Intumescentia – Facesoffungi Number: FoF 15839

Etymology – The name refers to the typical hyphal swellings that occur in this group of fungi.

Description – The slow-growing colonies on PDA are black-brown in colour (top and reverse), compact, superficial, with usually grey or greenish black, tomentose, and the margins may be entire, finely serrated or irregularly lobed. Hyphae are asperulous or smooth, brown in color, septate, multi-guttulate, and branched; their compartments are variable in size, usually with hyphal swelling that are apical or intercalary in position, with lateral branching usually arising from the swollen compartments. Conidial cells catenulate, three to eight or more in a chain, they are intercalary or apical in position, and are caducous. The conidia are columnar to doliiform in shape, dark brown in color, and basal and intercalary conidia have flat apices, and apical conidia with an acute apex are multi-guttulate. No sexual structures were observed.

Type species – Intumescentia tinctorum H. L. Si, R. L. Chang, T. Bose and Y. C. Wang

Notes – The genus Intumescentia displays a significant morphological variance with closely related genera Acidiella, Araucasphaeria, and Xenopenidiella. In comparison to Intumescentia, Acidiella, and Xenopenidiella, they yield morphologically distinct mitospores. Acidiella produces puffed and truncated arthroconidia, while Xenopenidiella produces branched chains of verruculose conidia that are ellipsoid to cylindrical-oblong in shape and brown in color. Araucasphaeria is known to produce sexual spores. Fungi from the genera Acidiella, Araucasphaeria, and Xenopenidiella have a faster growth rate than Intumescentia.