Argeneuthria cerealis Rochebrune & Mabille 1885, new comb.

Argeneuthria cerealis (Rochebrune & Mabille, 1885) new comb.

Figures 17 A–L, 18A–C

Euthria cerealis Rochebrune & Mabille, 1885: 100.

Euthria cerealis Rochebrune & Mabille, 1889: H.60, pl. 2, fig. 4.

Paraeuthria cerialis (Roch. y Mab., 1891). Castellanos, 1992: 18, pl. 1 fig. 4; Linse, 2002: 102, figs. 9.1.1–97/101. Pareuthria cerealis (Rochebrune & Mabille, 1885). Rosenfeld et al, 2015: 72, fig. 6A.

Type material. 29 spms., (MNHN 6844); 8 spms., (MNHN 6845); 10 spms., (MNHN 6846); 16 spms., (MNHN 6847); 14 spms., (MNHN 6848), all syntypes from Cape Horn Expedition.

Type locality. “ Terre de Feu ”; in 1889 the authors mentioned “ Baie Orange ”, Lapataia in 21 to 198 m depth [Tierra del Fuego].

Description. Shell small, around 10 mm in height, fusiform, of six flat whorls; protoconch of 2 1/2 flat or very weakly convex whorls, entirely smooth, transition to teleoconch weakly defined; suture impressed; aperture elliptic, usually with sharp lip, siphonal canal deep, short. Parietal callus very thin, well defined. Growth lines, faint, closely spaced over the entire shell. Shell color reddish, brownish, outside and inside.

Operculum (Fig. 17 E) shape elliptical, subterminal nucleus, attachment area surrounded by a thick rim.

Radula (Figs 18 A–C) with tricuspid, rectangular rachidian teeth, all cusps of the same size; base of rachidian slightly curved; lateral teeth Prosipho- like with the basal plate produced into a typical “handle” more than half the width of the tooth, with 3 cusps, innermost smaller, two externals curved, pointing towards the rachidian, outermost, simple and smaller.

Penis cylindrical, with a small papilla rising from a hole.

Material examined. 12 spms., 47°43’45.6”S, 65°50’17.7”W, Puerto Deseado, 15 m depth, (MACN-In 40535); 45 spms., Cabo Blanco, Santa Cruz, (MACN-In 17842); 2 spms., Puerto Deseado, (MACN-In 35274); 1 spm., 10 Km north of Cabo Curioso, Santa Cruz, (MACN-In 35039); 1 shell, Puerto San Julián, off the old Frigorífico, Santa Cruz, (MACN-In 40536); 6 shells, Baie Orange, Beagle Canal, (from Rochebrune & Mabille’s Cape Horn Expedition), (MACN-In 13915); 20 spms., Puerto Cook, Staten Is., (MACN-In 33772); 1 shell, 53°54’S, 67°18’W, 27 m depth, (USNM 898313); 2 spms., 53°59’04.3”S, 67°22’59.1”W, Estancia Viamonte, Tierra del Fuego, live collected during low tide, (MACN-In 40535); 1 spm. 54°17.647”S, 66°15.376”W to 54°17.346”S, 66°15.531”W, 56 m depth, with bottom trawl, CAV2014, St. 22/48 (MACN-In 40533); 20 spms., Ushuaia, (MACN-In 40534); 3 spms., Becasses Is., Ushuaia, (MACN-In 35214).

Distribution. Puerto San Julián, Santa Cruz to Ushuaia, Cape Horn, Tierra del Fuego and Staten Is.

Remarks: This species is hard to find, perhaps because of its small size. It is similar to A. paessleri; however, the shell is more slender and the aperture is smaller. A. cerealis lacks the distinctive spiral furrows at the base of the last whorl.