Zebina tridentata ( Michaud, 1830 )

Qi, Lu, Liu, Songyuan, Sun, Shengming, Kong, Lingfeng & Ma, Zhenhua, 2025, Zebinidae (Caenogastropoda, Rissooidea) from Hainan Island, China, with re-description of four species, Biodiversity Data Journal 13, pp. e 165463-e 165463 : e165463-

Zebina tridentata ( Michaud, 1830)

Materials

Type status: Other material. Occurrence: catalogNumber: XDH 61 ; recordedBy: Qi Lu; individualCount: 3; lifeStage: adult; occurrenceID: 1963B1AA-1DEF-597F-AE68-694D346B6FAF; Taxon: taxonID: Native; scientificName: Zebina tridentata ; originalNameUsage: Rissoa crassilabrum Garrett, 1857 , Rissoa tridentata Michaud, 1830 , Rissoina crassilabrum (Garrett, 1857) ; Location: country: China; stateProvince: Hainan; locality: Sanya ; Identification: identifiedBy: Qi Lu; dateIdentified: 2023

Description

Shell minute (6.2 ± 0.02 mm in height, 3.8 ± 0.11 mm in width), thick-walled, solid, opaque-white, smooth and glossy, ovate-conical (Fig. 3 A and B). Whorls approximately 7 (protoconch missing); body whorl inflated, its height exceeding that of spire; teleoconch whorls 1-3 with axial ribs, whorls 4 to body whorl smooth (Fig. 3 C, D and F). Aperture elliptical, slightly prosocline, anteriorly rounded and posteriorly angulate; outer lip lacking external varix, but internally thickened, with a single small denticle on anterior interior edge; inner lip smooth; peristome with fine axial striations (Fig. 3 E). Sutures indistinct.

Diagnosis

Shell conical ， white, smooth and glossy; aperture ovate, oblique and somewhat channelled; outer lip swollen, with three teeth on the inner side; columella with a distinct callus at the upper part ( Michaud 1830).

Distribution

Tropical and subtropical Indo-West Pacific (Hainan and Taiwan, China; Kyushu, Japan; Philippines), ranging from the Red Sea and Mozambique to Hawaii and Tuamotu Archipelago ( Sleurs and Strack 2021).

Taxon discussion

Species of Zebina resemble those of the family Eulimidae , but are distinguished by distinct apertural features, typically exhibiting a robust outer lip varix and posterior channel. Additionally, Zebina shells tend to be thicker and more opaque. The diagnostic character of Z. tridentata is the presence of three denticles on the anterior interior edge of the outer lip ( Michaud 1830). However, Cernohorsky (1978) noted that this species may exhibit 1–3 denticles. Therefore, we conclude that the denticle number in Z. tridentata exhibits intraspecific variation. In this study, the examined specimen possesses only a single denticle (Fig. 3 E), yet consistent with other diagnostic features, we identify it as Z. tridentata .

Figures

Figure 3. Zebina tridentata (Michaud, 1830). A, B shell illustration in colour; C scanning electron micrographs of frontal view of shell; D scanning electron micrographs of lateral view of shell; E detail of aperture; F scanning electron micrographs of lateral view of protoconch.