Truncospora macrospora B.K. Cui & C.L. Zhao, 2013

Zhao, Chang-Lin & Cui, Bao-Kai, 2013, Truncospora macrospora sp. nov. (Polyporales) from Southwest China based on morphological and molecular data, Phytotaxa 87 (2), pp. 30-38 : 33-35

Truncospora macrospora B.K. Cui & C.L. Zhao , sp. nov. ( Figs. 1–2 )

MycoBank no.: MB 801932

Differs from other Truncospora species by annual basidiocarps with a distinct dark brownish crust, a dimitic hyphal system with dextrinoid skeletal hyphae, and larger basidiospores (16.5–19.5 × 8.0– 9.5 µm).

Type.— CHINA. Yunnan Prov.: Baoshan, Gaoligong Mountains , alt. 2400 m, on fallen angiosperm branch, 25 October 2009, Cui 8106 (holotype, BJFC!) .

Etymology.— macrospora (Lat.) referring to the large basidiospores.

Fruitbody. —Basidiocarps annual, pileate, sessile, solitary, corky to wood corky upon drying. Pileus usually semicircular, projecting up to 1.5 cm, 3.5 cm wide, and 0.5 cm thick at base. Pileal surface clay-buff to orange-brown when fresh, reddish brown to greyish brown when drying, with a distinct dark brownish crust, glabrous; margin obtuse. Pore surface cream to cream buff when fresh, becoming buff upon drying; pores regular, more or less round, 3–4 per mm; dissepiments thick, entire. Sterile margin narrow, cream, up to 1 mm wide. Context cinnamon-buff to buff, soft corky, about 1 mm thick. Tubes concolorous with pore surface, woody hard, up to 4 mm thick.

Hyphal structure.— Hyphal system dimitic; generative hyphae with clamp connections; skeletal hyphae dextrinoid, CB+; hyphae slightly swollen in KOH.

Context. —Generative hyphae infrequent, hyaline, thin-walled, usually unbranched, 3.0– 4.5 µm in diam; skeletal hyphae dominant, hyaline, thick-walled with a wide to narrow lumen, unbranched, interwoven, 4.5–6.5 µm in diam.

Tubes. —Generative hyphae infrequent, hyaline, thin-walled, usually unbranched, 2.0–4.0 µm in diam; skeletal hyphae dominant, hyaline, thick-walled with a wide to narrow lumen, unbranched, interwoven, 3.0– 5.5 µm in diam. Cystidia absent, but fusoid cystidioles present, hyaline, thin-walled, 17–23 × 4.0–5.0 µm; basidia barrel-shaped, with four sterigmata and a basal clamp connection, 20–29 × 11–15.5 µm; basidioles dominant, in shape similar to basidia, but slightly smaller.

Spores.— Basidiospores ellipsoid, truncate, hyaline, thick-walled, smooth, strongly dextrinoid, CB+, (16–)16.5–19.5(–20) × (7.5–)8.0–9.5(–10) µm, L = 18.2 µm, W = 8.67 µm, Q = 2.07–2.11 (n = 60/2).

Additional specimen examined.— Truncospora macrospora : CHINA. Yunnan Prov.: Baoshan, Gaoligong Mountains , alt. 2450 m, on fallen angiosperm branch, 22 September 2007, Yuan 3777 (paratype, BJFC!) .

Molecular phylogeny

The combined ITS + nLSU dataset includes sequences from 75 fungal specimens representing 44 taxa. The dataset has an aligned length of 2089 characters in the dataset of which 1285 characters are constant, 184 are variable and parsimony-uninformative, and 620 are parsimony-informative. Maximum Parsimony analysis yielded 88 equally parsimonious trees (TL = 1402, CI = 0.397, RI = 0.705, RC = 0.280, HI = 0.603), and one of the maximum parsimonious trees was shown in Fig. 3 . The best model for the combined ITS + nLSU dataset for Bayesian inference was a GTR+I+G model, lset nst = 6, rates = invgamma; prset statefreqpr = dirichlet (1,1,1,1). Bayesian analysis resulted in a same topology with an average standard deviation of split frequencies = 0.007133.

Figures

FIGURE 1. Basidiocarps of Truncospora macrospora B.K. Cui & C.L. Zhao sp. nov. from holotype. Scale bars = 1cm.

FIGURE 2. Microscopic structures of Truncospora macrospora B.K. Cui & C.L. Zhao sp. nov. (drawn from the holotype). a Basidiospores. b Basidia and basidioles. c Cystidioles. d Hyphae from trama. e Hyphae from context.

FIGURE 3. Strict consensus tree illustrating the phylogeny of the new species and related species generated by Maximum Parsimony based on combined ITS + LSU sequences. Parsimony bootstrap values (before the slash markers) higher than 50% and Bayesian posterior probabilities (after the slash markers) more than 0.95 were indicated along branches.