Thericium incultum (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 : 30-31

Thericium incultum (Mayer, 1862)

Plate 1 H 1 -H 2 , I 1 -I 2

* Cerithium incultum Mayer , in Bronn in Reiss 1862: 31, fig. 13.

Cerithium incultum Mayer — Mayer 1864: 65, pl. 6, fig. 45 (48 in text: lapsus).

Type material. Three specimens, maximum height 34.0 mm, width 15.0 mm, Pinheiros, Santa Maria Island , Azores; whereabouts unknown ( Beu 2017:165) .

Santa Maria material examined. Maximum height 29.0 mm, width 11.0 mm. DBUA-F 1034-2 (6), Macela viewpoint; DBUA-F 1027-1 (1), Malbusca II, Santa Maria Island, Azores, Touril Complex, Lower Pliocene.

Original description. “ Drei unvollständige Exemplare, (sämmtlich ohne äussre Mundlippe), welche bis 1¼" lang sind und ergänzt wohl 1½" Länge erreichen w̧rden, ̧brigens aber von sehr veränderlicher Form erscheinen. Sie zählen bei abgebrochener Spitze noch 6 Umgänge und ḑrften mit derselben deren 9-10 gehabt haben. Die Schaale ist etwas bauchig-kegelf̂rmig, nicht halb so dick als lang, an dem bauchigsten Exemplare (Fg. b) mit schwach geŵlbten Umgängen und wenig vertiefter Naht; an einem minder bauchigen wenig monstr̂sen (Fg. a) sind die Umgänge flach, aber abgerundet breit und treppenf̂rmig abgesetzt; am dritten, dem schlankesten von allen, sind sie vom vierten an monstr̂s verbogen, so dass ihre Aussenflächen selbst etwas vertieft oder nach vorn verschmälert sind; die äussre Kante der Treppe scharf rechteckig. Im Übrigen ist die ganze Oberfläche sehr fein und dicht spiralstreifig, ohne anderweitige Verzierungen, aber mit Spuren einer braunen breit-flammigen Färbung. Aus einem ferneren kleinen Bruchsţcke ist zu entnehmen, dass die innre Lippe sehr dickwulstig war [Three incomplete specimens (all without an external lip) which are up to 1¼" [inches?] long and would probably reach 1½" length but appear of very variable shape. Consisting of 6 whorls with broken tip and should have had 9-10 with it. The shell is somewhat bulbous-cone-shaped, not half as thick as long, on the most bulbous specimen (Fig. b) with weakly arched whorls and shallow suture; on a less bulbous less monstrous (Fig. a) the whorls are flat, but rounded wide and scaled; on the third, the slimmest of all, they are monstrously bent from the fourth, so that their outer surfaces themselves are somewhat recessed or narrowed forward; the outer edge of the whorls sharply rectangular. Furthermore, the whole surface is very fine and densely spiral-streaked, without other decorations, but with traces of a brown broad-flamed colour. From a further small fragment, it can be seen that the inner lip was very thick.]” (Bronn in Reiss 1862: 31).

Latin description. “ Testa conico [sic]- turrita , apice acuta, crassa et solida; anfractibus 11, angustis, spiraliter sulcatis, transfersim obscurissime oblique-plicatis, medio subconcavis ad suturam saepe tumescentibus, contabulatis; primis sutura profunda separatis, raro varicosis; sulcis tenuibus, impressis, subregularibus; apertura magma ovata; labro varicoso, intus incrassato.”

Revised description. Shell medium sized, relatively solid, cerithiform, profile of early whorls cyrtoconoid, later whorls telescopic. Protoconch not preserved. Teleoconch composed of seven relatively low, cylindrical whorls, separated by weakly impressed linear suture. Later whorls, slightly swollen adapically forming periphery. Fine spiral sculpture partly preserved. Last whorl sub-cylindrical, with poorly delimited, swollen subsutural collar, slightly concave mid-whorl between collar and top of base, base rounded. Aperture incomplete.

Discussion. Thericium incultum (Mayer, 1862) is not typical for the genus, characterised by its rather telescopic spire and much reduced sculpture. The Azorean specimens at hand are all calcitic pseudomorphs and the surface sculpture is not clearly preserved, but the surface is probably completely covered in fine spiral cords. Mayer (1864: 65) considered this taxon to belong to the T. varicosum ( Brocchi, 1814) group. Indeed, its lack of tubercular sculpture separates it from almost all European Neogene Thericium species. It differs from T. varicosum in its telescopic profile and poorly delimited, swollen subsutural collar. Therefore, generic placement is tentative.

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.