Melanconis stilbostoma (Fr.) Tul. & C. Tul.

Wang, Caixia, Jiang, Ning, Liu, Chuli, Xu, ZiYan, Lu, Hailong & Ma, Rong, 2025, Morphology and molecular phylogeny reveal new species and records of Diaporthales from Betula in Xinjiang, China, MycoKeys 125, pp. 167-204 : 167-204

Melanconis stilbostoma (Fr.) Tul. & C. Tul. , Select. fung. carpol. (Paris) 2: 115 (1863)

Fig. 13

Description.

Conidiomata acervular, immersed to semi-immersed in the bark, scattered, conical, 850–1200 μm diam., 350–450 μm high. Central column beneath the disc conical, pale yellow. Ectostromatic disc dark brown to black, circular to ovoid, 200–400 μm diam. Conidiophores reduced to conidiogenous cells. Conidiogenous cells cylindrical, smooth, hyaline to pale brown, producing a conidium at apex, (38 –) 55–63.5 (– 69) × 2–3.5 (– 4) μm. Alpha conidia brown, aseptate, ovoid, (11.5 –) 12–13.5 (– 14.5) × (7 –) 7.5–8.5 (– 9) (av. = 12.7 ± 0.7 × 8.1 ± 0.6, n = 50) μm, L / W ratio = 1.4–1.7. Beta conidia hyaline, aseptate, cylindrical, (7 –) 7.5–9 (– 10) × 2–2.5 (av. = 8.4 ± 0.8 × 2.2 ± 0.2, n = 50) μm, L / W ratio = 3.4–4.2.

Culture characteristics.

Colonies on PDA flat, spreading, with moderate aerial mycelium and even margin, white to pale brown, reaching 90 mm diam. after 2 weeks at 25 ° C.

Materials examined.

China • Xinjiang Uygur Autonomous Region, Altay Prefecture, Altay City, Xiaodonggou Forest Park , from branches of Betula pendula , 6 October 2024, Rong Ma, Caixia Wang & Hailong Lu ( XJAU 4035 , cultures CFCC 71570 , CFCC 71571 , CFCC 71572 , CFCC 71573 , CFCC 71574 ) .

Notes.

Melanconis stilbostoma , the type species of the genus Melanconis , has been reported exclusively on hosts of the genus Betula worldwide ( Fan et al. 2018 b; Jaklitsch and Voglmayr 2020). In China, it is commonly found on branches and twigs of Betula platyphylla ( Fan et al. 2018 b) . The morphological characteristics of our collections are consistent with previous descriptions ( Fan et al. 2018 b; Jaklitsch and Voglmayr 2020). In the present study, this species was identified on branches of Betula pendula in XUAR, China, marking its first documented occurrence on this host within the region.

Figures

Figure 13. Morphology of Melanconis stilbostoma from Betula pendula. A – C. Habit of conidiomata on branch; D. Transverse section through conidiomata; E. Longitudinal section through conidiomata; F. Conidiophores and conidiogenous cells; G. Alpha conidia. H. Beta conidia. Scale bars: 500 μm (B – E); 10 μm (F – H).