Molecular phylogeny of the Ceratocystis moniliformis complex and description of C. tribiliformis sp. nov

Ceratocystis moniliformis is a colonist of fresh wounds on trees, mainly in the tropics. The fungus is not known to be a pathogen and has thus not been widely studied. Ceratocystis moniliformis has been reported on many taxonomically different plants and in many different climatic zones. It is thought to represent a complex of morphologically similar but physiologically and phylogenetically different species, some of which have recently been described. The aim of this study was to consider the phylogenetic relationship of C. moniliformis isolates from various hosts and origins, based on comparisons of DNA sequences of the Internal Transcribed Spacer (ITS) regions including the 5.8S gene of rDNA, beta -tubulin and EF1- alpha genes. Four distinct clades were discernable in the phylogenetic tree. Two recently described species, C. bhutanensis and C. moniliformopsis, were confirmed to be phylogenetically distinct. Ceratocystis moniliformis sensu stricto isolated from Bhutan, Costa Rica, Ecuador and South Africa represented a well-resolved monophyletic group. A collection of isolates initially identified as C. moniliformis, from Pinus merkusii in Sumatra, Indonesia was found to reside in a distinct clade. Ceratocystis tribiliformis sp. nov. is described here to accommodate this group of isolates. Morphologically, C. tribiliformis differs from C. moniliformis in having obpyriform to globose ascomata and both smooth and granular hyphae. Ceratocystis tribiliformis also has distinct optimal growth at 20-25 degree C on malt extract agar.