740 AQUATIC PHYCOMYCETES 



MONOBLEPHARIS BULLATA PerrOtt 



Trans. Brit. Mycol. Soc, 38: 266, pi. 11, figs. 1-2, text figs. 8-11. 1955 



"Mycelium of straight, rigid hyaline or pale brown, cylindrical, rare- 

 ly branched hyphae, 1.5-2.5 mm. long; attached to the substratum by 

 branching rhizoids. Diameter 5 \x (in narrowest parts) to 23 u, (at the 

 tips which are expanded to bear fascicles of sexual reproductive organs); 

 average for intermediate portions 9 jx. 



"Oogonia arranged singly, in superimposed series of 2-12 or in 

 fascicles of 2-8, borne at the tips of the hyphae or their sympodial 

 branches. Sometimes combinations of these three arrangements are to 

 be found on one hypha; occasionally intercalary. Oogonia usually cylin- 

 drical, opening when the oosphere is formed at the tip of the prominent 

 neck, which may be straight or curved, with its tip pointing towards 

 the antheridium. Oogonia occasionally exhibit irregularities of form 

 and size. Length 25-53 u. (majority 34-43 fji), diameter 16-42 (x (majority 

 21 <x). 



"Antheridia tapering at the tips, and varying from subcorneal to 

 cylindrical. Narrow, straight or slightly curved, with the tip bent inwards 

 towards the neck of the oogonium. Much variation in length even among 

 those in the same group. 10.5-25 [x long (majority 14-21 ;x) by 6-14 jx 

 diameter (majority 7-9 [x tapering to 5-7 (x). Not always present, but 

 usually so. Borne upon the terminal wall of the oogonium (epigynous), 

 to one side of the neck. Occasionally hypogynous and intercalary. Each 

 usually contains 5-6 amoeboid and uniflagellate antherozooids which 

 measure 4-6 [x by 4-5 [x. Protandry is well marked. 



"Each oogonium contains a single oospore which matures and ger- 

 minates within the oogonium (endogenous). The oospores have thick, 

 golden brown walls covered with small, pale yellow, transparent bul- 

 lations which are 1 [x in height. They vary in shape from spherical to 

 widely ellipsoid, and are occasionally irregular in outline; length 19-32 

 [x (majority 21-25 jx), diameter 12-27 ;x (majority 18-21 tx). Much var- 

 iation in size is often seen in the same series" (Perrott, loc. cit.). 



On submerged twigs of Quercus robur and Fraxinus excelsior, Great 

 Britain. 



The only species of the genus with cylindrical oogonia and endog- 

 enous, bullate oospores. 



