Plankton dynamics across the freshwater, transitional and marine research sites of the LTER-Italy Network. Patterns, fluctuations, drivers.

A first synoptic and trans-domain overview of plankton dynamics was conducted across the aquatic sites belonging to the Italian Long-Term Ecological Research Network (LTER-Italy). Based on published studies, checked and complemented with unpublished information, we investigated phytoplankton and zooplankton annual dynamics and long-term changes across domains: from the large subalpine lakes to mountain lakes and artificial lakes, from lagoons to marine coastal ecosystems. This study permitted identifying common and unique environmental drivers and ecological functional processes controlling seasonal and long-term temporal course. The most relevant patterns of plankton seasonal succession were revealed, showing that the driving factors were nutrient availability, stratification regime, and freshwater inflow. Phytoplankton and mesozooplankton displayed a wide interannual variability at most sites. Unidirectional or linear long-term trends were rarely detected but all sites were impacted across the years by at least one, but in many case several major stressor(s): nutrient inputs, meteo-climatic variability at the local and regional scale, and direct human activities at specific sites. Different climatic and anthropic forcings frequently co-occurred, whereby the responses of plankton communities were the result of this environmental complexity. Overall, the LTER investigations are providing an unparalleled framework of knowledge to evaluate changes in the aquatic pelagic systems and management options.

Revision of Recent and fossil Mixtacandona Klie 1938 (Ostracoda, Candonidae) from Italy, with description of a new species.

Although studies on ostracods dwelling in inland subterranean habitats of Italy have increased in the last decades, highlighting a considerable taxonomic diversity, available information is still far from sufficient to understand phylogenetic and biogeographic relationships. Mixtacandona Klie 1938 is one of the most common and diverse genera of ostracods in subterranean waters. Of the 20 living recognized species in the genus, all stygobiontic and restricted to the Palearctic Region, four are known for the Italian peninsula and Sardinia, one of which exclusively as fossil. Several other Recent and fossil taxa attributable to Mixtacandona, but identified at supraspecific level, have been reported from various Italian regions. Here we report Mixtacandona idrisi n. sp., collected in a cave near Palermo, the first cavernicolous ostracod from the island of Sicily; in addition, the description of material recently collected in northern Italy, consisting of M. laisi and of a putative new species that has been tentatively allocated to the same genus, is given. Mixtacandona (Trapezicandona) italica Karanovic & Pesce, 2000 is tentatively treated as a junior synonym of M. talianae Gliozzi & Mazzini, 1998. The validity of species-groups within Mixtacandona is discussed. Relying on the results of this study, the authors argue for the need of a comprehensive revision of the genus.

An annotated checklist of the Recent non-marine ostracods (Ostracoda: Crustacea) from Italy.

We present an updated checklist of non-marine ostracods from Italy. Data were obtained from the published literature up to April 2013 and new collections carried out in 18 out of 20 Italian regions. Altogether, 1665 ostracod samples were collected from 1241 new sites visited between 1981 and 2013. Sites were selected to encompass the most widespread types of freshwater aquatic habitats (i.e., pools, ponds, peat bogs, springs and streams, etc.). This field study led to the identification of 89 ostracod species. Five additional taxa remained at the generic level because only few (juvenile) individuals were available or the material was damaged. Of particular interest is the occurrence of four species new to Italy: Candonocypris novaezelandiae, Eucypris elongata, Ilyocypris getica and I. hartmanni. In addition, three putative new species (Pseudolimnocythere sp., Candona sp.1 and Eucypris sp.1) are left in open nomenclature. After synonymising several species and removing invalid taxa reported in the literature, the updated checklist now includes 152 species and 5 taxa identified at supraspecific level, belonging to 57 genera and 12 families (Candonidae, Cyprididae, Cytherideidae, Darwinulidae, Ilyocyprididae, Notodromadidae, Limnocytheridae, Leptocytheridae, Loxochonchidae, Hemicytheridae, Xestoleberididae and Entocytheridae). For each species, its distribution in Italy and its bibliographic records (including synonyms) for Italy are provided.

Contribution to the knowledge of the genus Vestalenula Rossetti & Martens, 1998 (Crustacea, Ostracoda, Darwinulidae), with the description of a new species, V. carinata n. sp., from the island of Florianópolis, Brazil.

The genus Vestalenula is the most species rich in the putative ancient asexual ostracod Family Darwinulidae. Several new Recent species were described from various continents, mostly based on carapace shape and structure. These species were found in a variety of aquatic and (semi-) terrestrial habitats, including springs, streams, interstitial waters, leaf litter in forests and in splash zones of waterfalls. Here, we describe V carinata n. sp. from moist leaf litter, collected from the Brazilian island of Florian6polis. The species belongs to the danielopoli-lineage within the genus because of its elongated internal tooth in the left valve and elongated external keel on the right valve. It can be distinguished from all other species in this group by its size, its L/H ratio and the relative length of the keel. The relationship of this new species to the enigmatic, putative marine species Senidarwinula terraenuxforna Choe, 1988, is discussed. An identification key to species of the genus is provided.

How ancient are ancient asexuals?

Ancient asexual animal groups, such as bdelloid rotifers and darwinuloid ostracods, are excellent model organisms to study the effects of long-term asexuality. However, the absolute length of time that these groups have been fully asexual is mostly ignored. In the case of the darwinuloid ostracods, the fossil record shows that sexual reproduction disappeared almost completely after the end of Permian mass extinction (ca. 245 Myr ago), although several putative records of males from the Mesozoic obscure the exact time-frame of obligate asexuality in darwinuloids. Here, we re-examine the Mesozoic darwinuloid records, with regard to the reproductive mode of the assemblages. Three criteria to distinguish males in fossil populations (lack of brood pouch, position of muscle scars and size dimorphism) are used here to test for the presence of males in darwinuloid assemblages. A large, well-preserved assemblage of Darwinula leguminella (Forbes 1885) from the latest Jurassic (ca. 145 Myr ago) of England is found to be markedly variable in size and shape, but nevertheless turns out to be an all female assemblage. The exceptional preservation of the material also allows the re-assignment of this species to the extant darwinuloid genus Alicenula. All other putative dimorphic darwinuloid records from the Mesozoic are re-examined using the same criteria. The hypothesis that these assemblages represent bisexual populations is rejected for all post-Triassic (ca. 208 Myr ago) records.