Streblonema anomalum S. et G. and Compsonema sporangiiferum S. et G. stages in the life history of a minute Scytosiphon

Abstract

Cultures were obtained from unilocular zoïdocysts of Streblonema anomalum Setchell et Gardner from California. These gave rise to plants identical to the mother plant when cultivated at 15 C or more, and soon produced erect plants identified as a small Scytosiphon, close to Scytosiphon pygmaeus Reinke, a species not yet recorded from California. Plurilocular zoïdocysts from this Scytosiphon gave rise without fusion to identical cultures. At 10 C cultures produced pseudodiscoid plants described by Setchell and Gardner as Compsonema sporangiiferum. One culture, started from C. sporangiiferum found in nature, gave identical results. Compsonema saxicola Kuckuck seems very close to this species. No evidence of an alternation of cytological phases was observed and meiosis apparently did not occur in these cultures. It is possible that part of the life cycle is missing or suppressed, perhaps by oceanographic or geographical conditions.