Abstract: The sub-Antarctic islands of the Southern Ocean harbor biogeographically peculiar biotas which are under threat from climate change, biological invasions and their interactions. Understanding both the indigenous and changing non-indigenous components of these islands is essential for the conservation and management of their biotas. Based on several years of systematic sampling, we present an updated list of terrestrial, free-living macro-invertebrates (insects and spiders) present on the islands of Possession (Crozet Archipelago) and Kerguelen. Ninety-four species were recorded in total on both islands. Forty-one are strictly endemic to one of the two islands, 16 are endemic to the South Indian Ocean Province, and only three were recorded on other sub-Antarctic islands. Beetles and more particularly weevils are the most characteristic group of the fauna of these islands: they include 35 species of which 89% are native and 66% are endemic. One third of the species (30 of 94) are non-indigenous species now naturalized. We discuss these results in terms of biogeography, ecological disharmony and impact of biological invasions.

Abstract: Dans un contexte de changement climatique, il est important de déterminer avec précision l’évolution actuelle et future des processus environnementaux pouvant avoir un impact sur les populations. Ainsi, connaitre l’évolution saisonnière du couvert neigeux s’avère crucial car c’est une composante du cycle de l’eau, jouant un rôle de stockage au printemps. La télédétection spatiale joue un rôle important pour le suivi de l’évolution du manteau neigeux aux échelles continentale et régionale. Des études ont déjà mis en avant certains avantages du radar en bande X (notamment son signal de phase). L’analyse du lien entre la réponse de plusieurs paramètres polarimétriques (K0, K3, K4, K7, CCOH et le CPD) et des données météorologiques (dont l’épaisseur du manteau), a permis de conforter l’utilité de la bande X pour la cible neige. On note un intérêt pour l’intensité totale (K0) qui s’avère être intéressante pour l’étude de la hauteur totale de neige. La différence de phase (CPD), ne s’avère pas concluante pour retracer l’épaisseur totale du manteau neigeux dans notre cas d’application. En revanche, elle offre un bon diagnostic des chutes de neige fraiche et pour la cartographie du métamorphisme de la neige.

Abstract: The genus Thelopsis was classified in the family Stictidaceae but its systematic position has never been investigated by molecular methods. In order to determine its family placement and to test its monophyly, fungal DNA of recent collections of Thelopsis specimens was sequenced. Phylogenetic analyses using nuLSU, RPB2 and mtSSU sequences reveal that members of Thelopsis form a monophyletic group within the genus Gyalecta as currently accepted. The placement of Thelopsis, including the generic type T. rubella, within the genus Gyalecta challenges the generic circumscription of this group because Thelopsis is well recognized by the combination of morphological characters: perithecioid ascomata, well-developed periphysoids, polysporous asci and small, few-septate ellipsoid-oblong ascospores. The sterile sorediate Opegrapha corticola is also placed in the Gyalectaceae as sister species to Thelopsis byssoidea + T. rubella. Ascomata of O. corticola are illustrated for the first time and support its placement in the genus Thelopsis. The hypothesis that O. corticola might represent the sorediate fertile morph of T. rubella is not confirmed because the species is phylogenetically and morphologically distinct. Thelopsis is recovered as polyphyletic, with T. melathelia being placed as sister species to Ramonia. The new combinations Thelopsis corticola (Coppins & P. James) Sanderson & Ertz comb. nov. and Ramonia melathelia (Nyl.) Ertz comb. nov. are introduced and a new species of Gyalecta, G. amsterdamensis Ertz, is described from Amsterdam and Saint-Paul Islands, characterized by a sterile thallus with discrete soralia. Petractis luetkemuelleri and P. nodispora are accommodated in the new genus Neopetractis, differing from the generic type (P. clausa) by having a different phylogenetic position and a different photobiont. Francisrosea bicolor Ertz & Sanderson gen. & sp. nov. is described for a sterile sorediate lichen somewhat similar to Opegrapha corticola but having an isolated phylogenetic position as sister to a clade including Gyalidea praetermissa and the genera Neopetractis and Ramonia. Gyalecta farlowii, G. nidarosiensis and G. carneola are placed in a molecular phylogeny for the first time. The taxonomic significance of morphological characters in Gyalectaceae is discussed.