Nonconstricting-ring formation in two species of nematode-capturing hyphomycetes

Dactylella leptospora and Dactylaria candida, and Arthrobotrys dactyloides (Hyphomycetes), capture nematodes by nonconstricting- and constricting-ring traps, respectively. In the formation of the constricting-ring trap of the latter fungus, the basal portion of a curved hyphal branch put forth a bud to fuse with its advancing tip to make a ring. However, in nonconstricting-ring formation in the former two fungi, the portion behind the tip of the curved branch did not develop such a bud before fusion with the tip.