Phylogenic Species Identification of Philobolus Associated with Horses in Indiana and Ohio

Abstract

Pilobolus, a coprophilous zygomycete, is associated with herbivores. The various species of this fungus have been collected from a wide range of hosts. Most species have been isolated from multiple hosts. However, P. longipes has been reported exclusively associated with Equus spp. This study was undertaken to examine the species specific relationship of P. longipes and members of Equus, specifically E. caballus (horses). Dung samples were collected from horses located within 25 miles of Richmond, Indiana for isolates of Pilobolus. Sporangiospores from these fungal isolates were used as the source of DNA. Sequences of taxonomically informative 18S and ITS regions of rDNA were obtained using previously published protocols. DNA sequences were aligned with BLAST and compared with sequences deposited in GenBank. Sequences of DNA from the isolates in this study were examined using MEGA 4 with Clustal W. By comparing the sequences of DNA from isolates in this study with those in GenBank, it was determined that P. longipes, P. sphaerosporus, P. kleinii and P. pullus are associated with horses in Indiana and Ohio. All isolates recovered in this study are large-spore producing species of Pilobolus.