Cephalotrichum and related synnematous fungi with notes on species from the built environment

A recent taxonomic revision of Microascaceae with an emphasis on synnematous fungi enabled re-identification of previously isolated indoor strains of Cephalotrichum. All available Cephalotrichum strains from the culture collection of the Westerdijk Institute were studied, 20 originating from the built environment. Phylogenetic relationships were inferred from DNA sequence data from the internal transcribed spacer 1 and 2 and intervening 5.8S nrDNA (ITS), and parts of β-tubulin (tub2) and translation elongation factor 1-α (tef1) genes. Additionally, herbarium material of 14 Cephalotrichum species described from soil in China was studied, and the taxonomy of C. album, not considered in recent revisions, was reevaluated. Sixteen phylogenetic species in Cephalotrichum are distinguished, five described as new species: C. domesticum, C. lignatile, C. telluricum, C. tenuissimum and C. transvaalense. Five Cephalotrichum species occur in the built environment: C. domesticum, C. gorgonifer (formerly known as Trichurus spiralis), C. microsporum, C. purpureofuscum, and C. verrucisporum. Based on the number of isolates, C. gorgonifer (nine strains) is the most common indoor species. The study of the Chinese herbarium material resulted in the acceptance of three additional Cephalotrichum species: C. casteneum, C. ellipsoideum, and C. spirale. Four species are considered nomena dubia (C. cylindrosporum, C. macrosporum, C. ovoideum, and C. robustum), five are placed in synonymy with other Cephalotrichum species (C. acutisporum, C. inflatum, C. longicollum, C. oblongum, C. terricola) and one species, C. verrucipes, is probably a synonym of Penicillium clavigerum. Cephalotrichum columnare, former Doratomyces columnaris, is transferred to Kernia. Cephalotrichum album, formerly known as Doratomyces putredinis, is transferred to Acaulium and redescribed.