Phylum:Oomycota >> Class: Oomycetes >>  Order: Saprolegniales 
 BCRC Number NO BCRC Number!  
 Scientific Name: Achlya formosana

Achlya formosana Chiou & Chang sp. nov.

 Description: Thallis non gynandromictibus. Mycelium, corporis modicum et deneum, Hyphis 60-110 μ crassis. Gemmis abundantibus, filiformibus vel subfiliformibus vel golbosis; singulis vel catnatis. Zoosporangiis fusiformibus clabatisve, vel moniliformibus; 150-700 μ longis, 20-45 μ diametro, plerumque 250-325 × 30-40 μ; sympodialiter vel basi seriatim proliferantibus. Zoosporiis generis propriis. Oogonia golbasa 37.5-62.5 μ, plerumque 40-45 μ diam. Tunica oogoniorum nullis punctulis notatts et omnino leve. Antheridiis diclinis, raro monoclinis, grailibus, multis in oogoniis applicatis. Oospaeris non maturesecentibus. Oosporis ecentro dispositis, oogonia non implentibus; numbero 2-17, plerumque 5-9; diametro 17.5-25 μ, plerumque 20-23 μ. Plant monoecious. Mycelium extensive, moderately dense; four-day old colony 1.5-2.0 cm in diameter on hempseed culture at 25℃. Principal hyphae stout, branched, 60-110μ in diameter at base; numerous, slender and profusely branched. Secondary hyphae intermingled with primary ones. Gemmae abundant; filiform or subfusiform, occasionally spherical; single or catenulate, functioning as zoosporangia. Zoosporangia abundant, clavate, fusiform, occasionally moniliform; 150-700 × 20-45 μ in basipetalous succession. Zoospore discharge achlyoid. Spore cluster not persistent at exit pore; encysted spore 9-11 μ in diameter. Oogonia proliferation not observed. Oogonial wall smooth, pitted only under the point of antheridial cells. Oogonial stalk 1-4 times the diameter of the oogonium in length, stout, straight, infrequently bent or curved. Antheridial branches diclinous, sometimes monoclinous; usually coiling about hyphae which may or may not bear oogonia, not losing this feature as colony ages; irregular, frequently branched; laterally appressed or attached by projections; persistent. Antheridia up to 25 μ in width. Fertilization tube not observed. Oosphere usually not maturing. Oospores eccentric; spherical, not filling the oogonium; 2-17 in umber, generally 5-9; 17.5-25 μ in diameter, predominantly 20-23 μ. Germination not observed.

Type locality: Taipei; garden soil; May 15, 1974. Type specimen: type culture is deposited in the herbaria of the Institute of Botany, Academia Sinica.

 Habitat: Soil and water



Beneke ES. 1948; Couch JN 1931;Dick MW. 1960.


T. S. Chiou and H. S. Chang

 Note: Our isolate is very similar to Achlya flexuosa Nagai in possessing diclinous or rarely monoclinous antheridial branches, which entirely wrap around the oogonium and contain immaturing oospheres. But A. flexuosa rarely from sexual organs, if any, only in some old culture (Nagai, 1931), which is similar to Wolf’s isolate of A. bisexualis (1944), and was thought to be self-conjugating from of A. bisexualis (Barksdale 1962). Our isolate is strictly monoecious when it derived single hyphal tip culture, and forms stable sexual organs at colony stage. We believe that our isolate is a new water mold. Concurrently our isolate is similar to A. proliferoides and Achlya flagellate. In fact A. proliferoides could be the synonymous of A. flagellate (Johnson, 1956). Oogonia of our isolate were not proliferating, always entirely covered by antheridial branches. The coiling antheridial branches were not losing as colony age. So our isolate can easily be separated from A. proliferoides. Although Elliott (1967) claimed that the coiling antheridial branches is not a reliable character for delimiting the species, however, our observation showed that the presence or absence of coiling antheridal branch and its persistency seemed to be the reliable criteria to separate the species. And whether the antheridial branches always wrapping about the oogonium or not is importnat character. So we think that our isolate differs from A. flagellate and A. proliferoides.