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 Add this item to the list  819700 Original description
Remarks (public):Phylogenetically, P. tyrrhenica resides in Clade 7a (Blair et al. 2008) forming a sister clade to P. uliginosa. Morphologically P. tyrrhenica is similar to its closest relative P. uliginosa. Main distinguishing characters are the exclusive production of elongated and mostly ellipsoid sporangia in P. tyrrhenica, largest oogonial and oospore diameters in P. uliginosa. Both species show similar slow growth rates, but differ in their optimum temperatures for growth and their growth rates at 25°C with P. tyrrhenica being more thermophilic. 
Description type:Original description 
Description:Phytophthora tyrrhenica produces sporangia in non-sterile soil extract. They areborne terminally on unbranched sporangiophores, non-caducous and nonpapillate. Sporangial shapes range from elongated ellipsoid (62 %) to elongated ovoid (20 %), elongated limoniform (18 %), limoniform (8 %), elongated obpyriform (4 %). Sporangia usually proliferate internally, mainly in a nested but also extended way. Zoospores are discharged through an exit pore 9.2–22.0 µm wide (av. 12.1 ± 2.4 µm). They were limoniform to reniform whilst motile, becoming spherical (av. diam = 14.6 ± 2.3 µm) on encystment. Cysts usually germinate directly by forming a hypha but diplanetism also occur. Sporangial dimensions of five isolates average 68.4 ± 1.7 x 28.9 ± 1.9 µm (overall range 45.3–110.2 x 16.2–39.4 µm and range of isolate means 66.1-70.0 x 27.5-31.9). The length/breadth ratio average 2.4–0.18 with a range of isolate means of 2.1–2.57. Catenulate, intercalary, globose to subglobose or irregular hyphal swellings with an average diameter of 18.6 ± 6.5 µm are abundantly produced in liquid culture. Chlamydospores are not produced. Phytophthora tyrrhenica produces oogonia in single culture on V8A. Oogonia are borne terminally or laterally and had globose to subglobose (93.3 %) or slightly excentric (6.7 %) shapes, often with a tapering base (52.3 %). Oogonial diameters average 37.2 ± 3.3 µm (overall range 25.0–39.3 µm and range of isolate means 26.6–44.1 µm). Oospores are plerotic, globose and usually contain a large ooplast. They have a mean diameter of 33.7 ± 1.3 µm (total range 24.6 – 39.9 µm), thick walls (av. 2.9 ± 1.5 µm, total range 1.4 – 4.4 µm) and a mean oospore wall index of 0.41 ± 0.03. With 5%, mean oogonial abortion rate is low. Antheridia are formed terminally or laterally and are exclusively paragynous, averaging 16.9 ± 4.6 x 12.8 ± 0.13 µm, with shapes ranging from clavate, globose to subglobose. 
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