Phylogenetic relationships in Leptographium based on morphological and molecular characters

Abstract

Species of Leptographium Lagerberg & Melin are characterized by mononematous conidiophores with dark stipes and conidiogenous apparatuses with complex series of branches. These fungi generally inhabit woody substrates, are associated with bark beetles (Coleoptera: Scolytidae) and cause blue-stain in conifers. Few phylogenetic studies have been conducted on Leptographium species, and those that have been undertaken have been focused on a small number of species. The objective of this study was to investigate the phylogenetic relationships among species in Leptographium based on partial DNA operon sequences and to ascertain whether morphological characters are congruent with DNA-based phylogeny. Morphological characters were analyzed and compared with results from DNA sequence analysis. Results indicate that there are three groups within Leptographium based on DNA sequence analysis. There was, however, no congruence between these groups and those emerging from morphological characters. Data from this study strongly support the connection between Leptographium and Ophiostoma Sydow & Sydow. They also provide us with an objective means to confirm the identity of many Leptographium species that are difficult to distinguish based on morphological characters.Key words: Leptographium, phylogeny, morphology, Ophiostoma, rRNA.