Vol. 45 TORREYA December 1945 



A New Mycelioid Ghytrid: Myceliochytrium fulgens 

 Gen. nov. et Sp. nov. 



Alfhild E. Johanson 



In studying various saprophytic chytrids which occur in soil and fresh 

 water in the eastern states an unusual species was isolated on bits of onion 

 skin, grass leaves, and other substrata, which differs in many respects from 

 all other known chytrids. This species is characterized primarily by a delicate, 

 extensive, richly-branched filamentous thallus which is strikingly similar to 

 the mycelium of the higher fungi and lacks the intercalary enlargements 

 commonly present in most polycentric cladochytriaceous chytrids. Its zoo- 

 spores, on the other hand, are posteriorly uniflagellate and structurally similar 

 to those of most known chytrids. Accordingly, this fungus is regarded as a 

 polycentric chytrid, and present observations indicate that it represents a new 

 genus and species for which the name Myceliochytrium fulgens is proposed. 



Myceliochytrium gen. nov. — Thallo polycentrico, intra-et extra-matricali, 

 levibus mycelioidibus et ramosis capillamentis, diametro plerumque uniformi. 

 Sporangiis terminalibus, extramatricalibus, singillatim vel acervatim occurren- 

 tibus. Zoosporis a posteriore uniflagellatis. Sporis perdurantibus dubiis vel 

 non visis. 



Myceliochytrium gen. nov. — Thallus polycentric, intra and extrama- 

 trical, consisting of fine, mycelioid, branched filaments of fairly uniform diame- 

 ter. Zoosporangia terminal, extramatrical, occurring singly or in clusters. 

 Zoospores posteriorly uniflagellate. Resting spores doubtful or unknown. 



Myceliochytrium fulgens, sp. nov. — Rhyzomycelio exili et angusto, 1.3- 

 1.7 fx diametro sine amplificationibus intercalaribus. Zoosporangiis hyalinis et 

 maxime refractivis, parietibus tenuibus, .3-.6 /x, subsphericis, 5.5-8.7 p., aliqua- 

 tenus rectangularibus et truncatis, 6.6-17.5 x 10.3-26.2 /a, ovatis, ellipsoidalibus, 

 8.7-20.7 /a, urceolatis, 9.6-21 fx, late pyriformibus, 6.2-38.5 \x oblongatis, irregu- 

 laribus vel saepe gibbosis ; dehiscentibus ruptura vel deliquiscente pariete 

 sporangiali. Zoosporis generatim linealiter constitutis ; exinde sporangiorum 

 species normalis ; sphericis 1.3-2 /a, globulo parvo .5 /x ref ractivo ; flagellis fere 

 1 1 fx longitudine ; saepe enatantibus in sporangium, et emergentibus singillatim 

 vel linealiter, sporangiis tumefacientibus et rumpentibus. Sporangiorum parie- 

 tibus et rhyzomycelii relicitis, reagentibus negative ad examina cellulosa. 



Myceliochytrium fulgens sp. nov. — Rhizomycelium delicate and nar- 

 row, 1.3-1.7 \x in diameter without intercalary enlargements. Zoosporangia 

 hyaline and highly refractive with thin, .3-.6 fx walls, sub-spherical, 5.5-8.7 /x, 

 somewhat rectangular and truncate, 6.6-17.5 fx x 10.3-26.2 fx, oval, ellipsoidal, 

 8.7-20.7 fx, urceolate, 9.6-21.0 fx, broadly pyriform, 6.2-38-.S tt, oblong, irregu- 



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