Riella cossoniana Trab. (Riellaceae, Marchantiophyta) new to France

Riella (Riellaceae, Sphaerocarpales) is a genus of aquatic liverworts with disjunct range in areas of Mediterranean-type climates. Riella has been traditionally subdivided into two subgenera, subgenus Riella, whose plants show smooth or papillose female involucres and Trabutiella, whose plants show winged female involucres. To date only three species of Riella are known in France, all belonging to subgenus Riella. During the course of a study of the plant diversity of temporary brackish ponds in the Camargue area (Southern France), soil sediments were collected from 10 localities and cultivated in the laboratory. From cultures of five of these localities emerged dioicous plants of Riella showing winged female involucres that unambiguously assigned them to subgenus Trabutiella. The study of those specimens with Light and Scanning Electron Microscopy allowed us to identify them as R. cossoniana var. cossoniana. Fresh materials allowed for detailed morphological analyses on these new French materials which were fully described and illustrated. These findings represent the first report of a species belonging to subgenus Trabutiella from France and the second European country where R. cossoniana is reported. Four nearby populations occur within the perimeter of the Tour du Valat Regional Natural Reserve, and another in the industrial polygon of the Grand Port Maritime de Marseille. © 2014 Adac. Tous droits réservés.Peer Reviewe

High resolution ancient sedimentary DNA shows that alpine plant diversity is associated with human land use and climate change

International audienceThe European Alps are highly rich in species, but their future may be threatened by ongoing changes in human land use and climate. Here, we reconstructed vegetation, temperature, human impact and livestock over the past ~12,000 years from Lake Sulsseewli, based on sedimentary ancient plant and mammal DNA, pollen, spores, chironomids, and microcharcoal. We assembled a highly-complete local DNA reference library (PhyloAlps, 3923 plant taxa), and used this to obtain an exceptionally rich sed aDNA record of 366 plant taxa. Vegetation mainly responded to climate during the early Holocene, while human activity had an additional influence on vegetation from 6 ka onwards. Land-use shifted from episodic grazing during the Neolithic and Bronze Age to agropastoralism in the Middle Ages. Associated human deforestation allowed the coexistence of plant species typically found at different elevational belts, leading to levels of plant richness that characterise the current high diversity of this region. Our findings indicate a positive association between low intensity agropastoral activities and precipitation with the maintenance of the unique subalpine and alpine plant diversity of the European Alps