A Phylogenetic Analysis of Heterocephalum: Using Molecular Tools to Reassess the Taxonomic Placement of an Unusual and Infrequently Collected Fungus

Abstract

Abstract from thesis: Heterocephalum aurantiacum is a little-known fungal species first described by Roland Thaxter in 1903 following collection of the type specimens from goat dung in Jamaica. Historical classification of the fungus by Raper and Fennell (1952) placed it with asexually-reproducing Ascomycete species based on morphological and developmental similarities. This study utilized molecular tools to update these classifications and elucidate the phylogenetic relationships between Heterocephalum and other species in the Aspergillus clade. Samples were cultured on antibiotic-containing media for 7-10 days before sporulating heads were removed for extraction of DNA. NS1 and NS4 primers were used for amplification of the 18S small-subunit (SSU) rRNA gene and ITS1f and ITS4 primers for amplification of the internal transcribed spacer (ITS) gene regions 1-4. Sequences were obtained from three samples, one of which was H. aurantiacum and two of which were believed to be H. taiense. These were aligned in ClustalX with published sequences from the GenBank database, and maximum parsimony analyses were generated using PAUP 4.0b10. Phylogenies for each gene were generated and Heterocephalum was placed in the order Eurotiales within the Aspergillus clade. This study supplemented the initial classification of this genus with molecular data and further supported the delineation of two distinct species of Heterocephalum. Future areas for research include creating a multi-gene phylogeny to expand the body of knowledge about this species within the economically and ecologically-important Aspergillus clade. Table of