Nudibranchia (Mollusca: Gastropoda) from San Matías Gulf, Northern Argentine Patagonia Cetra, Nicolás Roche, Andrea Zootaxa 2023 2023-02-22 5244 5 455 473 37DF6 d'Orbigny, 1837 d'Orbigny 1837 [151,539,151,177] Gastropoda Dorididae Doris Animalia Nudibranchia 3 458 Mollusca species fontainii  ( Figures 2A, 3A)   Material examined.  Argentina, San Matíasgulf, Caleta Los Hornitos, BENTOS 2008, two specimens(MLP-Ma 14653); Río Negro: Las Grutas, REDE 2009, one specimen,  15 m, 2011; San Antonio Este, Punta Villarino, five specimens( MACN 13367); San Matías gulf, one, three and seven specimens( MACN 21309, MACN 21310and MACN 21308, respectively).   Description. Length up to 70 mm, body oval, color varies from pale to dark yellow. Dorsal area covered by large tubercles that become smaller towards the edge of the mantle. Lamellate rhinophores, wide base and around 30 lamellae. Gill with 5-7 multipennate leaves around the anal papilla ( Figure 2A). Radular formula is 35 x 63.0.63 (MLP-Ma 14653). Lateral teeth curved without denticles ( Figure 3A).  Geographic distribution and depth range. Argentina, from San Antonio Cape ( Valdés & Muniain 2002); Arica,  Chile(Schrödl 2000) to Islote Ferrol ( 09°08′22″S; 78°37′15″W), Ancash,  Peru( Araya & Valdés 2016). Usuallyfound under rocks between six and  20 mdepth.   Remarks.  Doris fontainiiis easily recognizable due to its large size, the bright yellow color of its body and a mantle covered with conspicuous tubercles. Some of the examined specimens present dark brown pigment between the tubercles which Schrödl et al.(2005)described as a characteristic of central and northern Chilean specimens. 4035853326 REDE, MACN Argentina Las Grutas 15 San Matias Rio Negro 3 458 REDE 2009, MACN 13367, MACN 21309, MACN 21310, MACN 21308 4 4035853310 [231,1080,583,612] Chile -9.139444 Ancash 21 -78.620834 3 458 1 Ancash 4035853311 Peru 20 Usually 3 458 1