Morula mionigra Martín-González, 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 : 210

Morula mionigra Martín-González sp. nov.

Figure 8 F, G, H

Type material. Holotype: complete, well-preserved shell of an adult specimen of medium size (H: 10.6 mm and W: 7.5 mm), record number TFMCFO-4634. Paratypes: two adult specimens recorded as TFMCFO-6398 (A: 11.2 mm; W: 14.6 mm) and TFMCFO-3 704 (H: 9 mm; W: 7 mm).

Other material examined. Six specimens, all from of the type locality (TFMCFO-3704; 4634; 6398/1-2; 6360/1-2). The biometric results and descriptive statistics of the different variables are shown in Table 9.

Type locality. Bajas Amarillas ( Fuerteventura , Canary Islands). UTM 28 R 593643 m E 3161892 m N , 10 m asl. The level is composed of poorly cemented, dark gray fossiliferous sandstones. Tortonian dating defined by the gastropod association described above. The paratypes are from the same type locality.

Etymology. The specific epithet derives from the combination of the Miocene geological period with the color and shape of the species holotype (black), reminiscent of mulberries.

Description. Shell small, solid, globular to oval, with a small low spire and tapering base (Hmax: 16.6 mm; Wmax: 16.9 mm). Protoconch eroded in all of the studied specimens. Teleoconch consists of three whorls and suture wavy. First whorls almost flat in juvenile specimens and slightly concave in adults. Last whorl occupies 85% of the shell. Well-developed axial sculpture, formed by six wide, thick, prominent prosocline varix-like ribs with a rounded profile. Spaces between ribs delimited by a fine deep fluting. Spiral sculpture includes seven cords that are interrupted between ribs. Aperture narrow, oval, with distinct anterior and posterior notches, outer lip thickened by an axial ledge, featuring six internal denticles just within lip margin situated where furrows between spiral cords terminate. The four central denticles are sharp and widely separated from each other. Denticles located at the anterior and posterior ends of aperture are smaller; the posterior denticle is virtually hidden by the labrum; the anterior denticle is rather blunt. Columellar callus concave in parietal portion, being thickened by another fine well-marked columellar callus, which thickens and unfolds at the abaxial edge of the columella forming a false umbilicus. Deep narrow anal channel, delimited by a tiny parietal tuber. Anterior siphonal canal straight, short and rounded.

Remarks. We have assigned this new species to the genus Morula because of its wide axial ribs, narrow oval aperture, short siphonal channel and narrow deep anal channel, in addition to the internal denticles of the outer lip ( Houart 2004). Landau et al. (2007) cited the genus Cathymorula as including a small number of species from the European Neogene with characteristics described by Bellardi (1882): Purpura subumbilicata , P. gastraldii , P. arata , P. stazzanensis and P. megastoma (figured in Ferrero Mortara et al. 1981, pls 32, 33), as well as Cathrymorula cathyae (Landau, Houart & da Silva, 2007) from the Pliocene of Estepona. However, we consider there are insufficient arguments for the genus Cathymorula and consider is to represent a synonym of Morula ; consequently, this new species can be included in the genus Morula . Of all these species, those whose features are closest to Morula mionigra sp. nov. are C. cathyae and P. stazzanensis , although both have a slightly higher spire and less prominent axial ribs. Morula nodulosa ( Adams, 1845) differs strongly from Morula mionigra sp. nov. and is found in Cape Verde. It has a very high spire and denticles on both, the columellar edge and the labrum. A more detailed study of this species would likely include it in another genus of the subfamily Ergalataxinae .

Distribution. Upper Miocene, Tortonian: Fuerteventura.

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.