Bittium, Gray, 1847

Sacchetti, Claudia, Landau, Bernard & Ávila, Sérgio P., 2023, The Lower Pliocene marine gastropods of Santa Maria Island, Azores: Taxonomy and palaeobiogeographic implications, Zootaxa 5295 (1), pp. 1-150 : 32-33

Bittium an nov. sp.?

Plate 1 L 1 -L 2 , M 1 -M 2

Santa Maria material examined. Maximum height 4.5 mm, width 1.8 mm. DBUA-F 488-2 (29), Ponta do Castelo, Santa Maria Island, Azores, Touril Complex, Lower Pliocene.

Description. Shell small, turriculate, with tall, slender spire, apical angle about 33°. Protoconch not preserved. Teleoconch of nine weakly convex whorls, initially slightly cyrtoconoid in profile, separated by a narrow, moderately impressed, undulating suture. Sculpture of broad rounded, slightly opisthocline to orthocline ribs, about seven on penultimate whorl, extending between suture and weakly crenulating abapical suture. Last two whorls with one or two varices per whorl. Spiral sculpture weak, on early whorls three broad flattened cords separated by narrow grooves. Spiral sculpture weakens on fourth whorl, subobsolete on last three whorls. Axial sculpture predominant, without tubercles produced at intersections. Last whorl convex, moderately constricted at base, bearing a spiral cord at the level of the insertion of the outer lip, a peribasal cord of similar strength, and three weaker basal cords. Aperture ovate, features obscured by matrix.

Discussion. Bittium an nov. sp. is clearly similar to B. miradouroense nov. sp. but differs in having a wider apical angle (33° vs. 23°) and fewer axial ribs (7 vs. 12). The character of the spiral sculpture seems to be similar, slightly stronger on early whorls and both species have two spiral cords delimiting the base. However, comparison is hampered by the form of preservation: the specimen of Bittium an nov. sp. is somewhat decorticated, whereas the fossils of B. miradouroense are calcitic pseudomorphs. Nevertheless, the wider apical angle and the small number of ribs seem to be constant characters separating the two. As discussed under B. miradouroense , the shells of these two species are not particularly similar to any other Neogene or extant European species.

Distribution. Lower Pliocene: Atlantic, Santa Maria Island, Azores (this paper).

Figures

PLATE 1. A. Danilia pterostomus (Bronn, 1861), height 5.0 mm, width 4.0 mm, Forno da Cré (figure taken from Bronn in Hartung, 1861, pl. 19, fig. 2). B1-B2. Emarginula octaviana Coen, 1939, DBUA-F 487-1, height 1.8 mm, diameter 3.0 mm, Ponta do Castelo. C. Bolma cf. rugosa (Linné, 1767), DBUA-F 471-3, diameter 4.1 mm, Ponta do Castelo. D1-D5. Turbo hartungi Bronn 1861, DBUA-F 1295-1, height 9.0 mm, width 8.0 mm, Malbusca (east cave). E1-E3. Nerita cf. funata Dujardin, 1837, DBUA-F 917-1, height 4.0 mm, width 6.0 mm, Ponta do Castelo. F1-F2. Thericium crenulosum (Bronn, 1862), height 10.0 mm, width 6.0 mm, Ponta do Norte lighthouse, LNEG collection (unnumbered). G1-G2. Thericium hartungi (Mayer, 1862), height 29.0 mm, width 13.0 mm, Pinheiros (figure taken from Bronn in Reiss, 1862, pl. 1, fig. 11). H1-H2. Thericium incultum (Mayer, 1862), DBUA-F 1034-2, height 23.0 mm, width 10.0 mm, Macela viewpoint. I1-I2. Thericium incultum (Mayer, 1862), DBUA-F 1027-1, height 29.0 mm, width 11.0 mm, Malbusca II. J1-J2, K1-K2. Bittium miradouroense nov. sp., Holotype DBUAF 1034-5, height 6.8 mm, width 1.9 mm (J); Paratype DBUA-F 1034-6(1), height 5.3 mm, width 1.9 mm (K), Macela viewpoint. L1-L2, M1-M2. Bittium nov. sp., DBUA-F 488-2, height 4.5 mm, width 1.8 mm (L), height 4.2 mm, width 1.7 mm (M), Ponta do Castelo.

PLATE 2. A1-A2. Bittium nanum (Mayer, 1864), DBUA-F 1296-2, height 4.9 mm, width 2.0 mm, Malbusca. B. Tenagodus (Tenagodus) obtusus (Schumacher, 1817), DBUA-F 1283-2, height 12.0 mm, width 11.0 mm, Ponta do Castelo. C. Epitonium sp., DBUA-F 931-1, height 4.0 mm, width 2.8 mm, Pedra-que-pica. D1-D3. Janthina krejcii, SMF10135a, height 25.0 mm, diameter 32.0 mm, Macela viewpoint (pictures from Beu, 2017, fig. 26). E1-E3. Janthina typica (Bronn, 1861), DBUA-F-428, height 19.0 mm, diameter 21.0 mm, Ponta do Castelo, (pictures from Beu, 2017, fig. 25). F.Cheilea equestris (Linnaeus, 1758), DBUA-F 1283-1, diameter 30.0 mm, Ponta do Castelo. G1-G3. Hipponix sulcatus (Borson, 1820), DBUA-F 937-1, height 5.3 mm, diameter 14.0 mm, Ponta do Castelo. H1-H2. Euspira atlantica (Mayer, 1862), height 16.0 mm, diameter 19.0 mm, Ponta do Norte lighthouse, LNEG collection (unnumbered). I. Triphorid s.l., DBUA-F 471-5, height 3.2 mm, width 1.3 mm, Ponta do Castelo. J1-J2. Cerithiopsis cf. tubercularis (Montagu, 1803), DBUA-F 1023-1, height 3.0 mm, width 1.2 mm, Ponta do Castelo. K. Petaloconchus intortus (Lamarck, 1818), DBUA-F 946-2, height 13.0 mm, width 6.0 mm, Ponta dos Cedros. L. Thylacodes arenarius (Linnaeus, 1758), DBUA-F 869-1, height 33.0 mm, width 24.0 mm, Ponta dos Cedros. M1-M3. Alvania cancellata (da Costa, 1778), DBUA-F 1296-3, height 4.0 mm, width 2.2 mm, Malbusca.