The Rapid Sporulation of Some Myxomycetes in Moist Chamber Culture

Abstract

Myxomycetes which sporulate on bark in moist chamber very soon after the bark is wet, are usually among those whose plasmodia are of the aphano- plasmodium or protoplasmodium types. The theory is advanced that, in nature, aphanoplasmodia sclerotize on the bark during dry periods, forming microcysts, as they do in agar culture. If bark bearing microcysts is placed in moist chamber, the cysts rehydrate and coalesce into plasmodia which, under certain conditions, proceed to sporulate immediately. The moist chamber culture technique for the development of myx. omycete fructifications, introduced by Gilbert and Martin (1933), has been used with success by several investigators for the last 30 years and is now considered standard technique to supplement field collec- tions of fruiting bodies and plasmodia for use in floristic studies on Myxomycetes. The technique consists of placing bark, dead leaves, twigs, animal dung, or other organic material, on a filter paper disk in a Petri dish, pouring sterile distilled water over the material, allowing the latter to soak overnight, pouring off the excess water, and incubat- ing the culture for a week or longer. A remarkably large proportion of such cultures yield myxomycete fructifications. Although some of the species developed in such cultures are among those most commonly collected in the field, such as Physarum cine- reum, P. compressum, P. pusillum, Arcyria cinerea, and Didymium iridis, the majority of the species developed in moist chamber are characterized by minute fructifications which, because of their size, are often overlooked in the field. Examples are various species of the genera Licea, Echinostelium, Cribraria, Comatricha, and Perichaena. Several species of Myxomycetes are known only from moist chamber cultures. Among these are Echinostelium elachiston, E. cribrarioides, Licea pedicellata, Comatricha synsporos, Macbrideola scintillans, and Physarum dictyosporum. A week is usually required before mature fruiting bodies can be detected in such cultures and, in many instances, two or more weeks