Erato mayeri, Sacchetti & Landau & Ávila, 2023

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 : 54-55

Erato mayeri nov. sp.

Plate 3 H 1 -H 3 , I 1 -I 3

Erato laevis Gray —Bronn in Reiss 1862: 25.

Erato laevis Donovan — Mayer 1864: 81.

Type material. Holotype DBUA-F 1189 -C1, height 7.7 mm, width 5.3 mm ( Plate 3 H 1 -H 3 ), Pedra-que-pica; paratype DBUA-F 1291-1 , height 8.9 mm, width 6.0 mm ( Plate 3 I 1 -I 3 ), Ponta dos Frades. Santa Maria Island, Azores.

Other material. Maximum height 8.9 mm, width 6.0 mm. DBUA-F 830- A (1), DBUA-F 1292-C (2), Ponta dos Frades; DBUA-F 469 (1), DBUA-F 1058-C (1), DBUA-F 471-G (2), Ponta do Castelo; DBUA-F 1189-C2 (1), Pedra-que-pica, Santa Maria Island, Azores, Touril Complex, Lower Pliocene.

Type locality. Pedra-que-pica, Santa Maria Island , Azores .

Type stratum. Touril Complex.

Age. Lower Pliocene , Zanclean

Etymology. Named after Karl David Wilhelm Mayer-Eymar (1826–1907), Franco-Swiss palaeontologist and geologist, in recognition of his pioneering work on the Santa Maria fossil assemblages. Erato gender feminine.

Diagnosis. Erato species of medium size for genus, solid, without pustules or dorsal sulcus, greatly thickened outer lip with finely denticulate inner edge, two terminal folds.

Description. Shell medium sized for genus, solid, pyriform. Protoconch and spire whorls covered by callus, spire short. Last whorl greatly inflated, moderately constricted at anterior terminal. Dorsum smooth, rounded, without dorsal sulcus. Aperture about 90% of total height, straight and narrow. Outer lip greatly thickened; smooth, inner edge finely denticulated. Columella almost straight, inner edge obscured by matrix, two terminal folds variably developed.

Discussion. Erato mayeri nov. sp. is represented by several relatively well-preserved individuals in the Santa Maria Lower Pliocene assemblages. The outer lip is invariably greatly thickened and the inner labial teeth very fine. There are two folds in the terminal area strongly ( Fig. 3 H 1 ) to weakly ( Fig. 3 I 1 ) developed. The NE Atlantic and Mediterranean Erato voluta Montagu, 1803 differs in being higher spired, having stronger outer lip denticles and a single terminal fold. The Azorean species is most like E. prayensis Rochebrune, 1882 , reported from present-day Cabo Verde and northwestern Africa, with which it shares a low spire, fine denticulation and bearing two folds at the terminal end of the columella. However, the shells of the extant West African species are characterised by surface pustules placed around the spire and subsutural area. None of the Santa Maria specimens have pustules.

The Pliocene Mediterranean Erato species were reviewed by Fehse & Landau (2002). Of these, the Azorean species is most similar in profile to Erato subalata Sacco, 1894 , but in that species the adapical portion of the outer lip is somewhat alate and it has strong apertural dentition that covers the inner half of the outer lip and the abapical portion of columella. Erato pieris De Stefani & Pantanelli, 1879 , is larger shelled and again has stronger apertural dentition. In having weak apertural dentition, the Azorean species is most like E. elongata Seguenza, 1880 , but that species is more elongate, has a narrower outer lip, and especially the anterior terminal is more produced. Erato pernana Sacco, 1894 , like the Azorean species, has a bifid terminal fold but is smaller and stockier.

The diversity of Erato in the European Pliocene was much greater than it is today, with different species present along the European Eastern Atlantic Frontage (see Van Dingenen et al. 2016) at the level of NW France (subtropical Pliocene French-Iberian palaeobiogeographic Province) and the Mediterranean (tropical Pliocene Mediterranean-West African Province) ( Fehse & Landau 2002). All these species disappeared sometime between the mid-Pliocene cooling event and the Pleistocene, leaving only E. voluta , along the European Atlantic coast, Madeira, Canary Islands, and into the Mediterranean (Hernández et al. 2011: 158), and E. prayensis in Cabo Verde and NW Africa.

Distribution. Lower Pliocene: Atlantic, Santa Maria Island, Azores (Bronn in Reiss, 1862; Mayer, 1864).

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 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.

FIGURE 3. General cross-section of the Ponta do Castelo volcano-sedimentary sequence (Meireles et al. 2013).

FIGURE 1. Location map of the Azores Archipelago with information about the bathymetry and regional tectonic settings. NA—North American plate; EU—Eurasian plate; Nu—Nubian (African) plate; MAR—Mid‐Atlantic Ridge; TR—Terceira Rift; EAFZ—East Azores Fracture Zone; GF—Gloria Fault (adapted from Hyžný et al. 2021).