Oidiodendron tokumasui D. Hirose, 2022

Hirose, Dai, Tokiwa, Toshiyuki & Yaguchi, Takashi, 2022, Two novel Oidiodendron species isolated from roots of Vaccinium boninense in the Bonin Islands, Japan, Phytotaxa 566 (1), pp. 89-104 : 100-101

Oidiodendron tokumasui D. Hirose sp. nov. ( Fig. 4–5 )

MycoBank number: MB844531

Description:

Sexual morphs not observed. Colony diam., 28 d, in mm (minimum-maximum): CMA: 5 ˚C (1), 10 ˚C (1–2), 15 ˚C (4.5–11), 20 ˚C (13–19), 25 ˚C (20–29), 30 ˚C (25–28), and 35 ˚C (no growth); PDA: 25 ˚C (23–27); OA: 25 ˚C (29–32); MEA: 25 ˚C (21–27). Colonies on CMA at 25 ˚C, good sporulate, velvety, sparse, buff (45) and reverse buff (45). Colonies on PDA at 25 ˚C, good sporulate, velvety to lanose, radiate-wrinkled, brown soluble pigments, exudate produced as yellow to orange drops, oliveous buff (89) with yellowish white margins, and reverse dark brick (60) with buff (89) margin. Colonies on MEA at 25 ˚C, good sporulate, velvety to lanose, wrinkled, smoke grey (105) with yellowish white margin, and dark brick (60) with buff (89) margin. Colonies on OA at 25 ˚C, good sporulate at the center, velvety, brown soluble pigments, livid vinaceous (83) and partially brown vinaceous (84). Conidiophores abundant, unbranched or branched, melanized, smooth, 30.7–(87.5)–179.1 × 1.5–(2.0)–2.8 μm. Fertile hyphae hyaline, dichotomously branched, 1.3–(1.5)–1.7 μm diam. Conidia thin-walled, hyaline to lightly pigmented, subglobose to cylindrical, smooth, 3.0–(3.7)–4.8 × 1.3–(1.7)–2.0 μm. Chlamydospores absent. Good growth at 20–30 ˚C and pH 3–9, maximal growth at 25 ˚C and pH 7. Brown soluble pigments on PDA at pH 5–7. Ability to form hyphal coil in ericaceous rhizodermal cell.

Etymology:

The specific epithet refers to the Japanese mycologist, former Prof.Dr.Seiji Tokumasu, who has contributed significantly to biodiversity research on microfungi, including the genus Oidiodendron in Japan.

Type:

Chichijima Island , Tokyo, Japan, 2019, isolated from the roots of V. boninense (holotype, TNS-F-91408, dried culture on PDA; ex-type culture, NBRC 115411 ) .

Notes:

Oidiodendron tokumasui is phylogenetically closely related to O. maius (25 bp differences in ITS; 10 bp in LSU; 34 bp in MCM7; 37 bp in RPB1) but can be distinguished on the basis of the morphology of the conidiophores and the optimum temperature and pH. The conidiophores are shorter than those of O. maius . The optimum temperature and pH are higher than those for O. maius .

Figures

FIGURE 4. Morphology of Oidiodendron tokumasui sp. nov. A. 28 day old colony on CMA. B. 28 day old colony on PDA. C. 28 day old colony on MEA. D. 28 day old colony on OA. E. Conidia. F. Scanning electron micrograph of conidia. G‒H. Conidiophores, fertile hyphae, and conidia. I. Hyphal coils within hair roots of Vaccinium virgatum. Hyphae are stained brown. Scale bar: E, G‒I = 10 µm, F = 5 µm.

FIGURE 5. Line drawings of microscopic morphology of Oidiodendron tokumasui sp. nov. A‒B. Conidia. C‒D. Conidiophores, fertile hyphae, and conidia. Scale bar: A‒B = 5 µm, C‒D = 10 µm.