Resupinatus reviviscens Carpouron & Raspé, 2024

Carpouron, Julia Eva, Appadoo, Michée Akshay, Chomnunti, Putarak & Raspé, Olivier, 2024, Taxonomy, phylogeny and ecology of a new bambusicolous Resupinatus species (Agaricales, Resupinataceae) from Northern Thailand, Phytotaxa 677 (3), pp. 195-206 : 200

Resupinatus reviviscens Carpouron & Raspé , sp. nov. Figure 2

Etymology:—The specific epithet “ reviviscens ”, from Latin, refers to the ability of basidiomes to withstand drying.

Holotype:— THAILAND. Chiang Mai Province, Mae On District, Huay Kaew, 3 July 2022, Olivier Raspé 1769 ( MFLU24-0233 ).

Diagnosis:— Resupinatus reviviscens most resembles R. applicatus and R. trichotis but differs in having hyaline to yellowish basal hairs forming an off-white to yellowish grey subiculum-like felt, broadly ellipsoid to ellipsoid basidiospores, and clavate pleurocystidia.

MycoBank:—856548

Basidiomata astipitate, small, gregarious, attached dorsally, laterally or eccentrically, fleshy, leathery, hard when dry; base covered with coarse surface hairs forming a dense, off-white to yellowish grey mat near the point of attachment. Pileus 3–7 mm diameter, cupuliform when young, convex to plano-convex, and subcircular to rounded-flabelliform or flabelliform when mature; surface even and entirely covered with whitish minute pubescence when young, becoming radially rugulose-veined, sparsely mechulose and moist-hygrophanous except near the point of attachment, where it is densely covered by an off-white to greyish yellow strigose felt, brownish-grey to dark grey, light yellowish grey towards the margin; margin straight to slightly involute, striate; context greyish, gelatinous. Lamellae yellowish grey to brownish grey, moderately close to sub-distant, thick, with 1–3 unequal lamellulae. Stipe absent. Odor and taste not recorded.

Basidiospores (3.8–)4.4–5.7–6.8(–7.6) × (2.8–)3.2–3.9–5(–5.8) µm {N=204,5,5}, broadly ellipsoid to ellipsoid, smooth, inamyloid, thin-walled, guttulate, hyaline. Basidia (17.4–)18.2–23.3–28.8(–30.4) × (4.1–)4.5–5.8–7(–7.4) µm {N=105,5,5}, 4-sterigmate, clavate to cylindrico-clavate, hyaline in KOH. Pleurocystidia (29.5–)30.1–34.8–40.1(– 42.9) × (5.3–)5.6–6.9–8.9(–11.4) µm {N=47,4,4}, clavate, slightly thick-walled. Subhymenium compact and light brown. Hymenophoral trama subregular, with hyphae imbedded in a gelatinous matrix. Pileal trama monomitic, gelatinized, composed of branched, loosely interwoven hyphae, 3.3–4.1 μm broad, thin-walled, hyaline. Pileipellis a cutis composed of compact, interwoven layer of 2.3–5.5 μm broad hyphae with thin walls that are lightly encrusted with brownish and highly refractive materials. Clamp connections present in all tissues. Basal hairs composed of hyaline, frequently clamped hyphae that are thick-walled, dense and compacted near the base, loosely interwoven, thin-walled near the end, hyaline in isolation to greyish yellow in the mass, 3.0–4.2 μm in diam.

Habitat and distribution:—Gregarious on dead bamboo branches suspended or still attached to bamboo culms, in dry dipterocarp forests in Northern Thailand.

Ecology:—All collections of the new species were made on dead bamboo branches suspended or still attached to bamboo culms. In this environment, solar radiation and wind exposure is high and humidity level is low relative to other bamboo parts or debris fallen on the ground. Moreover, all specimens occurred in dry dipterocarp forests at the beginning of the rainy season, where and when temperature and humidity can reach challenging levels. Correspondingly, the basidiomes of Resupinatus reviviscens display a remarkable resistance to desiccation, capable of surviving dry conditions and fully recovering upon rehydration. This ability to revive after receiving moisture classifies them as truly reviviscent.

Additional materials examined (paratypes):— THAILAND. Chiang Mai Province, Mae Taeng District, Pa Pae , Baan Tha Pha, 4 August 2022, Olivier Raspé 1833 (MFLU-0234) ; Chiang Rai Province, Mueang Chiang Rai, Doi Pui community forest, 22 June 2022, Olivier Raspé 1764 (MFLU-0230) ; ibid., 22 June 2022, Olivier Raspé 1766 (MFLU-0231) ; ibid., 22 June 2022, Olivier Raspé 1767 (MFLU-0232) .

Notes:— R. reviviscens mostly resembles R. applicatus (Batsch) Gray (1821: 617) , R. striatulus (Pers.) Murrill (1915: 242) and R. trichotis (Pers.) Singer (1961: 48) in terms of basidiome color, size, and shape. In fact, the latter three species have long been considered as a single species owing to their numerous morphological similarities (Consiglio & Setti 2018). The basidiome shapes of all four species are similar and their sizes fall more or less within the same range (Consiglio & Setti 2018; Mcdonald 2015; Thorn & Barron 1986). Moreover, the basidiome colour of R. reviviscens is similar to R. applicatus and R. trichotis but differs at the margin where it is lighter in colour ( Table 2).

The hairs forming a subiculum-like felt at the base of the basidiomes is an important distinguishing feature in Resupinatus (Consiglio & Setti 2018; Mcdonald 2015). The off-white to greyish yellow hairs near the zone attached to the substratum is a characteristic macroscopic feature in Resupinatus reviviscens and a marked distinction from R. trichotis , which features black basal hairs (Consiglio & Setti 2018; Mcdonald 2015). Correspondingly, these basal hairs possess dark brown parietal and/or intracellular pigments in R. trichotis (Consiglio & Setti 2018) whereas they are mostly hyaline to greyish yellow in R. reviviscens . R. reviviscens also differs from R. applicatus and R. trichotis in its spore shape and size. Its spores resemble mostly those of R. cyathae Corner (1996: 125) which are ellipsoid and 4.5–6 × 3.5–4 µm ( Corner 1996). A morphological comparison between R. reviviscens and its closely related species is given in Table 2.

Figures

FIGURE 2. Resupinatus reviviscens: holotype, MFLU-0233 (OR1769). a–c) Basidiomata, d) Cross section of lamella, e) Pleurocystidia, f) Hyphae of hymenophore trama showing clamp connections, g) Basidiole, h–i) Basidia, j) Basidiospores. Scale bars: a–c = 5 mm, d = 30 μm, e–i= 10 μm, j = 5 μm.