Phaeoacremonium tuscanicum and Phaeoacremonium indicum sp. nov. associated with subcutaneous phaeohyphomycosis

Abstract

Two cases of phaeohyphomycotic infections were caused by Phaeoacremonium tuscanicum, not previously identified in human infections, and one new species, Phaeoacremonium indicum, respectively. Morphological and cultural investigation as well as phylogenetic analysis was constructed based on maximum likelihood analyses using actin and -tubulin sequences to identify the fungal isolates.

Keywords: Phaeoacremonium; Phaeohyphomycosis; actin; beta-tubulin.

Figure 1.

Maximum likelihood phylogeny of the genus Phaeoacremonium based on concatenated alignments of the β-tubulin (TUB2) and actin (ACT) regions. Bootstrap support (≥50%) and Bayesian posterior probability values (≥0.60) are indicated on the branches. Branches with complete support (100/1) are indicated with star symbols (★). Species included in this study are shaded with grey, and strains from this study are indicated in bold font. Clades with multiple strains of the same species have collapsed. Calosphaeria africana (CBS 120,870), Jattaea algeriensis (CBS 120,871), and Wuestineaia molkaiensis (STE-U 3797) were included as outgroup taxa.

Figure 2.

Phaeoacremonium indicum (STE-U 6377, ex-type). (a – c) Sixteen-day-old colonies on MEA (a), PDA (b), and OA (c). (d – v) Aerial structures on MEA; (d) Mycelium showing prominent exudate droplets observed as warts; (e – g) Mycelium with hyphal swellings; (h – j) Single conidiophores; (k – m) Branched conidiophores; (n – p) Type I phialides; (q – s) Type II phialides; (t – u) Type III phialides; (v) Conidia. (w – y) Structures on the surface of and in MEA; (w – x) Phialides and adelophialides with conidia; (y) Conidia. Scale bar: d–y = 10 µm.