Tubakia byeongjinii D. Hyeon Lee, S.E. Cho & K.C. Shin

Cho, Sung-Eun, Shin, Keumchul, Kim, Yong-Ho & Lee, Dong-Hyeon, 2024, Tubakia byeongjinii, a new species of Tubakiaceae, isolated from Quercus variabilis in South Korea, Phytotaxa 638 (3), pp. 294-300 : 298

Tubakia byeongjinii D. Hyeon Lee, S.E. Cho & K.C. Shin , sp. nov. ( Fig. 2 )

MycoBank No.: MB 851634

Etymology:— byeongjinii is given in honor of Professor Byeongjin Cha, for his contributions as a tree pathologist in South Korea

Type:— SOUTH KOREA. Sejong-si, 36°30'24.5"N 127°17'41.8"E, isolated from leaves on Quercus variabilis , 28 September 2020. The holotype, KA23-0901 , a dried culture of CDH041 was deposited in the herbarium collection (KH) of Korea National Arboretum . The ex-holotype culture ( CDH 041= KACC 49779) was deposited in the culture collection of the National Institute of Forest Science ( CDH) and Korean Agricultural Culture Collection for Type Cultures ( KACC).

Additional specimen examined:— SOUTH KOREA. Sejong-si, 36°30'24.5"N 127°17'41.8"E, isolated from leaves on Quercus variabilis , 28 September 2020, D. H. Lee, culture CDH 040.

Habitat:— On leaves of Quercus variabilis from South Korea.

Colonies on MEA attaining diameter of 65 mm in 10 days, initially white with dense aerial mycelium, spreading, smooth, flat, rapidly turning to olivaceous black, with dark green at 10 days, developing concentric rings of dense mycelium leading to irregular margins. Conidiomata (pycnothyria) superficial, epiphyllous on leaf, radiate scutella 75–107 μm diam., composed of a series of dark brown, thick-walled cells originating from a central cell, ending in a blunt to acute point. Sporodochia superficial with only a few radiating dark hyphae, mainly hypophyllous, on necrotic interveinal tissues and along leaf veins. Conidiophores on underside of scutella. Conidia hyaline, turning light brown with age, smooth to slightly varicose, aseptate, obovoid to ovoid, 7.7–18.6 × 6.3–14.3 μm. Microconidia not observed.

Comments:— Tubakia byeongjinii is phylogenetically closely related T. japonica . However, T. byeongjinii can be distinguished by relatively smaller pycnothyria and conidia compared to those that can be observed in T. japonica ( Saccardo 1913, Harrington & McNew 2018).

Based on morphology and phylogenetic analysis, the species of Tubakia found on Quercus variabilis in South Korea is distinct from all previously described species of Tubakia . In addition to its unique morphological characteristics, its phylogenetic position supports its classification as a novel species of Tubakia , proposed here as Tubakia byeongjinii .

Figures

FIGURE 2. Leaf spot on seedlings of Quercus variabilis caused by Tubakia byeongjinii. A. Symptoms on leaves. B. Scutellum and conidia in germination. C. Close-up view of symptoms and conidiomata. D. Top view of radiate scutellum. E. Conidia. Scale bar: 10 µm.