Par Fournier J., Pélissier M., Lechat C.
Vol. 6 (4) – 17 octobre 2014
Résumé (anglais) : During a survey of mycobiota in the island of Mayotte situated in the Comores archipelago, a remarkable Hypoxylon with unusual off-white to pale yellowish stromata was collected by one of us (MP). Besides its striking colour it is characterized by small orbicular effused-pulvinate stromata (< 6 mm diam), with conspicuous perithecial contours, papillate ostioles and subsurface with yellow waxy granules yielding orange brown pigments in 10% KOH. Upon microscopical observation, its asci appear devoid of an apical apparatus, thus not reacting with iodine, and its ascospores have a transversely striated perispore dehiscent in 10% KOH. This combination of characters is compared with the Hypoxylon spp. appearing morphologically the most closely related and this comparative study is summarized in a table. As this Hypoxylon features a set of characters deviating from known species, it is described as new, as H. flavocremeum. A culture derived from single spore isolation was obtained and described. The ex-type culture was deposited at the CBS Fungal Biodiversity Center (CBS, Utrecht, the Netherlands). All attempts to obtain the asexual state on various media remained unsuccessful. The few other species of Hypoxylon collected during this survey are listed and briefly commented upon. The rarely recorded H. lividipigmentum is illustrated in colour