Phylogenetic and morphological analyses of the mycoparasitic genus  Piptocephalis

ABSTRACT

The Piptocephalidaceae (Zoopagales, Zoopagomycota) contains three genera of mycoparasitic, haustoria-forming fungi: Kuzuhaea, Piptocephalis, and Syncephalis. Although the species in this family are diverse and ubiquitous in soil and dung, they are among the least studied fungi. Co-cultures of Piptocephalis and their hosts are relatively easy to isolate from soil and dung samples across the globe, making them a good model taxon for the order Zoopagales. This study focuses on the systematics of the genus Piptocephalis. Despite the fact that there are approximately 40 described Piptocephalis species, there are no modern taxonomic or molecular phylogenetic treatments of this group. Minimal sequence data are available, and relatively little is known about the true diversity or biogeography of the genus. Our study addresses two aspects: Piptocephalis systematics and analyses of the length and inter- and infraspecific variation of the nuc rDNA internal transcribed spacer (ITS1-5.8S-ITS2 = ITS) region. First, we generated a large subunit (28S) nuc rDNA phylogeny and evaluated several morphological characters by testing their correlation with the phylogeny using Bayesian Tip-association Significance testing (BaTS). We found monophyly of Piptocephalis species identified based on morphological traits, but morphological character states were not conserved across clades, suggesting that there have been multiple gains and losses of morphological characters. We also found that Kuzhuaea is nested within Piptocephalis. Second, we amplified the ITS from many Piptocephalis isolates, created a sequence alignment, and measured the lengths using the software ITSx. Piptocephalis species had ITS regions that were longer than the average for most Dikarya but were similar in length to those of the related genus Syncephalis.

KEYWORDS:

• Co-culture
• ITS
• morphology
• mycoparasites
• Piptocephalidaceae
• zygomycetes
• 1 new taxon

ACKNOWLEDGMENTS

We would like to thank K. O’Donnell and the NRRL culture collection of the USDA Agriculture Research Service for providing cultures. We also appreciate the efforts of Stephanie Cruz for helping to maintain the Piptocephalis culture collection at the University of Florida.

supplemental data

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Additional information

Funding

Funding was provided by NSF as part of the ZyGoLife project (DEB-1441677 to M. E. Smith), with additional funding by the Department of Plant Pathology and the Institute for Food and Agricultural Sciences (IFAS) at the University of Florida.