Phacidiella xishuangbannaensis D. P. Wei, sp. nov.

Index Fungorum number: IF 902253; Mycobank number: MB 902253; Facesoffungi number: FoF 16057 Fig. 60

Etymology: – The specific epithet is derived from Xishuangbanna District, Yunnan Province, China

Holotype – HKAS 134946

Saprobic on dead woody twig. Sexual morph: Apothecia 322–518 × 530–816 µm (x̄= 426 × 632; n = 10), cupulate, with a lager opening, immersed, gregarious, with entire, white-pruinose margin. Disc creamy yellow, splitting away from the margin when dry. Exciple 70–160 µm (x̄=101; n=15), consisted of three layers: (1) a accessory thalline margin, (2) a wall extended from subhymenium, of hyaline, thick-walled cell of textura angularis, (3) a crystalliferous layer. Periphysoidal layer not observed. Paraphyses 0.8–1.6 (x̄= 1.1; n = 20), filiform, aseptate, apically branched, circinate, not enlarged. Asci 247–289 × 5.3–8 µm (x̄= 260 × 6.2; n = 10), cylindrical, slightly narrow toward the apex and base, 8-spored, with a thick apex. Ascus cap 2.3–4.4 × 2.6–4.8 µm (x̄=3.5 × 4; n = 20), hemisphere, pierced by a pore, J−. Ascospores 138–252 × 1.2–2.4 µm (x̄=193 × 2; n=30), filiform, hyaline, slightly acute at both ends, aseptate, guttulate when young, becoming multiseptate, smooth-walled with age, non-disarticulating, no contraction at septa, the interval cell 3.6–7.5 μm (x̄=5.4, n=25) in length. Asexual morph: Not observed.

Culture characteristics – Culture was obtained from germinating ascospores. Colony on PDA reaching 16 mm diam. after 30 days at 25 °C, brown, slightly raised, mycelia dense, cottony, margin entire, surface dotted with brown liquid drops, reverse yellow–brown at periphery, dark brown at center.

Material examined – China, Yunnan Province, Xishuangbanna, on dead woody twig, 12 September 2022, De-Ping Wei, ST6 (HKAS 134946, holotype), ex-type, KUNCC 23-15698.

GenBank numbers – ITS=OR769025, LSU=OR808082, mtSSU=PP832018, RPB2=OR775513.

Notes – The new species Phacidiella xishuangbannaensis clusters with P. alsophilae, P. podocarpi and P. kunmingensis, forming a monophyletic clade in Stictidaceae with 94% ML and 0.99 BYPP. Phacidiella alsophilae (Crous et al. 2020a, b) and P. podocarpi (Crous et al. 2014) were known exclusively from asexual morphs, making it impossible to compare their morphologies with P. xishuangbannaensis. However, the pairwise comparison of nucleotide between P. xishuangbannaensis and P. alsophilae shows that there are 12 bp (512/527) and two bp (855/857) differences in ITS and LSU regions, respectively. The nucleotide comparison between P. xishuangbannaensis and P. podocarpi indicates that there are 54 bp (500/554, ITS) and 26 bp (770/796, LSU) differences. Phacidiella kunmingensis was introduced based on its sexual morph by Wei et al. (2022a, b). Phacidiella xishuangbannaensis has similar characteristics to P. kunmingensis in terms of the morphologies and dimensions of apothecia, exciple, paraphyses, asci and ascospores. However, the former differs from the latter species in 62 bp (503/565, ITS), 84 bp (869/953, LSU), 48 bp (642/690, mtSSU) and 155 bp (855/1010, RPB2).

Figure 1 – Phacidiella xishuangbannaensis (HKAS 134946, holotype). a Apothecia on a dead  twig. b, c Enlargement of apothecia. d, e Vertical section through apothecia. f Exceplium. g, h Asci. i Paraphyses. j–l Ascospores. m, n Apex of asci and paraphyses, respectively. o, p Upper and lower view of culture on PDA media. Scale bars: d, e=200 μm, f–k=50 μm, l–n=10 μm. (j–n treated with Melzer’s reagent)