Marasmius benghalensis A.K. Dutta & K. Acharya, sp. nov.
Index Fungorum number: IF557845; MycoBank number: MB 557845; Facesoffungi number: FoF 07864; Figs. 1, 2
Etymology – ‘benghalensis’ refers to West Bengal, India, the region from where the type species was collected.
Holotype – CUH AM214
Pileus 21–56 mm diam., convex when young, becoming broadly convex to undulate when old, with or without a small central depression, wrinkled, glabrous, semidry to moist, light orange (5A5), orange (5A6) to greyish orange (5B5-6) or brownish orange (5C6) or golden yellow (5B7), margin greyish yellow (4B3-4) to pale orange (5A3) or light orange (5A4), becoming yellowish with KOH, hygrophanous, non-striate. Context very thin, pale orange (5-6A3) to light orange (6A4) or orange grey (6B2) to greyish orange (6B3). Lamellae narrow, non-collariate, adnexed, subdistant (L=11–14) with 2–4 series of lamellulae, vein-like, nonintervenose, sometimes forked from the middle towards margin, white, concolorous, smooth, even, often not reaching to the margin of pileus. Stipe well-developed, 52–75×2–4 mm, central, cylindrical, equal, hollow, dry, minutely pruinose, shiny, greyish orange (5B6) to golden yellow (5B7) or brownish orange (6C8) to brown (7D7-8) towards base, light yellow (3-4A5) to olive yellow (3C6-7) from the middle towards apex, non-insititious, strigose, basal mycelium
white. Taste mild. Odour sweet. Basidiospores (7.2–)8.5–10(–10.8) × 3.5–4(–4.5) μm (x̅= 9.5 × 3.8 μm, n = 30), Q = 1.8–2.7 μm (x̅= 2.5 μm, n = 30), ellipsoid to lacrymoid, hyaline, inamyloid, one guttate when viewed with KOH, thin-walled. Basidia not observed. Basidioles 24–27(–29) × 5–6(–7.5) μm, fusoid to clavate, hyaline, thin-walled. Pleurocystidia absent. Lamellae-edge sterile, with crowded cystidia. Cheilocystidia composed of Siccus-type broom cells; main-body (11–)14–16(–18)×(3.5–)4.5–5.5(–7.5) μm, cylindrical to clavate, hyaline, thin- to thick-walled; apical setulae (6–)9–10(–11.5) μm long, cylindrical, less dense, often with obtuse apex, pale yellowish, thick-walled. Pileipellis a hymeniform layer, consists of Siccus-type of broom cells; main-body (18–)21–25(–36)×(5–)7.5–9(–15) μm, cylindrical to clavate or subclavate, hyaline, thin- to thick-walled walled; apical setulae 3.5–6(–11) μm long, cylindrical, pale yellowish, acute to obtuse, thick-walled. Lamellae trama hyphae 3.5–6(–7.5) μm broad, interwoven, cylindrical, hyaline, smooth, dextrinoid, thin- to slightly thick-walled. Pileus trama hyphae 6.5–7(–9) μm broad, interwoven, cylindrical to irregularly
cylindrical, sometimes branched, hyaline, dextrinoid, thin-to slightly thick-walled. Stipitipellis hyphae 3.5–4.5(–6.5) μm broad, parallel to subparallel, cylindrical, hyaline, dextrinoid, moderately thick-walled. Stipe trama hyphae 5–7(–11) μm broad, parallel, cylindrical, hyaline, strongly dextrinoid, moderately thick-walled (up to 0.9 μm). Caulocystidia (21–) 39–60(–76)×(5–)6.5–7.5(–8.5) μm, abundant, non-setulose, cylindrical to irregular in outline, hyaline, inamyloid, moderately thick-walled.
Material examined – INDIA, West Bengal, Darjeeling district, near Lebong Cart road, 27°04′07.9″ N 88°15′07.2″ E, 1836 msl, on decomposed leaf litter among Gleichenia sp., 24 June 2016, S. Paloi (CUH AM214, holotype); Darjeeling district, near Lebong Cart road, 27°04′07.9″ N 88°15′07.2″ E, 1836 msl, 25 June 2016, S. Paloi (CUH AM221).
GenBank numbers – ITS = MF189043, MF189044, LSU=MT255002, MT255001.
Notes – Diagnostic features of the present taxon include: a non-striate, wrinkled, greyish yellow to pale orange pileus with orange to brownish orange or golden yellow disc; narrow, vein-like, adnexed, subdistant (11–14), white lamellae that often do not reach the pileus margin; a minutely pruinose, strigose stipe with white basal mycelium; presence of a sweetish odour; ellipsoid to lacrymoid basidiospores with mean 9.5×3.8 μm; absence of pleurocystidia; presence of Siccus-type broom cells in the pileipellis and form of cheilocystidia; and simple cylindrical caulocystidia ranging 21–76×5–8.5 μm (Figs. 1 and 2). These combinations of features undoubtedly place Marasmius benghalensis under ser. Atrorubentes of the sect. Sicci (Tan et al. 2009; Wannathes et al. 2009). In the phylogenetic tree, Marasmius benghalensis appears to be close to M. luteolus (60% MLBS, 0.99 BYPP; Fig. 3). However, M. luteolus has minutely velutinous to pruinose pileus surface, adnate attachment of lamellae, presence of pleurocystidia of the Siccus-type, and two types viz. Siccus-type as well as non-setulose caulocystidia (Wannathes et al. 2009).
Figure 1 – Field pictures of the basidiomata. a, b Marasmius benghalensis (CUH AM214, holotype), habitats of basidiomata and lower side of the pileus showing lamellae features. Scale bars: a, b=10 mm
Figure 2 – Marasmius benghalensis (CUH AM214, holotype). a Basidiospores. b Basidioles. c Cheilocystidia. d Siccus-type pileipellis cells. e Caulocystidia. Scale bars: a–c=5 μm, d–e=10 μm
Figure 3 – Phylogram generated from maximum likelihood (ML) analysis based on nrDNA ITS sequence data of Marasmius species using best-fit model (HKY+G) with Bayesian Information Criterion (BIC) value of 14371.193718. Related sequences are mostly taken from Wannathes et al. (2009) and Antonín et al. (2012). Thirty-six taxa of Marasmius and one outgroup taxon are included in the analyses comprising 742 characters after alignment. Crinipellis dipterocarpi is used as the outgroup taxon following Wannathes et al. (2009). Bayesian analysis (BA) reached a standard deviation of split frequencies of 0.004984 after 106 generations and produced 11210 credible set of trees after discarding initial 3,792 trees as burnin phase. Tree topology of the ML analysis is similar to the BA. The best RaxML tree with a final likelihood values of − 6870.939953 is presented. The matrix had 483 distinct alignment patterns, with 17.46% proportion of gaps and completely undetermined characters. Estimated base frequencies were as follows: A=0.2461, C=0.2043, G=0.2006, T=0.3490; gamma distribution shape parameter=0.4030. ML Bootstrap values (MLBS) equal or greater than 50% (on the left of ‘/’) and posterior probabilities (BYPP) values equal or greater than 0.50 (on the right of ‘/’) from BA are labeled above or below the nodes. The newly generated sequences are in blue bold. Representative sections and series of the Marasmius taxa are marked in the right side