Trapania rocheae Cetra & Roche, 2019

Cetra, Nicolás & Roche, Andrea, 2023, Nudibranchia (Mollusca: Gastropoda) from San Matías Gulf, Northern Argentine Patagonia, Zootaxa 5244 (5), pp. 455-473 : 462

Trapania rocheae Cetra & Roche, 2019

( Figures 4A , 5A, 5B )

Material examined. Holotype: Argentina: Río Negro , Balneario Las Grutas, one specimen, 8m, 04/2017 (MLPMa 14834, 9mm) . Additional material: Plataforma: one specimen, 12m, 03/2017; one specimen, 8 m, 01/02/2018.

Description. Length up to 12 mm, body elongated and smooth, pale white with brownish spots extending over the entire mantle, including gills and rhinophores. A white notal crest runs along the posterior dorsal area, from the base of the gills to the end of the tail. It has two pairs of dorsal processes, one on the rhinophores and the other on the gills. Short and conical oral tentacles. Rhinophores foliated with 13 leaves. Tripinnate gills, arranged in a semicircle around the anus ( Figure 4A ). Radular formula 32 x 0.1.0.1.0. (MLP-Ma 14834). Lateral teeth are rectangular, with eight large denticles and between each of these there are three to six smaller denticles. External cusp of each lateral tooth more elongated and robust. Masticatory armature composed of plates. Masticatory edge slightly curved with denticles that decrease in size towards the interior of the plates ( Figure 5A, 5B ).

Geographic distribution and depth range. Only known from Balneario Las Grutas (40°49.291'S; 065° 04.498'W), Río Negro , Argentina ( Cetra & Roche 2019). Found on rocky bottoms between four and 12 m depth .

Remarks. This species has been recently described (see Cetra & Roche 2019). The family Goniodorididae has two species in the Argentine Sea, Ancula fuegiensis Odhner, 1926 and Trapania rocheae . The first one lacks records in the Argentine Sea since its original description by Odhner (1926) from Ushuaia, being recorded in the Chilean Pacific by Fischer and Ortea (1996) and Schrödl (2003). Both species have a similar coloration pattern differing in the location of the spots that, in A. fuegiensis , are found only on the dorsum around the gills, while in T. rocheae the spots extend throughout the body including rhinophores, digitiform processes and gills. The radulae are also different, A. fuegiensis presents marginal teeth, which are absent in the genus Trapania .

Figures

FIGURE 4. (A) Trapania rocheae, (B) Cadlina sparsa, (C) Polycera marplatensis, (D) egg mass of Polycera marplatensis, (E) Spurilla braziliana, (F) egg mass of Spurilla braziliana, (G-F) Aeolidia cf. campbellii photo by Nicolás Battini.

FIGURE 5. Scanning electron micrographs. (A–B) Trapania rocheae (MLP-Ma 14834), (A) radular teeth, (B) jaw, detail of the masticatory border. (C-D) Cadlina sparsa (MLP-Ma 14658), (C) radular teeth, (D) detail of the lateral teeth. (E–F) Polycera marplatensis (MLP-Ma 14661), (E) radular teeth, (F) detail of the lateral teeth. (G) Aeolidia cf. campbellii (MLP-Ma 14575): radular teeth. (H) Spurilla braziliana (MLP-Ma 14659): radular teeth.