Gymnodoris knutsonae 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 : 54

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

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( Figs. 12I–K , 13A–B , 14A–B )

Type material. Holotype: New Caledonia: North Province: Koumac, Plateau Karembé ( 20°38.1'S, 164°16.8'E), 13 m depth [Koumac 2.1 Expedition, stn. KR203, sandy and muddy bottom with big rocks, corals, Alcyonacea, rarely individual hard corals], 3 Sep 2018, 8 mm preserved length (MNHN-IM-2019-26381, isolate JD60) . Paratypes: New Caledonia: North Province: Koumac, Plateau Karembé ( 20°38.1'S, 164°16.8'E), 13 m depth [Koumac 2.1 Expedition, stn. KR203, sandy and muddy bottom with big rocks, corals, Alcyonacea, rarely individual hard corals] , 3 Sep 2018, 1 specimen 6 mm preserved length (MNHN-IM-2019-26380, isolate JD53); 1 specimen 6 mm preserved length (MNHN-IM-2019-26382, isolate JD64).

Description. Body elongate, narrow, covered with numerous, large, rounded to conical tubercles ( Figs. 12I–K ). Velum, notal rim undifferentiated. Posterior end of foot tapering into blunt “tail.” Color translucent white, with interior organs visible as brown, white masses. Rhinophores bulbous, with 9–10 lamellae, translucent white. Gill with 8–11 short, bipinnated leaves, opaque white, arranged in close circle around anus. Foot narrower than notum, translucent white, oral tentacles blunt.

Radular formula 17 × 23.0. 23 in a 6 mm preserved length specimen (MNHN-IM-2019-26382). Innermost lateral teeth hook-shaped, with curved cusps ( Fig. 13A ). Other lateral teeth elongate with broad bases, straight, narrow cusps, becoming smaller towards outer edge of half-row ( Fig. 13B ).

Reproductive system with an elongate, straight ampulla, connecting to female gland complex, prostate ( Fig. 14A ). Prostate large, tubular, with two folds, narrowing into a highly convoluted, long deferent duct, opening into a common atrium with vagina. Vagina short, slightly curved, connecting into bursa copulatrix near seminal receptacle connection, with an inconspicuous swelling near the bursa copulatrix connection. Bursa copulatrix spherical, about 10 times as large as oval seminal receptacle. Penial spines curved to straight, elongate, with wide bases ( Fig. 14B ).

Phylogenetic position. Gymnodoris knutsonae sp. nov. is sister to Gymnodoris tuberculosa Knutson & Gosliner, 2014 (PP: 1, MLB: 77), and these two species are sister to Gymnodoris sp. G (PP: 1, MLB: 88) ( Fig. 1A ).

Etymology. Named in honor of Vanessa Knutson in recognition for her contributions to the taxonomy and phylogenetics of Gymnodoris . The phylogenetic trees produced for this paper are largely based on her previous work.

Remarks. Gymnodoris knutsonae sp. nov. is closely related and very similar in external appearance and radular morphology to Gymnodoris tuberculosa , however these two species are genetically distinct and recovered as different species in the species delimitation analysis. Also, the viscera of G. tuberculosa illustrated by Knutson & Gosliner (2014) appears to be more brightly orange than that of the specimens here examined ( Fig. 12I–K ), which is brown, but this could be due to geographic variation in diet, and it is not conclusive. However, there is a key difference between these two species in the reproductive anatomy: the vagina of G. tuberculosa exhibits a large swelling near its proximal end, while in G. knutsonae sp. nov. is almost imperceptible. Another similar species is Gymnodoris sp. G , which is also covered by large tubercles. As in the case of G. tuberculosa , G. sp. G and G. knutsonae sp. nov. are genetically distinct, but there is no internal anatomical data for G. sp. G for comparison.

Gymnodoris knutsonae sp. nov. appears to be endemic to New Caledonia, it was most likely reported from Poindimié by Hervé (2010) as Gymnodoris sp. 3 .

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 12. Gymnodoris sp. 15, Gymnodoris sp. 16, Gymnodoris sp. 34, Gymnodoris sp. 51, and Gymnodoris knutsonae sp. nov., photographs of live animals showing color variation. A. G. sp. 15, specimen from Nouméa, New Caledonia (MNHN-IM- 2019-26462, isolate JD86). B. G. sp. 16, specimen from Koumac, New Caledonia (MNHN-IM-2019-26430, isolate JD45). C. G. sp. 16, specimen from Koumac, New Caledonia (MNHN-IM-2019-26429, isolate JD34). D. G. sp. 34, specimen from Koumac, New Caledonia (MNHN-IM-2019-26453, isolate JD163). E. G. sp. 34, specimen from Nouméa, New Caledonia (MNHN-IM- 2019-26454, isolate JD145), photo Y. Thévenet. F. G. sp. 34, specimen from New Caledonia: Loyalty Is.: Ouvéa, (MNHN-IM- 2019-26517, isolate JD184). G. G. sp. 51, specimen from Nouméa, New Caledonia (MNHN-IM-2019-26481, isolate JD73). H. G. sp. 53, specimen from Nouméa, New Caledonia (MNHN-IM-2019-26414, isolate JD79). I. G. knutsonae sp. nov., paratype, Koumac, New Caledonia (MNHN-IM-2019-26382, isolate JD64). J. G. knutsonae sp. nov., paratype Koumac, New Caledonia (MNHN-IM-2019-26380, isolate JD53). K. G. knutsonae sp. nov., holotype, Koumac, New Caledonia (MNHN-IM-2019- 26381, isolate JD60).

FIGURE 13. Gymnodoris knutsonae sp. nov., Gymnodoris fleuroti sp. nov., and Gymnodoris mariefranceae sp. nov., scanning electron micrographs of the radulae. A–B. G. knutsonae sp. nov., paratype, Koumac, New Caledonia (MNHN-IM-2019-26380, isolate JD53), inner lateral teeth (A), outer lateral teeth (B). C. G. fleuroti sp. nov., holotype, Poum, New Caledonia (MNHN- IM-2019-26428, isolate JD113), half-row. D–E. G. mariefranceae sp. nov., paratype, Koumac, New Caledonia (MNHN-IM- 2019-2624, isolate JD16), inner lateral teeth (D), outer lateral teeth (E).

FIGURE 14. Gymnodoris knutsonae sp. nov., Gymnodoris fleuroti sp. nov., and Gymnodoris mariefranceae sp. nov., and Gymnodoris lebouteillerorum sp. nov., drawings of reproductive systems. A–B. G. knutsonae sp. nov., paratype, Koumac, New Caledonia (MNHN-IM-2019-26382, isolate JD64), general view of reproductive organs (A), penial spines (B). C–D. G. fleuroti sp. nov., holotype, Poum, New Caledonia (MNHN-IM-2019-26428, isolate JD113), general view of reproductive organs (C), penial spines (D). E–F. G. mariefranceae sp. nov., paratype, Koumac, New Caledonia (MNHN-IM-2019-26389, isolate JD20), general view of reproductive organs (E), penial spines (F). G–H. G. lebouteillerorum sp. nov., holotype, Koumac, New Caledonia (MNHN-IM-2019-26486, isolate JD66), general view of reproductive organs (G), penial spines (H).