Alloexidiopsis xantha J. H. Dong & C. L. Zhao, 2024

Dong, Junhong, Zhu, Yonggao, Qian, Chengbin & Zhao, Changlin, 2024, Taxonomy and phylogeny of Auriculariales (Agaricomycetes, Basidiomycota) with descriptions of four new species from south-western China, MycoKeys 108, pp. 115-146 : 115-146

Alloexidiopsis xantha J. H. Dong & C. L. Zhao sp. nov.

Figs 13 , 14 , 15

Diagnosis.

Differs from other Alloexidiopsis species by its coriaceous basidiomata with cream to buff to yellow, smooth, slightly cracked hymenial surface, a monomitic hyphal system with clamped generative hyphae and allantoid to sickle-shaped basidiospores measuring 20–24 × 5–6.2 µm.

Holotype.

China • Yunnan Province, Lincang, Yun County, Dumu Village , 24 ° 32 ′ N, 100 ° 23 ′ E, altitude 2100 m, on the fallen branch of angiosperm, leg. C. L. Zhao, 20 October 2022, CLZhao 25093 ( SWFC).

Etymology.

xantha (Latin or Greek origin): referring to the buff to yellow hymenial surface of the type specimen.

Basidiomata.

Annual, resupinate, closely adnate, coriaceous, very hard to separate from substrate, without odour or taste when fresh, becoming leathery upon drying, up to 10 cm long, 2 cm wide, 200–300 µm thick. Hymenial surface smooth, slightly cracked, cream when fresh, turning to cream to buff to yellow upon drying. Sterile margin cream, thinning out, up to 1 mm wide.

Hyphal system.

Monomitic, generative hyphae with clamp connections, colourless, thin- to thick walled, branched, interwoven, 2.5–3.5 µm in diameter; IKI –, CB –, tissues unchanged in KOH. Hymenium. Cystidia numerous, thin-walled, subcylindrical to subconiform with an obtuse apex, 12.5–17.5 × 3.5–6 µm, with a clamp connection at base; cystidioles absent. Hyphidia arising from generative hyphae, nodulose, frequently branched, colourless, thin-walled, 2.5–4 µm in diameter. Basidia ellipsoid to ovoid, obconical, longitudinally septate, two to four-celled, 18–20.5 × 12–15.5 µm; basidioles dominant, similar to basidia in shape, but slightly smaller. Basidiospores. Allantoid, curved, sickle-shaped, colourless, smooth, thin-walled, IKI –, CB –, (18.5 –) 20–24 (– 24.5) × 5–6.2 (– 6.5) µm, L = 21.66 µm, W = 5.63 µm, Q = 3.60–4.05, Q m = 3.85 ± 0.10 (n = 30 / 1).

Figures

Figure 13. Basidiomata of Alloexidiopsis xantha in general and detailed views (CLZhao 25093, holotype). Scale bars: 1 cm (A); 1 mm (B).

Figure 14. Sections of hymenium of Alloexidiopsis xantha (holotype, CLZhao 25093) A basidiospores B basidia C hyphidia D cystidia. Scale bars: 20 µm (A – D); 10 × 100 Oil.

Figure 15. Microscopic structures of Alloexidiopsis xantha (holotype, CLZhao 25093) A basidiospores B basidioles C cystidia D basidia E hyphidia F part of the vertical section of hymenium. Scale bars: 10 µm (A – F).