Sporocadus changchunensis R. Xu, W. X. Su, Phukhams. & Y. Li sp. nov.

Fig. 2

Etymology.

Refers to the type location, Changchun City.

Description.

Saprobic on dried stems of Crataegus pinnatifida. Sexual morph: Ascomata 184–251 × 279–385 μm (x ̄ = 225 × 331 μm, n = 5), single or gregarious, scattered, submerged, depressed globose to globose, visible as light black circles or bark-colored bumps host surface. Ostiolar canal 72–80 × 44–53 μm (x ̄ = 75 × 50 μm, n = 5), cylindrical, sulcate, protruding fillen with periphyses. Peridium 15–47 μm wide, thin-walled, composed of 4–10 wall layers, outer part comprising brown cells of textura angularis, inner layer thin-walled, brown from the outside radiating to hyaline towards the inside. Hamathecium of dense, 4–7 μm (x ̄ = 5 μm, n = 10) wide, filamentous, septate, rounded at the apex, cellular paraphyses surrounding asci. Asci 71–88 × 7–8 μm (x ̄ = 79 × 7 μm, n = 10), 4–8 ascospores, bitunicate, fissitunicate, broad cylindrical, some curved, short-pedicellate, apically rounded or slightly pointed with J + ring. Ascospores 9–16 × 5–8 μm (x ̄ = 13 × 6 μm, n = 30), uniseriate, partially overlapping, fusiform to oval, primary septum median, slightly asymmetrical, with 0–3 transverse septa, without vertical septa, hyaline, surface verrucous, without mucilaginous sheath. Asexual morph: Undetermined.

Culture characteristics.

Colonies on PDA, reaching 2 cm diam after 7 days at 25 ° C. Culture from above, dense mycelium, sparse in the periphery, light yellow in the hyphae, light green in the edge of the colony, with three concentric circles on the back of the colony, black or yellow in the center, white to light green radiating outwards, round.

Material examined.

China • Jilin Province: Changchun, dead stem of Crataegus pinnatifida Bunge, 20 February 2022, W. X. Su and C. Phukhamsakda, HMJAU 60190 (holotype); ex-type, EMFCC 0014.

GenBank accession numbers.

ITS = OR 791294, LSU = OR 791292, rpb 2 = PQ 096954, tef 1 - α = PQ 096031, tub 2 = PQ 122556.

Notes.

In the BLASTn search, the ITS region of strain EMFCC 0014 showed 98.43 % similarity to S. lichenicola (CBS 446.70) with 99 % query cover, translating to 97.45 % similarity. Comparatively, the LSU gene region displayed 99.43 % similarity to S. lichenicola (CBS 160.25) with 99 % query cover, translating to 98.44 % similarity, while the closest match of the tub 2 sequence with 94.57 % similarity was S. rotundatus (CBS 616.83). Sporocadus changchunensis (EMFCC 0014) formed a sister clade to S. rotundatus (CBS 616.83) with strong bootstrap support (93 % ML and 0.99 BPP). The base pair differences between the two species are 3 bp in ITS, 29 bp in tef 1 - α, 20 bp in rpb 2, and 35 bp in tub 2. The new isolates also share a close phylogenetic affinity to S. cavernicola. However, there is no report for the sexual morph of S. cavernicola and S. rotundatus (Liu et al. 2019; Razaghi et al. 2024). Morphologically, Sporocadus changchunensis differs from S. italicus, which was also found on Crataegus, by its narrower ostiolar canal (75 × 50 vs. 80 × 75 µm), wider hamathecium (4–7 vs. 2.6–4.1 μm), and smaller asci (71–88 × 7–8 vs. 102–129 × 8.5–10 μm) (Hyde et al. 2017). Additionally, the ascospores of S. italicus are ellipsoidal-fusiform or ampulliform, multi-seriate, and sometimes contain one vertical septum, whereas those of S. changchunensis are fusiform to oval, uniseriate, and without a vertical septum (Hyde et al. 2017). Hence, we introduce S. changchunensis as a novel species, and this is the first report of Sporocadus species in Northeast China.