Gymnodoris boussionae De Souza-Canal et al., 2025

Gymnodoris boussionae De Souza-Canal et al., 2025

( Figs. 7D–L View FIGURE 7 )

Gymnodoris boussionae De Souza-Canal et al., 2025: 323–324 View Cited Treatment , figs. 2C–J, 3C–D, 4C–D. Type locality: East of Karembé , Koumac, New Caledonia.

Material examined. Holotype: New Caledonia: North Province: Koumac, East of Karembé ( 20°39.1'S, 164°17.6'E), 6 m depth [Koumac 2.1 Expedition, stn. KR633, species diverse sandy bottom], 26 Sep 2018, 1 specimen 10 mm preserved length ( MNHN IM-2019-26206 , isolate JD41). New Caledonia: North Province: Koumac , Reef of Infernet ( 20°36.7'S, 164°14,7'E), 5 m depth [Koumac 2.1 Expedition, stn. KR301], 6 Sep 2018, 1 specimen 7 mm preserved length, dissected ( MNHN IM-2019-26203 , isolate JD35). New Caledonia: North Province: Koumac , East of Karembé ( 20°39.6'S, 164°17.5'E), 2–5 m depth [Koumac 2.1 Expedition, stn. KR636, sandy bottom], 27 Sep 2018, 1 specimen 7 mm preserved length ( MNHN IM-2019-26204 , isolate JD23); 1 specimen 11 mm preserved length ( MNHN IM-2019-26200 , isolate JD43); 1 specimen 11 mm preserved length ( MNHN IM-2019- 26207 , isolate JD44); 1 specimen 5 mm preserved length ( MNHN IM-2019-26202 , isolate JD68); 1 specimen 9 mm preserved length ( MNHN IM-2019-26205 , isolate JD39). New Caledonia: North Province: Koumac ( 20°38.4'S, 164°16.5'E) [Koumac 2.2 Expedition, stn. KR252], 28 Feb 2019, 1 specimen 6 mm preserved length, dissected ( MNHN IM-2019-26199 , isolate JD51). New Caledonia: North Province: Koumac ( 20°33.3'S, 164°12.7'E), 4 m depth [Koumac 2.3 Expedition, stn. KR906, sandy bottom with Halophila , scattered coral colonies, hard bottom with Sargassum ], 4 Nov 2019, 1 specimen 8 mm preserved length ( MNHN IM-2019-26201 , isolate JD10). New Caledonia: North Province: Poum , Ouanne ( 20°20.73'S, 164°1.22'E), 0 m depth [ABC Poum Expedition, stn. ABC04, plateau slope], 11 Jun 2023, 1 specimen 4 mm preserved length (MNHN-IM-2019-26524, isolate JD114). GoogleMaps

Description. Body elongate, smooth, lacking tubercles ( Figs. 2D–L View FIGURE 2 ). Velum, notal rim slightly differentiated, smooth. Posterior end of foot tapering into narrow “tail.” Body color velvet black, with blurry neon-blue lines visible on mantle margin under certain light conditions. Rhinophores and branchial leaves with same color as dorsum. Rhinophores short, triangular, not fused together at base. Rhinophoral club occupying entire visible length, with transverse 10 lamellae. Gill composed of 16–19 simple leaves, arranged in a circle. Foot wider than notum; oral tentacles elongate, blunt lobes.

Phylogenetic position. Gymnodoris boussionae could be sister to a clade containing other species with a uniformly black body color: Gymnodoris nigricolor and G. nagoensis but this relationship is not supported (PP: 1, MLB: <50) ( Fig. 1A View FIGURE 1 ).

Remarks. Reported from Nouméa by Hervé (2010) as Gymnodoris nigricolor and recently described and characterized by De Souza-Canal et al. (2025) as a distinct species. The main external difference between G. boussionae and G. nigricolor is that in the former the rhinophores are separated whereas in the latter they are fussed together at their bases (see De Souza-Canal et al., 2025).

Unnamed species. The following undescribed species have been recorded from New Caledonia in this study, but also reported from other areas of the tropical Indo-Pacific by Knutson & Gosliner (2022) and not formally described yet. The material examined from New Caledonia was matched with the candidate species in Knutson & Gosliner (2022) using molecular data only. These species are listed below along with descriptions of the external morphology of New Caledonia specimens. To avoid confusion, we denote the species with the same codes used by Knutson & Gosliner (2022).