Phytophthora insulinativitatica

Name and publication

Phytophthora insulinativitatica Q.N. Dang, G. Hardy and T.I. Burgess (2021)

Dang QN, Pham TQ, Arentz F, Hardy GE, Burgess TI. 2021. New Phytophthora species in clade 2a from the Asia-Pacific region including a re-examination of P. colocasiae and P. meadii. Mycological Progress 20 (2): 111–129.





referring to the locality (Christmas Island) where this species was recovered


Type: AUSTRALIA, Christmas Island, rhizosphere soil from disturbed rainforest, March 2016, G. Hardy, holotype MURU468

Ex-type: culture CBS 146553

Sequences of ex-type in manuscript:  ITS KY212028, β-tubulin MT583631, hsp90 MT583676, cox1 MT583646, cox2 MT583661, nadh1 MT583691, rps10 MT583707

Molecular identification

Position in ITS phylogenetic tree

Clade 2a

Morphological identification

Colonies and cardinal temperatures

Colony morphology smooth and uniform on PDA, cottony and uniform on CA, stellate on MEA, produced a pattern of concentric circles on V8A. Minimum growth temperature 4°C, optimum 30°C, and maximum 35°C.

Conditions for growth and sporulation

Sporangia are produced in water cultures (soil extract) and not observed in solid media. Oogonia are formed readily in paired cultures on V8A after about 21 d.

Asexual phase

Sporangia were semi-papillate, caducous, and predominantly limoniform with no proliferation. Sporangia averaged 34.1 x 21.5 µm (overall range 25.4–45 x 16.1–28.8 µm). Sporangiophores umbellate and compound sympodia. Hyphal swellings present. Chlamydospores present.

Sexual phase

Heterothallic. Oogonia had smooth walls and size ranged from 20.3–32.5 µm. Oospores plerotic to semi-aplerotic, globose, size ranged 18.3–30.5 µm. Antheridia amphigynous.

Most typical characters

Phytophthora insulinativitatica resides in clade 2a most closely related to P. botryosa. The feature that most distinguishes P. insulinativitatica is the umbellate and compound symposia.

Additional specimen(s) evaluated

Australia, Christmas Island, rhizosphere soil from disturbed rainforest, 2016, G. Hardy, CBS 146553; CI21A

Hosts and distribution

Distribution: Australia (Christmas Island)
Substrate: rhizosphere soil
Disease note: no known disease
Host: disturbed rainforest vegetation

Additional references and links

none available

Fact sheet author

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