Peronosclerospora sp. nov. 2

Description

Sporangiophores/Conidiophores not observed.

Sporangia/conidia not observed.

Oogonia formed in the leaf blades which split into a tangled mass of vascular fibres, subglobose-globose, (32-)37-49(-50) µm in diameter, sides flattened; wall (exosporium) 2-12 µm thick, golden brown, often enclosed in remnants of the host’s necrotic parenchyma cells.

Oospores one per oogonium, globose-subglobose, (27-)30-36(-42) µm in diameter, adnate with oogonium wall, with a single vacuole; wall (endosporium) 1-3 µm thick, hyaline, even, smooth.

Hosts
   
Host family: Poaceae
   
Host species:

Triodia pungens - BRIP , ,

   
  Triodia microstachya - BRIP
   
  Triodia sp. - BRIP , , , , , VPRI 21578

Distribution

NT, QLD, WA

Comments

This downy mildew fungus has been collected intermittently on Triodia species at many localities in Queensland, Western Australia and the Northern Territory since 1952. Ryley and Langdon (2001) reported that although the dimensions of its oospores fall within the range for those of P. noblei, collection and examination of the asexual state and molecular phylogeny investigations are needed to determine its identity.  Molecular phylogenetic studies have demonstrated that the downy mildew fungus on Triodia species is a new species, which XXXXXX et al., (201X) formally described and named Peronosclerospora?

There are no other graminicolous downy mildews recorded on this host genus throughout the World, so P. x can for the time being be considered as an Australian indigenous species.
Highslide JS
Oospores of Peronosclerospora sp. on Triodia sp. - BRIP 44583.
Scale bar = 10 µm.