Fungalpedia – Note 1020, Exophiala

 

Exophiala. J.W. Carmich.

Citation when using this data: Tian Q et al. 2021 (in prep.) – Fungalpedia, Ascomycota.

Index Fungorum, Facesoffungi, MycoBank, GenBank, Fig 1

Classification: Herpotrichiellaceae, Chaetothyriales, Chaetothyriomycetidae, Eurotiomycetes, Pezizomycotina, Ascomycota, Fungi

Pathogenic, saprobic, endophytic and fungicolous on a variety of hosts. Vegetative hyphae branched, unswollen, forming protruding fascicles. Hyphae hyaline to pale brown, irregularly septate, smooth-walled, thin-walled, sometimes pigmented. Sexual morph: Undetermined. Asexual morph: hyphomycetous. Conidiophores absent or present, erect, multicellular, brown, septate, oblong to cylindrical. Conidiogenous cells sympodial, lateral, intercalary or terminal, mono- or polyphialidic, ovoid to clavate, subhyaline to pale brown, septate. Conidia ellipsoidal, cylindrical, allantoid, hyaline to brown, aseptate or 1-septate, with a conspicuous conidial scar, smooth-walled, with small oil drops. Chlamydospores absent (Carmichael 1966).

Notes – The black yeast genus Exophiala J.W. Carmich. was established by Carmichael (1966) to accommodate Exophiala salmonis J.W. Carmich. Species of Exophiala are characterized by brown, aseptate to 1-septate conidia, forming successively from the apex of the sporogenous cells and forming protruding fascicles, aggregating in slime balls (Carmichael 1966). Members of Exophiala have been linked to the sexual genus Capronia (Herpotrichiellaceae, Chaetothyriales) (Carmichael 1966, Hironaga et al. 1981, de Hoog et al. 2011). 

Exophiala has remarkable ecological traits. Species of Exophiala appears to be an opportunistic pathogen of animals, including humans (Richards et al. 1978, de Hoog et al. 2011, Najafzadeh et al. 2013, Wen et al. 2016) and environmental taxa in anthropogenic habitats or natural environments (Ávila et al. 2005, Bukovská et al. 2010, de Hoog et al. 2011, Ferrari et al. 2011, Isola et al. 2013), endophytes from roots (Ali et al. 2016, Maciá-Vicente et al. 2016) and saprobes or fungicolous taxa, occurring on a wide range of substrates (Madrid et al. 2016). Exophiala species are difficult to identify by morphology because of the polymorphic morphology, therefore, phylogenetic affinities and ecological traits are necessary for species identification (de Hoog et al. 2011, Isola et al. 2013, Maciá-Vicente et al. 2016). 

Type material – Canada, Alberta, isolated from the brain of Salmo clarkii Richardson (Salmonidae), 1966, J.W. Carmich. (CBS 157.67, ex-type).

Type species: Exophiala salmonis J.W. Carmich., Sabouraudia 5: 122 (1966).

Other accepted species: Species Fungorum – search Exophiala.

 

image

 

Figure 1 – Exophiala salmonis (redrawn from Seifert et al. 2011). a Conidia. b, d Conidiogenous cells. c Conidiogenous cells with conidia. e Conidiophore. Scale bar: a–e = 10 μm.

 

References

Ali T, Schmuker A, Runge F, Solovyeva I et al. 2016 – Morphology, phylogeny, and taxonomy of Microthlaspi (Brassicaceae: Coluteocarpeae) and related genera. Taxon 65(1), 79–98.

Ávila A, Groenewald JZ, Trapero A, Crous PW. 2005 – Characterisation and epitypification of Pseudocercospora cladosporioides, the causal organism of Cercospora leaf spot of olives. Mycological Research 109, 881–888.

Bukovská P, Jelínková M, Hršelová H, Sýkorová Z et al. 2010 – Terminal restriction fragment length measurement errors are affected mainly by fragment length, G + C nucleotide content and secondary structure melting point. Journal of Microbiological Methods 82, 223–228.

Carmichael JW. 1966 – Cerebral mycetoma of trout due to a Phialophora-like fungus. Sabouraudia 5(1), 120–123.

de Hoog GS, Vicente VA, Najafzadeh M, Harrak M et al. 2011 – Waterborne Exophiala species causing disease in cold-blooded animals. Persoonia 27, 46–72.

Ferrari BC, Zhang C, van Dorst J. 2011 – Recovering greater fungal diversity from pristine and diesel fuel contaminated sub-Antarctic soil through cultivation using both a high and a low nutrient media approach. Frontiers in Microbiology 2, 217.

Isola D, Selbmann L, de Hoog GS, Fenice M et al. 2013 – Isolation and screening of black fungi as degraders of volatile aromatic hydrocarbons. Mycopathologia, 175(5–6), 369–379.

Madrid H, Hernández-Restrepo M, Gené J, Cano J et al. 2016 – New and interesting chaetothyrialean fungi from Spain. Mycological progress 15, 1179–1201.

Najafzadeh MJ, Dolatabadi S, Saradeghi Keisari M, Naseri A et al. 2013 – Detection and identification of opportunistic Exophiala species using the rolling circle amplification of ribosomal internal transcribed spacers. Journal of Microbiological Methods 94, 338–342.

Wen YM, Rajendran RK, Lin YF, Kirschner R et al. 2016 – Onychomycosis associated with Exophiala oligosperma in Taiwan. Mycopathologia 181(1), 83–88.

 

Entry by

Qing Tian, Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai 57100, Thailand, School of Science, Mae Fah Luang University, Chiang Rai 57100, Thailand

 

Published online 16 December 2021

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