Name and publication

Phytophthora obscura Grünwald & Werres (2012)

Grünwald NJ, Werres S, Goss EM, Taylor CR, and Fieland VJ. 2012. Phytophthora obscura sp. nov., a new species of the novel Phytophthora subclade 8d. Plant Pathol. 61: 610–622.

Corresponding author: Nik.Grunwald@ars.usda.gov

Nomenclature

from Grünwald et al. (2012)

Mycobank

MB519834

Etymology

obscura, obscure: referring to the cryptic nature and the fact that it has (to date) not often been found in nature

Typification

Type: GERMANY, isolated from soil from Aesculus hippocastanum in 1994 by S. Werres (holotypus: BBA 2/ 94-IIB)

Ex-type: CBS 129273

Sequences for ex-type in original manuscript: BBA 2 ⁄ 94-IIB (type): ITS HQ917910, cox HQ917878, L10 HQ917862, β-tub HQ917870, EF1-A HQ917886, Enl HQ917894, HSP90 HQ917902, 28S HQ917854, TigA HQ917916

Ex-type in other collections

(ET) CBS 129273, S&T BL 84 (Abad), WPC P19796, 60E9 (Hong), 3106 P-09-003 (N. Grünwald)

Molecular identification

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

Phytophthora obscura isolate CPHST BL 84 (= P19796 WPC) = ITS rDNA MG865554, COI MH136946

Sequences for selected specimen

Phytophthora obscura isolate CPHST BL 85 (= NG3317) = ITS rDNA MG865553, COI MH136945

Voucher sequences for Molecular Toolbox with seven genes (ITS, β-tub, COI, EF1α, HSP90, L10, and YPT1

(see Molecular protocols page) (In Progress)

Voucher sequences for Metabarcoding High-throughput Sequencing (HTS) Technologies [Molecular Operational Taxonomic Unit (MOTU)]

(see Molecular protocols page) (In Progress)

Sequences with multiple genes for ex-type in other sources

• NCBI: Phytophthora obscura CPHST BL 84 
• NCBI: Phytophthora obscura BBA 2/94-IIB
• EPPO-Q-bank: Phytophthora obscura CBS 129273
• BOLDSYSTEMS: Phytophthora obscura (barcoding COI & ITS)

Position in multigenic phylogeny with 7 genes (ITS, β-tub, COI, EF1α, HSP90, L10, and YPT1)

Clade clade:
a taxonomic group of organisms classified together on the basis of homologous features traced to a common ancestor
8d

Morphological identification

adapted from Grünwald et al. (2012)

Colonies and cardinal temperatures

Colony colony:
assemblage of hyphae which usually develops form a single source and grows in a coordinated way
after 7 days of growth on potato dextrose agar with slightly stellate pattern, on V8A with no distinctive pattern. Minimum growth temperature 2°C; optimum 20-25°C and maximum 28°C.

Asexual phase

SporangiaSporangia:
sac within which zoospores form, especially when water is cooled to about 10°C below ambient temperature; in solid substrates, sporangia usually germinate by germ tubes
semipapillatesemipapillate:
pertaining to the production of shallow having papilla that are not well developed, shallow and less nipple-like than fully papillate structures
; persistentpersistent:
pertaining to sporangia that remain attached to the sporangiophore and do not separate or detach easily (cf. caducous)
; mainly ovoidovoid:
egg-shaped, with the widest part at the base of the sporangium and the narrow part at the apex
and also globoseglobose:
having a rounded form resembling that of a sphere
or limoniform (24–50 L × 14–32 W μm); born terminally on unbranched or on simple sympodial sporangiophoresporangiophore:
the hyphal strand on which the sporangium is formed; may be branched or unbranched to form compound sympodia or simple sympodia
. Hyphal swellings absent to rare. ChlamydosporesChlamydospores:
an asexual spore with a thickened inner wall that is delimited from the mycelium by a septum; may be terminal or intercalary, and survives for long periods in soil
absent.

Sexual phase

Homothallichomothallic:
pertaining to sexual reproduction that can take place within a single thallus (i.e. self-fertile, non-outcrossing) (cf. heterothallic).
. OogoniaOogonia:
the female gametangium in which the oospore forms after fertilization by the antheridium
smooth-walled, predominantly globoseglobose:
having a rounded form resembling that of a sphere
, sometimes ellipsoidellipsoid:
refers to a solid body that forms an ellipse in the longitudinal plane and a circle in cross section; many fungal spores are ellipsoidal or elliptic
, tapered basetapered base:
pertaining to the base of a sporangium or oogonium; funnel-shaped
(22–40 μm diam.); antheridia paragynous, nearly globoseglobose:
having a rounded form resembling that of a sphere
(6–16 × 6–18 μm); oosporesoospores:
zygote or thick-walled spore that forms within the oogonium after fertilization by the antheridium; may be long-lived
mainly spherical and pleroticplerotic:
pertaining to an oospore that fills the oogonium (cf. aplerotic)
to nearly apleroticaplerotic:
pertaining to a mature oospore that does not fill the oogonium; i.e. there is room left between the oospore wall and oogonium wall (cf. plerotic)
(18–36 μm diam.).

Most typical characters

Phytophthora obscura is characterized by the presence of mainly globoseglobose:
having a rounded form resembling that of a sphere
sporangia produced in unbranched sporangiophores.

Additional specimen(s) evaluated

Phytophthora obscura CPHST BL 84, duplicate of P19796 (World Oomycetes/Phytophthora Collection), which is a duplicate of ex-type CBS 129273

CPHST BL 85 = NG3317

Hosts and distribution

Distribution: North America (USA: OR), Europe (Germany)
Substrate: leaves, soil
Disease note: leaf blight, canker (?)
Host: Aesculus hippocastanum (Sapindaceae), Pieris sp., Kalmia latifolia (Ericaceae)

Retrieved January 31, 2018 from U.S. National Fungus Collections Nomenclature Database.

Additional references and links

 

• SMML USDA-ARS: Phytophthora obscura
• EPPO Global Database: Phytophthora obscura
• Forest Phytophthoras of the World: Phytophthora obscura
• CABI Digital Library: Phytophthora obscura
• Encyclopedia of Life (EOL): Phytophthora obscura
• Index Fungorum (IF): Phytophthora obscura

 

 

• Google All Phytophthora obscura
• Google Images Phytophthora obscura
• Google Scholar Phytophthora obscura

 

Fact sheet author

Z. Gloria Abad, Ph.D., USDA-APHIS-PPQ-S&T Plant Pathogen Confirmatory Diagnostics Laboratory (PPCDL), United States of America.