Two New Operculate Chytrids

Abstract

SUMMARY Chytridium aggregatum occurs as a saprophyte on dead and decaying filaments of Spirogyra crassa, Cladophora sp., and Oedogonium sp. in New Jersey and New York and has been cultured to a limited extent on synthetic nutrient media. It is characterized chiefly by the persistent brown zoöspore case, feeble motility of the swarmspores, and a pronounced gregarious habit of association. In the shape of the sporangia and the presence of the unexpanded portion of the zoöspore case as a protuberance near the base, this species is very similar and possibly closely related to C. Schenkii and C. gibbosum. Endochytrium digitatum is a saprophyte in internodes of Chara and Nitella and may be readily grown on cooked filaments of various algae. It is distinguished from the other species of this genus by the presence usually of one to several blunt digitations near the base of the sporangium or on the main axis of the rhizoidal system and light to medium brown, smooth resting spores. In most of its other characters it is similar to E. operculatum. The main axis of the rhizoidal system at the base of the sporangium may often become slightly inflated and irregular and have the appearance of an apophysis.