20 Nov 2019, 25 mm long, dissected (MNHN IM-2013-86198, isolate JI11).

Description.

Body oval, flattened, with an irregular, coriaceous texture (Fig. 14E ). Branchial and rhinophoral sheaths somewhat elevated, simple, irregular. Gill composed of five short, tripinnate branchial leaves, arranged upright. Rhinophores short, lamellated, with 15 lamellae. Visceral hump elevated over the rest of the mantle. Dorsum completely covered with small caryophyllidia, a longitudinal ridge, and several large, rounded tubercles. Body color yellowish brown, with scattered opaque white pigment, and areas or dark brown and dark gray. Branchial leaves and rhinophores dark brown.

Reproductive system (Fig. 15D, E ) with a long, wide, convoluted ampulla with several folds, which connects with the female gland complex and the elongate, convoluted prostate. The prostate is as wide as the ampulla, but narrows substantially into a very long duct, before expanding into the long, narrow deferent duct. The penis is armed with rounded spines having a short, sharp cusp (Fig. 15F ). The vagina is elongate, narrow, as wide as the deferent duct, connecting directly to the large, spherical bursa copulatrix. The elongate seminal receptacle also connects to the bursa copulatrix and the uterine duct that enters the female gland complex. The bursa copulatrix is ~ 3 × wider than the seminar receptable, but similar in volume (Fig. 15D ). No accessory gland was observed.

Radular formula 32 × 68.0.68 in a 25-mm long specimen (MNHN IM-2013-86198). Rachidian teeth absent. Inner and mid-lateral teeth hamate, having an elongate cusp (sometimes bifurcate) and lacking denticles (Fig. 16G-I ). Innermost teeth very small in comparison to mid-laterals (Fig. 16G ). The teeth increase in size gradually towards the medial portion of the half-row. Outermost teeth small, decreasing in size gradually, elongate, with a short cusp and numerous denticles (Fig. 13I ). No jaw was observed, labial cuticle smooth.

Biology.

Rare, found intertidally under rocks, possibly a New Caledonia endemic. The single specimen was obtained by brushing blocks of dead coral on the margin of a fringing reef flat.

Etymology.

This species is named after Sébastien Faninoz whose efforts were critical for the organization of the Koumac expeditions.

Remarks.

In the phylogenetic analyses conducted herein, Sclerodoris faninozi sp. nov. is sister to Sclerodoris tuberculata , the type species of Sclerodoris , forming a well-supported clade; for this reason, S. faninozi sp. nov. is placed in the genus Sclerodoris . Moreover, most of the anatomical characteristics of S. faninozi sp. nov. match the diagnosis of the genus Sclerodoris provided by Valdés and Gosliner (2001). Specifically, S. faninozi sp. nov. has a flattened, coriaceous dorsum covered with caryophyllidia, the rhinophoral sheaths are somewhat elevated; the penis is armed with hooks and the vagina is unarmed; the labial cuticle and radular teeth are smooth, hamate with the outermost lateral teeth multi-denticulate. The only exception is the accessory gland, which is a diagnostic trait for Sclerodoris , but was not observed in S. faninozi sp. nov. Although the absence of an accessory gland in S. faninozi sp. nov. could have been result of damage to the specimen, it appears that the presence of this organ is variable in Sclerodoris .

Sclerodoris faninozi sp. nov. is externally similar to Sclerodoris coriacea Eliot, 1904 introduced based on a specimen collected near Chwaka (as Chuaka), on the east coast of Zanzibar, Tanzania. Eliot (1904) described S. coriacea as yellowish brown in color with the dorsal surface covered with a "distinctly raised but somewhat irregular reticulate pattern." Rudman (1978) redescribed S. coriacea also based on specimens from Zanzibar, and a color photograph of a live animal was illustrated by Gosliner et al. (2018). The specimen of S. faninozi sp. nov. here examined is similar to all these descriptions with the exception of the presence of a dorsal ridge, absent in S. coriacea . The radular morphology of S. faninozi sp. nov. is also similar to that of S. coriacea as described by Rudman (1978) but the innermost teeth of S. faninozi sp. nov. have a bifurcated cusp, whereas they are simple in S. coriacea ( Rudman 1978: fig. 13).

Figures

Figure 13. SEM of the radula of specimens of Rostanga poddubetskaiae sp. nov., MNHN IM- 2013 - 86205 A innermost teeth B mid-lateral teeth C outer lateral teeth.

Figure 14. Photographs of live animals of the genus Sclerodoris Eliot, 1904 A Sclerodoris tuberculata Eliot, 1904, MNHN IM- 2013 - 86197 on black background B-D " Sclerodoris " Sclerodoris dutertrei sp. nov., Holotype (MNHN IM- 2013 - 86193) on black background (B), MNHN IM- 2013 - 86195 on black background (C), MNHN IM- 2013 - 86194 on black background (D) E Sclerodoris faninozi sp. nov., Holotype (MNHN IM- 2013 - 86198) on black background.

Figure 15. Drawing of the reproductive system of specimens of the genus Sclerodoris Eliot, 1904 A-C Sclerodoris tuberculata Eliot, 1904, MNHN IM- 2013 - 86197, general view (A), detail of the bursa copulatrix and seminal receptable (B), penial spines (C) D-F Sclerodoris faninozi sp. nov., Holotype (MNHN IM- 2013 - 86198), general view (D), detail of the bursa copulatrix and seminal receptable (E), penial spines (F) G " Sclerodoris " Sclerodoris dutertrei sp. nov., MNHN IM- 2013 - 86193. Abbreviations: ag, accessory gland; am, ampulla; bc, bursa copulatrix; dd, deferent duct; fg, female gland complex; pr, prostate; sr, seminal receptacle; vg, vagina.

Figure 16. SEM of the radula of specimens of the genus Sclerodoris Eliot, 1904 A-C Sclerodoris tuberculata Eliot, 1904, MNHN IM- 2013 - 86197, innermost teeth (A), mid-lateral teeth (B), outer lateral teeth (C) D-F " Sclerodoris " Sclerodoris dutertrei sp. nov., MNHN IM- 2013 - 86195, innermost teeth (D), mid-lateral teeth (E), outer lateral teeth (F) G-I Sclerodoris faninozi sp. nov., Holotype (MNHN IM- 2013 - 86198), innermost teeth (G), mid-lateral teeth (H), outer lateral teeth (I).