Cytospora kuanchengensis C.M. Tian & N. Jiang, 2020

Cytospora kuanchengensis C.M. Tian & N. Jiang sp. nov. Figure 4 View Figure 4

Diagnosis.

Cytospora kuanchengensis can be distinguished from C. oleicola and C. pruinose by longer conidia.

Etymology.

Named after the county where it was collected, Kuancheng County.

Description.

Sexual morph: not observed. Asexual morph: Pycnidial stromata ostiolated, immersed in bark, scattered, erumpent through the surface of bark, discoid, with multiple locules. Conceptacle black, circular surrounded stromata. Ectostromatic disc black, circular to ovoid, (350-)455-540(-575) µm diam., with 1-7 ostiole per disc. Ostioles black, at the same level as the disc, (40-)60-85(-115) μm diam. Locule numerous, arranged circularly or elliptically with independent walls, (285-)355-520(-605) µm diam. Peridium comprising few layers of cells of textura angularis, with innermost layer brown, outer layer brown to dark brown. Conidiophores hyaline, unbranched, thin walled, filamentous. Conidiogenous cells enteroblastic polyphialidic, (6.5-)8.5-11(-15) × 1-1.5 μm (x̄ = 9.8 × 1.3 μm). Conidia hyaline, allantoid, smooth, aseptate, thin-walled, (5.5-)6-7.5(-8) × 1-2 μm (x̄ = 6.9 × 1.6 μm).

Culture characters.

On PDA at 25 °C in darkness. Cultures are initially white, producing pale brown pigment after 10 d. The colony is flat, felt-like, with concentric circular texture. Pycnidia distributed irregularly on medium surface.

Specimens examined.

China, Hebei Province, Chengde City, Kuancheng County, chestnut plantation, 40°38'37"N, 118°27'54"E, on branches of Castanea mollissima , 13 October 2017, N. Jiang (holotype BJFC-S1695, ex-type living culture CFCC 52464; paratype BJFC-S1696, living culture CFCC 52465).

Notes.

Cytospora kuanchengensis is associated with canker disease of Castanea mollissima in China. Cytospora kuanchengensis differs from its phylogenetically closely species, C. pruinosa , by ITS and ACT loci (7/470 in ITS and 21/245 in ACT). Morphologically, C. kuanchengensis has slightly larger conidia than C. pruinose (5.5-8 × 1-2 μm in Cytospora kuanchengensis vs. 5-7.5 × 1-1.5 μm in C. pruinosa ) ( Fan et al. 2020).