Argeneuthria paessleri ( Strebel, 1905 ) Strebel, 1905

Pastorino, Guido, 2016, Revision of the genera Pareuthria Strebel, 1905, Glypteuthria Strebel, 1905 and Meteuthria Thiele, 1912 (Gastropoda: Buccinulidae) with the description of three new genera and two new species from Southwestern Atlantic waters, Zootaxa 4179 (3), pp. 301-344 : 328-330

Argeneuthria paessleri ( Strebel, 1905) new comb.

Figures 19 A–J, 20A–C

Euthria paessleri Strebel, 1905: 625 , pl. 21, figs. 9, 9 a, b.

Paraeuthria paessleri ( Strebel, 1905) . Castellanos, 1992: 18, pl. 1, fig. 5. Pareuthria paessleri ( Strebel, 1905) . Rosenfeld et al., 2015: 73, fig. 6C.

Type material. Lost? Not found in ZHM where most of Strebel’s material is housed.

Type locality. Strebel mentioned several localities all around Tierra del Fuego, i.e. Smyth Channel; Hope Harbour , 6 fms. [10.9 m] depth; Ushuaia, 12-25 fms. [21.9–45.7 m] depth; Puerto Eugenia in 10–15 fms. [18.2– 27.4 m] depth and Strait of Le Maire.

Description. Shell small, less than 10 mm in height, fusiform, of 6 flat whorls; protoconch ( Figs 19 G, H) of 2 1/2 slightly convex, smooth whorls, transition to teleoconch not clearly defined; suture impressed; aperture suboval, siphonal canal deep, short; parietal callus very thin; growth lines, faint, all over the shell; spiral ornamentation, of 8 to 9 furrows on the base of the last whorl ( Fig. 19 D); shell color reddish, brownish, outside and inside; operculum shape oval, subterminal nucleus ( Fig. 19 J). Radula ( Figs 20 A–C) very similar to that of A. cerealis . Tricuspid, rectangular rachidian teeth, with all cusps of the same size somewhat protruding, base of the rachidian curved; lateral teeth Prosipho- like, with 3 cusps, innermost smaller, externals curved, pointing towards the rachidian, outermost bifid.

Penis ( Fig. 19 I) cylindrical, flattish, with a small papilla rising from inside a depression.

Material examined. 24 shells, 4 km South of Punta Desengaño, San Julián , Santa Cruz, (MACN-In 36930); 1 spm., 52°44’S, 67°42’W, 40/ 49 m depth, RV ELTANIN, St. 981, ( USNM 870542 ) ; 4 shells, 53°42’S, 66°19’W, 81 m depth, RV ELTANIN, St. 967, (USNM 870487); 1 shell, 53°06’S, 67°04’W, 86 m depth, RV HERO, St. 450, (USNM 898478); 2 spms., Ushuaia , Tierra del Fuego, ( MLP 4963-4 ) ; 3 spms., 54º51.596’S, 68º31.618’W, Tierra del Fuego, 25 m depth, (MACN-In 40529); 2 spms., Punta Oriental, Ushuaia, 3 m depth, (MACN-In 40530); 19 spms., Ushuaia, (MACN-In 40531).

Distribution. Known only from Tierra del Fuego Is.

Remarks. A. paessleri is very similar to A. cerealis . The presence of the spiral furrows on the base of last whorl constitutes the main difference. In addition, there are some minor details of the radula that could be of diagnostic value, i.e. a bifid vs. simple external cusp on the lateral teeth, more curved base of rachidian and protruding cusps of rachidian. Also the protoconch of A. paessleri is more globose than A. cerealis . Very few lots of these species were available to understand their variation. Additional material may indicate that these two species are synonyms.

Linse (2002: 105, pl. 13, figs. 9.1.1 102–104) reported material with a tricuspid rachidian tooth and multicuspid lateral teeth as Pareuthria cf. paessleri . This radula is very different from P. paessleri and probably belongs in a different undescribed genus.

Figures

FIGURE 19. Argeneuthria paessleri (Strebel, 1905). A – D. MACN-In 40539, Ushuaia. E – F. MACN-In 36930; scale bar = 5 mm. G – H. Two views of the protoconch, scale bar = 500 µm. I. Penis, critical point dried, scale bar = 200 µm. J. External view of the operculum, scale bar = 50 µm.

FIGURE 20. Argeneuthria paessleri (Strebel, 1905). A – C. Three views of the radula, scale bars: A = 10 µm; B = 10 µm; C = 50 µm.