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Description type:Original description 
Description:Sporangia of P. bilorbang were observed on solid agar media including V8A, CA and CMA, and also sporangia were produced abundantly in V8A when flooded with non-sterile soil extract. Sporangia were borne terminally on unbranched sporangiophores, often in chains of internally extended or non-extended proliferating sporangia. Most of the sporangia were non-caducous and nonpapillate to semipapillate , although caducous sporangia were formed by all isolates infrequently. Sporangial shapes ranged from limoniform (41.6%; Fig. X) to ellipsoid (27.6%), ovoid (23.2%; Fig. X), and less frequently were obpyriform (3.6%), peanut shaped (3.2%) and club shaped (0.8%). Features such as a tapering base or a conspicuous basal plug were common. Sporangia usually proliferated internally in both a nested and extended way. Internally proliferating sporangiophores branched immediately after passing through the exit pore of empty primary sporangium regularly. External proliferation was observed as a short extension just behind the primary sporangium. In all isolates, two extended internal proliferating sporangia inside the primary sporangia were observed but infrequently. Occasionally, an external proliferating sporangium was formed inside the primary sporangium. Extended internal proliferation and also external proliferation were produced on V8A and CMA. Direct germination of sporangia and germination of zoospores inside of sporangia were observed on agar media. Sporangial dimensions of the five P. bilorbang isolates averaged 50.3 ± 10.57 x 27.3 ± 5.48 µm with a range of isolate means of 43.8 – 59.6 x 25.0 – 30.0 µm. The length/breadth ratio of the sporangia averaged 1.87 ± 0.34. Zoospores were discharged through exit pores 10.36 - 13.36 µm wide (av. 11.6 ± 2.49 µm). They were limoniform, ovoid to reniform whilst motile, becoming spherical (av. diam = 10.9 ± 1.7 µm) on encystment. Cysts germinated more often directly by forming up to three hyphae. In V8 agar flooded with non-sterile soil extract, globose, angular or irregular-elongated hyphal swellings, frequently catenulate and with radiating hyphae or forming branching points, were regularly formed. Hyphal swellings had a mean diameter of 18.6 ± 4.81 µm. Chlamydospores were not seen. Coiled hyphae were observed on agar media.

P. bilorbang is homothallic and all the five isolates readily produced oogonia in single culture on CA and V8A, and oospores matured within ~2 - 4 weeks. Oogonial shape ranged from globose and subglobose with smooth walls. Oogonial stalks were long and most of the time twisted. Oogonial diameters averaged 33.87 ± 6.03 µm with a total range of 26.49 – 37.42 µm. Most oogonia were viable, containing oospores with a large ooplast (aborted oospores = 3.4%) or with two ooplasts. Ooplasts with disraptured margins were observed.
Oospores of P. bilorbang were observed across the whole plate on carrot agar and on the colony edge on V8 agar. Oospores were also formed on malt extract agar, in dual culture plates when P. bilorbang colonies were paired with C. pauciseptatum. Oospores were highly plerotic to slightly aplerotic and averaged 32.2 ± 6.12 in diameter with relatively thick oospore walls (on av. 2.65 ± 0.69 µm; total range 2.0 – 3.0 µm) and a high mean oospore wall index of 0.42 ± 0.07.
Antheridia were one-celled, hyaline and globose to cylindrical, with a range of isolates means of 11.0 - 12.43 x 12.19 - 14.09 (av. 11.4 ± 2.28 x 13.0 ± 2.51). The antheridia were paragynous and finger-like projection(s) were observed in most of the antheridia. Most of the times, more than one antheridia were attached to one oogonium.
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