Rhizophydium brooksianum sp. nov., a multipored chytrid from soil

Abstract

Rhizophydium136 was isolated from pollen bait placed in a water culture containing garden soil from Penobscot County, Maine. It is an important isolate because its entire mitochondrial genome has been sequenced and it is the representative member of the Chytridiales in a fungal phylogeny based on mitochondrial protein sequences. Also, this isolate is included in an 18S rDNA, chytrid phylogeny. On nutrient agar, many inflated rhizoidal axes extend from the base of the zoosporangium, zoosporangia mature in 3 d and zoospores discharge through numerous, lenticular, discharge pores. Smooth-walled resting spores form in crowded cultures. Zoospores are a variation of the Rhizophydium subtype. This chytrid differs from R. sphaerotheca sensu Barr and because it cannot be placed in a described species it herein is described as Rhizophydium brooksianum sp. nov. Many of the differences between Rhizophydium brooksianum and other multipored Rhizophydium isolates were observed only in pure culture. Attributing a spherical, multipored Rhizophydium to a species that was described without developmental information from pure culture is untenable. Epitypes or neotypes for inadequately characterized species need to be selected, and cultures made available.