Dendrochytridium crassum gen. et sp. nov., a taxon in Chytridiales with unique zoospore ultrastructure

Abstract

A water culture of detritus collected from an Australian tree canopy yielded multiple isolates (designated JEL 352, JEL 353, JEL 354) of an unidentified chytrid that grew on pollen bait and encysted spores of a Dictyuchus sp. oomycete. Morphological information from JEL 352 and genetic information from JEL 354 of this unidentified chytrid have been in several publications but the organism has not been named. Because isolates JEL 352 and JEL 354 are no longer viable, we sequenced partial SSU and LSU rDNA of isolate JEL 353, documented its thallus morphology with light microscopy and determined its zoospore ultrastructure via transmission electron microscopy. DNA evidence placed JEL 353 in Chytridiaceae, and its genetic composition was identical to that of JEL 354. Thallus morphology of JEL 353 was similar to that of JEL 352. Its zoospore ultrastructure is less complex compared to other members of Chytridiaceae. In pure culture, the rhizoidal system differed from other members of the family in being unevenly broad and not tapering to fine tips. Based on genetic, morphological and ultrastructural evidence, we place this chytrid in a new genus in Chytridiaceae and describe it as the new species Dendrochytridium crassum.

• chytrid
• Chytridiaceae
• sampling
• systematics
• taxonomy

Acknowledgments

This study was supported by the National Science Foundation through MRI DEB-0500766 and REVSYS DEB-00949305. We thank Dr Steve Stephenson (NSF INT 0139547) for furnishing the samples from which Dendrochytridium crassum was isolated.