Crepidotus palodensis C.K. Pradeep & A.M. Kumar, 2018

Kumar, A. Manoj, Vrinda, K. B. & Pradeep, C. K., 2018, Two new species of Crepidotus (Basidiomycota, Agaricales) from peninsular India, Phytotaxa 372 (1), pp. 67-78 : 74-76

Crepidotus palodensis C.K. Pradeep & A.M. Kumar sp. nov. Fig.4 , 5

MycoBank MB: 827757

Etymology:—“palodensi s ” (Latin), refers to the type locality (Palode, Kerala).

Diagnosis:—This species is characterized by the small pure white to brownish orange basidiomata, elongate to cylindrical, verrucose basidiospores (8–10.5 × 4–5 μm), versiform cheilocystidia, a pileipellis as a cutis with pileocystidia and the presence of clamp connections.

Holotype:— INDIA. Kerala State: Thiruvananthapuram district, Palode, JNTBGRI campus, 15 May 2017, Manoj TBGT16716 ( CAL 1680 !). GenBank accessions: MH844890 (nrITS); MH310743 (nrLSU).

Description:— Pileus 3–15 mm diam., convex, reniform to orbicular when young, flabelliform in mature fruiting bodies; surface pure white to off white when young, becoming yellowish white then brownish orange when over mature (4A2/5C3), floccose (under stereo) when young, less prominent in old basidiomata, hispid near the attachment, dry, weakly striate, non-hygrophanous; margin inrolled when young, becoming straight, entire. Lamellae radiating from a lateral point or from a rudimentary stipe, white, yellowish white to orange-white (4A2/4A3/4A4/5A2/6A2) when young, becoming cream to grayish orange (4A3/5A3/5B4/6B4), up to 1 mm wide, close to subcrowded with lamellulae of different lengths; edge concolorous with faces, entire. Stipe absent in mature fruiting bodies, rudimentary in very young basidiomes and finally becoming a primordial hump covered with white pubescent hairs. Context thin, pale. White pubescent hairs present at the base. Odor mild. Spore print clay (5D5).

Basidiospores 8–10.5 × 4–5 μm (Lm = 9.04 ± 0.78, Wm = 4.44 ± 0.40); Q= 1.8–2.2; Qm= 2.04, broadly elongate to cylindrical, pale in KOH, thin-walled, finely verrucose. Basidia 18–21 × 8–9 μm, short, clavate, 4-spored, thin-walled, hyaline. Lamella edge sterile with crowded cheilocystidia. Cheilocystidia 16–44 × 7–9.5 μm, versiform, mostly clavate to cylindro-clavate with obtuse apices, some with irregular excrescences, or strangulated, septate with terminal cells reaching 28–32 μm length, thin-walled to thick-walled, hyaline. Pleurocystidia absent. Hymenophoral trama subregular with interwoven hyphae, 6–8 μm wide, thin-walled, hyaline. Subhymenium pseudoparenchymatous. Pileus trama composed of interwoven hyphae 5–8 μm wide, thin-walled, hyaline. Pileipellis near center a cutis composed of loose cylindrical, 2.5–3.0 μm wide, long septate, thin-walled hyphae. Pileipellis near margin forming a distinct trichoderm with cystidioid elements, 24–29.5 × 4–5 μm, flexuous, thin-walled, with pale yellowish contents. Incrusting pigments and oleiferous hyphae absent. Clamp connections abundant in all tissues.

Habitat:—Lignicolous, scattered on a dead stem of Ochlandra sp. or on living stem of Aroideae plant.

Additional specimens examined:— INDIA. Kerala State: Thiruvananthapuram district, Palode , JNTBGRI campus, 19 May 2017, Manoj TBGT 16775 ; 26 May 2017, Manoj TBGT 16777 ; 26 June 2017, Manoj TBGT 16846 ; 20 April 2018, Manoj TBGT 17365 ; 8 May 2018, Manoj TBGT 17401 .

Comments:—The following features make Crepidotus palodensis distinct: small, pure white basidiomata, broadly elongate to cylindrical, finely verrucose basidiospores, characteristic cheilocystidia and pileipellis a trichoderm. Closely related species include C. variabilis , C. martini and C. epibryus (Fr.) Quél. (1888: 107) . Crepidotus variabilis described from Norway ( Nordstein 1990) is similar in size, shape and colour of basidiomata, and the verrucose, cylindric to elliptic basidiospores. However, that species is well-differentiated by smaller [5.5–7 (–8) × 3–4 (5) μm] basidiospores, mostly branched angulate cheilocystidia, a pileipellis as a cutis and substrate specificity for Salix sp. Furthermore, phylogenetically it has a 98% nrLSU sequence identity. Crepidotus martini originally described from Panama is distinct morphologically by its smaller (2–9 mm) whitish to brownish hygrophanous, transparent-striate basidiomata, pip-shaped to ellipsoid (6–9.5 × 5–5.3 μm) punctate basidiospores, cylindric to ventricose cheilocystidia and a pileipellis as an epicutis and molecularly by a 98% sequence identity (nrLSU). Crepidotus epibryus is distinct by having wrinkled verruculose basidiospores, lack of clamp connections and having only 97 % nrLSU sequence similarity.

A BLASTn query using the nrLSU sequence (923bp) in the NCBI database led to Crepidotus sp. (AF205684) from Thailand as the closest hit with 99% sequence identity with zero e-value. ML bootstrap support (100%) also confirms its closeness to Crepidotus sp. (AF205684). However, that species remains undescribed and hence a comparison with it was not possible.

Figures

FIGURE 4. Crepidotus palodensis (CAL 1680, holotype). A–D. Habit in situ. Scale bar = 10 mm. Photos: By Manoj Kumar.

FIGURE 5. Crepidotus palodensis (CAL 1680, holotype). A. Basidium. B. Spores. C–E. Cheilocystidia. F. Pileipellis. G. Pileal elements near margin. Scale bar, A–C = 10 μm. Photos: By Manoj Kumar.