Capillitial Formation in the Stemonitaceae

SUMMARYThe development of the capillitia of Stemonitis, Comatricha, and Lamproderma is discussed. In all three genera the hypothallus is formed underneath the fruiting plasmodium. In Comatricha and Lamproderma the stalk is composed of an interlaced system of tubes, some of which bend out at intervals to form the lateral capillitial threads. The ends of these threads remain free. The capillitium of Comatricha and Lamproderma is derived primarily from the tubes originating from the columella. In Stemonitis the stalk is a single large tube, with no individual tubes to bend out and form lateral capillitial threads. The capillitium in Stemonitis arises from the apex of the columella and free in the peripheral cytoplasm. The capillitium in the periphery anastomoses to form the characteristic surface net. The capillitium in Stemonitis is derived primarily from the free-formed threads in the cytoplasm. The Stemonitaceae are believed to be a closely related group, and to be quite distinct from the rest of the Myxogastres.