Phytophthora parvispora

Name and publication

Phytophthora parvispora Scanu and Denman (2014)

Scanu B, Hunter GC, Linaldeddu BT, Franceschini A, Maddau L, Jung T, and Denman S. 2014. A taxonomic re-evaluation reveals that Phytophthora cinnamomi and Phytophthora cinnamomi var. parvispora are separate species. Forest Pathol. 44: 1–20. 

Corresponding author:


from Scanu et al. (2014)




= Phytophthora cinnamomi var. parvispora Kröber & Marwitz, Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz 100: 255 (1993) [MB360187]


refers to the small-sized reproductive structures


Type: ITALY, Sardinia, isolated from collar rot of a declining planted Arbutus unedo collected by B. Scanu, 2011; CBS H-21132 (holotype, dried culture on CA, Herbarium CBS-KNAW Fungal Biodiversity Centre)

Ex-type: CBS 132772 = PH072 (culture ex-type A1)

Sequences for ex-type in original manuscript: CBS 132772 = ITS KC478667, β-tub KC609402, Cox1 KC609413 (FM 85/84), Cox2 KC559763 (FM 75/78)

Ex-type in other collections

CBS 132772 = P19847 (WOC/WPC), CPHST BL 98 (Abad), 66C8 (Yang)

Molecular identification

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

Phytophthora parvispora isolate CBS 132772 = ITS rDNA KC478667
Phytophthora parvispora isolate CPHST BL 98 ( = P19847) COI MH136953

Sequences for selected specimens

Phytophthora parvispora isolate CBS 411.96 = ITS rDNA KC478672
Phytophthora parvispora isolate CPHST BL 107 ( = P8495 ) COI MH136955

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

Clade 7a

Morphological identification

adapted from Scanu et al. (2014)

Colonies and cardinal temperatures

Colonies on V-8 agar slight chrysanthemum to stellate patten, in potato dextrose agar and malt extract agar with slow growth, in carrot agar with chrysanthemum to stellate pattern. Minimum temperature for growth 10°C, optimum 27°C, maximum 37°C.

Conditions for growth and sporulation

Sporangia are abundantly produced in liquid cultures after 24 hrs.

Asexual phase

Sporangia nonpapillate; persistent; ovoid, ellipsoid or obpyriform (31–43 µm L x 20–26 µm W); showing nested and extended internal proliferation, frequently producing long chains of proliferating sporangia along the same sporangiophore, external proliferation is also observed; sporangia originated mostly in unbranched sporangiophores and sometimes intercalary. Hyphal swellings irregular or globose, often formed in cluster aggregations. Chlamydospores occasionally formed and are globose (19-24 µm diam.) and produced mostly laterally and rarely terminally.

Sexual phase

Heterothallic. Oogonia golden brown, smooth-walled and globose (31–33 µm diam.); antheridia amphigynous and globose; oospores aplerotic to slightly aplerotic (25–26 µm diam.).

Most typical characters

Phytophthora parvispora is very similar to P. cinnamomi in the morphological characters of the asexual phase. Phytophthora parvispora produces occasionally small chlamydospores in comparison to the frequent chlamydospores produced by P. cinnamomi.

Additonal specimen(s) evaluated

Phytophthora parvispora ex-type CPHST BL 98 (A1), duplicate of P19847 (World Oomycetes/Phytophthora Collection), which is a duplicate of CBS 132772

CPHST BL 13 = P8494 WPC A1 from Beaucamea sp., collected by R. Marwitz in Germany, Frankfurt in 1990 = CBS 411.96 (BBA 65507)

CPHST BL 107= P8495 WPC A2 from Beaucamea sp., collected by R. Marwitz in Germany, Frankfurt in 1990 = CBS 413.96 (BBA 65508)

Hosts and distribution

Distribution: Europe (Germany, Italy, Portugal), South Africa, South America (Brazil), Taiwan, possibly also Australia
Substrate: roots and stems
Disease note: collar and stem rot, dieback
Host: diverse hosts

Retrieved February 01, 2018 from U.S. National Fungus Collections Nomenclature Database.

Additional Info
Hosts: Arbutus unedo, Mandevilla sp., Pinus pinea, Beaucamea sp., and Agathosma betulina

Quarantine status

USA Status: This species was listed as a species of concern during the 2009 Phytophthora prioritization project conducted by USDA APHIS PPQ CPHST PERAL (Schwartzburg et al.).

Phytophthora parvispora is also listed in the U.S. Regulated Plant Pest Table (last modified Nov. 15, 2017).

Additional references and links

see also Phytophthora cinnamomi parvispora

Fact sheet author

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