Phytophthora chlamydospora

Name and publication

Phytophthora chlamydospora Brasier and Hansen (2015)

Hansen EM, Reeser P, Sutton W, and Brasier CM. 2015. Redesignation of Phytophthora taxon Pgchlamydo as Phytophthora chlamydospora sp. nov. North American Fungi 10 (2): 1–14. 

Corresponding author:


from Hansen et al. (2015)




refers to the distinguishing chlamydospores formed especially at higher temperatures


Type: UNITED KINGDOM, isolated from ornamental Prunus in Cheltenham, Gloucestershire in 1971 by C.M Brasier and R.G Strouts OSC # 153153 (Forest Research Advisory Service Record 72/445/82 - isolate P236)

Ex-type: P6133 (World Phytophthora Collection) duplicate of isolate P236

Sequences for ex-type in original manuscript: Phytophthora taxon Pgchlamydo isolate P236 = COX spacer KF750598, β-tubulin KF750602

Although sequence ITS AF541890 is cited as the holotype, it corresponds to Phytophthora gonapodyides strain P501 isolated from ivy roots in UK.

The correct code for the ITS rDNA for the type of P. chlamydospora is: Phytophthora sp. P236 = ITS rDNA AF541900 (provided by H. Hansen to G. Abad on 7.22.15).

Specimen P6133 ITS rDNA GU258890 (under P. gonapodyides

Ex-type in other collections

P6133 (WPC) = CPHST BL 156 (Abad)

Molecular identification

Voucher sequences for barcoding genes (ITS rDNA and COI) of the ex-type (see Molecular protocols page)

Phytophthora chlamydospora isolate CPHST BL 156 (= P6133 WPC) = ITS rDNA MG865471, COI MH136867

Sequences for ex-type in other sources
Position in ITS phylogenetic tree

Clade 6b

Morphological identification

adapted from Hansen et al. (2015)

Colonies and cardinal temperatures

Colonies on V8-A, PDA, and MEA with rosette (petaloid) pattern. Optimum 25–28°C, and maximum 36–37°C.

Conditions for growth and sporulation

Sporangia and hyphal swellings formed in water. Chlamydospores formed in agar media, often scarce at 22°C but usually abundant at 28°C.

Asexual phase

Sporangia nonpapillate, persistent (noncaducous), obpyriform or ovoid, often somewhat elongated, with internal proliferation; average 56 μm x 36 μm; sporangia produced in unbranched or occasionally sympodial sporangiophores. Hyphal swellings large globose, subglobose to elongate, produced in clumps and in branched chains (catenulate). Chlamydospores are globose, mostly intercalary but also lateral, terminal, and sessile.

Sexual phase


Additional specimen(s) evaluated

Phytophthora chlamydospora ex-type CPHST BL 156 = P6133 (World Phytophthora Collection)

Hosts and distribution

Distribution: Europe, North America
Substrate: roots, leaves, water and riparian areas, soil
Disease note: canker, root rot
Host: wide host range of hard and soft woods

Retrieved from U.S. National Fungus Collections Nomenclature Database.

Additional references and links

  • Phytophthora DATABASE: Phytophthora chlamydospora
  • EPPO-Q-bank: Phytophthora chlamydospora
  • SMML USDA-ARS: Phytophthora chlamydospora
  • EPPO Global Database: Phytophthora chlamydospora
  • CABI Invasive Species Compendium: Phytophthora chlamydospora
  • Encyclopedia of Life (EOL): Phytophthora chlamydospora
  • Index Fungorum (IF): Phytophthora chlamydospora
  • Plantwise Knowledge Bank: Phytophthora chlamydospora

Fact sheet author

Z. Gloria Abad, Ph.D., USDA-APHIS-PPQ-S&T Beltsville Laboratory, United States of America