Plectospira gemmifera Drechsler (1929: 358)

Jerônimo, Gustavo Henrique, Jesus, Ana L., Rocha, Sarah C. O., Gonçalves, Danilo R. & Pires-Zottarelli, Carmen L. A., 2017, New insights into Plectospira genus (Oomycetes, Straminipila): morphological and molecular analyses, Phytotaxa 307 (3), pp. 191-198 : 193-194

Plectospira gemmifera Drechsler (1929: 358)

Fig 1. A–M

Mycelium dense; hyphae slender, sparingly branched. Inflated elements of sporangia abundant, sometimes very extensive, which produces a long tube to release the zoospores. Zoospores forming an evanescent cluster in exit orifice and encysting with usually 10–12 μm diam. Gemmae abundant, spherical, 20–35 μm diam. and frequently pyriform or obpyriform, 40–35 × 25–28 μm diam. Oogonia mostly terminal on short branches or on longer hyphae, smooth, subsphaerical, 18–22 × 19–24 μm diam., spherical, 20–30 μm diam. provided with wall 2.5–3.0 μm in thickness. Antheridia absent or when present, diclinous. Oospore single, colorless, subcentric, spherical, 15–20 μm diam. and subsphaerical, 18–20 × 20–22 μm diam.

Specimen examined — BRAZIL. São Paulo: Votorantim, Itupararanga reservoir, from sample of surface sediment located 2 meters under the water column, 29 august 2012, CCIBt 4250 and MMBF 04/16.

Notes: The isolate CCIBt 4250 produces abundant gemmae of different formats when cultivated in culture medium (CMA + glucose) and in water cultures growing in Sorghum sp. seeds. In contrast with the original description of Drechsler (1929), that observed antheridia always present, in the isolate studied the antheridia production were rare or not frequent and most oogonia are abortive and/or parthenogenetic. Despite this, the abundant production of gemmae and the characteristics of oogonium, oospores and zoosporangium are in agreement with Drechsler (1929) and confirm our identification as Plectospira gemmifera .

collected in this study.

Figures

FIGURE 1. A–M. Plectospira gemmifera CCIBt 4250. A–D. Different formats of gemmae. E. Lobulated zoosporangia. F–G. Zoosporangium with a long tube and zoospores cluster. H. Catenulate gemmae. I. Spherical gemmae with germinative tube. J. Oogonium and antheridia. K. Subcentric oospores. L. Empty gemmae. M. Piriform gemmae germinating. Bars: 10 μm.