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Remarks (internal):Distribution, pathogenicity and ecology: P. europaea was recovered from forest soils in north-eastern France and Northern Germany, around mature Q. petraea and Q. robur, but can also be found below Carpinus betulus and Fraxinus excelsior growing in these mixed forests (Hansen & Delatour 1999). It seems to be restricted to soils with permanently or seasonally high water tables. It was the most abundant Phytophthora species in seasonally wet soils in the Forêt d'Amance, Lorraine France, where it was recovered from soil at all seasons of the year (Hansen & Delatour 1999). It was not associated with symptoms of oak decline. Isolate EUR1 of P. europaea was only weakly aggressive to Q. robur seedlings (Table 4), and caused extensive decay of inoculated apple fruits (Jung, unpubl.). However, additional pathogenicity tests comprising more isolates, other potential host species, e.g. F. excelsior and C. betulus, and older plants, are needed before firm conclusions about the host range and aggressiveness of this new species can be drawn.
 
Description type:Original description 
Description:Phytophthora europaea E. M. Hansen & T. Jung, sp.nov. (Figs 1-10)
Morphology and growth: Phytophthora europaea is homothallic; most isolates produce oogonia quickly and abundantly. Oogonia from 6 isolates averaged 33±4-6 µm, with isolate means ranging from 30 to 35 µm (type isolate : 30±4-6 µm). Antheridia are paragynous, sometimes with short hyphal extensions, about 122-2 x 9±1-7 µm, and attached near the stalk (Figs 2-4). Oogonia usually exhibit a tapering, often curved base (Figs 2-4). Oospores nearly fill the oogonia, and average 29±4-5 µm diam with isolate means rangingfrom 27 to 32 µm (type isolate : 27±4-2 µm). The oospore wall is about 2±0-5 µm diam, often turning golden-brown when ageing. Non-papillate, ellipsoid, ovoid and obpyriform sporangia with a broad exit pore and a sometimes pointed apex are formed in water (Figs 5-9). Sporangia sometimes exhibit a tapering base, often with the sporangiophore widening to the point of attachment (Fig. 9). Dimensions average 46±10-7 x 32±5-4 µm with isolate means of 36- 57 x 2-37 µm (type isolate : 57±13-6 x 37±4-5 µm); length/breadth ratio is about 1-4. Sporangia form on long, sparingly branched sporangiophores. Sporangial proliferation is usually internal, often nested (Figs 6-8), but occasionally sympodial. Irregular, mostly elongated hyphal swellings are produced by most isolates in liquid culture (Fig. 10). P. europaea shows moderately slow growth at 20 ° on CMA (radial growth about 4 mm d¹), V8A (5-6 mm d ̄¹) and MEA (3-7 mm d ̄¹), but slow growth on PDA (< mm d ̄¹). On CMA isolates exhibit a broad growth optimum from 21 to 25 ° (4-4-3 mm d ̄¹), and grow about 2-3 mm d ̄¹ at 30 ° (Fig. 29). Colonies are loosely aerial with no pattern on CMA, and exhibit a striate pattern on V8A and MEA with a dense central mound of aerial hyphae. On PDA, colonies are dense felty with a central mound of hyphae (Fig. 1). None of the isolates produced pigments on CHT agar. Similar species : P. europaea is a homothallic species with non-papillate sporangia, which belongs to Group V of the morphological classification system of Waterhouse (Waterhouse 1963, Stamps et al. 1990). ITSDNA sequences indicate P. europaea belongs to Clade 7a of Cooke et al. (2000), allied with P. cambivora, P. fragariae, the `alder phytophthora' (data not shown; Brasier et al. 1995, 1999) and P. uliginosa (described below) (Fig. 30). This relationship is confirmed by AFLP analysis (Jung & Cooke, unpubl.), and isozyme analysis (Man in't Veld, pers. comm.). P. europaea shares many morphological and growth features with other members of the P. cambivora clade (Cooke et al. 2000). It is distinguished by its combination of vegetative, sexual and physiological characters, its pathogenicity and ecology, and ITS-DNA sequences. Most other species of the P. cambivora clade have amphigynous or both amphigynous and paragynous antheridia (Table 2), and are aggressive pathogens, whereas P. europaea has exclusively paragynous antheridia, and seems to be only weakly aggressive to Q. robur (Table 4, Brasier, pers. comm.). P. cambivora is heterothallic with 2-celled amphigynous antheridia and bullate oogonia, and both optimum and maximum temperature for growth and growth rate at optimum temperature are higher than in P. europaea (Brasier et al. 1995). P. fragariae is homothallic with both amphigynous and paragynous antheridia, and both optimum and maximum temperature for growth, and growth rate at optimum are lower (Erwin & Ribeiro 1996, Wilcox et al. 1993, Kro$ ber 1985). The `alder Phytophthora' is homothallic with amphigynous 1- or 2-celled antheridia and bullate oogonia in most variants, but oospores often abort (Brasier et al. 1995, 1999). Like P. europaea, P. uliginosa (described below) is homothallic with one-celled paragynous antheridia and smooth-walled oogonia. P. europaea has smaller oogonia and oospores with tapering oogonium base, narrower exit pores, and different colony morphologies on CMA, V8A, MEA and PDA. It is less aggressive to Q. robur, has higher growth rates and cardinal temperatures for growth, and different ITS-DNA sequence than P. uliginosa (Table 2, Fig. 30). Isolates described as `type 6' in Hansen & Delatour (1999) or ` species 3' in Jung (1998) and Jung et al. (1996, 2000a, b) refer to P. europaea.
 
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