We compare data from a survey of ostracode species carried out during 1994-1998 from Northern Italian ricefields with data from the same area collected in the ’60s. Twenty-five species were recorded during a survey of 19 ricefields in 1994-98 as against 46 species found in 16 ricefields over thirty years ago. Three of these species (Ilyocypris biplicata, Chlamydotheca incisa and Chrissia sp.), as well as six among the 27 species found in the '60s but not recorded during 1994-1998, were found in Italy only in the ricefield habitat. Three species were recorded for the first time in Italy: Hemicypris dentatomarginata, Ilyocypris monstrifica and Chrissia sp. Eight taxa (Chlamydotheca incisa, Chrissia sp., Cypretta turgida, Dolerocypris sinensis, H. dentatomarginata, Isocypris beauchampi, Strandesia spinulosa and Tanycypris pellucida) were considered endemic to South America, Africa or Asia and are thought to have been introduced to Italy with useful plants, notably rice varieties. The recording of these species indicates once again the importance of man as an agent for passive dispersal of ostracode and the role of ricefields as a suitable habitat for new exotic colonising species. Heterocypris incongruens is the most widespread species and several other species (D. sinensis, Cypridopsis vidua, Ilyocypris gibba and Isocypris beauchampi cicatricosa) were found in more than 50% of the ricefields sampled: 40% of the species occur in just one or two ricefields. In Northern Italy today, species similarity between ricefields is inversely related to their geographic distance but is not spatially structured. This may be due to the fact that, in ostracodes, the production of passive dispersal resting eggs constrains regional differentiation. Species richness is significantly related to the amount of cultivated area. The decrease in species richness observed over the last thirty years or so may be related to the widespread use of pesticides in local current agricultural practices

We followed the artificial colonization of a temporary pond in Northern Italy by the freshwater ostracod Heterocypris incongruens. The species had not been found in the pond in previous years. In May 2009 we released five laboratory reared, genetically identical, parthenogenetic females and observed the population during colonization and growth until desiccation (May- July 2009) and two subsequent hydro-periods (February-March and May-July 2010). High population density was always reached in few weeks, although in late winter 2010 no ovigerous female was observed and in spring 2010 the population was recruited only from resting eggs. In all three hydro-periods swarms formed every day and could be easily seen near the border of the pond to the eye around the median time of the sun path. In laboratory observations, individuals sampled from the swarm forming population showed predatory behaviour: H. incongruens attack, kill and consume live, actively self-defending organisms (Chironomid and mosquito larvae). We also observed cannibalism among adult females. We found low fecundity and high mortality in females sampled from the crowded population and kept in low density laboratory conditions. We discuss how cannibalism, delayed egg hatching, fecundity loss and high mortality by crowding regulate high density populations of H. incongruens, a typical r strategy species. Key words

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Differences exist in the population structure of Heterocypris in five temporary ponds on the islands of Lampedusa and Linosa (Isole Pelagie, south of Sicily). In a temporary pond on Lampedusa (Cavallo Bianco) we found only H. incongruens females. All the other populations were bisexual, with the female/male sex ratio varying from 1 to 18. We analysed and measured a sub-sample from each population and observed, as a typical morphological feature of adult females in the bisexual populations, a lobe-like expansion of the selvage (lamella hyalina) on the posterior margin of the left valve. In another temporary pond from Lampedusa (Vallone della Forbice) both females with this lamella and others without it occur. We discuss the possible coexistence of two lineages of H. incongruens each having a different reproductive mode. The parthenogenetic lineage comprises females without a lamella hyalina whereas the bisexual females possess this feature. Alternatively, we hypothesise the sympatry of two different species of Heterocypris: H. incongruens and H. barbara. In this hypothesis, H. incongruens is parthenogenetic and H. barbara is amphimictic. Differences in mean body size between the adult females with and without the lamella hyalina are in accordance with values reported in the literature for niche differentiation among sympatric taxa.

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This paper reports on the occurrence of Daphnia pulex in a small fishless water body of Northern Italy (Bodrio del pastore III) and describes its population dynamics. Bodrio is a typical water body originated by erosion from the old Po river-bed surface. During a three year study (2011)(2012)(2013)

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