Gymnodoris fassioae De Souza-Canal & Valdés, 2025

Souza-Canal, Jade De & Valdés, Ángel, 2025, The genus Gymnodoris Stimpson, 1855 (Mollusca, Nudibranchia) in New Caledonia, with descriptions of eleven new species, Zootaxa 5710 (1), pp. 1-73 : 63-65

publication ID	https://doi.org/10.11646/zootaxa.5710.1.1
publication LSID	lsid:zoobank.org:pub:3A893C9C-17BF-43A0-84AF-6F8747C2ED45
DOI	https://doi.org/10.5281/zenodo.17883940
persistent identifier	https://treatment.plazi.org/id/352687AF-FFB1-A760-FF55-480FFD43FBA7
treatment provided by	Plazi
scientific name	Gymnodoris fassioae De Souza-Canal & Valdés
status	sp. nov.

Treatment

Gymnodoris fassioae De Souza-Canal & Valdés sp. nov.

urn:lsid:zoobank.org:act:

( Fig. 17H–I View FIGURE 17 , 18D View FIGURE 18 , 19C–E View FIGURE 19 )

Type material. Holotype: New Caledonia: North Province: Koumac, Passe Deverd ( 20°44.6'S, 164°15.7'E), 21 m depth [Koumac 2.1 Expedition, stn. KR623], 21 Sep 2018, 1 specimen 5 mm preserved length (MNHN-IM-2019- 26502, isolate JD24). GoogleMaps

Description. Body oval to elongate, with numerous, small conical to elongate tubercles of varying sizes. Notal rim distinct, with several larger tubercles than those on dorsum, velum absent, notal rim fuses into head forming a protuberance, edged by arch or small tubercles anterior to rhinophores ( Fig. 18D View FIGURE 18 ). Color translucent white, tubercles red with blurry edges; longitudinal lines of blurry red pigment joining some tubercles; posterior end of foot translucent grey with red tip. Internal organs visible through body wall as orange, white masses. Rhinophores very close together, bulbous, with 8 lamellae, stalk white, club red. Gill with 35 small, elongate, simple, translucent leaves with red tips, opaque white bases, arranged in circle around anus, opened posteriorly. Foot narrower than notum, opaque white. Oral tentacles small, blunt.

Radular formula 24 × 21.0. 21 in the 5 mm preserved length holotype (MNHN-IM-2019-26502). Innermost lateral teeth small, broad, irregular bases, with central curved cusp ( Fig. 19C View FIGURE 19 ). Other lateral teeth elongate, with broad bases, long, slightly curved cusps ( Fig. 19E View FIGURE 19 ).

Reproductive system with a large, broad, slightly curved ampulla, connecting to female gland complex, prostate ( Fig. 17H View FIGURE 17 ). Prostate tubular, curved around bursa copulatrix, narrowing into a highly convoluted deferent duct, opening into a common atrium with vagina. Vagina long, narrow, slightly curved, connecting into bursa copulatrix near seminal receptacle connection. Bursa copulatrix ovoid, about five times as large as spherical seminal receptacle. Penial spines slightly curved, elongate (about 80 µm long), with narrow bases ( Fig. 17I View FIGURE 17 ).

Phylogenetic position. Gymnodoris fassioae sp. nov. is sister to Gymnodoris sp. 18 (PP: 1, MLB: 99) but the position of these two species within the overall phylogeny of Gymnodoris remains unresolved ( Fig. 1A View FIGURE 1 ).

Etymology. This species is named in honor of Dr. Giulia Fassio in appreciation for her help and support during the expeditions to New Caledonia.

Remarks. Gymnodoris fassioae sp. nov. is externally similar in body shape to Gymnodoris inariensis Hamatani & Osumi, 2003 described from Kagoshima Bay, Japan. Both species have rhinophores very close to each other at the base, a well-defined notal rim, and an anterior protuberance instead of a velum. However, there are clear differences between the two species, for instance, G. inariensis lacks a gill, which is present in G. fassioae sp. nov., and G. inariensis is blackish with densely scattered, minute dark brown-black spots, whereas G. fassioae sp. nov. is translucent white, with red tubercles with blurry edges. No other species included in Knutson & Gosliner (2022) is similar externally or genetically to G. fassioae sp. nov.