Gymnodoris cf. alba ( Bergh, 1877 )

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 : 40

Gymnodoris cf. alba ( Bergh, 1877)

( Figs. 8A–B )

Material examined. New Caledonia: North Province: Koumac, Ilôt Pouh ( 20°30.7'S, 164°07.1'E), 0 m depth [Koumac 2.3 Expedition, stn. KM714 ], 8 Nov 2019, 1 specimen 9 mm preserved length (MNHN-IM-2019-26421, isolate JD19); 1 specimen 12 mm preserved length (MNHN-IM-2019-26422, isolate JD38) .

Description. Body narrow, elongate, with numerous, low, conical tubercles, minute opaque white dots all over dorsum ( Figs. 8A–B ). Velum differentiated, with several small tubercles. Notal rim absent, velum merges with notum behind rhinophores. Posterior end of foot broad, flat, tapering abruptly near tip. Color translucent white, with orange tubercles with blurry edges, posterior end of foot with dorsal orange line of dots. Head surrounded by narrow orange line. Some internal organs visible through body wall. Rhinophores bulbous with narrow tips, 8 lamellae, brownish-grey clubs with orange tips. Gill with 10 short, bipinnate, translucent white to cream leaves with orange tips, opaque white bases, arranged in circle around anus. Foot narrower than notum, opaque white, except at posterior end.

Phylogenetic position. Gymnodoris cf. alba is sister to Gymnodoris sp. X (PP: 1, MLB: 98) and nested in a well-supported clade (PP: 1, MLB: 99) also including Gymnodoris bricei sp. nov. ( Fig. 1A ).

Remarks. The single specimen examined herein, together with a specimen in GenBank, was recovered as a distinct species that was not included in the phylogenetic analyses by Knutson & Gosliner (2022). The material here examined is very similar to specimens identified by Nakano (2018) and Rudman & Darvell (1990) as Gymnodoris alba , and could belong to the same species, but is probably different from the specimen identified as G. alba by Gosliner et al. (2018). The original description of G. alba by Bergh (1877) from Burias Is., Philippines, is vague and the only indication of the external coloration is a note by Semper stating: “color completely white with bright yellow spots.” Thus, in the absence of an in-depth revision of G. alba , it is not possible to determine the identity of this species name and/or of the specimen here examined.

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 8. Gymnodoris cf. alba (Bergh, 1877), Gymnodoris sp. AB, Gymnodoris sp. J, and Gymnodoris sp. M, photographs of live animals showing color variation. A. G. cf. alba, specimen from Koumac, New Caledonia (MNHN-IM-2019-26421, isolate JD19). B. G. cf. alba, specimen from Koumac, New Caledonia (MNHN-IM-2019-26422, isolate JD38). C. G. sp. AB, specimen from Koumac, New Caledonia (MNHN-IM-2019-26506, isolate JD62). D. G. sp. AB, specimen from Koumac, New Caledonia (MNHN-IM-2019-26501, isolate JD61). E. G. sp. J, specimen from Koumac, New Caledonia (MNHN-IM-2019-26415, isolate JD08). F. G. sp. J, specimen from Nouméa, New Caledonia (MNHN-IM-2019-26416, isolate JD91). G. G. sp. J, specimen from Poum, New Caledonia (MNHN-IM-2019-26417, isolate JD124). H. G. sp. M, specimen from Koumac, New Caledonia (MNHN-IM-2019-26482, isolate JD65). I. G. sp. M, specimen from Poum, New Caledonia (MNHN-IM-2019-26483, isolate JD110). J. G. sp. M, specimen from Poum, New Caledonia (MNHN-IM-2019-26485, isolate JD98). K. G. sp. M, specimen from New Caledonia: Loyalty Is.: Ouvéa, (MNHN-IM-2019-26484, isolate JD161). L. G. sp. M, specimen from New Caledonia: Loyalty Is.: Ouvéa, (MNHN-IM-2019-26523, isolate JD185).