Gymnodoris sp. 9

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 : 48-50

Gymnodoris sp. 9

( Figs. 11A–K )

Material examined. New Caledonia: North Province: Koumac, Ilôt Rat ( 20°33.4'S, 164°10.9'E), 0 m depth [ Koumac 2.1 Expedition, stn. KM200 , sand-mud flat with seagrass; reef flat, rocky shore with living/dead corals], 4 Sep 2018, 1 specimen 8 mm preserved length (MNHN-IM-2019-26394, isolate JD59). New Caledonia: North Province: Koumac, Infernet Reef ( 20°37.1'S, 164°15'E), 3 m depth [ Koumac 2.1 Expedition, stn. KR302, at the foot of the reef, sandy sediment with silt, coral debris, and seagrass], 7 Sep 2018, 1 specimen 5 mm preserved length (MNHN-IM-2019-26435, isolate JD70). New Caledonia: North Province: Koumac, Ilôt Kendec ( 20°40.1'S, 164°15.4'E), 0 m depth [ Koumac 2.1 Expedition, stn. KM302 , living corals, coral rubble, sand patches], 9 Sep 2018, 1 specimen 10 mm preserved length (MNHN-IM-2019-26395, isolate JD07). New Caledonia: South Province: Nouméa, Ilôt Song, Ouémo ( 22°16.91'S, 166°28.84'E), 1–6 m depth [Quinzaine des Nudibranches Expedition, stn. QNPF-DA, detrital sandy-muddy, live Porites ], 6 Sep 2022, 1 specimen 9 mm preserved length (MNHN-IM-2019-26396, isolate JD85). New Caledonia: South Province: Ouémo, Platier Ricaudy ( 22°18.67'S, 166°27.49'E), 0.5 m depth [Quinzaine des Nudibranches Expedition, stn. QNAV-FA], 4 Sep 2022, 1 specimen 6 mm preserved length (MNHN-IM-2019-26436, isolate JD131). New Caledonia: North Province: Poum , Mouac Is. ( 20°12.84'S, 164°0.61'E), 0 m depth [ABC Poum Expedition, stn. ABC46 ], 18 Jun 2023, 1 specimen 7 mm preserved length (MNHN-IM-2019-26434, isolate JD140). New Caledonia: North Province: Poum, Bay of the Grotte ( 20°2'S, 163°47.92'E), 0 m depth [ABC Poum Expedition, stn. ABC52 ], 19 Jun 2023, 1 specimen 7 mm preserved length (MNHN-IM-2019-26431, isolate JD122); 1 specimen 7 mm preserved length (MNHN-IM-2019-26432, isolate JD141). New Caledonia: North Province: Poum , Mouac Is. ( 20°13.02'S, 164°1.4'E), 0 m depth [ABC Poum Expedition, stn. ABC63 ], 21 Jun 2023, 1 specimen 9 mm preserved length (MNHN-IM-2019-26433, isolate JD99). New Caledonia: Loyalty Is.: Ouvéa, Pont de Mouly ( 20°41.91'S, 166°28.33'E) [Quinzaine des Nudibranches Ouvéa Expedition, stn. QUP63, night dive], 18 Jan 2024, 1 specimen 9 mm preserved length (MNHN-IM-2019-26516, isolate JD153). New Caledonia: South Province: Nouméa, Ilôt Song ( 22°16.91'S, 166°28.84'E), 10 m depth, 28 Jun 2022, 1 specimen 11 mm preserved length (MNHN-IM-2019-26518, isolate JD144), leg. Y. Thévenet.

Description. Body narrow, elongate, with numerous low, conical tubercles of varying sizes ( Figs. 11A–K ). Anterior end of notum with distinct velum having 15–18 small papillae; notal rim absent, velum merges with notum behind rhinophores. Posterior end of foot broad, tapering into pointy “tail.” Color translucent white, tubercles, velum papillae yellow-orange; posterior end translucent grey. Internal organs, posterior branched glandular structure visible through body wall. Rhinophores bulbous with narrow tips, 12–14 lamellae, cream, brow, or reddish, with apical orange-red dot. Gill with 8 short, irregular, bipinnate leaves, translucent white, sometimes with small orange dots, opaque white bases, arranged in circle around anus, opened posteriorly. Foot wider than notum, translucent yellow. Oral tentacles large, flap-like.

Phylogenetic position. Gymnodoris sp. 9 is the most basal member of a well-supported clade (PP: 1, MLB: 100) also including Gymnodoris alba and Gymnodoris sp. 49, which are sister to one another (PP: 1, MLB: 100) ( Fig. 1A ).

Remarks. This undescribed species is similar to G. citrina , both having the anterior margin of the head with a distinctive row of low tubercles, but the anterior end of the foot has two flap-like oral tentacles, instead of a well-developed but blunt oral tentacles in G. citrina . Moreover, G. citrina lacks a glandular structure behind the gill.

Gymnodoris sp. 9 appears to be widespread in the Indo-Pacific region ( Gosliner et al., 2018). Knutson & Gosliner (2022) studied specimens from Papua New Guinea, Vanuatu, and Saudi Arabia. Also, possibly reported from French Polynesia ( Boutet et al., 2020) as Gymnodoris sp. 2 , from Okinawa, Japan by Nakano (2018) as Gymnodoris sp. 17 and G. citrina (large photo), and from Hong Kong, China by Rudman & Darvell (1990: pl. 4, fig. C) as G. citrina atypical form. Very common in New Caledonia, it has possibly been reported from Nouméa by Hervé (2010) as Gymnodoris sp. 2 (small photo).

Figures

FIGURE 1. A. Bayesian consensus phylogenetic tree of the concatenated dataset including PP above branches and MLB below branches. Branches fully supported (PP: 1, MLB: 100) marked with asterisks. New species described in this paper highlighted in red font and illustrated; other species reported from New Caledonia in this study highlighted in blue font. Clades are collapsed according to the results of the ASAP and bPTP species delimitation analyses. B. Histogram representing the distance plot from the ASAP analysis using the COI gene showing pairwise p-distances (Kimura 2 model) among candidate species. The dashed line represents the distance threshold provided by the lowest ASAP score for species delimitation.

FIGURE 11. Gymnodoris sp. 9 and Gymnodoris sp. 14, photographs of live animals showing color variation. A. G. sp. 9, specimen from Koumac, New Caledonia (MNHN-IM-2019-26394, isolate JD59). B. G. sp. 9, specimen from Koumac, New Caledonia (MNHN-IM-2019-26395, isolate JD07). C. G. sp. 9, specimen from Koumac, New Caledonia (MNHN-IM-2019- 26435, isolate JD70). D. G. sp. 9, specimen from Nouméa, New Caledonia (MNHN-IM-2019-26396, isolate JD85). E. G. sp. 9, specimen from Nouméa, New Caledonia (MNHN-IM-2019-26436, isolate JD131). F. G. sp. 9, specimen from Poum, New Caledonia (MNHN-IM-2019-26434, isolate JD140). G. G. sp. 9, specimen from Poum, New Caledonia (MNHN-IM-2019- 26431, isolate JD122). H. G. sp. 9, specimen from Poum, New Caledonia (MNHN-IM-2019-26432, isolate JD141). I. G. sp. 9, specimen from Poum, New Caledonia (MNHN-IM-2019-26433, isolate JD99). J. G. sp. 9, Specimen from New Caledonia: Loyalty Is.: Ouvéa, (MNHN-IM-2019-26516, isolate JD153). K. G. sp. 9, specimen from Nouméa, New Caledonia (MNHN- IM-2019-26518, isolate JD144), photo Y. Thévenet. L. G. sp. 14, specimen from Touho, New Caledonia (MNHN-IM-2019- 26459, isolate JD151), photo A. Doulas. M. G. sp. 14, specimen from Nouméa, New Caledonia (MNHN-IM-2019-26458, isolate JD143), photo A. Doulas. N. G. sp. 14, specimen from New Caledonia: Loyalty Is.: Ouvéa, (MNHN-IM-2019-26457, isolate JD169).