Agaricales » Inocybaceae » Pseudosperma

Pseudosperma keralense

Pseudosperma keralense (K.P.D.Latha & Manim.) Matheny & Esteve-Rav.

MycoBank number: MB830515, Index Fungorum number: IF830515


Pileus 11–15 mm in diameter, convex to plano-convex, slightly depressed around the centre with a small obtuse umbo, margin almost straight, slightly uplifted at some places; surface dull and dry, radially rimose, becoming fibrillose near the margin, brownish orange (5C6–5C8) at the centre to light brown (6C4–6C5) the margin; thin context 1–2 mm, off-white (6A1), unchanging when bruised; soft and fleshy. Stipe central, cylindrical, 30–35 × 1–3 mm, slightly tapering toward the apex; surface dull and dry, fibrillose throughout, finely pruinose towards the apex, cream, brownish orange (6C3) towards the base; slightly enlarged and whitish base, basal mycelium off-white; context hollow, thin, white. Hymenophore lamellate, adnexed to adnate with a decurrent tooth; lamellae close, thick, slightly wavy, grayish orange (5B3) to light brown (5D4–6D4), becoming brown (6E5–6E8) with age, lamellae edge serrate. Smell and taste not distinctive.  Basidiospores [120/1/1] (8.6–)8.8–11–13.2(–13.4) × (6.7–)6.9–7.8–8.6(–8.8) μm, Q = (1.28–)1.28– 1.4–1.53(–1.53), smooth, ellipsoid to phaseoliform, slightly thick-walled, yellowish brown. Basidia (22.2–)22.9–28.3–32.6(–33.5) × (11.2–)11.3–12.9–14.4(–14.6) μm, clavate, thin-walled, pale yellowish brown, 4-spored, sterigmata up to 5 μm long. Cheilocystidia (19.3–)19.6–27.5–31.8(–35.7) × (8.7–)9.2– 11.7–13.7(–14.6) μm, abundant, clavate to fusiform, thin to thick-walled, hyaline, pale yellow in KOH or NH4OH, rarely with encrustations. Pleurocystidia absent. Pileipellis a double layered cutis with a first one superficially disrupted, composed of thin- to slightly thick-walled, smooth hyphae 5–8.9–13 μm wide with a yellowish-brown spiral encrustation. Caulocystidia absent. Stipitipellis a cutis with disrupted loose hyphae with cystoid terminal cell at the stipe apex; hyphae 5–7.1–10 μm wide, thin to thick-walled, pale yellow or brownish yellow in KOH, encrusted with yellowish brown contents; terminal cells (39.5– )39.9–47.3–70.3(–71) × (10–)10.2–14.9–20(–20.2) μm, thin to thick-walled, cylindrical or clavate with obtuse apex; hyaline. Clamp connections present in all tissues.

Habitat: In small groups or occasionally solitary, on the ground near Vateria indica L., Hopea parviflora Bedd. and Hopea ponga (Dennst.) Mabb. (Dipterocarpaceae) and Calophyllum L. (Calophyllaceae J.Agardh), and Myristica Gronov. (Myristicaceae R.Br.) trees in India; on forest soil in tropical forest dominated by Dipterocarpaceae (Dipterocarpus spp., Shorea spp.) with some Fagaceae (Quercus spp., Lithocarpus spp. and Castanopsis calathiformis) in Thailand.

Known distribution: Known from India and Chiang Rai Province, northern Thailand.

Notes: Matheny et al. 2019 raised the status of I. sect. Rimosae (Fr.) Quél. to the genus Pseudosperma based on a six gene phylogenetic analysis. Species of Pseudosperma are probably widely distributed in Southeast Asia. Pseudosperma keralense can be recognized by its yellowish-brown pileus; lamellae with whitish, serrate edges; smooth, ellipsoidal basidiospores; a duplex pileipellis with superficial hyphae devoid of encrustations and encrusted hyphae beneath. The macro- and micro-morphological characters of the specimens from Thailand are similar to P. keralense reported from India. The combined phylogenetic analyses indicate the sequences of the Thai specimen OR1629 cluster with the holotype of P. keralense from India with BS = 100%, PP = 1.0.

Fig. 1 Maximum likelihood phylogenetic tree inferred from the three gene dataset (tef1, LSU, rpb2). Seven species of Pseudosperma Matheny & Esteve-Rav. and one species of Nothocybe Matheny & K.P.D.Latha were used as outgroup taxa. Maximum likelihood bootstrap (MLB, left) ≥ 70% and Bayesian posterior probabilities (BPP, right) ≥ 0.95 are shown above supported branches. The new species and new record are in bold.