We report the enigmatic parasite Dermocystidium ranae in a green frog population (Solomeo, Umbria, Italy) of the Rana esculenta complex, consisting of the parental species R. lessonae (L) and hybrid form R. esculenta (E). In this population a rapid 50% decline of the parental form L was observed. Large dermal U-shaped cysts of D. ranae were found primarily on the ventral aspect of infected individuals, with a significantly higher incidence of infection in the parental species compared to the clonal hybrid. In each form, however, there was little pathological change associated with infection, and the cause of the recent declines of R. lessonae at this site remains unknown. In this paper we present the first ultrastructural description of an amphibian Dermocystidium sp. and we review the taxonomy of Dermocystidium, Dermosporidium and Dermomycoides spp. from amphibians. We conclude that Dermosporidium multigranulare Bro= & Kulda, 1954 is synonymous with Dermocystidium ranae Guyénot & Naville, 1922 and, due to lack of sufficient differences between genera and significant dissimilarities with fish Dermocystidium spp., the 3 amphibian genera are synonymous. We propose that they should be designated to a new genus, Amphibiocystidium n. gen., and Dermocystidium retained for those species parasitic in fish.KEY WORDS: Amphibian · Rana · Dermocystidium· Amphibiocystidium · Amphibian declines Resale or republication not permitted without written consent of the publisherDis Aquat Org 56: [65][66][67][68][69][70][71][72][73][74] 2003 undergoes a premeiotic or occasionally a prediplotene meiotic endoreduplication (Tunner & Heppich-Tunner 1991) and 2 apparently normal meiotic divisions resulting in functional, genetically identical haploid gametes that contain an unrecombined R genome. Hybridity in these lineages is restored each generation through fertilization of these gametes by gametes from syntopic L. The vast majority of E lineages coexist as sexual parasites with the host species L.The L-E system population is widespread throughout Europe (Uzzell & Berger 1975). The proportion of parental species and hybrids in natural populations depends on the environment. It it hypothesized that this is because hybrids are more tolerant to environmental stress than parental species: E, in contrast to L, appears to produce metamorphs that are better adapted to hypoxic conditions and fungicides ordinarily used in agriculture (Tunner & Nopp 1979, Semlitsch & Reyer 1992, Fioramonti et al. 1997, Hotz et al. 1999. Because of this apparent dichotomy in susceptibility to environmental variables, the hybridogenetic system may represent an interesting model for examining the ecology of pathogens. A hybridogenetic L-E system is present on the Italian peninsula; it is formed by a lessonae-like parental species and its esculenta-like hybrid (Uzzell & Hotz 1979, Uzzell 1983, Günther & Plötner 1994. Previous research on the composition of the hybridogenetic system conducted in the Trasimeno Lake district in Central Italy suggests that t...

Pounds et al. argue that global warming contributes to amphibian declines by encouraging outbreaks of the chytrid fungus Batrachochytrium dendrobatidis. Although our findings agree with the climate-linked epidemic hypothesis, this pathogen is probably not the only proximate factor in such cases: in the Trasimeno Lake area of Umbria in central Italy, for example, the water frog Rana lessonae first declined in the late 1990s, yet chytridiomycosis was not observed until 2003 (refs 5, 6). Here we show that the chytrid was common there throughout 1999-2002, in a previously unknown form that did not cause disease. We therefore think that the focus by Pounds et al. on a single pathogen is hard to justify because the host-parasite ecology is at present so poorly understood.

The pathogen of frogs Amphibiocystidium ranae was recently described as a new genus. Due to its spherical shape, containing hundred of endospores, it was thought to be closely related to the pathogens of fish, mammals, and birds known as Dermocystidium spp., Rhinosporidium seeberi, and Sphaerothecum destruens in the Mesomycetozoea, but further studies were not conducted to confirm this relationship. To investigate its phylogenetic affinities, total genomic DNA was extracted from samples collected from infected frogs containing multiple cysts (sporangia) and endospores. The universal primers NS1 and NS8, used to amplify the 18S small-subunit rRNA by PCR, yielded Ϸ1,770-bp amplicons. Sequencing and basic local alignment search tool analyses indicated that the 18S small-subunit rRNA of A. ranae from both Rana esculenta and Rana lessonae was closely related to all of the above organisms. Our phylogenetic analysis placed this pathogen of frogs as the sister group to the genus Dermocystidium and closely related to Rhinosporidium. These data strongly supported the placement of the genus Amphibiocystidium within the mesomycetozoeans, which is in agreement with the phenotypic features that A. ranae shares with the other members of this class. Interestingly, during this study Dermocystidium percae did not group within the Dermocystidium spp. from fish; rather, it was found to be the sister group to Sphaerothecum destruens. This finding suggests that D. percae could well be a member of the genus Sphaerothecum or perhaps represents a new genus.In Italy, Rana esculenta complex water frogs constitute mixed populations of a nonhybrid taxon and hemiclonally reproducing hybrids that are directly analogous to the well-studied central European Rana lessonae/Rana esculenta systems (3,7,16,17). Since 1999, a significantly high incidence of Amphibiocystidium ranae was observed in the parental species, whose frequency has decreased (50%) relative to the hybrid Rana esculenta (12). The skin lesions were observed as small regular hemispherical elevations between 3 and 5 mm in diameter that in some cases became ulcerated. The elevations were observed as single or multiple skin lesions on the infected frogs. Histopathologically, those studies reported several ovoid, U-shape, and/or spherical cysts (sporangia in some mesomycetozoeans) of 100 to 600 m in diameter, containing 2-to 6-m-diameter endospores (2). In the vicinity of these cysts, an inflammatory infiltrated composed by lymphocytes, macrophages, and other leukocytes was always present (2, 9, 12).The phenotypic features of Dermocystidium ranae were recently determined from samples collected in a population of Rana esculenta in central Italy (12). Based on the ultrastructural characteristics of this spherical pathogen, it was found that the so-called Dermocystidium specie in frogs have some features not found in its homologous pathogens of fish, both of which were for a long time classified in the genus Dermocystidium. Thus, the epithet Amphibiocystidium ranae was introduced (12). Th...

The rock partridge, Alectoris graeca, is a polytypic species declining in Italy mostly due to anthropogenic causes, including the massive releases of the closely related allochthonous chukar partridge Alectoris chukar which produced the formation of hybrids. Molecular approaches are fundamental for the identification of evolutionary units in the perspective of conservation and management, and to correctly select individuals to be used in restocking campaigns. We analyzed a Cytochrome oxidase I (COI) fragment of contemporary and historical A. graeca and A. chukar samples, using duplicated analyses to confirm results and nuclear DNA microsatellites to exclude possible sample cross-contamination. In two contemporary specimens of A. graeca, collected from an anthropogenic hybrid zone, we found evidence of the presence of mtDNA heteroplasmy possibly associated to paternal leakage and suggesting hybridization with captive-bred exotic A. chukar. These results underline significant limitations in the reliability of mtDNA barcoding-based species identification and could have relevant evolutionary and ecological implications that should be accounted for when interpreting data aimed to support conservation actions.

In human and wildlife populations, the natural microbiota plays an important role in health maintenance and the prevention of emerging infectious diseases. In amphibians, infectious diseases have been closely associated with population decline and extinction worldwide. Skin symbiont communities have been suggested as one of the factors driving the different susceptibilities of amphibians to diseases. The activity of the skin microbiota of amphibians against fungal pathogens, such as Batrachochytrium dendrobatidis, has been examined extensively, whereas its protective role towards the cutaneous infectious diseases caused by Amphibiocystidium parasites has not yet been elucidated in detail. In the present study, we investigated, for the first time, the cutaneous microbiota of the Italian stream frog (Rana italica) and characterized the microbial assemblages of frogs uninfected and infected by Amphibiocystidium using the Illumina next-generation sequencing of 16S rRNA gene fragments. A total of 629 different OTUs belonging to 16 different phyla were detected. Bacterial populations shared by all individuals represented only one fifth of all OTUs and were dominated by a small number of OTUs. Statistical analyses based on Bray-Curtis distances showed that uninfected and infected specimens had distinct cutaneous bacterial community structures. Phylotypes belonging to the genera Janthinobacterium, Pseudomonas, and Flavobacterium were more abundant, and sometimes almost exclusively present, in uninfected than in infected specimens. These bacterial populations, known to exhibit antifungal activity in amphibians, may also play a role in protection against cutaneous infectious diseases caused by Amphibiocystidium parasites.