Radix (Radix) brevicauda (G.B. Sowerby II, 1872)

Vinarski, Maxim V., Aksenova, Olga V. & Bolotov, Ivan N., 2020, Taxonomic assessment of genetically-delineated species of radicine snails (Mollusca, Gastropoda, Lymnaeidae), Zoosystematics and Evolution 96 (2), pp. 577-608 : 577

3. Radix (Radix) brevicauda (G.B. Sowerby II, 1872) Fig. 3D, E ; Table 1

Limnaea brevicauda G.B. Sowerby II 1872: pl. XV, fig. 105.

Limnaea brevicauda - Hanley and Theobald 1876: 64, pl. 158, fig. 7; Annandale and Rao 1925: 157, figs 1-6.

Lymnaea (Radix) brevicauda - Subba Rao 1989: 134, figs 302, 303.

Radix brevicauda - Glöer and Bössneck 2013: 153, figs 61-63.

TL.

The type locality was originally stated as ‘Australia’ ( Sowerby 1872). It is, however, erroneous. Hanley and Theobald (1876) gave the proper type locality: Kashmir.

Types.

NHMUK. The syntypes were inspected by us.

R. brevicauda inhabits Northern India (Kashmir), Nepal, China (Western Tibet and Himalaya Range) and, probably, Tajikistan (Pamir Mts.) [ Subba Rao 1989; Glöer and Bössneck 2013; Aksenova et al. 2018a]. The record of this species from Tajikistan is based on numerous shells from ZISP collection (see Fig. 3E ), virtually identical with the syntypes of R. brevicauda . This species has not been registered from the ex-USSR territory ( Vinarski and Kantor 2016) and hereby we, for the first time, include it in the malacofauna of the former Soviet Union. However, this record is still not corroborated genetically.

The shell of R. brevicauda is ear-shaped, with low spire and greatly expanded aperture. Generally, in many ways, it resembles the shell of R. auricularia and Glöer and Bössneck (2013: 153) note that there are no substantial differences between the two species, which are probable synonyms. However, Annandale and Rao (1925) reported the structure of the jaw and radula of R. brevicauda is distinct from that of R. auricularia . The anatomical structure of the discussed species, described and illustrated by Glöer and Bössneck (2013), is typical for the genus Radix . Our molecular analysis recovered R. brevicauda as a species sister to R. auricularia ( Aksenova et al. 2018a).

We may indicate some conchological differences between R. auricularia and R. brevicauda . The latter species is of smaller size, the largest syntype shell is 18.1 mm (our data) and Glöer and Bössneck (2013) mention that R. brevicauda may reach 20 mm in height. Next, the columellar depression in shells of R. brevicauda is very prominent, whereas, in R. auricularia , it is typically weakly developed (compare Fig. 2A and 2D, E ). Lastly, the spire whorls in R. auricularia are usually flattened, while in R. brevicauda these are visibly convex and rounded.

Nomenclature remark.

The name Limnaea brevicauda Sowerby is the oldest available one to designate a lymnaeid species, sister to R. auricularia , restricted in its distribution to the Central Asia mountain regions. The taxonomic identity of R. brevicauda , as well its close affinity to R. auricularia , was confirmed by the inspection of the extant syntypes.

Figures

Figure 2. The scheme of measurements of the shell (A) and the parts of the copulatory apparatus (B). Abbreviations: SH - shell height; SW - shell width; SpH - spire height; BWH - body whorl height; AH - aperture height; AW - aperture width; PP - length of praeputium; PS - penis sheath length. A - after Vinarski (2016 b).

Figure 3. Shells of species in the genus Radix. A. Radix auricularia (28.08.2013, Kazakhstan, Karaganda Region, Suresai River; LMBI); B. R. alticola (20.06.2012, Tajikistan, a hot spring near Djelandy village; LMBI); C. R. alticola (01.07.2016, Tajikistan, a warm brook near Dzhaushangoz village; LMBI); D. R. brevicauda (Kashmir, a syntype; NHMUK); E. R. brevicauda (05.08.1948, Tajikistan, Pamir Mts., Shaimak village, in a warm spring; ZISP); F. R. euphratica (26.06.2016, Tajikistan, Dushanbe, a fountain near the President's palace; LMBI); G. R. euphratica (04.07.2016, Tajikistan, a roadside ditch near Kurban-Shakhid village; LMBI); H. R. euphratica (without date, Iraq, Bagdad; NHMUK); I. R. makhrovi, the holotype (China, Tibet, a roadside ditch west of the Lhasa River mouth; ZISP); J. R. plicatula, a probable syntype (China, Chusan, NHMUK); K. R. plicatula (26.07.2017, China, Uyghuria, Bagrash-kol' Lake; LMBI); L. R. plicatula (26.11.2014, China, Bejing, an artificial pond in the former Emperor's summer palace; LMBI). Scale bars: 2 mm (B-C, F-L), 5 mm (A, D-E, K).