Costoanachis sp.

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 : 67-68

Costoanachis sp.

Plate 4 J

Santa Maria material examined. Maximum height 2.7 mm, width 1.6 mm. DBUA-F 1059 (1), Baía do Raposo, Santa Maria Island, Azores, Touril Complex , Lower Pliocene .

Description. Shell small, broadly fusiform. Protoconch missing. Teleoconch of three convex whorls, separated by deeply impressed, undulating suture. Sculpture on spire whorls of strong orthocline axial ribs, 11 on last whorl, roughly equals into space, extending slightly adapically, crenulating suture. Last whorl globose, evenly rounded, strongly constricted at base, with 16 broad weakly opisthocline ribs and fine spirals cords restricted to the base and siphonal fasciole. Aperture obscured by matrix, outer lip and siphonal canal incomplete.

Discussion. The species is represented by a single incomplete juvenile specimen from Baía do Raposo. It is characterised by the strong axial ribs and spiral sculpture that is restricted to the base and the siphonal fasciole on the last whorl. Costoanachis arpula ( Michelotti, 1840) and C. turbinellus ( Sacco, 1890) are both more evenly fusiform with spiral sculpture throughout. The last two species are better placed in Zafrona Iredale, 1916 (Landau et al. 2019a: 150). The Azorean specimen is more closely similar to C. rectecosta ( Sacco, 1890) (syntype illustrated in Ferrero Mortara et al. 1981: pl. 58, fig. 3) from the upper Miocene of Italy, that also has strong ribs and spiral sculpture restrict to the base. The preservation of the Azorean specimen does not allow further identification.

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

Figures

PLATE 4. A. Tethystrombus coronatus (Defrance, 1827), CIADP-F 32, height 119.1 mm, width 107.2 mm, Figueiral. B. Talisman scrobilator (Linnaeus, 1758), Ponta dos Cedros, size not known, LNEG collection (unnumbered, specimen not seen, part of a photograph database). C. Aspa marginata (Gmelin, 1791), DBUA-F 1428-1, height 28.0 mm, width 20.0 mm, Ponta dos Cedros. D1-D2. Monoplex comptus (A. Adams, 1855) height 25.0 mm, width 14.0 mm, Pinheiros (figure D1 taken from Bronn in Reiss, 1862, pl, 1, fig.10 and figure D2 from Mayer, 1864, pl. 7, fig. 52). E1-E3. Distorsio mcgintyi Emerson & Puffer, 1953, DBUA-F 1189-1, height 31.0 mm, width 18.0 mm, Pedra-que-pica. F. Xenophora sp., height 70.0 mm, diameter 15.0 mm, unknown locality, LNEG collection (unnumbered). G1-G3. Gibberula vignali Dautzenberg & Fischer, 1896, DBUA-F 1044-1, height 2.8 mm, width 1.6 mm, Pedra-que-pica. H1-H2. Cancellaria parcestriata Bronn, 1862, height 10.0 mm, width 6.5 mm, Pinheiros (figure H1 taken from Bronn in Reiss (1862), pl. 1, fig. 7 and figure H2 from Mayer (1864), pl. 7, fig. 51). I1-I2. Costoanachis semicostata (Sacco, 1890), DBUA-F 1034-4, height 6.9 mm, width 3.0 mm, Macela viewpoint. J. Costoanachis sp., DBUA-F 1059, height 2.7 mm, width 1.6 mm, Baía do Raposo. K. Angustifusus longiroster (Brocchi, 1814), height 36.0 mm, width 18.1 mm, unknown locality, LNEG collection (unnumbered). L. Fusinus nov. sp.?, height 51.0 mm, width 24.0 mm, Ponta do Norte lighthouse, LNEG collection (unnumbered).