Ancistrobasis costulata ( Watson, 1879 )

Salvador, Rodrigo B., Cavallari, Daniel C. & Simone, Luiz R. L., 2014, Seguenziidae (Gastropoda: Vetigastropoda) from SE Brazil collected by the Marion Dufresne (MD 55) expedition, Zootaxa 3878 (6), pp. 536-550 : 537

Ancistrobasis costulata ( Watson, 1879)

( Figs. 1–3 )

Basilissa costulata Watson, 1879: 600 .

Basilissa (Ancistrobasis) costulata: Abbott, 1974: 37 .

Ancistrobasis costulata: Quinn, 1983b: 729 ; Benkendorfer & Soares-Gomes, 2009: 151; Rios, 2009: 72 (textfig.); Rosenberg et al., 2009: 622.

Ancistrobasis reticulata: Gofas et al., 2001: 184 .

Type locality: The three juvenile syntypes ( Watson 1879) stem from the H.M.S. Challenger Expedition Station 24 (25/iii/1873), off Culebra Island ( Puerto Rico) and St. Thomas ( United States Virgin Islands), ca. 710 m of depth.

Distribution: From Georgia, USA, to southern Brazil, ca. 27–1170 m depth ( Rios 2009; Rosenberg et al. 2009). Records in Brazil: Rio de Janeiro, off Cabo Frio, 70 m, and off Rasa Island, 120 m; São Paulo, off Santos, 150 m; Rio Grande do Sul, off Tramandaí, 150 m ( Rios 2009).

New occurrence: Off Espírito Santo, 250–940 m depth.

Description: Shell small, conical, relatively thick-walled. Color homogeneous white to beige, often with diffuse, darker blotches. Protoconch (~1 whorl) rounded, with pitted surface; transition visible as orthocline suture. Teleoconch sculpture (except whorl base) consisting of reticulate pattern of axial and spiral cords, with marked angular nodules at intersections. Base of body whorl sculptured by numerous (8–10) spiral ribs, which may be ornamented by nodules near umbilical periphery and peristome. Whorls slightly convex. Suture deep, well-marked. Aperture quadrangular, with strong columellar and strong basal teeth. Umbilicus wide, deep; umbilical crenae nodulose, well-marked, but not too strong.

Measurements (in mm): 6–6½ whorls, H = 4.4 ± 0.3, D = 5.9 ± 0.5, h = 1.6 ± 0.2, d = 2.4 ± 0.3.

Material examined: Brazil: Espírito Santo: off São Mateus, continental slope of Abrolhos, 18°59’S 37°50’W, 295 m, MNHN, 8 shells, MZSP 116288, 2 shells (MD55, sta. DC75, 27/v/1987); 18°59’S 37°48’W, 607–620 m, MNHN, 9 shells, MZSP 116289, 4 shells (MD55, sta. DC73, 27/v/1987); 19°40’S 37°48’W, 790–940 m, MNHN, 1 shell (MD55, sta. CB77, 27/v/1987); Montague Bank, 20°26’S 36°41’W, 525–600 m, MNHN, 1 shell (MD55, sta. DC28, 14/v/1987); Columbia Bank, 20°44’S 32°08’W, 250–300 m, MNHN, 1 shell (MD55, sta. DC48, 19/v/1987).

Remarks: The present specimens compare well to Ancistrobasis costulata from the North Atlantic. Previous Brazilian records are from Rio de Janeiro, São Paulo and Rio Grande do Sul states ( Rios 2009). The present records expand the known distribution of this species in Brazil ca. 450 km northward to Espírito Santo state. Ancistrobasis costulata has lately (e.g., Rosenberg 2013) been considered to represent a synonym of A. reticulata ( Philippi, 1844) , a species originally described from fossil material from the Pliocene of Italy ( Philippi 1844; Quinn 1983b). We consider that simply synonymizing these species without a thorough revision of both fossil and recent taxa, is problematic and, thus, we prefer a more conservative classification of the present material.

Figures

FIGURES 1 – 6. Ancistrobasis and Carenzia from the MD 55 expedition. 1 – 3. Ancistrobasis costulata from Espírito Santo; 1. MNHN (MD 55 sta DC 75, H = 4.0 mm), apertural view; 2. MNHN (MD 55 sta DC 73), protoconch detail under SEM (scale bar = 0.1 mm); 3. Same, lateral view under SEM (H = 2.8 mm). 4 – 6. Carenzia carinata from Espírito Santo; 4. MNHN (MD 55 sta DC 70), apertural view (H = 2.0 mm); 5. Same, apical view under SEM (D = 3.5 mm); 6. Same, protoconch detail under SEM (scale bar = 0.1 mm).