Psilocybe keralensis K.A. Thomas, Manim. & Guzmán, Mycotaxon 83: 196, 2002.
Index Fungorum number: IF 380972; MycoBank number: MB 380972; Facesoffungi number: FoF 10681;Fig. 1
Pileus 13–25 mm diameter, hemisphearic, subconic or campanulate, hygrophanous, brownish-orange (6C4) to greyish orange (5B6), fading to light orange (5A4) to orangewhite (5A2), surface glabrous, lucidus when dry and often somewhat bluish when touched or on drying, especially at the edge, not viscid and the margin finely translucent striate when moist; context pale yellow (2A3) or yellowish-white (2A2), bruising ink blue. Lamellae adnate to slightly sinuate, close, light orange (5A4) to orange (5A6) to brownish grey (9C2) or reddish-brown (9E5), often with ink blue tinge, edges serrulate and remaining whitish. Stipe 45–80×1.5–3 mm, equal, sometimes flattened and becoming tapered toward the base, nearly concolorous with the pileus, darker below, often with ink blue to blackish tinge when touched or when dry, and shiny when dry; surface longitudinally striate and covered with appressed whitish fibrils or flocculose, sometimes uneven and with scrobicula and grooves; base with white mycelium and often radicating; annulus absent; context fragile, yellowish and yellowish brown towards the surface and base, staining somewhat ink blue when bruised. Spore print dark brown.
Basidiospores 6–10×5–7×4–6 μm, often subrhomboid or ovoid, sometimes ellipsoid, occasionally inconspicuous subhexagonal in face view, Q =1.1–1.7, Qm =1.35±0.13, ellipsoid or subovoid, sometimes nearly oblong inside view, Q=1.2–1.8, Qm =1.55±0.15; yellowish-brown with a purple tinge in water, dark yellow to yellowish-brown in KOH, dark purplish-brown in deposit; wall smooth, slightly thick (0.5–1 μm), complex, with 0.8–1.5 μm wide apical germ pore. Basidia 18–28×5–8 μm, hyaline, long subcylindric to clavate, often constricted in middle and narrowed
in the lower half, 4-spored and 2-spored, rarely 1-spored; sterigmata up to 6 μm. Pleurocystidia are relatively rare and scattered, 13–22 × 4–6.5 μm, hyaline, ventricose to sublageniform, sometime fusoid or clavate, occasionally nearly cylindric-clavate or obclavate, often with a 1–7.5×1–2 μm neck or rostrum, not branched, the top or apex often seems wall thickened or contain some matter. Cheilocystidia abundant, 14–35.5×4–8 μm, hyaline, similar to pleurocystidia, mostly with a 1.5–13 ×1–3 μm rostrum or neck, sometimes with an acuminate apex, the top or apex often seems wall thickened or contain some matter. Pileipellis an ixocutis, 15–80 μm thick, made up of creeping, interwoven, 2–6 μm wide filiform to slender tubular hyphae, hyaline and colourless, wall-smoothed and thin; subpileipellis more pigmented to dark yellow in KOH. Subhymenium subcellular, hyaline, composed of irregular vesiculose to polygonal or subglobose cells. Caulocystidia abundant, 14–49 × 3.5–12 μm, scattered, gregarious to clustered at the upper part of the stipe, hyaline, similar to cheilocystidia, hyaline, thick-walled. Clamp connections present in all tissues.
Material examined – Thailand, Ubon Ratchathani Province, Phibun Mangsahan, District, 15° 3′ 25″ N 105° 26′ 50″ E, elevation 164 m, on soil, 4 May 2019, N. Suwannarach & J. Kumla, SDBR-CMUNK0448.
Habitat – Growing solitary to scattered on dung or soil of meadows, or grassland in an open area.
Distribution – India (Thomas et al. 2002), Southwestern China (Ma et al. 2016) and Thailand (This study).
GenBank numbers – MZ452082 (ITS), MZ452083 (LSU).
Notes – Morphologically, P. keralensis is similar to P. columbiana Guzmán; however, P. columbiana differs significantly in the absence of pleurocystidia. It has been known to only be from Colombia (Guzmán 1978, 1983; Guzmán et al. 2005). Phylogenetically, P. keralensis formed a sister taxon to P. thaizapoteca (Fig. 2). However, the large pileus (20–50 mm in diameter) and small basidiospores (6–7×3–4.5×3–3.5 μm) of P. thaizapoteca clearly differ from P. keralensis (Guzmán et al. 2012).
Figure 1 – Psilocybe keralensis (SDBR-CMUNK0448, new record). a. Basidiomata. b. Basidiospores. c. Basidia. d. Cheilocystidia. Scale bars: a=10 mm; b–d=5 μm
Figure 2 – Phylogenetic tree derived from maximum likelihood analysis of a combined ITS and LSU genes of 25 sequences and the aligned dataset was comprised of 1640 characters including gap. The average standard deviation of the split frequencies of the BI analysis was 0.00962. Panaeolus acuminatus (CBS 270.47) and Pa. subbalteatus (CBS 326.34) were used as outgroup taxa. The numbers above branches are the bootstrap statistics percentages (left) and Bayesian posterior probabilities (right). Branches with bootstrap values≥70% are shown at each branch and the bar represents 0.1 substitutions per nucleotide position. Hyphen (-) represents support values≤70/0.90. Extype strains are in black bold. The newly generated sequences are indicated in blue