Alvania sleursi ( Amati, 1987 )

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 : 48-49

Alvania sleursi ( Amati, 1987)

Plate 3 B, C 1 -C 2

* Manzonia (Alvinia) sleursi Amati 1987: 26 , figs. 1-2.

Alvania sleursi ( Amati, 1987) — Ávila et al. 2002: 353, figs. 54-56, 58-61.

Alvania sleursi ( Amati, 1987) — Martins et al. 2009: 62, pl. 9, figs. 141-142.

Alvania sleursi ( Amati, 1987) — Ávila et al. 2009b: 20, 23, 26.

Alvania sleursi ( Amati, 1987) — Ávila et al. 2010: 36, fig. 28 (1-6).

Alvania sleursi ( Amati, 1987) —Ávila 2013: 110, fig. 5B.

Alvania sleursi ( Amati, 1987) — Meireles et al. 2013: 141, fig. 5G.

Alvania sleursi ( Amati, 1987) — Ávila et al. 2015a: 137, 139, 142.

Alvania sleursi ( Amati, 1987) — Amati & Chiarelli 2017: 841, fig. 17.

Santa Maria material examined. Maximum height 3.2 mm, width 1.8 mm. DBUA-F 962-3 (1), DBUA-F 1058- A (1), DBUA-F 827-B (3), DBUA-F 471-4 (1), Ponta do Castelo; DBUA-F 1044- A (1), Pedra-que-pica, Santa Maria, Azores, Touril Complex, Lower Pliocene.

Description. Shell medium sized for genus, rissoiform, imperforate, with scalate spire. Protoconch paucispiral, of 1.5 whorls, nucleus medium sized, post-nuclear whorl bearing spiral cords.Teleoconch of three shouldered whorls, subsutural ramp moderately wide, delimited by adapical spiral cord, weakly convex below. Suture undulating and weakly impressed. Sculpture of axial ribs and spiral cords, about one-third as wide as their interspaces, forming a square reticulate pattern. Axial sculpture of strong, orthocline, rounded ribs, about 14 on penultimate whorl. Spiral sculpture of strong rounded cords, two on spire whorls, with a third appearing just above the abapical suture on second half of penultimate whorl with pointed tubercles developed at sculptural intersection. Last whorl 70% of total height, with three spirals placed above aperture, two further spirals over base. Aperture ovate, peristome complete. Outer lip greatly thickened by broad labial varix bearing coarse tubercles where the spiral cords run onto the lip, inner edge bevelled, smooth within, anal sinus shallow. Peristome broad and greatly thickened.

Discussion. Alvania sleursi ( Amati, 1987) is characterised by its paucispiral protoconch bearing spiral cords, scalate spire whorls, and coarsely cancellate teleoconch sculpture with two spiral cords on spire whorls and three above the aperture on the last whorl. The Pliocene specimens from the Azores are some of the few in which the protoconch is preserved and confirms the identification. Today, A. sleursi is reported from the Azores, Madeira and Selvagens ( Hoenselaar & Goud 1998: Ávila 2000b; Freitas et al. 2019). It seems therefore, that these two species of Alvania species ( A. mediolittoralis and A. sleursi ) was already present in the Lower Pliocene. For further discussion see under A. cancellata (da Costa, 1778).

Distribution. Lower Pliocene:Atlantic, Santa Maria Island, Azores ( Meireles et al. 2013). Present-day, Atlantic, Azores ( Amati 1987; Hoenselaar & Goud 1998; Ávila 2000; Martins et al. 2009; Ávila et al. 2009b; Amati & Chiarelli 2017), Madeira and Selvagens Archipelago ( Hoenselaar & Goud 1998).

Genus Rissoina d’Orbigny, 1840

Type species. Rissoina inca d’Orbigny, 1840 ( d’Orbigny 1840: 394), by monotypy. Present-day, Peru.

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.

PLATE 3. A. A1-A2. Alvania mediolittoralis Gofas, 1989, DBUA-F 962-2, height 2.1 mm, width 1.2 mm, Ponta do Castelo. B. Alvania sleursi (Amati, 1987), DBUA-F 471-4, height 2.0 mm, width 1.1 mm, Ponta do Castelo. C1-C2. Alvania sleursi (Amati, 1987), DBUA-F 962-3, height 3.2 mm, width 1.8 mm, Ponta do Castelo. D1-D3. Rissoina pusilla (Brocchi, 1814), DBUA-F 488-1, height 5.2 mm, width 2.1 mm, Ponta do Castelo. E1-E3. Macromphalina depressa (Boettger, 1907), DBUA-F 1023-3, height height 1.0 mm, width 1.8 mm, Ponta do Castelo. F. Calyptraea chinensis (Linnaeus, 1758), DBUA-F 926-1, diameter 18.0 mm, Malbusca 2. G1-G2. Schilderia utriculata (Lamarck, 1810), height 24.0 mm, width 15.0 mm, unknown locality, LNEG collection (unnumbered). H1-H3. Erato mayeri nov. sp., Holotype DBUA-F 1189-C, height 7.7 mm, width 5.3 mm, Pedra-que-pica. I1-I3. Erato mayeri nov. sp., Paratype DBUA-F 1291-1, height 8.9 mm, width 6.0 mm, Ponta dos Frades. J1-J4. Pseudopusula parcicosta (Bronn, 1862), DBUA-F 469-1, height 9.0 mm, width 6.5 mm, Ponta do Castelo.