Rhodocollybia ciliatomarginata K. P. D. Latha & Manim., 2018

Deepna Latha, K. P., Anil Raj, K. N. & Manimohan, Patinjareveettil, 2018, Two new species of Rhodocollybia from tropical India, Phytotaxa 340 (2), pp. 157-166 : 159-161

Rhodocollybia ciliatomarginata K. P. D. Latha & Manim. , sp. nov. Figs. 1A–F

MycoBank MB 823798

Etymology:— ciliatomarginata (Latin) , with ciliate margin; refers to the ciliate pileus margin of this species.

Diagnosis:—Characterized by small to medium-sized, fleshy basidiocarps; a ciliatulate pileal margin; emarginate lamellae with a small decurrent tooth, a strong odor, pip-shaped to oblong-ellipsoid or subphaseoliform basidiospores; versiform cheilocystidia and clamped hyphae. Differing from Rhodocollybia amica in having smaller basidiocarps, larger and slightly thick-walled basidiospores, a sterile lamella-edge, absence of caulocystidia, a strong, unpleasant odor and a distinctive nrITS sequence.

Holotype:— INDIA. Kerala State: Wayanad District, Kurava Islets , 27 September 2013, K. P. Deepna Latha DKP241 ( CAL 1244 ).

Description:— Basidiocarps small to medium-sized, tricholomatoid. Pileus 2–29 mm diam., initially convex, becoming broadly convex with a small depression on a raised center; surface pinkish white (7A2/OAC696) at the center, (OAC767) or paler towards the margin, hygrophanous and becoming paler, neither striate nor pellucid-striate, dry, finely appressed-fibrillose all over; margin incurved to decurved, crenate or slightly wavy, finely fissile, ciliatulate. Lamellae emarginate or emarginate with a small decurrent tooth, close, pale orange (6A3/OAC766), up to 5 mm deep, with lamellulae of 3 tiers; edge crenate or somewhat wavy, concolorous with the sides. Stipe 4–45 × 1–6 mm, central, terete, tapering towards the apex, solid when young, becoming hollow with age; surface orange-white (6A2/ OAC794) or grayish orange (6B3/OAC765), appressed-fibrillose as well as longitudinally-striate all over or twistedstriate towards the base; base enlarged with a slight bent and also with a white, basal mycelium. Context up to 1 mm thick, soft. Odor strong, unpleasant, reminiscent of dried natural rubber latex. Taste not distinctive. Spore print not obtained.

Basidiospores 6–8 × 3–3.5 (6.7 ± 0.56 × 3.02 ± 0.61) μm, Q = 2–2.66, Qm = 2.21, pip-shaped to oblong-ellipsoid or subphaseoliform, hyaline, smooth, slightly thick-walled, acyanophilous, inamyloid. Basidia 19–28 × 4.5–7 μm, clavate, hyaline, thin-walled, 4-spored; sterigmata up to 2 μm long. Pleurocystidia absent. Lamella edge sterile. Cheilocystidia 20–45 × 6–13 μm, versiform-vesiculose, clavate with an apical protrusion or finger-like projections, rarely irregular in outline, thin-walled, hyaline. Lamellar trama subregular with inflated hyphae at the center and narrow hyphae towards the periphery; hyphae 4–7 μm wide, closely septate, thin- to slightly thick-walled, hyaline, inamyloid. Pileus trama interwoven; hyphae 4–17 μm wide, thick-walled (up to 1.5 μm thick), hyaline, inamyloid. Pileipellis a differentiated cutis composed of inflated hyphae (6–12 μm wide) towards the pileus trama and narrow hyphae (2.5–7 μm wide) towards the periphery; thin- to slightly thick-walled, hyaline with faint encrustations. Stipitipellis an undifferentiated cutis; hyphae 3–9 μm wide, thin-walled, hyaline. Caulocystidia absent. Clamp connections observed on all hyphae.

Habitat: — Growing in small groups on sandy soil among decaying litter around Madhuca neriifolia H.J.Lam ( Sapotaceae ) and Hopea ponga (Dennst.) Mabb. ( Dipterocarpaceae ) trees.

Geographical distribution range:—Known only from the type locality in Kerala State, India.

Comments:—Fleshy, tricholomatoid basidiocarps with a smooth, convex pileus, crowded, pale orange lamellae, a striate and slightly twisted stipe, acyanophilous basidiospores often with a thick-wall, and a cutis-type pileipellis indicate the genus Rhodocollybia ( Antonín & Noordeloos 1997; Mata et al. 2004) and its phylogenetic signal also places it among other species of Rhodocollybia . Rhodocollybia amica J. L. Mata & Halling (in Mata et al. 2004: 339), a species described from Costa Rica, shows some similarities with R. ciliatomarginata in having somewhat similarcolored (apricot gold) pileus with a shallow depression, acyanophilous and inamyloid basidiospores with a smooth wall, an interwoven-type pileus trama with thick-walled hyphae, the absence of pleurocystidia and clamped hyphae. However, R. amica has larger basidiocarps with a glabrous and shiny pileus, adnate lamellae, a light brown and glabrous stipe, smaller (4–6 × 2.4–3.6 μm) and thin-walled basidiospores, heterogeneous lamella-edge, inconspicuous cheilocystidia, stipitipellis with caulocystidia and a fragrant or spicy odor ( Mata et al. 2004). Rhodocollybia tablensis J. L. Mata & Halling (in Mata et al. 2004: 349), another Costa Rican species, also shares a few characters such as acyanophilous and inamyloid basidiospores, and clamped hyphae. However, R. tablensis is distinguished by its larger basidiocarps with a pinkish brown pileus, free lamellae, smaller (4.8–6 × 2.8–4 μm) and thin-walled basidiospores and presence of both pleuro- and caulocystidia.

Comparison of the nrITS sequence data (751 bp) generated from R. ciliatomarginata with the nucleotide sequences of taxa available in the GenBank suggests that it has a distinct nrITS sequence. In a BLASTn search using the nrITS sequence, the closest hit was R. purpurata (HQ533009; 91% identity) followed by R. butyracea (EU486454; 90% identity) and R. pandipes (AF505752; 90% identity). Rhodocollybia purpurata (G. Stevenson 1962: 73) J.A. Cooper (2014: 278) , R. butyracea ( Bulliard 1792: 572) Lennox (1979: 218) and R. pandipes Halling & J.L. Mata (in Mata et al. 2004: 346) have larger and differently-colored pilei and slightly larger and dextrinoid basidiospores ( Cooper 2014; Antonín & Noordeloos 1997; Mata et al. 2004).

Figures

FIGURE 1. A–F: Rhodocollybia ciliatomarginata (CAL 1244, holotype). A. Basidiocarps; B. Basidiospores; C. Basidium; D. Cheilocystidia; E. Pileipellis. F. Stipitipellis. Scale bars: A = 5mm; B–D = 10 μm; E–F = 20 μm. Photos by K. P. Deepna Latha.