Xerolenta obvia
Xerolenta obvia is a species of air-breathing land snail, a terrestrial gastropod mollusk in the family Geomitridae.
;Subspecies:Xerolenta obvia depulsa Xerolenta obvia obvia Xerolenta obvia pappi
- ''Xerolenta obvia razlogi''
Habitat and Distribution
The species is associated with dry, exposed, grassland, often in ruderal sites. It has been found up to an altitude of 2000 m in the Swiss Alps. It often occurs at very high densities.Xerolenta obvia is supposed to be native to the Balkans and parts of eastern Europe. In the Czech Republic and Slovakia two fossil finds are from the middle Holocene but most such occurrences are from later. The species has been introduced more widely since the end of the 19th century, so that it now occurs from Asia Minor to Spain and north to Scandinavia. It has also been introduced to Canada and the USA.
In the USA, this species is considered to represent a potentially serious threat as an invasive species that could negatively affect agriculture, natural ecosystems, human health or commerce. Attempts have been made to control introduced populations in the USA and Spain. It has been suggested that this species be given top national quarantine significance in the USA.
Description and identification
Shells of adult Xerolenta obvia are 7–10 mm high and 14–20 mm wide, so relatively flat. Up to 5–6 whorls are present. The umbilicus is about 1/4 the width of the shell. The shells are thick and opaque, and almost smooth. The shell colour is white or yellowish-white, most often decorated with quite variable, dark-brown to almost-black spiral bands. As the animals reach maturity, the body whorl scarcely descends more steeply, and no rib develops inside the aperture, but the umbilicus widens so that the centre of the spiral looks more excentricly placed.In Central Europe X. obvia is most likely to be confused with Cernuella neglecta and Helicella itala. The former develops a brown rip inside the aperture when it is fully grown. The latter has a somewhat wider umbilicus and the body whorl redirects downwards before growth ceases. The two dart sacs provide the clearest distinguishing characters. In X. obvia they are symmetrical and diverge from the vagina at their tips, which are slightly angular. In contrast, in H. itala the sacs are longer and closely bound to the vagina; in C. neglecta the sacs lie connected over one another on one side of the vagina.