- Helix nitidula Draparnaud [1805]: 117.
- Other synonyms in Europe.
Identification. Shell flattened, subdiscoid, with low rounded spire. Whorls 3½–4½, convex; whorls rapidly enlarging; in apical view, last whorl decidedly broader than penultimate whorl. Periphery rounded, medial. Protoconch smooth. Teleoconch smoothish with inconspicuous fine spiral striae that cross minute colabral striae to form a microscopically reticulate sculpture. Aperture subovate, moderately oblique, edentulous, wider than high. Lip thin, simple. Umbilicus relatively wide, c. 1/4.5 of shell width. Shell thin, nearly opaque, with a waxy lustre (not glossy); reddish amber-brown but with milky-whitish area around umbilicus. Width to c. 6–11 mm (wider than high).
Animal dark bluish grey, paler on sides and tail; sole pale. Tentacles blue-black.
Comparison. Shells of Oxychilus are glossier and without the minute reticulate sculpture of A. nitidula. Under strong magnification, the shell of A. nitidula has microscopic spiral striae that are absent in Oxychilus shells. Under strong magnification, the shell of A. nitidula has microscopic spiral striae that are absent in Oxychilus shells. Zonitoides species are also similar, but spiral striae in Z. arboreus are much weaker, scarcely visible with standard magnification, and spiral striae are absent in in Z. nitidus.
Geographic range. This species is introduced to BC, where it is known from Metro Vancouver (Forsyth et al. 2001). Although Dall (1905) reported “Retinella nitidula” from Great Slave Lake, NWT, this seems likely in error (Forsyth et al. 2001) for, perhaps, Zonitoides nitidus, which he listed from the same locality. Strangely, it remains unknown from elsewhere in North America, although presumably it may have just been overlooked. Aegopinella nitidula is native to Western Europe, from southern Scandinavia to the Iberian Peninsula, and there are scattered occurrences in Eastern Europe, east to Ukraine (Welter-Schultes 2012).
Habitat. In BC, A. nitidula is a synanthrope, living in mature, unkempt gardens and places where garden waste is dumped, such as vacant lots and roadside areas. In lives in leaf litter and under dead wood, dense vegetation such as ivy, stones, and garbage.
Biology. A. nitidula is omnivorous, eating mostly dead plant material but also preying on small snails and slugs, earthworms, and other small invertebrates. This species has a biennial life cycle, maturing and breeding in the summer following its second winter (Mordan 1978).
Etymology. Aegopinella is derived from the land-snail genus Aegopis and the Latin diminutive suffix –ella; Aegopis may mean “goat meadow” (Forsyth 2004), but this is not certain. The gender is feminine. The species epithet is derived from nitidus is Latin, meaning shining, with the diminutive suffix –ula added.
Remarks. See Welter-Schultes (2012) regarding the availability of the name Helix nitidula Draparnaud, 1805.
References
- Dall WH (1905) Land and fresh water mollusks. Doubleday, Page and Co., New York, New York, USA, 1–171, pp.
- Draparnaud J-P-R ([1805]) Histoire naturelle des Mollusques terrestres et fluviatiles de France, ouvrage posthume. Louis Colas, Paris, 164 pp., 13 pls. pp. https://doi.org/10.5962/bhl.title.12856
- Forsyth RG, Hutchinson JMC, Reise H (2001) Aegopinella nitidula (Draparnaud, 1805) (Gastropoda: Zonitidae) in British Columbia—first confirmed North American record. American Malacological Bulletin 16: 65–69.
- Mordan PB (1978) The life cycle of Aegopinella nitidula (Draparnaud) (Pulmonata: Zonitidae) at Monks Wood. Journal of Conchology 29: 247–252.
- Welter-Schultes F (2012) European Non-marine Molluscs, a Guide for Species Identification. Bestimmungsbuch für europäische Land- und Süsswassermollusken. Planet Poster Editions, Göttingen, [3] + 679 + [78] pp.