Coniosporium epidermidis sp. nov., a new species from human skin

Abstract

Coniosporium epidermidis sp. nov. is described from a superficial skin lesion with blackish discolouration in an 80-yr-old Chinese patient. The species produces dark, thick-walled, inflated, reluctantly liberating arthroconidia without longitudinal septa. Sequences of the ribosomal operon, as well as of the translation elongation factor 1-alpha support its novelty. The species is found in a lineage basal to the order Chaetothyriales, amidst relatives from rock, but also species repeatedly isolated from human skin and nails and eventually causing mild cutaneous infections. Coniosporium epidermidis is consistently found on humans, either asymptomatic or symptomatic. The species indicates a change of life style towards human pathogenicity, which is a recurrent type of ecology in derived Chaetothyriales. Superficial and cutaneous infection by melanized fungi is a new category in dermatology.

Keywords: Black yeasts; Coniosporium; superficial mycosis; taxonomy.

Fig. 1.

Blackish discoloured skin of toes and toe webs with scaling.

Fig. 2.

Skin biopsy stained with HAE; some fungal elements are visible (arrows). Size bar = 5μm.

Fig. 3.

Coniosporium epidermidis, CBS 120353. A. Colony on OA (3 wks). B, C. Elongated and monilioid hyphae, anthroconidia; D, E. Conidial chains; F–J. Mature conidial chains and large conidia with transverse septa. Scale bars 5 μm (B–E); 1 μm (F–J).

Fig. 4.

Phylogenetic tree of Coniosporium epidermidis and allied black fungi based on the completed ITS 1–2 domain including the 5.8S rDNA gene, generated with the TREEFINDER package using the Neighbor-joining algorithm and Kimura correction. The tree was subjected to 100 bootstrap replications; Phialophora europaea, CBS 656.82 was selected as outgroup.

Fig. 5.

Microscopic morphology of Coniosporium epidermidis, CBS 120353; slide culture on SGA, 28 d.