Clitocybula sulcata K.N.A. Raj & Manim., 2015

Deepna Latha, K. P., Anil Raj, K. N., Sharafudheen, Shahina A. & Manimohan, Patinjareveettil, 2015, Clitocybula sulcata-a new species from India, Phytotaxa 208 (1), pp. 63-69 : 65-68

Clitocybula sulcata K.N.A. Raj & Manim. , sp. nov. Figs. 1A–F

MycoBank MB 812054

Etymology:—The specific epithet refers to the sulcate pileus surface of this species.

Diagnosis:—Collybioid basidiomata with a distinctly sulcate, granulose pileus; sinuate, transvenose, somewhat waxy lamellae; plentiful, versiform cheilocystidia; and a cutis-type pileipellis disrupted by cystidioid terminal elements are the diagnostic features of the present species. Differing from Clitocybula omphaliiformis Pegler in having larger basidiomata with a granulose pileus, brownish yellow, sinuate, subdistant lamellae, an inserted stipe base devoid of strigose mycelium, broadly ellipsoid to almost subamygdaliform basidiospores, the absence of a well-developed subhymenium and a stipitipellis with cystidioid terminal elements confined to the stipe apex.

Holotype:— INDIA. Kerala State: INDIA. Kerala State: Kozhikode District, Atholi , 6 August 2011, K. N. Anil Raj, AR791 ( CAL 1246 !) . Paratype:— INDIA. Kerala State: Kollam District, Thenmala Forest, 18 July 2011, K. N. Anil Raj, AR753 (CAL 1245!).

Description:—Basidiomata small to medium-sized, collybioid, in small clumps of 2-3 basidiomata. Pileus 13–52 mm diam., convex to broadly convex or rarely plano-convex with a slight central depression; surface light brown (6D8/OAC782) or brown (6E8/OAC734) all over, gradually becoming grayish orange (5B6/OAC776) towards the margin, initially translucent-striate, becoming distinctly sulcate with age, slightly tacky, finely granulose all over; margin incurved when young, becoming decurved to straight, entire or somewhat wavy. Lamellae sinuate, transvenose, somewhat waxy, subdistant, brownish orange (5C6/OAC798) or brownish yellow (5C7/OAC797), up to 6 mm wide, with 2-3 tiers of lamellulae; edge entire or finely torn under a lens, concolorous with the sides. Stipe 16–62 × 2–4 mm, central, terete or compressed, equal or tapering towards the base, hollow; surface brownish yellow (5C7/OAC782) or golden brown (5D7/OAC796), glabrous to the naked eye, sparsely pruinose all over, densely so towards the apex under a lens; base inserted into the substratum. Odor and taste not distinctive.

Basidiospores 5–6.5 × 4–5.5 (5.7±0.4 × 4.8±0.5) μm, Q = 1.1–1.5, Qm = 1.2, broadly ellipsoid to subamygdaliform, with a prominent, refractive guttule, smooth, thin-walled, amyloid. Basidia 29–39.5 × 5–7 μm, clavate, hyaline, thin-walled, 4-spored; sterigmata up to 4 μm long. Lamella edge heterogeneous. Cheilocystidia 18–75 × 6–21 μm, abundant, versiform: flexuose, balloon-shaped, broadly conical, ovoid, narrowly lageniform, narrowly utriform, fusoid or nearly cylindrical, often pedicellate, thin-to slightly thick-walled, hyaline. Pleurocystidia none. Lamellar trama broad, subregular; hyphae 3–27 μm wide, thin-to slightly thick-walled, hyaline, inamyloid. Pileus trama interwoven; hyphae 3–20 μm wide, thin-walled, hyaline, inamyloid. Pileipellis a cutis often disrupted by cystidioid terminal elements somewhat resembling cheilocystidia, 27–146 × 4–30 μm, often with some amorphous contents at the apex; hyphae 3–38 μm wide, thin-walled, hyaline. Stipitipellis a cutis frequently disrupted with cystidioid elements at the extreme stipe apex; hyphae 3–20 μm wide, thin-walled, with a pale brown wall pigment, rarely with faint encrustations; terminal cystidioid elements 19–123 × 8–23 μm, almost similar to cheilocystidia in morphology, hyaline, thin-walled. Caulocystidia absent. Clamp-connections observed in all tissues.

Habitat:— in small clumps, growing on the bark of living Hydnocarpus ( Flacourtiaceae ) trees.

Geographical distribution range:—known only from Kerala State, India.

Comments:—Characters such as the collybioid basidiomata, the smooth, amyloid, broadly ellipsoid to almost subamygdaliform basidiospores, a heterogeneous lamella edge, plentiful cheilocystidia, a hymenium devoid of pleurocystidia, the pileipellis with cystidioid terminal elements, the presence of broad and often thick-walled hyphae, the absence of a cellular hypoderm, clamped hyphae and a lignicolous habitat reveal that this species belongs to the genus Clitocybula ( Bigelow 1973; Pegler 1977; Singer 1986; Barrasa et al. 2006). However, the present collections lack a radially-fibrillose or squamulose pileus, a feature shown by several species of the genus. Instead, the present species has a finely granulose pileus.

The keys to the North American and European species of Clitocybula by Bigelow (1973) and Barrasa et al. (2006) lead to C. abundans ( Peck 1878: 38) Singer (1954: 110) owing to the size (4.5–6(–7.5) × 3.5–5.5(–6) μm) and shape of basidiospores, features of the stipe surface and the presence of cheilocystidia. But that species has at first whitish, later pale beige-grey or brown-grey basidiomata occurring on decaying wood of conifers or hardwoods, an innately radiatefibrillose or densely fibrillose pileus surface, adnate lamellae and subsaccate cheilocystidia ( Bigelow 1973; Barrasa et al. 2006). Clitocybula oculus ( Peck 1873: 84) Singer (1962: 53) is also comparable with the present species in having similar-sized basidiospores (5–6.5 × 4–5.5 μm) and cheilocystidia. However, C. oculus has a pale gray-brown pileus with a squamulose or furfuraceous surface and a dark gray, squamulose stipe ( Bigelow 1973; Barrasa et al. 2006).

Clitocybula omphaliiformis , a tropical species, shares a few characters such as the brown, translucent-striate pileus, the hollow stipe with a pruinose surface, somewhat similar-sized basidiospores (4–6 × 3–4.2 μm) with a large refractive guttule, and a rather similar type of pileipellis. However, C. omphaliiformis has a very small (9 mm diam.), umbilicate pileus, crowded, white, decurrent lamellae, a stipe with a strigose base, smaller cheilocystidia of a different shape, a well-developed subhymenium, hair-like pileocystidia and a stipitipellis of a different structure ( Pegler 1977). The neotropical C. azurea has entirely blue-colored basidiomata ( Singer 1973).

Comparison of ITS sequence data generated from the Kerala collection with the nucleotide sequences of taxa available in GenBank indicates that Clitocybula sulcata has a distinct ITS sequence. A BLASTn search using the ITS sequence of the present Clitocybula species showed C. flavoaurantia (GenBank HM191745) as the closest hit with only 77% sequence identity with an e-value of 1e-90. Obviously, Clitocybula flavoaurantia ( Contu 2003: 62) E.F. Malysheva, O. Morozova & Contu (2011: 98) , a species reported from Italy, is not a close relative of the present species. It resembles the present species in having a brown pileus when young, a translucent-striate pileus, broadly ellipsoid to almost globose basidiospores, numerous, versiform cheilocystidia and clamped hyphae. However, C. flavoaurantia has smaller, clitocyboid or omphalinoid basidiomata, an infundibuliform pileus with a deeply depressed center, a pileus that becomes orange or lightly reddish yellow with age, deeply decurrent lamellae, a stipe with a strigose basal mycelium, larger basidiospores (6.2–7.8 × 4.8–7.0 μm), a sterile lamella edge, occasional pleurocystidia, pileipellis hyphae with a minute encrusting pigment, pileo- and caulocystidia and a different habitat ( Malysheva et al. 2011).

Molecular analyses yielded phylogenetic trees that depicted the relative placement of C. sulcata within the genus. The phylogeny was inferred from both Maximum Likelihood and Bayesian Analyses of the ITS sequence data matrix. The Maximum Likelihood (ML) and Bayesian Analyses (BA) generated the trees that were similar in topology. Therefore, only the BA tree is represented in Fig. 2 . Both ML and Bayesian analyses revealed a monophyletic clade in the tree where the present Clitocybula species nested with full ML (100% BS) bootstrap support and BI posterior probability (1.0 PP). Within this monophyletic clade, C. sulcata was well-differentiated as an independent lineage from C. flavoaurantia with significant ML (95% BS) bootstrap support and BI posterior probability (0.99 PP).

Figures

FIGURE 1. A–F: Clitocybula sulcata (CAL 1246, holotype). A. Basidiomata; B. Basidiospores; C. Basidium; D. Pileipellis; E. Cheilocystidia; F. Stipitipellis. Scale bars: A=10 mm; B–F=10 μm. Photos: A. Taken by Mr K. N. Anil Raj and B–F by Ms Shahina A. Sharafudheen.

FIGURE 2. The 50% majority-rule consensus tree obtained from Bayesian analysis using the data matrix of ITS sequences. Values above branches indicate the posterior probability (PP) and values below branches indicate the ML bootstrap (BS) support of that clade. PP values ≥0.5 and BS values ≥50% are shown. Clitocybula sulcata is shown in bold font to highlight its position in the tree. GenBank accession numbers are given after the name of each taxon.