Folia Malacol. 29(1): 43–50 https://doi.org/10.12657/folmal.029.006 ANALYSIS OF THE ADVENTITIOUS FAUNA OF TERRESTRIAL MOLLUSCS IN THE CENTRE OF THE RUSSIAN PLAIN EVGENIY V. SCHIKOV Tver State University, St. Pos. Kalinina, 37-21, Lyubertsy, Moscow region, Russia, 140002 (e-mail: [email protected]) ABSTRACT: The terrestrial mollusc fauna of the central part of the Russian Plain has been analysed with respect to its species composition and the proportion of adventitious species. The classification of adventitious species follows that accepted in Russia. Considerable changes in the fauna took place in the period 2016–2020. Helix lucorum Linnaeus and Cornu aspersum (O. F. Müller) were added to the terrestrial malacofauna of the area. Within the last four years, Arion vulgaris Moquin-Tandon colonised anthropogenic habitats and its spread continues. Krynickillus melanocephalus Kaleniczenko, Arianta arbustorum (Linnaeus), and Helix pomatia Linnaeus are now firmly established in natural ecosystems. Populations of A. vulgaris, K. melanocephalus, and A. arbustorum have become so abundant that now they cause significant damage to agricultural crops. In both natural and anthropogenic habitats K. melanocephalus and A. arbustorum displace Succinea putris (Linnaeus), Deroceras laeve (O. F. Müller), D. sturanyi (Simroth), D. invadens Reise, Hutchinson, Schunack et Schlitt, D. agreste (Linnaeus), D. reticulatum (O. F. Müller), Fruticicola fruticum (O. F. Müller) and Euomphalia strigella (Draparnaud). Interactions between invasive species are discussed. The proportion of alien species in several European countries and in Central Asia is compared. KEY WORDS: adventitious fauna; gastropods; terrestrial gastropods; interactions between species INTRODUCTION Consequences of the introduction of invasive spe- diseases. At the same time, still very little is known cies are diverse and largely negative. This is observed about adventitious species and, as the situation in both natural and anthropogenic habitats. They is changing rapidly, the processes of introduction enter into a variety of interactions with autochtho- should be monitored. nous species, as competitors, predators or vectors of The first alien species in the centre of the Russian parasites and diseases. This, in many cases, leads to plain were recorded in the early 19th century. At the impoverishment or even extinction of native mollusc end of the 20th century, the number of adventitious species and sometimes to changes in the structure species began to increase markedly. Because of the of whole biocoenoses. The consequences in anthro- explosive character of introductions within the last pogenic ecosystems (horticultural and agricultural four years, it seemed necessary to assess the changes cultivations) often include grave economic losses. since the last survey (SCHIKOV 2016a) and to update Some introduced species are vectors of parasites and the state of knowledge. MATERIAL AND METHODS The basis for this work was the study of the ter- habitats of the Moscow, Novgorod and Tver regions restrial malacofauna of natural and anthropogenic [oblasts] of 1963–2020. The research was carried 44 Evgeniy V. Schikov out in two periods. The collections from 1963– permanent populations. Alien species include species 2015 were analysed in the previous paper (SCHIKOV which are not present in natural habitats and species 2016a). Further field work was done in 2016–2020 whose appearance in such habitats has been reliably in order to identify changes in the faunas that took established during long-term studies. Random, ac- place in recent years. Collecting was done in various cidental or casual alien species are species which districts of the Moscow, Pskov and Tver regions. In are found outside their native range in an area where total, 452 samples were taken. Of these, in 279 cas- they cannot form stable populations. This category es, the collection was carried out exactly at the same does not include species that naturally appear out- places which had been surveyed in 1963–2015. In side their natural habitats, such as birds during mi- many cases, over the past years, the habitats have gration, flood-swept molluscs, etc. Invasive species been radically changed: meadows are now overgrown are alien species which expand their range relatively with forests, floodplain meadows of the Volga are fast (over several decades) or increase the range of overgrown with tall grasses, pine forests have be- habitats which they occupy. come mixed pine-small-leaved forests, etc. The sur- Adventitious fauna is a group of species in the vey repeated after a long interval made it possible to regional fauna which is heterogeneous in origin and trace the changes in the terrestrial malacofauna of a heterochronous in time of advent, formed as a re- large number of ecosystems: several types of natural sult of migrations, due to direct or indirect human and secondary pine and spruce forests, various kinds influence. The term is analogous to the “adventitious of natural and secondary deciduous forests (oak, ash, flora” (GRIGORYEVSKAYA et al. 2004). aspen, birch, alder), willow thickets, floodplain and Introduction – deliberate introduction of a new dry meadows, and anthropogenic habitats (botanic species into the fauna by man. Induction is an un- garden, parks, lawns, fallow land, abandoned fields controlled, spontaneous spread of species as a result with tall weeds, commercial greenhouses). of anthropogenic changes in landscapes or accidental The materials obtained during the study period importations. I regard occasional importation of mol- were compared with the review data published in luscs as souvenirs, or importation by merchants for 2016 (SCHIKOV 2016a). The results of the comparison sale in pet shops, as accidental importation. were partially published in 2020 (SCHIKOV 2020a). In the general review of the terrestrial malacofauna CLASSIFICATION OF ADVENTITIOUS SPECIES of the central part of the Russian Plain, the earliest OF TERRESTRIAL MOLLUSCS arrivals: Deroceras reticulatum (O. F. Müller, 1774), D. sturanyi (Simroth, 1894), Arion fasciatus (Nilsson, The division of adventitious species into groups 1822) and Trochulus hispidus (Linnaeus, 1758), are re- was carried out in accordance with the European garded as “partly autochthonous”. This is due to the standards (WEIDEMA 2000, GENOVesI & SHINE 2004, fact that they are native to the central and southern Głowaciński et al. 2013). Alien species are classified parts of the Moscow and Tver regions and adven- in geographical, chronological, and ecological terms. titious in the northern parts (SCHIKOV 1979, 1982, 1984, 2016a, SCHILEYKO 1982). DIVISION OF ADVENTITIOUS SPECIES The estimate of the number of species in the fau- ACCORDING TO THE ORIGIN nas of the studied regions was carried out taking into account new records and modern ideas of their sys- Three groups: T – transcontinental, i.e. immi- tematics (SYSOEV & SCHILEYKO 2004, SCHIKOV 2007), grants from other continents; R – regional, i.e. spe- except for Vertigo lilljeborgi Westerlund, 1868, which cies from the same continent. The latter are divided I regard as a separate species. The classification of in two subgroups: RE – immigrants from Europe, adventitious species of terrestrial molluscs used here and RA – immigrants from Asia. follows that developed for Russia (SCHIKOV 2016a). Species originating from the Mediterranean coun- tries of Europe and North Africa, from the Black TERMINOLOGY Sea region, the Carpathians and the Transcaucasia, as well as from the Balkans and Asia Minor, are in- The basic terminology follows that of cluded in group RE. This is based on the fact that Głowaciński et al. (2013) and GRIGORIEVSKAYA et their northward spread started from Europe and the al. (2004). Some of the terms are proposed for the Balkans. first time. Native, indigenous or autochthonous species DIVISION OF ADVENTITIOUS SPECIES are species which live within their natural distribu- ACCORDING TO THE TIME OF ARRIVAL tion range. Alien, non-native, introduced, non-in- digenous, foreign, or exotic species are species liv- Three groups: A – archaic-advent species arrived ing outside their natural range, where they can form in the study area before the 19th century, H – histor- Adventitious fauna of Russian plain 45 ical-advent species entered the area from the begin- DZ – domestizoids are species that live in buildings: ning of the 19th century until 1990, L – latest-advent houses, basements, vegetable stores, hothouses and species were discovered after 1990. greenhouses; CZ – colonozoids, their populations may live in secondary habitats for a long time, but DIVISION OF ADVENTITIOUS SPECIES do not spread further; EZ – epecozoids have invaded ACCORDING TO THE DEGREE OF anthropogenic habitats and continue to spread; AZ – NATURALISATION agriozoids are adventitious species which are firmly established in natural ecosystems. The terminology is analogous to that adopted by botanists (GRIGORYEVSKAYA et al. 2004). Four groups: RESULTS Ninety eight species of terrestrial molluscs were genera. The autochthonous terrestrial malacofauna recorded from the territory of the Moscow, Novgorod of these regions includes 72 species of 21 families and Tver regions. They represent 23 families and 49 and 39 genera (SCHIKOV 1971, 2016b). Ten of them Table 1. Adventitious species of terrestrial molluscs in the fauna of the central part of the Russian Plain. Source: SCHIKOV (2016a) supplemented with data from 2016–2020. For explanations of categories see text