0LPIDI0P8IDACEAE 



3 1 



Chapter IV 



Olpidiopsidaceae 



Sparrow. 1942. Mycologia 34: 11. "i. 



This family name appropriately replaces the Pseu- 

 dolpidiaceae previously proposed by Petersen in 

 1909. Since Olpidiopsis was the first genus to 

 be created for fungi of tliis type it is appropriate 

 that the family take its name from this genus. 

 Furthermore, there is considerable doubt about the 

 validity of Pseudolpidium and should this genus 

 prove to be synonymous with Olpidiopsis the name 

 Pseudolpidiaceae would no longer be descriptive nor 



tenable. Petersen included two genera, Olpidiopsis 

 and Pseudolpidium, in his family and placed it in 

 the Lagenidiineae next to the family Lagenidiaceae. 



Sparrow likewise placed his Olpidiopsidaceae in 

 tin Lagenidiales but extended the family to include 

 Petersenia, Pythiella, and Pseudosphaerita as well 

 as Olpidiopsis and Pseudolpidium. Whether or not 

 Pseudosphaerita belongs in this family is open to 

 serious question, because nothing is known about the 

 presence of sexuality and the nature of tile resting 

 spores in this genus. In the event it proves to be a 

 valid genus of this family. Dangeard's Pseudo- 

 sphaeritaceae may also be merged with the Olpidiop- 

 sidaceae. However, if Dangeard's ('83) and Mitch- 

 ell's ('28) reports that the thallus segments after 



each nuclear division are correct. Pseudosphaerita 

 differs markedly from Olpidiopsis in method of de- 

 velopment. The present writer is nevertheless in- 

 cluding it here temporarily for want of a better 

 group in which to place it. Blastulidiopsis is also in- 

 cluded here provisionally for the same reason, al- 

 though the development of the thallus by the en- 

 largement, growth, and elongation of the intramatri- 

 cal tip of tin- germ tube is more suggestive of rela- 

 tionship with the Lagenidiaceae than the Olpidiop- 

 sidaceae. 



Petersenia is excluded from this family because 

 the thalli of all known species, except /'. andreii, 



are strikingly similar to those of Sirolpidium and 



Pontisma in the Sirolpidiaceae. According to Spar- 

 row's account /'. andreii is apparently a species of 

 Olpidiopsis and is accordingly transferred to this 



genus. The inclusion of Pythiella in the Olpidiop- 

 sidaceae is likewise questionable. While its method 

 of zoosporogenesia and behavior of the zoospores is 



similar to those of some Olpidiopsis species, the 

 presence of periplasm in the so-called oogonium sug- 

 gests a more direct relationship with the Pvthiaeeae. 



Furthermore, its walls give no positive cellulose re- 

 action when tested with chloro-iodidc of zinc, a 

 character which is considered to be of fundamental 



significance in phylogeny and relationship. As it is 



herewith described, the Olpidiopsidaceae includes 

 three incompletely known genera. Pseudosphaerita, 

 Blastulidiopsis and Pseudolpidium in addition to 



Olpidiopsis and Pythiella, genera which future stud- 

 ies may or may not prove to be closely related. As 

 such it includes species with markedly hetcrocont 

 and isocont zoospores, and is accordingly not a very 

 coherent family of closely related genera. The se- 

 quence in which the genera are described below is no 

 indication of their primitiveness or complexity. 



OLPIDIOPSIS 



Cornu, 1872. Ann. Sei. Nat. 5 ser. 15: 114. 



(plates 9 to 13) 



Pleocystidium Pisch. 1884. Sitz'b. I'liys. Med. Soc. Er- 

 langen lfi: 60. 



Diplophysa Schroeter, issii. Cohn's Kryptog'fl. Schle- 

 siens :S: 19.5. 



Olpidiopsis (Cornu) Fischer, ISO.'. Rabenhorst's Kryp- 

 tog'fl. I, 4: 37. 



Pseudolpidium Fischer (pro parte) I.e., p. 33. 



PseudolpidiopsU Minden, 1911. Kryptog'fl. Mark Bran- 

 denburg 5: .'.5.3. 



Thallus intramatrieal, appearing more or less 

 naked but immiscible with the host protoplasm when 

 young but soon becoming invested with a cellulose 

 wall. Zoosporangia solitary or numerous, up to SO 

 or more in a host cell, hyaline or greyish-granular. 

 smooth or covered with non-cellulosic spines, knobs. 

 or warts; spherical, oval, ellipsoid, fusiform, elon- 

 gate, lobed, sac-like or irregular with one to several 

 broad, tapering or cylindrical, straight, curved, 

 coiled, short or elongate exit tubes which may end 

 Hush witli the surface of the host cell or project be- 

 yond it. Zoospores hyaline with numerous minute re- 

 fractive granules, and in some species containing a 

 contractile vacuole; oval, ellipsoid, elongate, .and 

 slightly renif'orm. iso- or hetcrocont; flagella in- 

 serted laterally near the anterior end or anterior! v. 

 shorter flagellum extending forward and the longer 

 one backward in swimming; emerging fully formed 

 and swimming directly away or occasionally lying 

 quiescent in a mass for a few moments at the mouth 

 of the exit tube before becoming actively motile; 



diplanetic in one species, primary swarmers aflagel- 



latc and amoeboid, or flagellate, encysting to form 

 Cystospores; movement of zoospores more or less 

 even in swimming, not darting, interrupted by one 



to several rest periods during which the Hagella may 



be retracted. Resting spores parthenogenetic or 



sexual; spherical, oval, ellipsoid or elongate, hya- 

 line, golden, yellowish-brown or brown with a 

 smooth or knobby, warty, spiny, undulating and 



