Cuisenerita tuberosa, Symonds, Malcolm Francis & Pacaud, Jean-Michel, 2010

Symonds, Malcolm Francis & Pacaud, Jean-Michel, 2010, New species of Neritidae (Neritimorpha) from the Ypresian and Bartonian of the Paris and Basse-Loire Basins, France, Zootaxa 2606, pp. 55-68 : 63-65

Cuisenerita tuberosa sp. nov.

( Fig. 8 a–d)

Derivatio nominis. The name is derived from Latin tuberosus, referring to the protuberances on the base of the shell.

Type material. Holotype NHM PI TG 26450 (S. Tracey coll., Fig. 8 a–d).

Stratum typicum. Middle Eocene, Ypresian, Cuisian.

Locus typicus. Trosly-Breuil, near Cuise-la-Motte, Oise, France. 49˚24ˏ05˝ N 2˚59ˏ25˝ E.

Diagnosis. Capuliform, apex not terminal, slightly involute, radial ribs with ornament of tubercles, septum well developed, tuberculate, margin prominently dentate, outer lip thickened, lirate, tuberculate.

Description. Protoconch worn in the only known specimen. Teleoconch capuliform with raised apex anterior to posterior end, slightly involute, curved to left. Anterior, posterior margins rounded with posterior slightly narrower than anterior. On dorsal surface approximately 30 ribs radiate from apex to margin. Ribs fairly evenly spaced, increasing in width from apex towards margin, each bearing single row of prominent, closely spaced tubercles throughout length, also increasing in size towards margin. Although surface rather worn, prominent, closely spaced growth lines clearly seen between ribs. Inner whorls reabsorbed. No colour pattern visible. Aperture relatively large, semicircular. Inner lip protruded as broad septum that covers rather more than half of base of shell, surface more or less flat near septum edge becoming slightly convex towards posterior end, covered with prominent tubercles. Septum edge slightly concave in centre, 4 narrow, prominent, evenly spaced teeth bordered on abapical side by larger, rounded tooth, on adapical side by larger cubed tooth adjacent to which is narrower tooth, both continue for short distance as ridges on outer surface of septum. Outer lip considerably thickened, 12 prominent lirae on inner side, row of tubercles on surface.

Size. The holotype is 14 mm long and 12.5 mm wide.

Remarks. The above description is based on the holotype, which is the only known example of C. tuberosa , and accordingly takes no account of any variation that may occur within this species.

No other species of Cuisenerita is known and C. tuberosa is quite unlike any other Caenozoic taxon. The differences between Cuisenerita and Tomostoma are outlined above. Of the other gastropods of capuliform shape, Calyptronerita Le Renard, 1980 lacks prominent ribs on the dorsum and has a smooth, edentate septum. In Crepidulidae the septum, if present, is smooth and edentate.

The coordinates for the type locality are only approximate as there were several Cuisian sites around Trosly-Breuil and it is not known from which one the holotype originated.

Range and distribution. Only known from type locality.

Figures

FIGURES 5 – 8. 5. Neritodryas guillioui sp. nov., paratype, a. apertural, b. abapertural, c. apical views. Height 14.5 mm, width 15 mm. Ypresian, Pourcy, Marne, France. MNHN A 31491 (Faullummel coll.). 6. Neritodryas globosa (J. de C. Sowerby, 1823), neotype, a. apertural, b. abapertural, c. apical views. Height 18.2 mm, width 13.8 mm. Bartonian, Highcliff, Hampshire, U. K. NHM GG 22558 (A. G. Davis coll.). 7. Neritodryas dutemplei (Deshayes, 1864), a. apertural, b. abapertural, c. apical views. Height 9 mm, width 9.1 mm. Ypresian, Pourcy, Marne, France. MNHN A 31493 (Faullummel coll.). 8. Cuisenerita tuberosa sp. nov., holotype, a. apertural, b. abapertural, c. & d. side views. Length 14 mm, width 12.5 mm., Ypresian, Trosly-Breuil, Oise, France. NHM PI TG 26450 (S. Tracey coll.).