New data on sinistral and scalariform shells among roman snail Helix pomatia Linnaeus, 1758 in Poland

Abstract

As seen from the literature, each occurrence of sinistral and scalariform shell abnormalities among gastropods may have importance for variously aimed studies (e.g. ecological, developmental, genetic) due to the rarity of such abnormalities in nature. Three new records of atypically developed shells of the Roman snail: one sinistral (Wielkopolskie Province) and two scalariform (one record in Wielkopolskie Province and one in Mazowieckie Province) are reported. key words: Helix pomatia, shell abnormalities, Poland Shell abnormalities have long been of interest to malacologists (e.g. HarTmann 1841–1844, rossmassler 1853, meisenHeimer 1912, drozdowski 1962, koralewska-BaTura 1997, Jackiewicz et al. 1998, 1999). Malformations have been described in case of both aquatic (e.g. Jackiewicz 1972, 2000, cHeca & Jimenez-Jimenez 1997, okumura et al. 2008, zuykov et al. 2011, 2012) and terrestrial snails (e.g. okumura et al. 2008, ksiązkiewicz 2011), and several factors have been pointed out as producing deformities, such as genetic abbreviation (e.g. related with radiation), disturbances during embryonic development, population density as well as parasites (Bidwell et al. 1986, Panova et al. 1999, zBikowska & zBikowski 2005, zuykov et al. 2011, 2012). Two types of shell deformities have been intensively studied: sinistral (deviato sinistrorsa) and scalariform (deformatio scalaris) (e.g. cHeca & JimenezJimenez 1997, okumura et al. 2008, zuykov et al. 2012). Some of studies on the occurrence of sinistral and scalariform shells have concerned the Roman snail Helix pomatia Linnaeus, 1758 and emphasised rarity of such deformations. For example meisenHeimer (1912) reported that amongst 20,000 dextral individuals of the Roman snail only one was sinistral. Such data were confirmed by kilias (1960) and nieTzke (1963). nieTzke (1963) also noticed that the frequency of shell deformations was higher under breeding conditions. In his studies 455 shells were regularly developed and 10 were sinistral (2%). Also dziaBaszewski (1977) recorded one horn-shaped individual of the Roman snail in such conditions. wlosik & musial (1982) reported only one sinistral specimen among 585 dextral individuals and only one scalariform amongst 1,140 individuals. Images of such abnormal shells are provided by ferussac & desHayes (1820–1851), Geyer (1927) and Germain (1929) in their publications. In 2008–2014 we conducted monitoring of the Roman snail populations across whole Poland as well as intense quantitative studies on its local populations in the vicinity of the Adam Mickiewicz University in Morasko (northern part of Poznan, Wielkopolskie Province, Fig. 1). The studies were conducted in accordance with the general methodology developed for this species. The snails were searched visually along transects in previously designated areas (Bloszyk & kalinowski 2015, in press). We pinpointed a 48 Jerzy Bloszyk, Tomasz Kalinowski, Zofia Ksiązkiewicz, Krystyna Szybiak total of 15,000 individuals of the Roman snail (Fig. 2) whereas only one snail was abnormal. The living, sinistral individual (Fig. 3) was found in a pine forest near a housing estate and Rozany Potok stream (52.4667391°N, 16.9344401°E) in 2014. Another two abnormal, scalariform specimens were found by accident. A scalariform shell (Fig. 4) was found on the railway embankment near residential buildings, in 2012 (Wielkopolskie Province, 52.4149°N, 16.91519°E, Fig. 1). A live, adult scalariform Roman snail (Fig. 5) was found in Duchnice village (Mazowieckie Province, 52.195429°N, 20.798583°E, Fig. 1). The individual was found near a compost storage, in an area covered with ruderal vegetation and partially shaded by a birch plantation and pine forest. The population size of the Roman snail in the area is difficult to estimate (probably a few hundred individuals), because the species was not subject to detailed surveys in this site. The sinistral as well as the two scalariform specimens were deposited in the Natural History Collection, the Malacology Section (Faculty of Biology, Adam Mickiewicz University, Poznan).