Vuilleminia tropica Hembrom, A. Ghosh, A. Parihar & K. Das, 2022

Buyck, Bart, Eyssartier, Guillaume, Armada, François, Corrales, Adriana, Hembrom, Manoj Emanuel, Rossi, Walter, Bellanger, Jean-Michel, Das, Kanad, Dima, Bálint & Ghosh, Aniket, 2022, Fungal biodiversity profiles 111 - 120, Cryptogamie, Mycologie 20 (2), pp. 23-61 : 54-59

120. Vuilleminia tropica Hembrom, A. Ghosh, A. Parihar & K. Das , sp. nov.

( Figs 23-25 )

DIAGNOSIS. — Differs from other species because of its tropical distribution, lemon yellow hymenophore delimited by a white floccose margin when actively growing and its erumpent nature with a tendency to grow on bark of dead wood, further also by the smaller basidiospores (11-16 × 5-8 µm), basidia (45-75 × 7-9 µm) and rare dendrohyphidia in the hymenium, the thin- to distinctly thick-walled generative hyphae with clamped septae.

HOLOTYPE. — India. Jharkhand, Rajmahal hills, Sahibganj district, Brindaban Panchayat , Joshkuti , on dead fallen branch of Bauhinia vahilii Wight & Arn. , 63 m, 25°01’50.9”N, 87°42’17.2”E, 29.VIII.2013, M. E. Hembrom, MEH-70133 (holo-, CAL [ CAL1845 ]!).

MYCOBANK. — MB840192.

GENBANK. — MZ314343 (nrITS, holotype), MZ314344 (nrITS, paratype); MZ314347 (nrLSU, holotype), MZ314346 (nrLSU, paratype).

ETYMOLOGY. — Tropica (Lat.) refers to the tropical distribution of the taxon.

ADDITIONAL MATERIAL STUDIED. — India. Bihar, Valmiki National Park, West Champaran district, Valmiki Nagar, on the fallen branch (un-barked wood) of Shorea robusta Gaertn. , 27°26’26.1”N, 83°56’10.4”E, 141 m, 2019, M. E. Hembrom, MEH-19; West Bengal, Howrah district, AJCBIBG, Div.: VIII near Kyd monument, on dead branch of Psidium guajava L., 5 m, 22°33’25.4”N, 88°17’30.1”E, 30.VII.2020, M. E. Hembrom, KMA-20-26; Bihar, West Champaran, Valmiki National Park, Ganouli Forest Range, on the decorticant log of unidentified tree, 180 m, 27°22’33.6”N, 83°59’38.5”E, 01.VIII.2020, A. V. Kisku, MEH-20-50 (CAL1846).

DESCRIPTION

Basidiomata

Annual, widely effused (5-200 × 5-100 mm or even much larger), up to 0.3 mm thick, growing on bark and more or less separable when fresh, but becoming closely adnate when dried, initially starting to form as small round patches with white margin that quickly merge to form large , effused, crusty basidiomata, leathery and slightly sticky when fresh, brittle and waxy on drying. Margin up to 1 mm wide when actively growing, distinct to indeterminate in older specimens, sterile, floccose, chalky-white (1-2A1) to pale yellow (3A3).

Hymenophore

Smooth, glabrous, pale yellow to pastel yellow (3A3-4) when young then yellow to lemon yellow (3B5-8), becoming bright yellow to almost egg yellow at maturity, finally ochraceous in older dried specimens.

Flesh

Papery thin, waxy, yellowish white (1-2A2).

Hyphal system

Monomitic, generative hyphae septate, clamped at most septa, thin- to moderately thick-walled, branched, with smooth, hyaline, acyanophilic walls (but contents cyanophilic) and not amyloid.

Subhymenium & subiculum

Composed of compactly arranged vertical elements ending with indistinct subiculum with crystal elements; basal hyphae 3-5 µm wide, thin to moderately thick-walled, loosely interwoven, cytoplasmic contents cyanophilic; hyphae in the middle part 2-4 µm wide, towards subhymenium less interwoven and less branched, more or less parallel, thin-walled.

Hymenium

Composed of hyphoid elements, rare delicate dendrohyphidia, basidia and basidioles; hyphoid elements 30-45 × 3-4 µm, embedded to projecting up to 16 µm beyond the hymenium, cylindrical, smooth. Dendrohyphidia often difficult to observe, up to 2 µm wide, less branched, thin-walled, smooth, hyaline. Basidia 45-75 × 7-9 µm, clavate to elongated cylindrical, 4-sterigmate with sterigmata 3-10 × 1-3 µm, clamped at base with clamps often delicate and difficult to observe, thin-walled, when young filled with dense and globular contents, becoming empty and collapsed with maturity, smooth, hyaline, when older with occasionally transverse septa.

Basidiospores

11-13.6-16 × 5-6.35-8 µm, Q = 1.7-2.15-2.76, cylindrical to narrowly ellipsoid, moderately thick-walled with walls up to 1 µm thick, smooth, hyaline and acyanophilic; contents cyanophilic, inamyloid.

NOTES

Vuilleminia Maire is mostly confined to Europe with few exceptions ( Bernicchia & Gorjón 2010; Ghobad-Nejhad et al. 2010). Very recently, one of us (MEH) came across some specimens in eastern tropical India growing on bark as well as invading the xylem vessels below the bark. Morphological features and molecular phylogeny place these specimens in the genus Vuilleminia , but none of the described species matches the present collections.

The genus Vuilleminia fits the morphological features of our species, including the gelatinous (when fresh) to ceraceous basidiomata with monomitic hyphal system and clamped hyphae, pedicellate-clavate basidia producing large basidiospores and presence of dendrohyphidia ( Hjortstam et al. 1988; Bernicchia & Gorjón 2010; Ghobad-Nejhad et al. 2010; Ghobad-Nejhad & Duhem 2013).

Growing in the tropics and forming basidiomata (up to 300 µm thick) with lemon yellow hymenial surface and whitish floccose margin on fallen wooden logs, make it easy to identify our species in the field. The more or less thickwalled basidiospores with cyanophilic cytoplasmic contents are unrecorded from other Vuilleminia , viz. V. alni Boidin, Lanq. & Gilles ; V. comedens (Nees) Maire ; V. corticola Parmasto , V. coryli Boidin, Lanq. & Gilles ; V. cystidiata Parmasto ; V. erastii Ghob. -Nejh., V. macrospora (Bres.) Hjortstam ; V. megalospora Bres. ; V. nilsii Ghob. -Nejh. & Duhem, V. oyensis Duhem & M. Gérard , and V. pseudocystidiata Boidin, Lanq. & Gilles. ( Hjortstam et al. 1988; Gorjón 2009; Bernicchia & Gorjón 2010; Ghobad-Nejhad et al. 2010, 2012; Ghobad-Nejhad & Duhem 2013). Many Vuilleminia have numerous dendrohyphidia, but in the present species dendrohyphidia are very few and become difficult to trace in older specimens and usually lack any side branching.

Our phylogeny places this novel species sister to V. macrospora , which differs morphologically in its white basidiomata with abundant dendrohyphidia, and capitate, thick-walled, tubular cystidia, and it also has a temperate distribution ( Bernicchia & Gorjón 2010; Ghobad-Nejhad et al. 2010). Vuilleminia nilsii shares the creamish to yellowish white hymenial surface and basidiospores with cyanophilic contents (Ghobad-Nejhad & Duhem 2013), but its spores are thinwalled and longer (14.5-18 µm).

Figures

FIG. 23. — A Maximum Likelihood (ML) phylogram inferred from raxmlGUI 2.0 (Edler et al. 2021) on a concatenated dataset of nrITS and nrLSU sequence data of Vuilleminia and related genera. One thousand bootstrap replicates were analyzed to obtain nodal support values. Bootstrap support values (>70%) obtained from ML analysis are shown above or below the branches at nodes. Two collections of our novel Indian species are shown in red and the holotype in bold in the phylogram. See Table 3 for details on used vouchers for the phylogenetic analysis.

FIG. 24. — Vuilleminia tropica Hembrom, A. Ghosh, A. Parihar & K. Das, sp. nov. (from holotype): A, B, basidiomata showing decorticant tendency of growth on bark; C, habit; D, basidioles filled with dense globules in cytoplasm and empty septate basidia; E, section through hymenium showing basidia, basidioles and hyphidia; F, indistinct subiculum with crystalline contents; G, H, dendrohyphidia; I, hyphidia; J, septate, moderately thick-walled hyphae in indistinct subiculum; K, clamped moderately thick-walled hyphae with cyanophilic cytoplasmic contents; L, delicate thin-walled clamped hyphae; M, basidiospores in phloxine; N, basidiospore in cotton blue showing thick-wall and cyanophilic cytoplasmic contents. Scale bars: D-I, M, 10 µm; J-L, N, 5 µm.

FIG. 25. — Vuilleminia tropica Hembrom, A. Ghosh, A. Parihar & K. Das, sp. nov. (holotype): A, basidia and basidioles; B, dendrohyphidia, hyphidia and thin to thick-walled hyphae; C, thick-walled basidiospores; D, part of indistinct subiculum below subhymenial layer; E, section through hymenium and subhymenium. Scale bars: 10 µm.