Stephanoconus candidatus (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 : 83-84

Stephanoconus candidatus (Mayer, 1862)

Plate 5 P 1 -P 2 , Q

* Conus candidatus Mayer , in Bronn in Reiss 1862: 23, pl. 1, fig. 1.

Conus candidatus Mayer — Mayer 1864: 78, pl. 7, fig. 58.

Type material. Single specimen, diameter 40.0 mm, height 22.0 mm (incomplete spire fragment), Pinheiros (Baía da Cré), Santa Maria Island, Azores; whereabouts unknown ( Beu 2017:165) .

Santa Maria material examined. Maximum diameter 19.0 mm (apical fragment of juvenile). DBUA-F 913 (1), Ponta dos Frades, Santa Maria Island, Touril Complex, Lower Pliocene.

Original description. “ Eine Art mit Kronen-f̂rmigem Gewinde, wovon aber nur dieses selbst in einem einfachen Exemplare vorliegt und auf ein 1½" grosses Individuum deutet. Die 9-10 Windungen sind oben mit 3-4 SpiralStreifen versehen, ein wenig nach aussen abfallend, schwach Treppen-f̂rmig abgesetzt und auf der gerundeten Kante mit je 11-12 Knoten geziert. Der obre Theil des letzten Umganges etwas bauchig, glatt. Stimmt (soweit er erhalten) im Ausehen etwas mit C. miliaris Lk., C , nebulosus Solander und zumal C. nocturnus ̧berein; er ist aber etwas minder gestreckt, die Umgänge des Gewindes sind etwas ĥher und schärfer gekantet als an diesem. [ A species with crown-shaped suture, of which only this is present as one specimen and points to a 1½" [inches?] tall individual. The 9-10 whorls, slightly sloping outwards and slightly scaled, bear 3-4 spiral threads and the edge bears 11-12 tubercles. The upper part of the last whorl is a bulbous, smooth. Agrees (as far as it is preserved) somewhat with C. miliaris Lk. , C. nebulosus Solander and especially also C. nocturnus ; but it is somewhat less elongated, the circumferences of the thread are slightly higher and sharper than on this.]” (Bronn in Reiss 1862: 23).

Latin description. “ C. testa mediocri , oblongo-conica; spira acuta, paulum depressa ; anfractibus carinatis, scalatis, ad suturam plano-concavis, spiraliter lennuesulcatis, tuberculatisque; tuberculis crassis, obtusis, distantibus.” ( Mayer 1864: 78).

Description. Apical fragment. Protoconch missing. Spire strongly depressed, slightly graded. Nine teleoconch whorls preserved, bearing broad, rounded poorly delimited tubercles and fine spiral sculpture.

Discussion. The spire fragment illustrated by Mayer, in Bronn in Reiss (1862: fig. 1) has strong tubercles at the shoulder and can undoubtedly be ascribed to the genus Stephanoconus M̂rch, 1852. This was already noted by Tucker & Tenorio (2009: 125). The spire fragment at hand, from Ponta dos Frades, matches closely the fragment illustrated by Mayer (1864: fig. 58) and clearly shows the tubercles and spiral sculpture on the spire. Stephanoconus is a tropical genus included by Landau et al. (2008, appendix A) in their list of paciphile genera. That is, genera that prior to the closure of the Central America Seaway (CAS) were distributed on both sides of the Isthmus of Panama but became restricted to the Pacific side of their originally wider distribution during or subsequent to the closure. Today Stephanoconus occurs in the eastern Pacific, represented by S. bartschi ( Hanna & Strong, 1949) . In the Caribbean Neogene it is represented by S. wiedenmayeri Jung, 1965 , and several species from the Dominican Republic (NHMW collection) ( Hendricks 2015). This record in Santa Maria, Azores is the most western Atlantic for the genus and the only genus with strong tropical western Atlantic rather than Mediterranean affinities in the assemblage.

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

Genus Conus s.l.

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).