Vararia tenuata Ghobad-Nejhad, sp. nov.
Index Fungorum number: IF 901609; Mycobank number: MB 901609; Facesoffungi number: FoF 15298; Fig. 1
Etymology – Referring to the thin basidiomata of the new species.
Holotype – RAMK. Isotype: KAS, ICH.
Basidiomata annual, resupinate, thin, ceraceous, tightly adnate, confluent, hymenial surfacecream, uniform, smooth, margin determinate to slightly thinning out. Hyphal system dimitic with only few binding hyphae, tissues generally strongly colored in CB, generative hyphae with simple septae, colorless, thin-walled, tightly interwoven, 2–3 μm diam., binding hyphae (dichohyphae) infrequent, IKI−to moderately dextrinoid, 2–4 μm diam. Dendrophyses abundant, bush-like at apex, strongly dextrinoid, upper branches narrow and thin-walled, 0.5–1 μm wide, stem 2–3 μm wide. Dendrohyphidia numerous, little to moderately branched, width uneven, in general 2–2.5 μm wide at upper branches and 3–6 μm wide in lower parts. Gloeocystidia numerous in subhymenium, irregular in size and shape, with refractive contents, subcylindrical to clavate with pleural base, 28–40(–60) × 7–10 μm, walls thickened up to 2–2.5 μm. Basidia subcylindrical to utriform, with four stout sterigmata, without clamp connection, 37–55×7.5–10 μm (mature basidia, excluding sterigmata), walls thickened. Basidiospores fusiform, more or less bent near apiculus, with a small, distinct apiculus, colorless, thin-walled, smooth, with irregular guttules, IKI−, CB−, 13.5–15×5–6 μm.
Material examined – Thailand, Chiang Mai, Mae Rim District, Mae Raem, Queen Sirikit Botanical Garden, in dry deciduous forest with Dipterocarpus obtusifolius, D. tuberculatus, Shorea obtusa, and Hopea odorata, on fallen branches of Bambusa Schreb. (Poaceae), 15 January 2012, Ghobad-Nejhad 3018 (RAMK holotype, isotypes KAS, ICH).
GenBank numbers – ITS: OQ612724, LSU: OQ607809
Notes – Vararia tenuata is characterized by thin, light cream, tightly adnate basidiomata, dextrinoid, bush-like dendrophyses, and fusiform basidiospores. It resembles V. breviphysa with regard to its basidiomata texture and shape of dendrophyses and basidiospores. The two species also cluster closely in the phylogenetic tree. However, V. tenuata differs from V. breviphysa by the color of basidiomata, being isabelle grey to beige-cinnamon in the latter, and smaller basidiospores [(14–)16–20×4.8–6 µm in V. breviphysa; Boidin & Lanquetin 1975)]. The two species show only 93% similarity in Blast searches.
Based on a megablast search of NCBI’s GenBank nucleotide database (as of March 2023), the closest hits using the ITS sequence had the highest similarity to Vararia breviphysa (strain CBS 644.81 from Type material, GenBank NR_175095.1; identities = 650/701 (93%), gaps 27/701 (3%)), V. breviphysa (strain CBS 643.81, GenBank MH861395.1; identities = 641/697 (92%), gaps 21/697 (3%)), and V. pirispora (strain CBS 721.86, GenBank MH862017.1; identities = 603/659 (92%), gaps 27/659 (4%)). The closest hits using the LSU sequence were V. pirispora (strain CBS 721.86, GenBank MH873707.1; identities=891/906 (98%), gaps 4/906 (0%)), V. breviphysa (strain CBS 644.81 from Type material, GenBank NG_078651.1; identities=867/876 (99%), gaps 0/876 (0%)), and V. breviphysa (strain CBS 643.81, GenBank MH873144.1; identities=867/877(99%), gaps 1/877(0%)).
Figure 1 – Vararia tenuata (RAMK, holotype). a Habitat. b Basidiomata. c Squashed hyphae in Melzer’s reagent. d, e Basidia. f Gloeocystidium. g Dichophyses. h, i Basidiospore in KOH (h) and cotton blue (i). Scale bars: b=2 cm, c=50 µm, d–g=10 µm, h, i=5 µm
