Tectarius isletaensis Vera-Peláez, 2018

Martín-González, Esther, Vera-Peláez, José Luis, Castillo, Carolina & Lozano-Francisco, M. Carmen, 2018, New fossil gastropod species (Mollusca: Gastropoda) from the upper Miocene of the Canary Islands (Spain), Zootaxa 4422 (2), pp. 191-218 : 209

Tectarius isletaensis Vera-Peláez sp. nov.

Figure 8 D, E

Type material. Holotype: shell of an adult specimen (H: 5.3 mm; W: 4.2 mm), with record number TFMCFO- 6335c/1. Paratypes: two adult specimens with record numbers TFMCFO-6335c/2 (H: 5.5 mm; W: 4.2 mm) and TFMCFO-6535c/3 (H: 5.2 mm; W: 4.6 mm).

Other material examined. Six specimens, all from the type locality. Biometric data are displayed in Table 8.

Type locality. La Esfinge ( Gran Canaria , Canary Islands), UTM 28 R 459801m E 3115759 m N , 30 m asl. The level is composed of a poorly consolidated sandy matrix approximately 30 cm in thickness, with great abundance of bioclasts. Tortonian dating defined by the gastropod association described above. The paratypes are from the same type locality.

Etymology. The species name refers to La Isleta, linked to Gran Canaria by an isthmus where La Esfinge quarry is located.

Description. Shell small (Hmax: 6.3 mm; Wmax: 5.1 mm), conical-turbiniform, pyramidal. Five spire whorls. Protoconch missing or much worn. Studied specimens well preserved but slightly eroded, still displaying original color. First whorls almost twice as wide as high. The suture is strongly undulating and not very deep. Thick spiral cord on first two whorls, with rounded nodules nearly half the height of each whorl. During ontogeny, cord unfolds into two on the penultimate whorl. Growth lines well defined, strongly prosocline, and clearly visible on the last whorl. Last whorl makes up 75% of total shell height and is slightly wider than high. Spire whorls with subsutural ramp occupying 1/3 of its height, slightly concave, smooth and oblique. Below ramp, two spiral cords run parallel to each other, bearing 12–15 rounded and protruding tubercles each. Tubercles may be linked by an axial costula or alternatively separated by a very narrow space. Base flat with a very thin circular white band. A small siphonal fasciola can be seen in some specimens. Aperture holostomatous, completely circular with a weak siphonal notch, rotated adaxially. Columellar, parietal, and basal edges covered by a thin white callus. Outer lip unthickened, smooth and simple. Non-umbilicate. Intense red color. Tubercles can be red or display white ends.

Remarks. We assign Tectarius isletaensis sp. nov. to the genus Tectarius Valenciennes, 1832 because of the conical-pyramidal shell shape with its base perpendicular to the axis (not rounded as in Littorina Fèrussac, 1822 , Melarhaphe Menke, 1828 or Nodilittorina Martens, 1897 ), the circular aperture and the indistinct short siphonal channel which is absent in these three genera.

Tectarius isletaensis sp. nov. presents some similarity with Tectarius striatus ( King, 1832) from which it can be separated by its thick last-whorl tubercles and by the conical-pyramidal shell shape, which is far from the typical more rounded-turbiniform shape of the latter species. The new species differs from Echinolittorina tuberculata ( Menke, 1828) , with an amphiatlantic distribution according to García-Talavera (1986), in its greater number of tubercled cords that decorate the entire shell, its larger size and the globular profile of its last whorl. Tectarius isletaensis sp. nov. shows great similarity to Echinolittorina granosa Philippi, 1845 from the coasts of Gabon and western equatorial Africa, but T. granosus is distinguished by its greater size (17 mm) and by the two much finer and wider-spaced spiral cords, with very small granules that develop between them.

Regarding other forms from the European Neogene, specifically from the Bartonian of the Paris Basin, Nodilittorina guaspallensis Dolin & Pacaud, 2000 differs from T. isletaensis sp. nov. by having spiral cords with very small nodules and from Nodilittorina lozoueti Dolin & Pacaud, 2000 by its more rounded shape and small nodules evenly scattered throughout the shell, as shown by Dolin & Pacaud (2000).

Joksimowitsch (1910) reported Tectarius cf. nodulosus Gmelin from the Miocene of the Selvagens Islands; this material probably represents Tectarius isletaensis sp. nov.

Distribution. Upper Miocene, Tortonian: La Isleta, Gran Canaria.

Figures

FIGURE 8. Cerithium miocanariensis sp. nov., holotype, H: 37.4 mm; W: 18.1 mm; A. ventral view; B. dorsal view; C. detail of sculpture shell; scale 1 cm. Tectarius isletaensis sp. nov., holotype, H: 5.3 mm; W: 4.2 mm; D. ventral view; scale 0.5 cm. E. dorsal view. Morula mionigra sp. nov., holotype, H: 10.6 mm; W: 7.5 mm; F. frontal view; G. ventral view; H. detail of denticles on outer lip; scale 0.5 cm. Conus fuerteventurensis sp. nov., holotype, H: 27.3 mm; W: 18 mm; I. ventral view; J. dorsal view; K. adapical view; scale 1 cm.