Tritia atlantica (Mayer, 1862)

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 : 71

Tritia atlantica (Mayer, 1862)

Plate 5 A 1 -A 2

* Buccinum (Nassa) Atlanticum Mayer , in Bronn in Reiss 1862: 26, pl. 1, fig. 6.

Buccinum atlanticum Mayer — Mayer 1864: 75, pl. 7, fig. 56.

Type material. Four specimens, height 16.0 mm, width 9.0 mm, Pinheiros, Santa Maria Island , Azores; whereabouts unknown ( Beu 2017:165) .

Santa Maria material examined. Maximum height 13.0 mm, width 6.5 mm. DBUA-F 1295-2 (5) , Malbusca (east cave); DBUA-F 908 (1) , DBUA-F 1305 - A (3) , Malbusca; DBUA-F 924 - A (2) , Malbusca; DBUA-F 542-3 B (1), Ponta dos Frades; two specimens from LNEG collection (unnumbered), unknown locality, Santa Maria Island, Azores, Touril Complex, Lower Pliocene .

Original description. “ In Gr̂sse und Bildung ganz mit der vorigen ( B. vetulum ) ̧bereinstimmend, mit 5-6 Umgängen, aber dicker und kürzer von Form, so dass die Dicke der Schaale ⅝ der Länge beträgt und der letzte Umgang fast 6 / 8 der ganzen Schaale ausmacht; der nicht dicke Umschlag der innern Lippe reicht ̧ber den ganzen Bauch hinweg und bis an die Naht des vorletzten Umganges. An der Spitze des Gewindes zeigen sich schon feine Längs-Rippchen (queer auf den Umgängen), und die äussre Lippe ist innen fein spiral-streifig, feiner als in B. corniculum . Der letzte Umgang hat an seiner Basis auch einige feine Spiralstreifen. Die Naht ist nur schwach vertieft [In size and form quite identical to the previous one ( B. vetulum ), with 5-6 whorls, but thicker and shorter in shape, so that the thickness of the shell is ⅝ of the length, and the last whorl is almost 6 / 8 of the whole shell; the not thick callus of the inner lip extends over the whole venter and up to the suture of the penultimate whorl. At the top of the whorls there are already fine longitudinal ribs (strange on the whorls), and the outer lip is finely lirate inside, finer than in B. corniculum . The last whorl also has some fine spiral cords at its base. The suture is only slightly deepened.]” (Bronn in Reiss 1862: 26).

Latin description. “ Testa obovato-conica, perpaulum obliqua, crassiuscula, solidula, sublevi; spira acuta; anfractbius 6, convexiusculis, angustis, sutura profunda separatis, tenuissime et laxe spiraliter striatis; ultimo magno, 5/8 testae longitudinais efformante, paulum obliquum, basisulcato; apertura ovata, in canalem brevíssimo, truncato, exeunte; labro laeviter marginato; columella callo repando ” ( Mayer 1864: 75).

Revised description. Shell small, solid, bucciniform, with a moderately elevated, conical spire. Protoconch dome-shaped, consisting of 3.25-3.5 convex whorls, with a small nucleus. Junction with teleoconch sharply delimited. Teleoconch consisting of four weakly convex to flat-sided whorls with periphery at abapical suture. Suture impressed, linear. Axial sculpture of low, slightly prosocline, poorly define ribs, that weaken rapidly on the penultimate whorl. Last two whorls devoid of ribs.

Spiral sculpture consisting of about eight very weakly developed flattened cords, separated by shallow grooves, the sculpture weakening abapically, indistinct on the penultimate whorl. Last whorl relatively globose, broadly rounded, about 70% of total height, hardly constricted at the base, with sculpture obsolete, except for a few flattened cords separated by narrow grooves over the base and siphonal fasciole; fasciole not delimited. Aperture pyriform, outer lip slightly thickened adapically by a weak labral varix, rounded in profile, filled with matrix within; anal canal marked by narrow groove; siphonal canal short, open. Columella concave in the mid-portion, smooth. Colummelar and parietal calluses reduced to a poorly defined callus wash over venter.

Discussion. Tritia atlantica (Mayer, 1862) is closely similar to T. pyrenaica ( Fontannes, 1879) from the Atlantic and Mediterannean Miocene and Pliocene, but the latter differs in having weak ribs on the early teleoconch whorls that fade on the penultimate whorl. Tritia atlantica is completely devoid of axial sculpture. These two species are somewhat analogous to T. semistriata ( Brocchi, 1814) and T. elata ( Gould, 1845) which are separated by the presence of axial ribs on the early ribs in the latter ( Landau et al. 2009). The protoconch is well preserved in the Azorean material; multispiral and dome-shaped which is typical for most European Tritia species ( Landau et al. 2009).

Distribution. Lower Pliocene: Atlantic, Santa Maria Island, Azores (Mayer, in 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 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 5. A1-A2. Tritia atlantica (Mayer, 1862), DBUA-F 1295-2, height 13.0 mm, width 6.5 mm, Malbusca (east cave). B1-B2 C1-C2. Tritia serraticosta (Ĥrnes, 1852), DBUA-F 1292-A, height 6.2 mm, width 4.1 mm (B); height 8.1 mm, width 4.2 mm (C), Macela viewpoint. D. Tritia vetulum (Mayer, 1862), height 12.0 mm, width 6.0 mm, Pinheiros (figure taken from Bronn in Reiss, 1862, pl. 1, fig. 5). E1-E2. Aplus sp., height 7.5 mm, width 4.0 mm, Ponta do Castelo, LNEG collection (unnumbered). F1- F2. Orania cf. bellardiana (Foresti, 1884), DBUA-F 828-2, height 17.0 mm, width 12.0 mm, Ponta dos Frades. G1-G2. Favartia suboblonga (d’Orbigny, 1852), DBUA-F 946-3, height 19.0 mm, width 10.0 mm, Ponta dos Cedros. H1-H2. Bellardithala obsoleta (Brocchi, 1814), DBUA-F 542-4, height 5.9 mm, width 2.0 mm, Ponta dos Frades. I1-I2 J. Cancilla volvaria (Bronn, 1862), DBUA-F 937-2, height 10.9 mm, width 4.8 mm (I), Ponta do Castelo; height 15.5 mm, width 5.5 mm (J), Pinheiros (figure taken from Bronn in Reiss, 1862, pl. 1, fig. 4). K. Mitra (s.l.) peregrinula Mayer, 1864 species inquirenda, height 5.5 mm, width 2.5 mm, Feteirinhas (= Ponta das Salinas) (figure taken from Mayer, 1864, pl. 7, fig. 61). L1-L2. Mitra (s.l.) sp., DBUA-F 1295-3, height 12.9 mm, width 7.0 mm, Malbusca (east cave). M. Africonus trochilus (Mayer, 1864), length 16.0 mm, width 9.0 mm (incomplete spire fragment), Pinheiros, (figure taken from Mayer, 1864, pl. 7, fig. 60). N1-N2. Lautoconus cf. anomalomamillus (Sacco, 1893), DBUA-F 924-1, height 22.0 mm, width 11.0 mm, Malbusca. O. Plagioconus sp., height 35.5 mm, width 16.0 mm, unknown locality, LNEG collection (unnumbered). P1-P2 Q. Stephanoconus candidatus (Mayer, 1862), DBUA-F 913, diameter 19.0 mm (apical fragment of juvenile), Ponta dos Frades (P); diameter 40.0 mm, height 22.0 mm (incomplete spire fragment), Pinheiros (figure taken from Bronn in Reiss, pl. 1, fig. 1).