Polycera marplatensis Franceschi, 1928

Cetra, Nicolás & Roche, Andrea, 2023, Nudibranchia (Mollusca: Gastropoda) from San Matías Gulf, Northern Argentine Patagonia, Zootaxa 5244 (5), pp. 455-473 : 463

Polycera marplatensis Franceschi, 1928

( Figures 4C, 4D , 5E, 5F )

Material examined. Argentina, San Matías gulf: Plataforma, one specimen, 10 m, 21/01/2018; Isla, two specimens, 9 m, 30/03/2018 .

Description. Length up to 30 mm, body elongated, white with orange dorsal lines, laterally spotted with yellow. Nine unipinnate posterior dorsal gill leaves, surrounding the anal papilla. A pair of digitiform projections surrounding the gills. Rhinophores lamellate with 18-20 lamellae. 6-7 digitiform processes in the oral veil ( Figure 4C ). The radular formula is 14 x 4.2.0.2.4. (MLP-Ma 14661). Rachidian teeth absent. The lateral teeth are simple with a spur on the end, the first inner lateral teeth differ in shape from the second one, usually larger; marginal teeth reduced. Jaw with a winglike process ( Figure 5E, 5F ).

Geographic distribution and depth range. Brazil, S„o Paulo ( Rios 1975) and Argentina, Mar del Plata ( Franceschi 1928), Puerto Quequén ( Carcelles 1944) both in Buenos Aires Province; Punta Pardelas, Chubut, Argentina (as “Patagonia”) (42°36´S, 64° 16´W) ( Muniain & Ortea 1998) and Camarones Bay ( Schrödl 1996). Found on rocky bottoms between four and 25 m depth.

Biology. The white eggs masses are a slightly wavy ribbon with a full spiral turn. The egg mass is deposited on algae ( Figure 4D ).

Remarks. Franceschi (1928) described a Polycera marplatensis as a variation of the European species Polycera quadrilineata (M̧ller 1776). Muniain and Ortea (1998) reevaluated its taxonomic status considering Polycera marplatensis as a distinct species. These authors redescribed it with the reexamination of the type material from Mar del Plata and based on material collected in Nuevo gulf, Patagonia. In that redescription the authors argue that P. marplatensis differs from P. quadrilineata in the body coloration pattern, with the absence of black coloration on the mantle, the larger size of the mandibles and radula, and a greater number of digitiform projections on the mantle in P. marplatensis . Our observations of the specimens studied agree with the descriptions of the species P. marplatensis , recording it for the first time in the San Matías gulf.

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.