Complete sequences of 18S rDNA of seven strains of Tetracladium were determined. The following species were included: T. apiense, T. furcatum, T. maxilliforme, T. setigerum (one strain each) and T. marchalianum (3 strains). Sequence homology among the 7 strains was >98%. The closest published match (NCBI database) to the Telracladium sequences is one by Bulgaria inquinans (homology 95-96%). Phylogenetic analysis placed the Tetracladium complex in the vicinity of the Ascomycete orders Onygenales, Erysiphales and Leotiales.
Nikolcheva L. G., Bärlocher F. (2002): Phylogeny of Tetracladium based on 18S rDNA. – Czech Mycology 53(4): 285–295.