腐霉属的一个新种和二个新记录

本文报告作者1982—1983年在北京和广东一些地区土壤中用已知方法(余永年,1975)分离到的几种腐霉,其中1个新种(Pythium borealis sp.nov.)、2个国内未报道的种(P.oligandrum和P.myriotylum)和1个已知种的变异株(P.ultimum variant)。文中对以上各菌进行了形态学描述。

A NEW SPECIES AND TWO NEW RECORDS OF PYTHIUM IN CHINA

A new species Pythium borealis isolated from soil in Beijing is described and illustrated. Two species, P. oligandrum and P. myriotylum, and a variant? of P. ultimum, are newly reported in China and are briefly described. The new species P. borealis is characterized by (1) the typically monoclinous sessil antheridium formed immediately below oogonium, (2) the tangentially intercalary oogonium, (3) the plerotic and thick walled oospore, and (4) the sphaerical sporangium. P. borealis is separated from P. ultimum Trow by the less curved antheridium, the tangentially intercalary oogonium, the thicker walled and plerotic oospore. It also differs mainly from P. connatum Yu in the typically sessil antheridium and the thicker wall of the oospore. The variant of P. ultimum was isolated from soils and diseased seedlings of cucumber in Beijing with a higher frequency than that of the species P. ultimum. All of it's morphological characteristics and habits of hyphae, appressoria and sporangia, the growth-temperatures and optimum daily growth rate are quite similar to that of the species P. ultimum. Type specimens of the new species are deposited in the Herbarium Mycologicum, Beijing Agricultural University, Beijing, China and the cotype in the Institute of Microbiology, Academia Sinica.