Ol.lMIMOI'slll VcT V I 



15 



I.ir. size unknown, with one or two short exit tubes 



which do not project beyond the surface of the host 

 hypha. Zoospores heterocont, spherical 1.5—6 p in 

 diameter, or oval, hyaline with small refractive 

 globules; with one short flagellum directed for- 

 ward and tin- longer one backward in swimming; 

 often lying quiescent in a mass at the mouth of the 

 exit tube before becoming motile. Resting spores un- 

 known. 



Parasitic in Saprolegnia s|>.. occasionally in asso- 

 ciation with Rosella septigena, in Roumania (Con- 

 stantineanu, I.e.) and Denmark (Sparrow. '84), 

 causing large terminal clavate swellings in the host 

 hyphae. 



Tliis speeies takes its name from tile irregular 



shape (fig. 102) of the sporangia, hut sporangium 



shape is obviously a questionable diagnostic char- 

 acter in parasites as variable as Olpidiopsis speeies. 

 Constantineanu was doubtful about its identity be- 

 cause no resting spores were found, and he assigned 

 it tentatively to Olpidiopsis as a new species. It dif- 

 fers from the other parasites in Saprolegnia, as far 

 as they are now known, by heterocont zoospores. As 

 noted above. (). irregularis may be associated with 

 R. teptigena, and Constantineanu was of the opinion 

 that it feeds of the latter's thallus. 



PARASITES OF ACHLYA 



O. FUSIFORMIS Cornu, I.e., p. 147. pi. +, figs. 1-4. 

 I), miliar Fischer. I.e., p. 39. 

 /'..< nihil jiiiliiim fusiforme Fischer, I.e., p. 37. 



Zoosporangia solitary or numerous, smooth or 

 spiny, elongate, fusiform. L'(i-78 p X 98-350 p, oval, 

 7-10 a X 21.7-80 /x X 120 /J., spherical, 10-120 ^, 

 with 1 to 3 exit tubes. Zoospores isoeont (?) egg- 

 shaped, oval, slightly elongate. 2 X 4 /"•• Resting 

 spores parthenogenetic or sexual, solitary or nu- 

 merous, yellowish-brown, spherical. 80—60 fi, cov- 

 ered with fine short, or broadly conical and tri- 

 angular spines up to 10.5 \>. in height; contents 

 coarsely granular with one to several refractive 

 globules; companion or male cells when present 1 

 tu 3 per resting spore, hyaline and smooth, oval, 

 spherical 16— 24/t; germination unknown. 



Parasitic in Achlya leucosperma, A. racemosa and 

 Achhia sp., in France (Comu, I.e.) ; ./. /lar/ellata, 

 A. leucosperma, A. racemosa and A. polyandra in 

 Germany [Cienkowski, ">"i (?); Reinsch, '78 (?); 

 Fischer, '82, '92; Minden. 'llj; Achlya sp.. and 

 Saprolegnia sp. i ?), in Russia (Sorokin, '83, '89); 



Achltfa sp.. in I)e ark (Petersen. '09. '10) J '. 



flagellata and A. flagellata var. yesoensis and A. 

 racemnsa in Formosa and Japan I Sawada. '16, 19; 



Tokunaga, '.'(3 i : Achlya sp., A. flagellata, A. race- 

 mosa, A. imperfecta, A. klebsiana, and Saprolegnia 

 sp.. ? ) in the I'. S. A. (Sparrow, ''.i'2 ; Matthews, 

 '85; Shanor, '89, '40); Achlya sp., in England 

 (Sparrow. '86), and ./. racemosa in Czechoslovakia 



( ejp, '84 I, causing large terminal and intercalary 

 fusiform and clavate swellings in the bust hyphae. 



This speeies was named fiisiformis by Cornu I" 



cause of the fusiform, elongate, and almost linear 

 shape of its zoosporangia. This character, however, 

 is not very specific, since fusiform and greatly elon 

 gale zoosporangia have been reported in other spe 

 eies as well. Furthermore, resting spores with broad 



triangular hyaline spines, which arc reported to be 



characteristic of (). fiisiformis, may occur in 0. 



Achlyae and (). variant also. 



Shanor ('40) found that (). fiisiformis is limited 

 in host range to ./. racemosa and ./. imperfecta and 

 will not infect the other Achlya species which he 

 tested (table 1). Particularly noteworthy is the fact 

 that it did not infect ./. flagellata, although seven in- 

 fection attempts were made. These results contra- 

 dict the reports of Sawada, Tokunaga, and Matt- 

 hews of its occurrence in this host. Achlya imper- 

 fecta and A. klebsiana were heavily parasitized, but 

 A. racemosa was infected only slightly in Shanor's 

 experiments. 



Sorokin and Sparrow are the only two workers 

 who have reported (). fiisiformis in Saprolegnia, and 

 here again it is possible that they were mistaken 

 about the identity of the host plants. On the other 

 hand, they may equally well have had 0. Saproleg- 

 niae or 0. incrassala at hand. Sparrow believed that 

 the fungus which Petersen reported as 0. fiisiformis 

 relates to (). Aphanomyces (O. luxurious), but this 

 is unlikely inasmuch as the latter species is limited 

 in host range to Aphanomyces. 



As has been pointed out elsewhere, the parasite 

 of A. imperfecta and A. flagellata which Coker ('23) 

 described as 0. Saprolegniae Fischer may possibly 

 relate to 0. fiisiformis or 0. varians, or in part to 

 both species. 



Whether 0. index (Cornu) I.e., p. I 15, pi. 3, (fig. 

 11) is a valid species or identical to O. fiisiformis is 

 not certain. Cornu described it as a parasite of Ach- 

 lya sp., usually with solitary, very large elliptical 

 zoosporangia and resting spores and echinulatc com- 

 panion cells (fig. 107). No measurements were given 

 of the size of the sporangia, zoospores, and resting 

 spores. The presence of echinulate companion cells 

 was nevertheless regarded by Cornu as specific, and 

 he accordingly diagnosed the parasite as a distinct 

 speeies. However, it is very doubtful that the oc- 

 currence of echinulations and spines on the com- 

 panion cells is a specific character, since both smooth 

 and spiny male cells have been reported in 0. va- 

 rians, (>. curvispinosa, and 0. brevispinosa. 



Olpidiopsis spinosa (Tokunaga. '33. Trans. Sap- 

 poro Nat. Hist. SOC. 13; 25. PL 2, figs. 10-11) para- 

 sitizes ./. flagellata and occurs in association with 

 0. fusiforme .and (). minor in Japan. Tokunaga de- 

 scribed it as follows: Zoosporangia solitary or nu- 

 merous, hyaline, smooth, ellipsoid, elongate or cylin- 

 drical, 34-61 pX 92-198/1, with one or two exit 

 tubes; zoospores isoeont. ellipsoid or elongate, size 

 unknown, with the flagella attached laterally near 

 the anterior end; resting spnres hyaline, spherical. 

 51-73//. covered with numerous line. 9.6 ju long 



spines; germination unknown; companion cells sin 



