Gerronema keralense K. P. D. Latha & Manim Phytotaxa 364 (1): 85–88 (2018).
Index Fungorum number: IF 824928; MycoBank number: MB 824928; Facesoffungi number: FoF 10687; Fig. 1
Pileus 20 mm diam., infundibuliform, appressed-fibrillose, brownish orange to light brown (5C5-5D5); Lamellar decurrent to deeply decurrent, distant (12) with 2–3 series of lamellulae, greyish yellow (4B6) up to 1.5 mm.; Stipe 21×0.75 mm, central, cylindrical, pruinose, slightly broadened at base, solid, greyish yellow (4B6) overall. Context thin, Odor and taste not distinctive.
Basidiospore 7–9 × (3–) 4–5 μm [x=7.76±0.78×4.4±0.65, Q =1.4–2.3, q=1.79±0.25, n=25, s=1] ellipsoid, smooth, hyaline, inamyloid, thin-walled. Basidia 25–34 × 5–7 μm, clavate, with 4 sterigmata, thin-walled, inamyloid. Cheilocystidia scattered, 27–31×5–8 µm, clavate, flexuose, irregular in shape, hyaline, inamyloid, thin-walled. Pleurocystidia absent. Lamellar trama subregular, hyphae 4–15 µm diam., smooth, hyaline, inamyloid, thin-walled. Pileipellis cutis with pileocystidia, 3–12 µm, cylindrical, hyaline in KOH, inamyloid, inclusion cytoplasm turns to brown to light brown in Melzer’s reagent, thin-walled. Pileus trama sarcodimitic, subregular, composed of 2 type of hyphae a) sarco-hyphae, elongate
fusoid cell 98–196×10–14 µm, hyaline, smooth, inamyloid, thin-walled; b) generative hyphae 2–5 µm wide, cylindrical, branched, hyaline, smooth, inamyloid, thin-walled. Stipitipellis cutis, hyphae 3–6 µm diam., parallel, cylindrical, pale yellow in KOH, smooth, inamyloid, slightly thick-walled. Stipe trama sarcodimitic, parallel, composed 2 type of hyphae: a) sarco-hyphae, elongate fusoid cell 74–230 × 7–10 µm, hyaline, smooth, inamyloid, slightly thick-walled; b) generative hyphae 3–7 µm wide, cylindrical, branched, hyaline, smooth, inamyloid, slightly thick-walled. Caulocystidia 28–47×7–9 µm, agglutinated, cylindrical to clavate, hyaline in KOH, inamyloid, slightly thick-walled. Clamp connections present in all tissues.
Habit, habitat and known distribution – Solitary on decayed wood, known from topical India and Thailand.
Material examined – Thailand, Sukhothai Province, Si Satchanalai National Park, Natural trial, 15 June 2019, collector N Wannathes, N Suwannarach J Kumla, S Khuna, BKF10263.
GenBank numbers – BKF10263- MZ452107 (ITS), MZ452144 (LSU).
Notes – Gerronema keralense is characterized by a medium-sized omphaliod basidiomata, infundibuliform, brownish orange to light brown pileus, decurrent to deeply decurrent, distant, greyish yellow lamella, cylindrical, central, greyish yellow stipe, ellipsoid basidiospores with mean dimensions of 7.8 × 4.4 µm, pileipellis with pileocystidia, non-incrusted hyphae, cytoplasmic inclusion that turned from brown to light brown in Melzer’s reagent, the presence of irregular cylindrical cheilo-, cualocystidia and sarcodimitic trama tissue. Our Thai description is consistent with Gerronema keralense that was originally described from India, except for the type specimen that formed an applanate with a slight central depression pileus (Latha et al. 2018). Notably, these variations may be caused by a mutuality of basidiomata. Gerronema keralense is morphologically similar to G. kuruvense K.P.D. Latha & Manim, but the latter differs by having bigger basidiospores with mean dimensions of 9.1×4.9 µm, a cytoplasmic inclusion of pileocystidia that never changes colour with Melzer’s reagent and caulocystidia that are not agglutinated (Latha et al. 2018).
Figure 1 – Gerronema keralense (BKF10263) a Basidiomata, b Basidiospores, c Basidium, d Cheilocystidia, e Caulocystidia f Pileipellis cell. Scale bars: a=20 mm, b–e=10 μm, f=20 μm. Drawing by W. Phonrob