Helicostoa sinensis E. Lamy, 1926

Helicostoa sinensis E. Lamy, 1926

Lectotype: MNHN-IM-2000-33309 , ‘P type’, ‘ Koué-Tchéou, ville située sur le Yang Tsé Kiang, à plus de 1200 kms de Chang-Hai’ .

Paralectotypes: MNHN-IM-2000-38619 , 204 specimens of ‘P type’, on the same limestone of the lectotype ; MNHN-IM-2000-38620 , 60 specimens of ‘P type’ .

Description: shell ( figure 3 View Figure 3 , table 1 View Table 1 ) 9.30 to 11.80 mm in width, discoidal, orange yellow to light red in colour; usually with 3 inflated whorls, protoconch broad smooth, teleoconch whorls with dense fine ribs, with one obvious keel on the upper part of second whorl; body whorl turning upward, covering spiral whorls partly, and turning downward to attach the substrate, sometimes open-coiled due to obstacle, the edge of body whorl attaching the rock sometimes extended, forming a narrow flat ridge, the area attaching the substrate flat; on the middle of the last half whorl upper end and lower end of outer lip extending and merging together, enclosing a large round or oval opening, seam between both ends of outer lip clearly visible; original aperture completely sealed by shell and attached rock.

Operculum ( figure 3 i View Figure 3 ) calcareous, nearly round, thin, transparent white in colour; on exterior surface the nucleus not clearly visible, with many scales on central part and concentric growth line on outer region; on interior surface a large inner opercular region visible.

Morphological comparisons: see in Helicostoa liuae sp. nov.

Ecology: this species was only found on the surface of limestones in rivers.

Distribution: this species was only known from the type locality ‘Koué-Tchéou, ville située sur le Yang Tsé Kiang, à plus de 1200 kms de Chang-Hai’, viz. ‘Kouei-Tchéou, city located on the Yangtze River, more than 1200 km away from Shanghai.’ ‘Kouei-Tchéou’ in French may refer to ‘夔州’ (Kuizhou, current Fengjie County near Three Gorges region) or ‘贵州’ (Guizhou Province).