Pseudodiala puncturina, Santos, Franklin Noel Dos & Absalão, Ricardo Silva, 2006

Santos, Franklin Noel Dos & Absalão, Ricardo Silva, 2006, A new genus of Barleeidae Gray, 1857 (Mollusca, Gastropoda) and the first occurrence of the genus Pseudodiala Ponder, 1967 off the Brazilian coast, Zootaxa 1232, pp. 59-68 : 65-68

Pseudodiala puncturina new species

( Figs. 12–18 )

Description

Shell conical­elongated, solid, whorls variously convex, opaque. Protoconch paucispiral with 7–8 spiral cords, axial cordlets originating from these cords. Pits irregularly over entire protoconch. Teleoconch without pits, with subsutural shallow furrow. Aperture subcircular, slightly opistocline. Lip thickened. Umbilicus absent.

Operculum oval, solid, red, with sulcus along inner edge, strong longitudinal rib near columellar edge. Peg at posterior part of longitudinal rib extending beyond its inner edge.

m.

Dimensions

Holotype with 3.5 teleoconch whorls; height: 2.0 mm; width 1.0 mm.

Type­material

Holotype: MNRJ 10502. Paratypes, 1: IBUFRJ 14697, Bacia Potiguar — Petrobras sta.6, 4 º52’48,904" S 36º17’43,199" W, 16 m, 30.vii.2002 [1]; paratype 2: MZSP 55459, Bacia Potiguar — Petrobras sta.14, 04 º47’18,161" S 36º29’20,275" W, 12 m, 28.vii.2002 [3]; paratype 3: MORG 50448, Bacia Potiguar — Petrobras sta.15, 4 °52’52,312" S 36°29’31,517" W, 12 m, 29.vii.2002 [3]; paratype 4: MNHN, MD55 Seamounts, [1]; paratype 5: DOUFPE 5023, REVIZEE Nordeste IV sta.130A, 3º342 S 38º181 W, 14.xi. 2000, 70 m, [1]; IBUFRJ 14737 Revizee Central sta.24, 20 º21.10’ S, 036º38.04’ W, 55 m, 13.vii.2001, [5]; IBUFRJ 12039, Atol das Rocas Island, northeastern Brazil [21]; IBUFRJ 14738, REVIZEE Central sta. C64 Banco Abrolhos, 19º17’42” S, 038º42’02” W, 63 m, 25.iv.1996, [1].

Distribution

Espírito Santo State, Southeast of Brazil.

Etymology

puncturina from Latin punctura = hole, suffix ­ ina f. dim., which means with small holes, referring to the tiny pits on the protoconch.

Discussion

The specimens studied have a smooth teleoconch (without pits even under high magnification), which distinguishes them from Caelatura , Fictonoba , Lirobarleeia , and Tropidorissoia . They have spiral cords on the protoconch, which distinguishes them from Barleeia . The presence of pits irregularly distributed over the protoconch, together with the smaller size, separates them from Protobarleeia .

The degree of convexity of the whorls is quite variable in P. puncturina ; similar variability occurs in P. corollaria ( Gofas, 1995: 25, fig. 21).

In the Atlantic basin, P. puncturina can be distinguished from P. n i s o Gofas, 1995 by the presence of pits on the protoconch. Pseudodiala aequinoctialis Gofas, 1995 has a keeled protoconch and a distinct umbilicus; both characters are absent in P. puncturina . Pseudodiala corollaria shows pits arranged in spiral rows on the protoconch while in P. puncturina those pits are randomly distribution over both protoconch and teleoconch. The reddish colour of the operculum is typical for Barleeidae . The operculum has a characteristic sulcus bordering its inner side.

Apparently Pseudodiala is distributed over almost the entire Atlantic Ocean, since its type species ( P. acuta ) is from Eastern North America, while P. niso , P. aequinoctialis , and P. corollaria occur along the North­West African coast. Pseudodiala puncturina is the first member of the genus known from the southwestern Atlantic.

Figures

FIGURES 12 – 18. Pseudodiala puncturina n. sp. ­ 12: holotype (MNRJ 10502), length 2.0 mm; 13: paratype (IBUFRJ 14697) lenght 2.0 mm; 14: aperture of holotype; 15: detail of microsculpture of the protoconch; 16: operculum; 17: protoconch of holotype; 18: detail of sculpture of the protoconch of holotype. Scale bar: 12 – 13: 200 m; 14: 200 m; 15: 5 m; 16 – 17: 50 m; 18: 10