Ringicula circumscripta

Helwerda, Renate A., 2015, Acteonidae, Bullinidae and Ringiculidae (Gastropoda: Heterobranchia) from the Plio-Pleistocene of the Philippines, Zootaxa 3990 (2), pp. 197-220 : 211-212

publication ID	https://doi.org/ 10.11646/zootaxa.3990.2.2
publication LSID	lsid:zoobank.org:pub:BDF1BC11-4848-4858-99DC-0336A5FBEE2B
DOI	https://doi.org/10.5281/zenodo.6116537
persistent identifier	https://treatment.plazi.org/id/03FA878C-951E-FE45-FF26-E0BD0738CBE8
treatment provided by	Plazi
scientific name	Ringicula circumscripta
status

Treatment

Ringicula circumscripta View in CoL nov. spec.

( Figure 27 View FIGURE 23 – 28. 23 )

Type material. Holotype RGM 961.754 (Type locality), 3 paratypes RGM 961.854 (AndaDeVos).

Other material. Anda6 (17) RGM 961.818, AndaDeVos (25) RGM 961.819, AndaClif3 (2) RGM 961.820, Roxas (3) RGM 961.821.

Type locality. Roxas.

Derivatio nominis. Enclosed, adjective. Named after the prominent ridge that delimits the parietal callus of the aperture.

Diagnosis. Shell moderately large; H 5.07 mm, W 3.64 mm; protoconch rather elevated, 1.1 whorl, 0.24 mm; nucleus small, DN 0.13 mm; teleoconch with spiral grooves; outer lip thick and crenulated; inner lip callused, delineated by lamella, additional lamella extending into aperture; columella callused and with two folds.

Description. Shell rather high-spired, moderately large for its genus. Largest specimen has a total of 6.3 whorls, including a protoconch of 1.1 whorl. Protoconch small, smooth, rather inclined. Teleoconch sculpted with thin spiral grooves and very weak, prosocyrt growth lines. Spiral grooves are regularly spaced, but absent from the upper one-sixth part of the whorl, numbering 14 on the body whorl. Whorls convex, but not globose. Suture obscured by a narrow subsutural ridge, below which is a narrow groove. Aperture covered by thick callus, delineated by a prominent ridge on the inner lip. An additional lamella is present on the parietal callus, extending into the aperture. Columellar lip bears two pronounced, smooth folds. Outer lip thick, crenulated, with a distinct nodule present on the middle of the lip. Exterior of the outer lip bears weak striations. Anterior and posterior sinus well-developed.

Differentiation. Ringicula circumscripta nov. spec. is similar to Ringicula bella nov. spec., but the latter is slightly larger, it has more spiral grooves and it has two or three small nodules on the parietal callus instead of a lamella. Ringicula titanica Schepman, 1913 has a similar aperture with a lamella, but it is much larger (H 8.5 mm, W 6 mm) and it has fewer spiral grooves, present only on the lower half of the whorl.