Diaporthe ulmina Y.K. Bai & X.L. Fan, 2023

Bai, Yukun, Lin, Lu, Pan, Meng & Fan, Xinlei, 2023, Studies of Diaporthe (Diaporthaceae, Diaporthales) species associated with plant cankers in Beijing, China, with three new species described, MycoKeys 98, pp. 59-86 : 59

Diaporthe ulmina Y.K. Bai & X.L. Fan sp. nov.

Fig. 4

Etymology.

Named after the host genus on which it was collected, Ulmus .

Description.

Sexual morph: Ascostromata immersed in bark, erumpent, with 3-4 perithecial in black entostromata, conceptacle absent, 300-600 μm diam. Perithecia black, scattered, arranged circularly, ovoid to spherical, 250-380 μm (av. = 310 ± 30 μm, n = 30) diam. Asci 8-spored, unitunicate, clavate to cylindrical, sessile, 37-43 × 4.5-7 μm (av. = 40 ± 1.5 × 5.6 ± 0.5 μm, n = 50). Ascospores fusoid, hyaline, 2-4 guttulate, smooth-walled, 9-11 × 2-3.5 μm (av. = 9.9 ± 0.4 × 2.8 ± 0.4 μm, n = 50), L/W = 3-4 (av. = 3.4 ± 0.2, n = 50). Asexual morph not observed.

Culture characteristics.

Cultures with felty aerial mycelium are initially white, growing slowly and entirely covering the 9 cm Petri dish after 8 days, felty with a uniform texture and regular edge. Conidiomata were not observed until 30 days.

Specimens examined.

China, Beijing, Mentougou District, Mountain Dongling, Xiaolongmen Forestry Centre , 39°58'19.65"N, 113°12'39.24"E, from branches of Ulmus pumila , 16 Jun 2022, Y.K. Bai & X.L. Fan (holotype BJFC CF202212142, ex-type living culture: CFCC 58828; other living culture: CFCC 58829; ibid. BJFC CF2022121423, culture CFCC 58830) .

Notes.

Diaporthe ulmina is associated with canker disease of Ulmus pumila . In this study, the isolates CFCC 58828 and 58829 formed a single-lineage clade with high support values (ML/BI = 100/1.00) and it appears to be most closely related to D. huairouensis (Fig. 1 ). Diaporthe ulmina differs from D. huairouensis isolated from Corylus heterophylla by host association ( Bai et al. 2022). Phylogenetically, D. ulmina can be distinguished from D. huairouensis by base differences as follows: 16/466 for ITS, 4/420 for cal, 17/473 for his3, 34/329 for tef1-α and 10/420 for tub2 ( Bai et al. 2022). Therefore, D. ulmina is described as a new species.

Figures

Figure 1. Phylogenetic tree of Diaporthe resulting from a Maximum-Likelihood (ML) analysis, based on the concatenated sequences from ITS, cal, his 3, tef 1 - α and tub 2 genetic regions. Numbers above the branches indicate ML bootstraps (left, ML BS ≥ 50 %) and Bayesian posterior probabilities (right, BPP ≥ 0.90). The tree is rooted with Diaporthella corylina CBS 121124. Isolates from the present study are marked in blue and holotype isolates are indicated in bold.

Figure 4. Diaporthe ulmina from Ulmus pumila (BJFC CF 202212142) A, B habit of ascomata on branch C transverse section through ascomata D longitudinal section through ascomata E asci F ascospores G top (left) and bottom (right) sides of colonies on potato dextrose agar (PDA) after 7 days. Scale bars: 500 μm (B-D); 10 μm (E, F).