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The morphology of fossil remains of Vestalenula (Darwinuloidea, Ostracoda) from Crete (Greece), Serbia and Italy were analysed using morphometric valve variability analysis. Three new species were distinguished and described, Vestalenula angulata n. sp., Vestalenula longissima n. sp. and Vestalenula pliocenica n. sp., and represent the first record of this genus in the Neogene of Italy and Serbia. Vestalenula angulata n. sp. was recorded from the early Messinian of Tuscany, Italy (Baccinello and Velona Basins), Vestalenula longissima n. sp. was collected in the Upper Pliocene (Gelasian) sediment core drilled in the Sabina area (Latium, Italy), and Vestalenula pliocenica n. sp. was collected from the Early Tortonian of Vrysses (Rethymnon Basin, Crete), from the lower Messinian deposits of the Velona Basin (Tuscany, Italy), in the Late Pliocene of the Paludinian Beds (Middle Danube Plain) and Mazgoš deposits (Serbia), and in the Upper Pliocene deposits of the Sabina area (Latium, Italy). Despite the freshwater character of most living species of Vestalenula, the fossil species here analysed were found associated with halotolerant forms, showing they could also withstand oligohaline conditions.

The nine papers collected in this special issue of Micropaleontology are a selection of contributions on presented at the 17th International Symposium on Ostracoda (ISO), which was held in Rome, Italy, on 23rd-26th July 2013, and attended by 141 scientists from 29 countries (see text-figure 1).

Ostracoda are microcrustaceans whose soft parts are enclosed in a bivalve carapace composed of low-Mg calcite. Their small dimensions (0.4 to 2.0 mm on average) and hard parts coupled with a long evolutionary history (from Ordovician to Present) and adaptation to all kinds of aquatic habitat make them a successful taxonomic group for paleontological analyses (Rodriguez-Lazaro and Ruiz-Muñoz, 2012). Ostracoda are mainly benthonic and are very strictly linked to their environment. They are particularly sensitive to salinity, depth, temperature, and bottom substrate, as well as hydrochemistry, nutrient content, and pollution. In addition, their carapace is a source of biogenic carbonate, suitable for geochemical studies (Ito et al., 2003). For all these reasons, Ostracoda represent an excellent proxy for the studies of paleoenvironmental changes during the Phanerozoic (Boomer et al., 2003) aswell as for climate reconstructions during Quaternary as widely demonstrated by the recent volume edited by Horne et al. (2012). The present volume, “Ostracoda as proxies for palaeoenvironmental changes — Selected papers from 17th ISO” assembles selected research on paleoenvironments based on Ostracoda that was presented at the 17th International Symposium on Ostracoda, held in Rome (Italy) from the 22nd to the 26th of July, 2013. Prior to this volume, three special issues of Palaeogeography, Palaeoclimatology, Palaeoecology (Holmes and Horne, 1999; Ikeya et al., 2005; Mischke and Holmes, 2008) have stemmed from the International Symposium on Ostracoda (ISO), one of the largest international micropaleontological conferences with a focus on a single microfossil group. The ISO meetings bring together ostracod researchers from all around the world every 4 years to discuss and exchange classic and novelmethods and applications in the study of Ostracoda in a professional but collegial atmosphere. Presentations at these symposia have often been the prelude to notable and significant publications that have advanced our knowledge on the biology, taxonomy, evolution, and ecology of this group of micro-crustaceans and enhanced their application to the earth sciences. The principle of publishing these works in a special issue of a prestigious international journal such as Palaeogeography, Palaeoclimatology, Palaeoecology is intended to bring the latest developments in ostracod research not just to ostracodologists, but also to the wider earth science scientific community.

The living euryhaline species Cyprideis torosa (Jones) undergoes morphometric variations in size, noding and sieve-pore shape linked to the environmental salinity. In particular it is known that salinity values around 8-9 psu represent the osmoregulation threshold and also the turning point between smaller and greater valve dimensions and prevailingly noded against un-noded valves. The variation of the percentage of round-, elongate- and irregular-shaped sieve-pores on the valves has shown an empiric logarithmic correlation with the water salinity from 0 to 100 psu. Due to this ecologically cued polymorphism, C. torosa represents 28 an invaluable palaeosalinometer for the Quaternary brackish basins. In this paper we attempt to verify whether the ecophenotypical behaviour of the post-evaporitic Messinian species Cyprideis agrigentina Decima was comparable with that of C. torosa. To reach this goal, three morphometric characters have been analysed: 1) size variability; 2) noding and ornamentation; 3) variability of the percentage of the sieve-pore shapes. The palaeoenvironmental interpretation was made using synecological and geochemical approaches [stable isotopes, trace elements, Sr-isotopes and natural radioactivity (NRD)]. For this study, the 250 m-thick Messinian Lago-Mare succession of Eraclea Minoa (Agrigento, Sicily) was chosen for the presence of monotypic assemblages made only by C. agrigentina for around 70 m of thickness. The results of the morphometric analyses showed that: 1) size variations are not related to the salinity changes recognized both from synecological and geochemical analyses; 2) no noded specimens have been recovered along the section; 3) the salinities calculated on the basis of the percentage of the sieve-pore shape are not correlated with the salinities inferred from the synecological and geochemical analyses. Thus in this paper we conclude that C. agrigentina cannot be considered a palaeosalinometer for the Messinian Salinity Crisis. There is a correlation of the 13 C and NRD data with the percentages of sieve-pore shapes, linking them to the oxygen availability at the bottom of the basin.

The 7.5 m long SK13 sediment core, drilled at Lake Shkodra (Albania) bottom depth of 7 m in the central southern part of the lake, was selected for multidisciplinary analysis. Ostracods, Characeae, pollens, and stable isotopes were studied with the aim to reconstruct the past biodiversity and the palaeoenvironmental and palaeoclimatic changes occurred during the Middle-Late Holocene. The chronological framework of SK13 was already known and well constrained through radiometric datings. The sediment core age spans from 4560 cal year BP to present. Thirteen ostracod and five charophyte species were identified. Among them, the ostracods Candona montenigrina and Limnocythere scutariense are endemic of the lake; Candona meridionalis and Paralimnocythere georgevitschi have been collected for the first time in the Lake Shkodra while formerly were considered endemic respectively of Lake Dojran and Lake Prespa; Metacypris cordata, ?Carpathocandona sp., and Cyclocypris sp. were never recorded in the lake and were found only in the lower portion of the sediment core. Among the charopytes, Lychnothamnus barbatus and N. hyalina are recorded for the first time in the lake and occurs with high frequency throughout interval A of core. The faunal composition is quite homogeneous, with the percentages of the different species varying along the sediment core. The main change occurs between 1274 and 1197 cal yr BP, where charophytes disappear abruptly as well as 8 ostracod species out of 13, and the frequency of the remaining 5 species dramatically increases. Moreover at that moment, it occurs also the appearance of a peculiar not-tuberculate morphotypes of Ilyocypris monstrifica. The micropaleontological data suggest a decrease of the lake biodiversity since around 1200 cal years BP linked to the transition between an ancient marshland to a lacustrine environment. This drastic change seems to be independent from any global or local climate changes and could be related to the co-occurrence of two phenomena: 1) the Adriatic sea level rise during the Middle and Late Holocene, that that would have uplifted the base level of the River Bojana causing a decrease of its discharge and, consequently, reducing the drainage of the water from the Shkodra swamp; 2) the periodical change of the River Drin course over the last five centuries, which, when deviated into the Bojana river, blocked the River Bojana outflow.

Ilyocypris Brady & Norman, 1889 is a widespread freshwater ostracod genus including about 30 living and 190 fossil species. The specific identification of the living Ilyocypris relies mainly on the appendages, being an identification exclusively based on valves rather complicated because of the high intraspecific variability of their characters in several species. This study aims to test the taxonomic significance of the carapace characteristics through the examination of specimens unambiguously identified on the basis of their soft part morphology, in order to provide useful taxonomic criteria for the identification of Ilyocypris shells in fossil assemblages. Sixty-five ilyocypridid specimens collected in mainland Italy and surrounding islands were analysed. All specimens were dissected and soft parts checked in light microscopy. The patterns of valve surface ornamentation and of marginal ripplets were examined by electron microscopy. Moreover, the geometric morphometric analysis of the valve outlines was performed. Sixty-two specimens could be easily accommodated in eight Ilyocypris species (I. bradyi, I. decipiens, I. getica, I. gibba, I. hartmanni, I. inermis, I. monstrifica, and I. salebrosa) according to the morphology of their appendages. Three additional specimens, with soft parts typical of Ilyocypris but clearly distinct valve morphology, were left in open nomenclature. Our results show that the outline analysis is often a valid tool to discriminate between different species. Conversely, valve ornamentation displays different degrees of intraspecific variability in some Ilyocypris species. The marginal ripplets are constant within each species, but they do not always mirror the patterns reported by other authors; therefore, we do not consider them as reliable diagnostic character for specific determination. This study confirms that the identification of Ilyocypris species requires accurate description of appendages as well as external and internal carapace characteristics, and stresses the advantage of a combined neontological and paleontological investigation in solving taxonomic problems related to non-marine ostracods.