Three new species of Hypoxylon and new records of Xylariales from Panama

Abstract

Three new species of Hypoxylon (Hypoxylaceae, Xylariales) are described based on a polyphasic approach that included morphological examination, molecular phylogeny and chemotaxonomic studies of specimens collected in Panama. Specifically, we compared the sexual morph (stromata, asci, and ascospores) of the specimens collected with known species of Hypoxylon and inferred a phylogeny of this genus based on a Randomized Axelerated Maximum Likelihood (RAxML) analysis of partial β –tubulin (TUB2) DNA sequences and the internal transcribed spacer regions (ITS). Hypoxylon baruense sp. nov. is phylogenetically related to H. subgilvum but differs in the shape of stromata, and by having larger ascospores and a smooth perispore. Hypoxylon bellicolor sp. nov. is phylogenetically well differentiated, featuring effused– pulvinate stromata with orange granules and ostioles lower than the stromatal surface. Hypoxylon sporistriatatunicum sp. nov. , is phylogenetically related to H. shearii var. minor but differs in the shape of the stromata, in having ostioles higher than the stromatal surface, and in having larger ascospores. The secondary metabolite profiles of these species were studied by HPLC–DAD–MS and these correspond to the results of the morphological and phylogenetic studies. Additionally, we also report Amphirosellinia evansii, H. howeanum, H. cinnabarinum and Stilbohypoxylon quisquiliarum from Panama for the first time and Citrus sinensis as a new host of H. cinnabarinum . With this work, the number of species of Xylariales and Hypoxylon reported from Panama have increased to 103 and 18, respectively. – 7 μm (n=6), with apical apparatus bluing in Melzer’s reagent, 2 – 3.6 μm long x 1 – 1.4 μm broad (n=5). Ascospores: dark brown, unicellular, ellipsoid–inequilateral, 10–15 x 5– 7.6 μm (n=50), with straight conspicuous germ slit less than spore–length; perispore indehiscent in 10% KOH, smooth. Culture characteristics – Colonies on PDA covering a 60 mm Petri dish in 3 weeks, mycelium white above, reverse dark green, with concentric zones. No asexual morph observed in the culture media used i.e. PDA, 2% MEA, V8 agar, oatmeal agar and potato carrot agar. (n=11). Ostioles: than the stromatal