CONTRIBUTION TO THE FRESHWATER GASTROPODS OF THE ISLAND OF ANDROS IN THE NORTHERN CYCLADES (AEGEAN ISLANDS, GREECE)

New data on the freshwater gastropods of the island of Andros (Northern Cyclades, Greece) are presented. We surveyed the gastropod fauna of 27 freshwater springs, rivulets and water reservoirs located mainly in the central part of the island. Six gastropod species were identified. At least two more species of the genera Pseudamnicola and Bythinella were also recorded. Although all the gastropod species are known from mainland Greece, Theodoxus fluviatilis (Linnaeus), Physa acuta Draparnaud, Planorbis atticus (Bourguignat) and Galba truncatula (O. F. Müller) are reported for the first time from Andros. Literature records, material examined, taxonomic remarks, and ecological information such as altitudinal ranges and habitat preferences are given for each species. Illustrations and distribution maps are provided; the history of the fauna is briefly discussed. kEy words: Aegean archipelago, distribution, Greece, new records, habitat preferences, taxonomy


INTRODUCTION
Freshwater gastropods from Greece have been recorded by various authors in the last two centuries (e.g. clEssin 1878a, b, boEttGEr 1889, schütt 1980, rEischütz et al. 2008).bank (2006) published a comprehensive catalogue of freshwater molluscs, including distribution records and references.Since then, many notable works have added to our knowledge of freshwater gastropods of Greece with exploration of new localities, description of new species and genetic analyses (e.g.GlöEr et al. 2010, albrEcht et al. 2012, Falniowski et al. 2012, radEa et al. 2013a, b, szarowska et al. 2016a, b).So far, only few Greek islands have been surveyed for freshwater gastropods (e.g. rählE 1980, schütt 1980, 1982, 1986, rEischütz 1985, bank 1988, sEidl 2001, radEa et al. 2016, szarowska et al. 2016a, b), whereas in older studies mainly general information, for example prefecture names and spe-cies lists from collecting trips, was provided (e.g.clEssin 1878a, b).Contemporary works, fortunately, provide detailed information on localities and very often adopt a comprehensive approach to species delimitation, including genetic and morphological analyses (e.g.radEa et al. 2016, szarowska et al. 2016a, b).These works often focus on single species or species-groups (e.g.Falniowski et al. 2012, szarowska et al. 2014, radEa et al. 2016).
Andros is the northernmost island of the Cyclades in the central Aegean Sea; it is located about 12 km southeast of Evvoia Island and approximately 55 km east of mainland Greece (Attica).With its area of ca.379 km 2 , it is the second largest island of the Cyclades after Naxos.It is mainly mountainous, with the highest altitude at 994 m (Mount Petalo, peak of Kouvara).Andros has the highest annual precipitation in the Cyclades, and holds a richness of vascular plants consisting mainly of maquis, phrygana and forests (polEMis et al. 2012).It is also one of the richest Cycladic islands in terms of freshwaters, partly due to its geographical position and geological relief (broGGi 1996).The central part of the island is rich in small rivulets and freshwater springs.Several wetlands exist in its northern part (broGGi 1996).Andros was isolated from the mainland around 30 to 18 kya BP (lykousis 2009), and was completely detached from the other Cycladic islands around 8 to 6 kya BP (kapsiMalis et al. 2009).Archaeological excavations show that the earliest human presence on the island was during the Mycenaean times or even earlier (liritzis 2010).
Here, we provide new distribution data on the freshwater gastropods of Andros with notes on their taxonomy and habitat preferences.There is a need for modern and integrative work (genetic and morphological) regarding several freshwater gastropod species to disentangle their biogeographic history and to serve conservation purposes.

MATERIAL AND METHODS
Samples were collected along the central valley of the island (Messaria), located between Mount Petalo (994 m) in the north and Mount Gerakonas (720 m) in the south, on the 22nd-24th August 2014, 14th May 2015 (1 site), and 28th-31st August 2015.The 27 surveyed localities included freshwater springs, ephemeral waters, tanks, natural pools, ditches and rivulets/streams between 0 (site 9) and 663 m (site 21) a.s.l (Figs 1-27, Table 1).The specimens were collected by hand from fallen leaves, spring walls and floor and submerged vegetation.
All specimens were preserved in spring water and subsequently in 70% ethanol.They were identified based on shell and/or anatomical characters, using a ZEISS Discovery.V20 stereomicroscope and photographed with the attached AxioCam MRc5 using the stacking module of the software ZEISS AxioVision SE 64 4.9 to obtain focused images .
The material is deposited in the Malacological Collection of the 3rd Zoological Department at the Natural History Museum of Vienna (NHMW).

RESULTS
"Previous records" refer to previously recorded occurrences of the species on the island of Andros."Distribution and IUCN status" is provided for the species when available from the IUCN Red List.

Class: Gastropoda Cuvier, 1795
Family: Neritidae Rafinesque, 1815   The occurrence of T. fluviatilis in six sites does not support schütt's (1986) view that Andros (and possibly other Cycladic islands) was inhabited by T. saulcyi.Our findings agree with bunjE & lindbErG (2007) who propose that most probably Theodoxus spp.from Greece belong to four distinct clades; our specimens fall in the distribution area of T. fluviatilis and other clades of Theodoxus sp.However, there is urgent need for an integrative taxonomic revision of the genus in Greece as there is no agreement between the existing morphological and phylogenetic findings.
The only record of H. acuta, a widely introduced species originating in North America, is a site near the main settlement of the island, including an extensive cultivated land and a bird-reserve wetland; it could be a result of transport by humans or birds.The species is known to be carried by water birds or large mammals (see van  Our work is a step towards increasing and establishing the knowledge of Greek freshwater gastropods.The results presented here suggest the need for innovative work on multiple species-groups and the need for systematic revisions.For example, the south-eastern Mediterranean (including Greece) is probably inhabited by a separate species in addition to the European A. fluviatilis which is so often mentioned in the literature (for discussion see pFEnninGEr et al. 2003, albrEcht et al. 2006)

Table 1 .
This is the first record from Andros.Habitat notes: The species was collected from six localities between 185 and 441 m a.s.l.The snails were attached to rocks or concrete walls of usually fast flowing waters.In site 17 (and 17a), the species was abundant.Distribution and IUCN status: T. fluviatilis is a Western Palaearctic species, ranked as Least Concern (IUCN 2016).Site 8, Apoikia, village entrance, on road curve, stream with flowing and stagnant water, 295 m a.s.l., 37°50'44.9"N,24°54'21.8"E,leg.List of surveyed sites and their coordinates.The name of the closest village or settlement is given Strapouries, fountain Metoxi-Ipsilou and concrete tank next to it 37°50'05.64"N,24°54'25.29"E Figs 1-27.The surveyed localities.Site numbers correspond to those in Table1