Marasmiellus thailandicus W. Lu, N. Suwannar. & J. Kumla, 2024

Lu, Wenhua, Nutaratat, Pumin, Kumla, Jaturong, Tibpromma, Saowaluck, Elgorban, Abdallah M., Karunarathna, Samantha C. & Suwannarach, Nakarin, 2024, Morphological and molecular identification of two new Marasmiellus species (Omphalotaceae, Agaricales) from Thailand, MycoKeys 109, pp. 31-48 : 31-48

Marasmiellus thailandicus W. Lu, N. Suwannar. & J. Kumla sp. nov.

Figs 2 A, B , 3

Type.

Thailand • Chiang Mai Province, Chiang Mai University ; 18 ° 48 ' 5 " N, 98 ° 57 ' 23 " E; elevation 337 m; on bark of Lagerstroemia macrocarpa Wall. ex Kurz , 5 August 2023, N. Suwannarach & J. Kumla ( CMUB 40052 ). GenBank accession numbers PP 889929 (nrITS) and PP 890009 (nrLSU) .

Etymology.

“ thailandicus ” refers to the country Thailand, where the type species was collected.

Diagnosis.

Differs from M. candidus by the presence of a reddish gray to dull red, dry, radially wrinkled surface, grooved pileus with distant lamellae, and obovate or ellipsoid spores.

Macrostructures.

Basidiomata small-sized, marasmioid. Pileus 6–20 mm diam., hemispherical first, expanding to plano-convex with slightly concave, radially sulcate with age, with involute then deflexed or straight margin, not distinctly hygrophanous, translucently striate up to center, reddish gray (10 B 2) to dull red (10 B 3) all over with grayish red (7 B 3) center, grayish red (7 B 3) margin, surface smooth, dry, and dull. Lamellae distant, broadly adnate to subdecurrent, sometimes anastomosing, white to cream-colored, with a reddish white (7 A 2) edge, particularly in young specimens, I = 2–3, L = 11–14. Stipe 4–8 × 1–2 mm, cylindrical, curved, base often slightly swollen, inconspicuous fibrils or scurfy, creamy-white at apex, slightly reddish white (7 A 2) at the base, dry, pruinose all over, Context thin, fistulose or solid, concolorous with surface. Smell and taste indistinct.

Microstructures.

Basidiospores (– 12) 13–16 (– 17) × 4–5 (– 6) μm (average = 15 × 5 μm), Q = (2.1) 2.5–3.5 (– 3.75), Qm = 3.05 ± 0.38, sub-cylindrical to elongate with apiculus, inamyloid, thin-walled. Basidia 20–45 × 7–11 μm, 4 - spored, clavate, sterigmata up to 5 μm. Cheilocystidia 50–53 × 8–13 μm, clavate. Pleurocystidia absent. Trama hyphae cylindrical, thin-walled, hyaline, inamyloid. Pileipellis, a cutis with transitions to a trichoderm, made up of cylindrical; pigment brown, intracellular and minutely incrusting, hyphal 2–4 μm, negative in Melzer’s reagent. Stipitipellis, a cutis of parallel, somewhat skewed, cylindrical, or clavate-shaped, smooth hyphae, thin-walled, up to 7.5 um wide. Caulocystidia absent. Clamp connection present.

Ecology and distribution.

Caespitose, in small groups growing on the bark of Lagerstroemia macrocarpa . Known only from the type locality in northern Thailand.

Additional material examined.

Thailand, • Chiang Mai Province, Chiang Mai University ; 18 ° 48 ' 5 " N, 98 ° 57 ' 23 " E; elevation 337 m; on bark of Lagerstroemia macrocarpa , 24 August 2023, N. Suwannarach & J. Kumla ( CMUB 40053 ). GenBank accession numbers PP 889930 (nrITS) and PP 889930 (nrLSU) .

Figures

Figure 2. Habitat of Marasmiellus species in the present study A, B Marasmiellus thailandicus (CMUB 40052, holotype) C Marasmiellus minutisporus (CMUB 40054, holotype) D Marasmiellus scandens (CMUB 40056, new record). Scale bars: 10 mm (A – D).

Figure 3. Marasmiellus thailandicus (CMUB 40052, holotype) A basidiospores B basidia C cheilocystidia D terminal elements of pileipellis E hyphae of stipe. Scale bars: 10 μm (A – E).