Abstract
Two new wood-inhabiting fungal species, Steccherinum tenuissimum and S. xanthum spp. nov. are described based on a combination of morphological features and molecular evidence. Steccherinum tenuissimum is characterized by an annual growth habit, resupinate basidiomata with an odontioid hymenial surface, a dimitic hyphal system with clamped generative hyphae, strongly encrusted cystidia and basidiospores measuring 3–5 × 2–3.5 μm. Steccherinum xanthum is characterized by odontioid basidiomata and a monomitic hyphal system with generative hyphae bearing clamp connections and covering by crystals, colourless, thin-walled, smooth, IKI–, CB–and has basidiospores measuring 2.7–5.5 × 1.8–4.0 μm. Sequences of the ITS and nLSU nrRNA gene regions of the studied samples were generated, and phylogenetic analyses were performed with maximum likelihood, maximum parsimony and Bayesian inference methods. The phylogenetic analyses based on molecular data of ITS + nLSU sequences showed that two new Steccherinum species felled into the residual polyporoid clade. Further investigation was obtained for more representative taxa in Steccherinum based on ITS + nLSU sequences, which demonstrated that S. tenuissimum and S. xanthum were sister to S. robustius with high support (100% BP, 100% BS and 1.00 BPP).
Highlights
Steccherinum Gray (Steccherinaceae, Polyporales) is typified by S. ochraceum
According to our result based on the combined internal transcribed spacer (ITS) + nLSU sequence data (Fig 1), two new species are nested into the residual polyporoid clade with strong support (100% Branch support (BS), 100% BP, 1.00 Bayesian posterior probabilities (BPP))
Steccherinum tenuissimum and S. xanthum were closely related to S. robustius based on rDNA sequences (Fig 2)
Summary
Steccherinum Gray (Steccherinaceae, Polyporales) is typified by S. ochraceum Ex J.F. Gmel.) Gray, and this genus is characterized by resupinate to effused-reflexed or pileate basidiome with a membranaceous consistency, odontioid to hydnoid hymenophore, a monomitic or dimitic hyphal system with clamped or simple-septate generative hyphae, subclavate to clavate basidia and basidiospores that are colourless, thin-walled, smooth, ellipsoid to subcylindrical, acyanophilous and negative to Melzer’s reagent [1, 2]. Approximately 40 species have been accepted in the genus worldwide [3]. Molecular studies related to Steccherinum have been carried out [4–8]. Larsson [4] analysed the classification of corticioid fungi, and suggested that S. ochraceum was nested in the Meruliaceae and grouped with Junghuhnia nitida (Pers.) Ryvarden.
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