46 



THE SIMPLE IIOLOCAKPIC BIFLAUELLATE PHYCOMS CETE8 



gle, hyaline, globose, 25.2 /x— 32.4 /x, covered with 

 numerous fine spines. 



The size and shape of the sporangia of this spe- 

 cies are strikingly similar to those of 0. fusiformis, 

 and besides the presence of long, fine spines on the 

 companion cells (fig. 109) there are few or no char- 

 acters to distinguish it from the latter species. While 

 the spines on the resting spores of 0. fusiformis and 

 O. minor are reported to be broad and triangular, it 

 is not improbable that they vary considerably in 

 thickness, shape and length and may attain the di- 

 mensions of those described by Tokunaga. The pres- 

 ent writer is accordingly inclined at present to re- 

 gard 0. spinosa as a synonym of O. fusiformis. 



It is quite possible that Pseudolpidium stellatum 

 (Sawada, 1912. Spec. Bull. Agr. Expt. Sta. For- 

 mosa, 3: 70, pi. 8, figs. 11—16) is synonomous with 

 this species also. Sawada found this species in A. 

 prolifera in 1912 and 1919 in Japan, and it was sub- 

 sequently reported by Tokunaga in 1933. Zoospo- 

 rangia and zoospore were not observed, and the rest- 

 ing spores were reported to be hyaline, spherical, 

 ovoid, or globoid, 24-100 p., and covered with long 

 9-24 ii, pointed and sharp spines. No male or com- 

 panion cells were found. Sawada reported that P. 

 stellatum may occur independently or in association 

 with O. fusiformis. 



O. VARIANS Shanor, 1939. Jour. Elisha Mitchell Sci. 

 Soc. 55: 171. PI. 24. 



Zoosporangia solitary or numerous, smooth, warty 

 or spiny, spines up to 7 ju, in length, spherical, oval, 

 ellipsoid, 40-140 jit by 60-350 /x, frequently 80 X 

 .200 ft, with 1 to 5 exit tubes. Zoospores isocont, oval 

 to elongate, 2.3-3 yu. X 3.8-4.6 /u; flagella 4.2 to 

 4.6(11 long. Resting spores yellowish-brown, spheri- 

 cal 26-83 jx; exospore hyaline to yellowish in color, 

 1.2 fi thick, usually bearing coarse, abruptly-taper- 

 ing spines, 8.6 /x high, which are connected by a 

 reticulum; endospore yellowish-brown, 1.7 fi thick; 

 companion or male cells 1 to 2 per resting spore, 

 usually spherical, 17 to 30 /x, occasionally smooth, 

 usually enveloped by the spiny exospore of the rest- 

 ing spores, spines 1.7 /x long; resting spore trans- 

 formed directly into a zoosporangium in germina- 

 tion with an exit tube which usually penetrates the 

 companion cell. 



Parasitic in Achlya flagellata, A. racemosa, A. 

 colorata and A. proliferoides in North Carolina, 

 U. S. A. (Shanor, '39a, '39b, '40) causing large 

 terminal or intercalary swellings in the host hyphae. 



Shanor found that this species is limited to the 

 Achilla species listed above and will not infect A. 

 americana, A. imperfecta, A. klebsiana, A. recurva, 

 A. apiculata, A. glomerata, nor any of the species of 

 Saprolegnia, Aplanes, Protoachl i/a, Isoachl i/a, 

 Aphanomyces, Dictyuchus, and Leptolegnia shown 

 in table 1. This species is highly variable in sporan- 

 gium size and shape as well as in the character of the 

 exospore, and was named varians because of its 

 variability. The spines are broad and triangular as 



in some specimens of O. fusiformis and O. Achlyae 

 (figs. 86, 87), and some of the resting spores are 

 strikingly similar to those of O. minor (fig. 106). 

 Furthermore, the companion cells are usually en- 

 veloped by the spiny exospore of the resting spore, 

 although the spines in the vicinity of such cells are 

 usually shorter. A similar envelopment has been 

 shown to occur in O. Achlyae (fig. 66). 



O. ACHLYAE McLarty (ad int.) 1941a. Bull. Torrey 

 Bot. Club. 68:62, figs. 1-26. 1941b, Ibid. 68:75, figs. 

 1-80. 



Zoosporangia solitary or up to 50 in a hypha, 

 smooth or covered with fine or coarse noncellulosic 

 spines or bristles, variable in size and shape, spheri- 

 cal, oval, ellipsoid or elongate, 13.2-112.4 X 115- 

 666.4 ix. with 1 to 3 exit tubes which may extend 

 considerably beyond the surface of the host fila- 

 ment. Zoospores hyaline with numerous small re- 

 fringent granules, oval or somewhat reniform 2.3— 

 2.9 /x X 4.3-5.7 /x, usually about 3.1 X *.2 p., with 

 two approximately equal flagella attached laterally 

 near the anterior end. Resting spores parthenogene- 

 tic or sexual, spherical or oval, 22.8-122.4 fx, usu- 

 ally 41 X 50 fx, brown, with several or usually one 

 large refringent globule; endospore smooth cellu- 

 losic, 1 to 1.5 /x thick; exospore noncellulosic, 1 to 

 11.4/x thick, covered with warty protuberances, 

 small or large, narrow or broad-based spines, hair- 

 like fibrillae, or with an entire, undulant or slightly 

 serrate margin ; companion or male cells 1 to 3 per 

 resting spore when present, thin-walled, hyaline, 

 smooth, sometimes embedded in the exospore, oval 

 or spherical; resting spore transformed directly 

 into a zoosporangium with an exit tube in germina- 

 tion. 



Parasitic in Achlya flagellata, London, Ontario, 

 Canada (McLarty, '39, '40, '41), causing large ter- 

 minal and intercalary swellings in the host hyphae. 



McLarty diagnosed this parasite temporarily as 

 a new species, until the other Olpidiopsis species 

 with which it appears to be identical have been more 

 intensively studied. As is shown in Plates 9 and 10, 

 it is highly variable in structure and may produce 

 resting spores with exospores which are characteris- 

 tic of most species of this genus. In general it resem- 

 bles O. fusiformis most closely, so that the writer 

 and his student, McLarty, were inclined to regard it 

 as closely related or identical to this species. But if 

 Shanor's data that O. fusiformis will not infect A. 

 flagellata are correct, these two species are different 

 in host range at least. Since O. Achlyae occurs on 

 the same host and shows much the same variations as 

 O. varians, it is possibly identical to the latter spe- 

 cies. Although spiny companion cells have not been 

 observed in O. Achlyae, this does not exclude the 

 possibility of its being the same as O. varians. On 

 t lie other hand, it is equally probable that O. various, 

 (). Achlyae and possibly O. index and 0. spinosa 

 may be biological varieties or races of O. fusiformis 

 which are limited to particular hosts. If this proves 



