Multi-Gene Phylogeny and Taxonomy of Hypoxylon (Hypoxylaceae, Ascomycota) from China

Abstract

The Hypoxylon species play an important ecological role in tropical rainforest as wood-decomposers, and some might have benefical effects on their hosts as endophytes. The present work concerns a survey of the genus Hypoxylon from Hainan Tropical Rainforest National Park of China. Four new species: H. wuzhishanense, H. hainanense, H.chrysalidosporum, and H.cyclobalanopsidis, were discovered based on a combination of morphological characteristics and molecular data. Hypoxylon wuzhishanense is characterized by Rust pulvinate stromata, amyloid apical apparatus and brown ascospores, with most of the perispore being indehiscent in 10% KOH. Hypoxylon hainanense has effused–pulvinate and Violet stromata, amyloid apical apparatus, light-brown to brown ascospores with straight germ slit and dehiscent perispore. Hypoxylonchrysalidosporum is distinguished by glomerate to pulvinate stromata, highly reduced or absent inamyloid apical apparatus, and light-brown to brown ascospores with very conspicuous coil-like ornamentation. Hypoxyloncyclobalanopsidis has Livid Purple pulvinate stromata, highly reduced amyloid apical apparatus, faint bluing, brown ascospores and dehiscent perispore, and it grows on dead branches of Cyclobalanopsis. Detailed descriptions, illustrations, and contrasts with morphologically similar species are provided. Phylogenetic analyses inferred from ITS, RPB2, LSU, and β-tubulin sequences confirmed that the four new species are distinct within the genus Hypoxylon.

Three New Species of Hypoxylon (Xylariales, Ascomycota) on a Multigene Phylogeny from Medog in Southwest China

“…The stroma and perithecia were observed, photographed and measured with a VHX-600E 3D microscope from the Keyence Corporation (Osaka, Japan). Fresh material was respectively immersed in water, 10% KOH, and Melzer’s reagent to observe micromorphological structures as determined by Ma et al and Song et al [ 20 , 21 ]. The observations, micrographs, and measurements of asci and ascospores were performed by using an Olympus IX73 inverted fluorescence microscope (Olympus, Tokyo, Japan) and the CellSens Dimensions Software (Olympus, Tokyo, Japan).…”

“…Fresh tissue of stroma was used for DNA extraction and sequence generation following the suggestions by Ma et al and Song et al [ 20 , 21 ]. Sequences of four DNA loci—ITS (internal transcribed spacer regions), nrLSU (nuclear large subunit ribosomal DNA), RPB2 (RNA polymerase II second largest subunit), and β-tubulin (beta-tubulin) were selected for multi-gene phylogenetic analyses [ 2 , 25 ].…”

“…The latter was used for an added validation to the former. Maximum likelihood analyses used raxmlGUI 2.0 with 1000 bootstrap replicates and GTRGAMMA+G as a substitution model [ 20 , 31 , 32 ]. Bayesian analyses used MrBayes 3.2.6 with jModelTest 2 conducting model discrimination and Markov chain Monte Carlo (MCMC) sampling.…”

“…Bayesian analyses used MrBayes 3.2.6 with jModelTest 2 conducting model discrimination and Markov chain Monte Carlo (MCMC) sampling. Every 100th generation was sampled as a tree with 1,000,000 generations running for six MCMC chains [ 20 , 33 ]. Phylogenetic trees were viewed and edited by FigTree version 1.4.3 and Photoshop CS6.…”

“…In this genus, more than 200 species with 1189 epithets included in the Index Fungorum have been reported so far [ 4 , 15 , 16 ]. Despite species of Hypoxylon being widely distributed throughout Asia, only 57 species were reported in China currently [ 17 , 18 , 19 , 20 , 21 ].…”