ENTOMOPHTHORALES (ANCYLISTES) 1067 



all of which are parasites of desmids. They are fairly common in bogs, 

 wet cow pastures, and like situations. Indeed, any collection of Clos- 

 terium or Netrium is sure to yield a few cells containing Ancylistes in 

 some stage of development. There is definite evidence for host specificity 

 among the species. Thus, while Berdan's material of A. closterii was 

 confined to Closterium striolatum, A.berdcmii ("A.pfeifferr), from the 

 same locality and distinct morphologically from A. closterii, occurred 

 only on C. areolatum. We have frequently encountered A. netrii on the 

 saccoderm desmid Netrium and, although the host was associated with 

 many other types of desmids, no other alga was attacked. 



Both Berdan and Couch noted that infection may either take place by 

 germ tubes from discharged conidia or by extramatrical mycelial ele- 

 ments. Conidia are formed only when infected desmids are floating on or 

 near the surface of the water. They may be shot into the air for as much 

 as two mil'imeters. 



KEY TO THE SPECIES OF ANCYLISTES 



Parasitic in Closterium; resting spore formed in the gametangium 

 Resting-spore container evenly contoured; conidia in water, 15 [x in 



diameter A. closterii, p. 1067 



Resting-spore container with bioad, truncated protuberances; conid- 

 ia in water, 22.2-30 jj. in diameter A. berdanii, p. 1069 



Parasitic in Netrium; resting spore formed in conjugation tube 



A. netrii, p. 1070 



Ancylistes closterii Pfitzer 



Monatsber. Beilin Akad., 1872: 396, figs. 1-15. 1873. Emend. Berdan, 



Mycologia, 30: 401, figs. 1-8. 1938 



(Fig. 91 A-B, p. 1066) 



"Intramatrical mycelium irregularly, 7.5-1 1 (jl, wide before septation ; 



cells or segments swollen, more or less constricted at septa, 1 1-15 u. x 



12.5-55 [x, mostly 25-35 [i long, usually with one median and two ter- 



nearly mature zygotes; D, young zygote apparently formed in conjugation 

 tube; E, desmid near surface of water (dotted line) showing conidiophores 

 in various stages of development, each emerging from a hyphal segment; 

 F, apices of two conidiophores, one at left with attached conidium, other 

 with just discharged conidium. G. Ancylistes berdanii, mature zygotes (re- 

 drawn from a photomicrograph). 



{A-B, Pfitzer, 1873; C-F, Couch, 1949; G, Berdan, 1938) 



