Radix (Exsertiana) natalensis (Krauss, 1848)

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

publication ID	https://dx.doi.org/10.3897/zse.96.52860
persistent identifier	https://treatment.plazi.org/id/680F03FC-C786-579E-A8BA-E093170C1F09
treatment provided by	Zoosystematics and Evolution by Pensoft
scientific name	Radix (Exsertiana) natalensis (Krauss, 1848)
status

Treatment

8. Radix (Exsertiana) natalensis (Krauss, 1848) View in CoL Figs 4H View Figure 4 ; 6D-F View Figure 6 ; Table 1

Limnaeus natalensis Krauss 1848: 85.

Limnaea hovarum Tristram 1863: 61.

Limnaeus natalensis var. exsertus von Martens 1866: 101, pl. 3, figs 8, 9.

Limnaea electa Smith 1882: 385.

Limnaea caillaudi Bourguignat 1883: 89, figs 100, 101.

Limnaea exserta - Bourguignat 1883: 90.

Limnaea gravieri Bourguignat 1885: 23.

Limnaea nyansae von Martens 1892: 16.

Limnaea arabica Smith 1894a: 142, fig. 3.

Limnaea elmeteitensis Smith 1894b: 167, fig. 5.

Limnaea humerosa von Martens 1897: 135, pl. 6, fig. 1.

Limnaea undussumae von Martens 1897: 135, pl. I, fig. 18; pl. VI, figs 2, 5.

Limnaea kempi Preston 1912: 190, pl. 32, fig. 1.

Limnaea (Radix) elmeteitensis - Germain 1919: 186.

Limnaea (Radix) gravieri - Germain 1919: 186.

Limnaea (Radix) natalensis - Germain 1919: 185.

Limnaea (Radix) tchadiensis - Germain 1919: 186.

Limnaea (Radix) vignoni - Germain 1919: 186.

Lymnaea exserta - Mandahl-Barth 1954: 71, fig. 32a-c.

Lymnaea natalensis natalensis - Mandahl-Barth 1954: 67, fig. 30a, b.

Lymnaea natalensis caillaudi - Mandahl-Barth 1954: 68, fig. 31a-h.

Lymnaea natalensis nyansae - Mandahl-Barth 1954: 70, fig. 30c-h.

Lymnaea (Radix) natalensis - Brown 1994: 166, figs 76a, b; 79a.

Radix natalensis - Neubert 1998: 354; Lotfy and Lotfy 2015: 29; Glöer 2019 p. 241, fig. 301.

TL.

South Africa, Natal.

Types.

Probably lost. We failed to find them either in ZMB collection or in other institutions (NMNH, NHMUK) known to contain vast collections of African aquatic snails.

R. natalensis is widely distributed in the sub-Saharan Africa as well as in the Nile Basin of Northern Africa ( van Damme 1984; Brown 1994; Lotfy and Lotfy 2015). It also occurs in Arabia ( Neubert 1998) and Atlantic and Indian Ocean islands: Anjouan (Comores), Madagascar ( Brown 1994; Stothard et al. 2000) and the Cabo Verde Islands ( Aksenova et al. 2018a).

The shell of this species is (in its typical form) ovate-conical, with somewhat oblong and narrow spire and ovoid body whorl (see Fig. 6D, E View Figure 6 ). However, some varieties of R. natalensis possess an almost spheroid shell with very low spire (see Fig. 6F View Figure 6 ). The shell height is up to 23 mm ( Lotfy and Lotfy 2015).

We studied anatomically a sample of R. natalensis collected from the crater lake Kyamwiga in Uganda and found that the soft body anatomy of this snail is generally the same as in the species of Radix discussed above. Praeputium is relatively narrow and oblong, darkly pigmented (grey), whereas the penis sheath is typically light coloured and much narrower and a little longer than the praeputium (see Fig. 4H View Figure 4 ); the ratio of their lengths is 0.96 ± 0.07 (see Table 1 View Table 1 ).

The intraspecific shell variation in R. natalensis is very prominent (see Fig. 6 View Figure 6 ) that led some authors to split this species into several ones ( Germain 1919; Mandahl-Barth 1954). Another outcome of this enormous variation is a plethora of nominal species and variety of names proposed to designate the African Radix snails. The synonymy given above represents a small part of this abundance of names (see Germain 1919 for a fuller list of these).

Kingdom	Animalia
Phylum	Mollusca
Class	Gastropoda
Order	Hygrophila
Family	Lymnaeidae
Genus	Radix
SubGenus	Exsertiana