Phytophthora cacuminis

Name and publication

Phytophthora cacuminis I. Khaliq and T.I Burgess (2019)

Khaliq I, Hardy GE, McDougall KL, Burgess TI. 2019. Phytophthora species isolated from alpine and sub-alpine regions of Australia, including the description of two new species; Phytophthora cacuminis sp. nov and Phytophthora oreophila sp. nov. Fungal Biology 123 (1): 29–41.

Nomenclature

Mycobank

MB825231

Etymology

The species name cacuminis is derived from a Latin word ‘cacumen’ for a ‘peak’. The name is given to the species based on its isolation from a mountain peak in Tasmania.

Typification

Type: AUSTRALIA south Australia: Tasmania, Mount Field NP, from symptomatic Eucalyptus coccifera, May 2016, collected by Treena Burgess, isolated by I. Khaliq. holotype MURU 482 (dried culture on V8A, Herbarium of Murdoch University, Western Australia)

Ex-type: culture CBS 144708 = U40

Sequences of Ex-type in manuscript: ITS MG542997, ß-tubulin MG543045, HSP90 MG543032, cox1 MG543010, nadh1 MG543019

Molecular identification

Position in ITS phylogenetic tree

Clade 8a

Morphological identification

Colonies and cardinal temperatures

Colonies had a halo of submerged hyphae on CA, plumose growth pattern on V8A, uniform growth on MEA, and dense growth on half PDA. Minimum growth temperature 4°C, optimum 20°C, and maximum 25°C.

Conditions for growth and sporulation

Sporangia are produced in water cultures (soil extract or river water) and not observed in solid media. Oogonia not formed in culture even when paired with different mating types.

Asexual phase

Sporangia were non-papillate, persistent, and predominantly ovoid in shape with internal proliferation, both nested and extended. Sporangia averaged 27.4 x 22.4 µm (overall range 14.5–40.2 x 10.8–37.3 µm). Sporangiophores simple (often twisted and narrow). Hyphal swellings absent. Chlamydospores present.

Sexual phase

Sterile in culture.

Most typical characters

Phytophthora cacuminis closely resembles P. fallax; the most distinguishing characteristics are that it is sterile in culture and has a low temperature maxima for growth.

Specimen(s) evaluated

Australia, Tasmania, Mount Field National Park, from rhizosphere soil collected symptomatic Eucalyptus coccifera, TI Burgess, 2016, CBS 144708 = U40 and U41

Hosts and distribution

Distribution: Australia
Substrate: roots
Disease note: no known disease
Host: native vegetation

Additional references and links

none available

Fact sheet author

Treena Burgess, Ph.D., Phytophthora Science and Management, Harry Butler Institute, Murdoch University