Taxonomic and phylogenetic position of Rinocladiella mackenziei (Ramichloridium mackenziei), causal agent of cerebral abscission in human

Back ground and Cerebral phaeohyphomycosis in humans is caused by fungal agent which belongs to black yeasts. The disease is apparently restricted to Middle East been reported from Saudi Arabia, occupied Palestine and Qatar. The disease has not been recorded from Iran yet or its existence has not been noticed. Ramichloridium mackenziei is responsible for this disease, which belongs to fungal order chaetothyriales. Members of this order are mainly opportunistic pathogens on humans and animals causing a wide range of infections such as chromoblastomycosis (cutaneous, subcutaneous) and cerebral phaeohyphomycosis. Species recognition and delineation in members of this order is based on morphological features of asexual stage (anamorph). This order encompasses several genera such as Ramichloridium, Rhinocladiella, Exophiala, Veronaea, Cladophialophora. Some members of this order are morphologically similar to plant pathogenic or saprotrophic species and there is no clear-cut morphological differences among these genera. Accurate identification of human pathogenic species in both clinics and natural ecological niches will play important role in our understating on ecology of these fungi. In present study, 24 isolates belonging to 15 species from three genera viz., Ramichloridium, Rhinocladiella and Veronaea were subjected to morphological and molecular examinations. Morphological features were evaluated on malt extract agar, using a slide culture technique. Phylogenitc relationship among isolates was inferred based on sequence data from two genomic regions of ribosomal DNA including partial sequences from ITS-rDNA and LSU-rDNA. Phylogeny inferred from DNA sequence data placed isolates in two groups. Clade one included Rhinocladiella and Veronaea together with Ramichloridium mackenziei and R. fasiculata, R. anceps and Rhinocladiella basitona which all belong to the order Chaetothyriales. The second clade included type species of genus Ramichloridium (R. apiculatum) together with other plant pathogenic Ramicholridium species which belong to the order Capnodiales. Putting together DNA sequence data, ecology and morphology, Rhinocladiella is an appropriate genus to accommodate Ramichloridium mackenziei. taxonomic and phylogenetic position of Ramichloridium mackenziei is ascertained in Chaetothyriales. Combination of DNA data set together with morphology and ecology is indispensable in identification of human pathogenic Chaetothyriales. Current work is good starting point towards studying importance and diversity of these fungi in Iran.