Stosicia annulata ( Dunker, 1860 )

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-

Stosicia annulata ( Dunker, 1860)

Materials

Type status: Other material. Occurrence: catalogNumber: EM 19 ; recordedBy: Qi Lu; individualCount: 2; lifeStage: adult; occurrenceID: FADFC8CD-7185-5D00-AA9F-69CEF492FF14; Taxon: taxonID: Native; scientificName: Stosicia annulata ; originalNameUsage: Alvania ligata A. Gould, 1861 , Ravadia trochlearis (A. Gould, 1861) , Rissoina ( Iravadia) annulata Dunker, 1860 , Rissoina annulata Dunker, 1860 , Rissoina trochlearis A. Gould, 1861 , Rissoina trochlearis var. minor G. Nevill, 1885; Location: country: China; stateProvince: Hainan; locality: Danzhou ; Identification: identifiedBy: Qi Lu; dateIdentified: 2023

Description

Shell minute (4 ± 0.01 mm in height, 1.9 ± 0.03 mm in width), thick-walled, white, but frequently stained pale reddish-brown by iron deposits (Fig. 4 A and B). Whorls approximately 7, body whorl height greater than spire; teleoconch sculptured exclusively by strong spiral cords with axial lamellae between cords, interspaces about twice the width of cord (Fig. 4 G); body whorl bearing 4 spiral cords (Fig. 4 C and D). Sutures indistinct, shallow (Fig. 4 F). Base with 3 spiral cords. Aperture elliptical, anteriorly canaliculate, posteriorly angulate; outer lip with strong external varix bearing spiral cords, interior smooth, but with 3 weakly-developed tubercular ridges; inner lip smooth to anterior canal, slightly arcuate, broad; peristome thickened (Fig. 4 E). Protoconch multispiral (approximately 2.5 whorls), distinctly demarcated from teleoconch; clear boundary between first and second protoconch whorls, smooth (Fig. 4 H and I).

Diagnosis

A species distinguished by its transverse ribs, of which seven are present on the last whorl ( Dunker 1860).

Distribution

Widely distributed, currently known from the Bōsō and Noto Peninsulas to Kyushu ( Japan), Southeast Asia, India, East Africa and Hainan Island ( China) ( Gajera et al. 2024).

Taxon discussion

The genus Stosicia Brusina, 1871 was divided by Ponder (1985) into two subgenera: Stosicia s. s. (with only spiral cords and multispiral protoconch) and Isseliella (with cancellate sculpture formed by axial and spiral ribs and paucispiral protoconch). These two subgenera have now been elevated to separate genera. S. annulata is reported from China for the first time and is, therefore, identified as a new record for the country.

Figures

Figure 4. Stosicia annulata (Dunker, 1860). 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, G detail of teleoconch surface; H scanning electron micrographs of lateral view of protoconch; I scanning electron micrographs of apical view of protoconch.