Phaeobotryon rhoinum Fan, 2018

Zhu, Hai-Yan, Tian, Cheng-Ming & Fan, Xin-Lei, 2018, Studies of botryosphaerialean fungi associated with canker and dieback of tree hosts in Dongling Mountain of China, Phytotaxa 348 (2), pp. 63-76 : 68

Phaeobotryon rhoinum Fan sp. nov. Fig. 2

MycoBank MB 824808

Holotype:— China, Beijing City, Mentougou District, Dongling Mountain , Xiaolongmen Forestry Centre , from branches of Rhus typhina , 17 Aug. 2017, H. Y. Zhu & X. L. Fan, deposited by X. L. Fan, holotype CF 2017820, ex-type living culture CFCC 52449 .

Etymology:—Named after the host genus on which it was collected, Rhus .

Descriptions:—Asexual morph: Pycnidial stromata immersed in the bark, globose, scattered to gregarious, erumpent slightly through the surface of bark, unilocular. Ectostromatic disc honey to hazel, inconspicuous, circular. Ostioles black, inconspicuous, at the same level as the disc surface, surrounded below disc by lighter entostroma. Locule single, globose, (230–)250–420(–450) μm in diam. Conidiogenous cells formed from the cells lining the inner walls of the locules, hyaline, smooth, inconspicuous. Conidia ellipsoid to oblong, smooth to verruculose, moderately thick-walled, guttulate, ends rounded, initial hyaline, aseptate, becoming brown, 1-septate when mature, (18.5–)19– 21(–21.5) × (7–)7.5–9 (= 20.1 ± 0.8 × 8.2 ± 0.5 μm, n = 50) μm. Sexual morph: not observed.

Culture characteristics: Culture on PDA is initially white, becoming olivaceous to fuscous black after 7–10 days. The colony is felt-like, thick and fluffy with abundant aerial mycelium. Pycnidia distributed irregularly on the medium surface.

Materials examined: — China, Beijing City, Mentougou District, Dongling Mountain, Xiaolongmen Forestry Centre , from branches of Rhus typhina , 18 Aug. 2017, H. Y. Zhu & X. L. Fan, deposited by X. L. Fan, CF 2017825, living culture CFCC 52450 ; ibid. CF 2017828, living culture CFCC 52451 .

Notes:— Phaeobotryon rhoinum is associated with canker disease of Rhus typhina , which has similar characteristics with P. rhois . Morphologically, P. rhoinum has smaller conidia (19–21 ×7.5–9 μm) as compared with the conidia (20– 25 × 10–12 μm) of P. rhois ( Fig. 2 ) ( Fan et al. 2015a). Phylogenetically, it clusters in a separate lineage ( MP / ML / BI = 99/100/1) compared to all other strains included in this study, and therefore we describe this species as a new.

Figures

FIGURE 2. Morphology of Phaeobotryon rhoinum from Rhus typhina (CF 201782). A: Symptoms on the host. B, C: Habit of pycnidia on a twig. D: Transverse section of pycnidia. E: Longitudinal section through pycnidia. F–H: Conidiogenous cells and conidia. I: immature conidia. J–K: mature conidia. Scale bars: B = 1 mm; C–E = 500 μm; F–K = 10 μm.