Pareuthria venustula Powell, 1951

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 : 312

Pareuthria venustula Powell, 1951

Figures 5 A–K, 6A–H, 7A–D

Pareuthria venustula Powell, 1951: 134 , pl. 6, fig. 17.

? Pareuthria ringei ( Strebel, 1905) . Forcelli, 2000: 96, fig.

Type material. [ Pareuthria venustula ] holotype NHMUK 1661491, paratype ANSP 235420.

Type locality. Between Cape Horn and Staten Is., 56°19.5’S, 67°09’W, 121 m depth, St. 388 DISCOVERY expedition.

Description. Shell medium size, up to 25 mm in height, fusiform, of 6½ convex whorls; translucent, color pinkish or reddish over axial varices, dirty, chalky whitish over whole shell, interior white; protoconch ( Figs 6 A, C) of 2½ convex whorls, translucent, smooth, transition to teleoconch visible; suture impressed; short subsutural ramp weak but present, producing a subquadrate profile more evident on the last whorl of mature specimens; aperture elliptic with the posterior angle acute, outer lip thin and sharp, reflected; siphonal canal wide and short; parietal callus very thin; growth lines close spaced over the entire shell; axial ornamentation of irregularly disposed and sinuous growth lines; some specimens with 10 to 14 irregularly spaced varices per whorl; spiral ornamentation of very delicate lirae ( Figs 6 F–H), 16 to 18 on the spire and about 50 on the last whorl; periostracum worn. Operculum ( Fig. 6 B) brown, elliptic; nucleus subterminal, internal thick rim; attachment area ovate, small.

Radula ( Figs 7 A–D) rachiglossate, central tooth with three cusps, the central cusp larger, base strongly curved; lateral teeth with two curved, hook-shaped cusps, inner smaller, external larger with a lateral indentation where same cusp of the anterior row stands.

Penis ( Figs 6 D–E) as in the type species, however appears to be more rounded, with a shorter papilla and circular margin tip.

Material examined. 2 spms., 54°4'12"S, 63°34'48"W, 247–293 m depth, RV ELTANIN, St. 369, Cr. 6, (USNM 881887); 3 spms., 54°37.91’S, 63°59.22’W– 54°38.17’S, 63°58.37’W, 120 m depth, collected with Rauchert dredge, (MACN-In 40511); 7 spms., 37°58.651´S, 55°9.104´W, Station 5, 528 m depth, (MACN-In 40512); 2 spms., 37º59.647’S, 55º10.010’W, Station 6, 517 m depth, (MACN-In 40513), both of Talud Continental expedition on board RV PUERTO DESEADO, collected with bottom trawl; 2 spms. with no precise locality collected by fisherman off Buenos Aires province (ex F. Scarabino), (MACN-In 40514); 3 shells, 54°35.902’S, 62°51.319’W, 608 m depth, with bottom trawl, (MACN-In 40515).

Distribution. Known from Cape Horn, Burdwood bank and Staten Island area. New records from deep waters (517 to 528 m depth) off Buenos Aires province extends considerably the range of the species.

Remarks. The original description was based on only one complete specimen and several empty shells with no axial ornamentation. However, shells with a variable number of varices are common. It is similar to some specimens of P. atrata that lack varices, however the particular lirae are thinner and weaker on Powell’s species. In addition, the protoconch is globose and larger in P. at r at a. Forcelli (2000: 96, fig.) illustrated what appears to be this species under the name P. r i ng e i ( Strebel, 1905).

Figures

FIGURE 5. Pareuthria venustula Powell, 1951. A – C. holotype, NHMUK 1661491, between Cape Horn and Staten Is., 56 ° 19.5 ’ S, 67 ° 09 ’ W, St. 388 DISCOVERY expedition. D – E. MACN-In 40515; F – G. MACN-In 40515. H – I. Paratype, ANSP 235420. J. MACN-In 40514. K. MACN-In 40512. Scale bar = 1 cm.

FIGURE 6. Pareuthria venustula Powell, 1951. A. Protoconch, MACN-In 40514, scale bar = 1 mm. B. Internal and external view of operculum, scale bar = 1 mm. C. Protoconch, MACN-In 40515, scale bar = 1 mm. D. Penis, critical point dried, scale bar = 1 mm. E. Detail of the penial papilla, critical point dried, scale bar = 200 µm. F. Spiral ornamentation of the specimen in A, scale bar = 1 mm. G. Detail of the same specimen, scale bar = 500 µm. H. Detail of the spiral ornamentation of fig. C, scale bar = 500 µm.

FIGURE 7. Pareuthria venustula Powell, 1951, radular variation. A. Radula, MACN-In 40514, specimen in fig. 5 J, scale bar = 100 µm. B. Radula, MACN-In 40511, scale bar = 100 µm. C, D. Radula, MACN-In 40512, scale bar. C = 50 µm, D = 200 µm.