Alvania wangi Xu, Qi & Kong, 2022

Xu, Biyang, Qi, Lu, Kong, Lingfeng & Li, Qi, 2022, Description of Alvania wangi Xu, Qi & Kong, sp. nov. (Mollusca, Gastropoda, Littorinimorpha, Rissoidae) from the East China Sea, ZooKeys 1110, pp. 201-217 : 201

Alvania wangi Xu, Qi & Kong sp. nov.

Figs 3 , 4

Type locality.

China, Zhejiang: Pingyang County, the Nanji Islands National Nature Reserve, Dalei Island, 27°29.82'N, 121°06.17'E.

Holotype: Alcohol-fixed, photographed by SEM; original label: "CN, ZJ, Pingyang, Dalei, 27°29.82'N, 121°06.17'E, 23 Jul. 2020, B.Y. Xu & L. Qi" "LSGB mg325408 0601".

Paratypes: Alcohol-fixed, five specimens, original label: "CN, ZJ, Pingyang, Dalei, 27°29.82'N, 121°06.17'E, 23 Jul. 2020, B.Y. Xu & L. Qi" "LSGB mg325408 0602 to 0606"; alcohol-fixed, ten specimens, original label: "CN, ZJ, Zhoushan, Miaozihu, 30°11.77'N, 122°41.41'E, 09 Apr. 2021, B.Y. Xu & L. Qi" "LSGB mg316141 0601 to 0610".

Diagnosis.

Shell minute, ovate-conical, thin, with weakly convex whorls, non-umbilicate. Protoconch paucispiral, sculptured with micro pits and lamellae between spiral lirae. Teleoconch with subobsolete cords and growth lines. Umbilicus chink very narrow and slit-like. Aperture oval, broadly rounded anteriorly, slightly angled posteriorly; peristome simple; outer lip orthocline, without varix. Periostracum thin.

Description.

Shell: (Figs 3A-D , 4A-D ) minute, ovate-conical, semitransparent, thin but not fragile. Protoconch (Figs 3E, F , 4E, F ) dome-shaped, with 1.5 whorls, height ~190 μm, diameter 353 μm, translucent; nucleus apparently smooth, followed by half whorl ornamented with dense and irregular micro pits (Fig. 3F ) which subsequently fuse into micro-lamellae between 9-10 spiral lirae (Fig. 3E, F ), roughly three times wider than interspaces. Protoconch-teleoconch border simple, marked by a shallow depression of the spire (Fig. 4F ). Teleoconch with 2 whorls, slightly convex, with 3-4 subobsolete spiral cords on penultimate whorl, 9-10 on body whorl, 3-4 relatively distinct spiral cords on base, roughly equidistant and broader than interspaces, crossing with exceedingly fine growth lines, and few weak spiral furrows in the periumbilical area. Periphery of body whorl broadly rounded. Suture impressed, simple. Aperture oval, with simple peristome, angled posteriorly, rounded anteriorly; inner lip narrow, anteriorly slightly separated from lower base, posteriorly attached to base; outer lip orthocline, without external varix and internal lirae. Umbilical chink represented by a narrow and short groove. Periostracum very thin, barely visible. Background color yellowish and brownish, forming interlaced band.

Operculum: (Fig. 3G, H ) subovate, horny, simple, thin, smooth, posteriorly broadly angled, anteriorly rounded; nucleus eccentric; last whorl long and large, yellowish, and translucent.

Radula : (Fig. 4G-J ) typical of Alvania . Central teeth 2-3+1+2-31+11+1, with long triangular cutting edge, small cusps, a single pair of basal denticles and a pair of smaller denticles produced from the thickened lateral margins; U-shaped ventral extension poorly to not developed. Lateral teeth 3 + 1 + 6-7, elongate, each with triangular and asymmetric cusps: larger primary cusp long and wide; 3 inner and 6-7 outer, smaller pointed denticles at the sides. Marginal teeth elongated, cusps subequal; inner marginal teeth with ~17 cusps on outer 1/3 of teeth, outer marginal teeth with ~6-7 cusps on inner distal 1/3.

Soft parts: Yellowish head and foot. A pair of black-pigmented eyes (Fig. 4D ) can be seen through the translucent shell. Cephalic tentacles yellow, behind the eyes.

Etymology.

The species is named after Prof. Rucai Wang, who established LSGB and was one of the founders of shellfish culture in China.

Known distribution.

In addition to the type locality, this species can also be found in the middle intertidal zone of Miaozihu Island, the northeastern part of Zhoushan City, China, 30°11.77'N, 122°41.41'E.

Remarks.

The characteristics of Alvania wangi Xu, Qi & Kong, sp. nov. are consistent with those of Alvania described by Risso (1826) and Ponder (1967, 1985). It also possesses some unique features, such as the subobsolete spiral cords and the protoconch sculptured with pits, lirae, and micro-lamellae. The new species can be clearly distinguished from other Alvania species in adjacent waters (Suppl. material 2). Additionally, it resembles A. carinata (da Costa, 1778), A. cimex (Linnaeus, 1758), A. lineata Risso, 1826, A. punctura (Montagu, 1803), and A. scabra (Philippi, 1844) in radula morphology, but differs both in clathrate sculpture and protoconch features. Among all species of Rissoidae , the new species may be most closely related to Crisilla simulans (Locard, 1886) and C. perminima (Manzoni, 1868), which are found independently in the Mediterranean Sea ( Morena and Luigi 2005) and northwestern Africa ( Oliver et al. 2019). It shares similar color patterns, sizes, the general outline of the shell, and the lack of conspicuous axial sculpture with the two Crisilla species. However, it differs from these species in the presence of 9-10 relatively clear spiral cords on the body whorl and in the spiral microsculptures of the protoconch. Furthermore, the new species has a similar protoconch sculpture to those of Cingula aequa (E. A. Smith, 1890) and C. farquhari (E. A. Smith, 1910) in terms of the number and sculpture of spiral lirae with axial micro-lamellae. However, the two Cingula species lack the rows of pits and smooth zones found in the protoconch of Alvania wangi Xu, Qi & Kong, sp. nov. (Fig. 3E, F ). Moreover, the central tooth of the new species (Fig. 4G-I ) is similar to that of Cingula trifasciata (J. Adams, 1800), the type species of Cingula Fleming, 1818, which, however, has a moderately developed “U-shaped” ventral extension ( Ponder 1985) and lacks pustules (Fig. 4H ) on the base. Alvania wangi Xu, Qi & Kong, sp. nov. can be distinguished from the above-mentioned species based on its peculiar characteristics and is therefore regarded as a distinct species of Alvania .

Figures

Figure 3. Holotype of Alvania wangi Xu, Qi & Kong, sp. nov. (A-D) shell A apertural view of shell B scanning electron micrographs of apertural view of shell C lateral view of shell D dorsal view of shell E protoconch F apical view of protoconch (G, H) operculum G outer face of operculum H inner face of operculum. Scale bars: 500 μm (A-D); 200 μm (E); 100 μm (F-H).

Figure 4. Paratype of Alvania wangi Xu, Qi & Kong, sp. nov. (A-D) shell A apertural view of shell B scanning electron micrographs of apertural view of shell C lateral view of shell D dorsal view of shell E protoconch F apical view of protoconch (top two arrowheads show the two growth lines of the protoconch; bottom arrowhead indicates demarcation between protoconch and teleoconch) G radula H oblique view of central teeth (arrowhead indicates pustules on base of central teeth) I central teeth J lateral and marginal teeth. Scale bars: 500 μm (A-D); 200 μm (E, F); 10 μm (G); 2 μm (H); 5 μm (I, J).