Pseudotaeniolina globosa and Quambalaria cyanescens: Rare fungal species within the microbiome of green frogs’ integument (Pelophylax esculentus complex) in Serbia

Abstract

Fungi and bacteria are among the most frequently encountered microbiome constituents of the nutrient-rich amphibians’ integument. Mycological analyses of the integument of the water green frogs from the Pelophylax esculentus complex were conducted in three localities in the region of the South Banat District where all three taxa (P. ridibundus, P. lessonae, and P. esculentus) coexist. Identification of fungal isolates was conducted by molecular methods, namely by amplification of ITS and BenA genes. After BLAST analyses, two rare fungal species: Quambalaria cyanescens (Microstromatales, Basidiomycota) and Pseudotaeniolina globosa (Capnodiales, Ascomycota), were documented. As a plant-colonizing fungus, Q. cyanescens is predominantly associated with Eucalyptus spp. in Australia. The presence of this fungus on P. esculentus in the locality Jaruga is the first record for amphibians, as well as the first record for Serbia. Although reported as a predominantly plant symbiont, Q. cyanescens is regarded as a potential opportunistic pathogen whose impact on amphibians has yet to be determined. On the other hand, P. globosa is a microcolonial, rock-inhabiting fungus seldom isolated worldwide, mostly on stone surfaces of historic monuments (eg., Djoser Pyramid in Saqquara, Egypt; the church of “Santa Maria di Mili” in Messina, Italy), and hence, has a limited dataset available in the GenBank database. The finding of P. globosa on P. lessonae from the canal DTD is also the first record of this fungus in Serbia as well as on amphibians. This finding is significant since P. globosa as a melanised fungus belongs to a large group of potential amphibian pathogens. In the case of P. lessonae, this is of particular importance since its global population trend is declining due to its constant and growing environmental threats (which include pathogenic fungi, e.g. Batrachochytrium) and consequently has a higher local extinction vulnerability than the other two taxa.