Trechispora khokpasiensis Pinruan, Sommai & Khamsuntorn

Deng, Peng-Tao, Yan, Jun, Liu, Xiang-Fen, He, Zheng-Mi, Lin, Yuan, Lu, Ming-Xin & Zhang, Ping, 2023, Three coralloid species of the genus Trechispora (Trechisporales, Basidiomycota) in China: two newly discovered taxa and one reported for the first time, MycoKeys 99, pp. 153-170 : 153

Trechispora khokpasiensis Pinruan, Sommai & Khamsuntorn

Figs 2 , 3 , 4

Basidiomata.

Clavarioid, scattered or fascicled, 25-30 mm tall, 15-36 mm broad, chalk white (1A1), slightly yellow (2A2) with age, apices white (1A1), yellowish white (3A4) when dry. Stipe single, short and flattened, 10-15 × 3-4 mm, white. Branches flattened or palmate, palmately branched from flattened stipe, dense, 4-7 mm wide, polychotomous below, dichotomous towards apices, internodes becoming gradually longer, branches 6-8 mm diam, divided 3-5 times, apices cristate or flattened, blunt, axils V-shaped. Flesh white to pale yellow, waxy. Taste and odor unrecorded.

Micromorphology.

Generative hyphae septate, clamped, interwoven, smooth, thin-walled, hyaline; tramal hyphae parallel arranged, 2-4 μm wide, smooth, thin-walled, hyaline. Subhymenial hyphae branched and wide, 3-8 μm; ampulliform septa present in the hyphae, 5-6 µm wide. Basidia: approximately 22-28 × 5.5-8 µm with four sterigmata 3-4.5 µm long, hyaline, subcylindrical to clavate, slight constriction, clamp connection in base. Cystidia absent. Basidiospores [40/4/3] 5-6 (-6.5) × 3-4 μm [Q = 1.33-1.72(1.83), Qm = 1.57 ± 0.16], ellipsoid, angular, finely verruculose or echinulate, hyaline, thin-walled, spines 0.5-1 μm long, apex slightly blunt; hilar appendage extremely small, obscured by spore ornamentation, inamyloid, contents usually uniguttulate.

Habit and distribution.

Solitary to caespitose, grows on humus in broadleaf forest or grows on soil; basidiomata generally occur in summer. Known from Thailand ( Sommai et al. 2023), Laos and China.

Notes.

Trechispora khokpasiensis is mainly characterized by chalk-white basidiomata and flattened branches. Trechispora pallescens (Bres.) Singer is easily mistaken for T. khokpasiensis in the field on account of its similar size, shape, and color. However, the two species occur in different habitats: T. khokpasiensis grows in the humus layer on soil without any plant root association. Trechispora chartacea (Pat.) Gibertoni also has flattened, narrowly spathulate branches, grayish white in age, axils U-shaped, arising from scarce white mycelia on the soil. However, T. khokpasiensis differs in that the axils are V-shaped, the basidiomata are pale yellow with age, and it grows on dead branches and leaves. Trechispora caulocystidiata is distinguished from T. khokpasiensis by having subglobose basidiospores and possessing caulocystidia.

In the present phylogenetic analyses, Scytinopogon cryptomerioides was close to T. khokpasiensis , but the two species differ in that T. khokpasiensis has relatively smaller basidia (22-28 × 6-8 μm vs. 35-42 × 5.5-6 μm in S. cryptomerioides ). Trechispora copiosa has similar branches to T. khokpasiensis , but in T. copiosa the branches are moderately open and the basidia are primarily 2-4-spored.

Figures

Figure 2. Basidiomata of Trechispora khokpasiensis (MHHNU 7529). Scale bars: 1 cm.

Figure 3. Microscopic features of Trechispora khokpasiensis (MHHNU 7529) a basidiospores b basidia.

Figure 4. Scanning electron micrograph of basidiospores of Trechispora khokpasiensis (MHHNU 7529).