A new ballistosporous species of Protostelium

Abstract

During surveys of the protostelids of the Hawaiian Islands and the South Island of New Zealand, an undescribed species of Protostelium was discovered fruiting on collections of substrates found in several sites on the southern and western parts of the island of Hawaii and from one site near Port Elizabeth, New Zealand. The new species, P. okumu-kumu, has a sporocarp with a bipartite stalk that supports a single, spherical spore. The basal portion of the stalk is straight and rigid. The upper part of the stalk is a nearly spherical apophysis. The junction between the stalk base and the apophysis is flexible such that the spore and apophysis swing back and forth as a unit. Spores are forcibly discharged from the stalk, and only the straight base of the stalk is left behind. Amoebae typical of the taxon Protostelium germinate from the spores, and when an amoeba differentiates into a prespore cell, it becomes lozenge shaped (nearly ellipsoid) in top view, as is typical for species of Protostelium. This represents the seventh species of protostelids described to have forcible spore discharge, and the possibility of forcible discharge needs to be examined in several other species.

• Eumycetozoa
• Hawaii
• New Zealand Protosteliidae
• taxonomy

This work was supported in part by National Geographic Society Grant 6372-98, NSF PBI grant (DEB 0316284) and NSF PEET grant (DEB 0329102). We thank Dr Kalena Silva of the UHH Hawaiian Studies Department for helping us decide on a specific epithet. Finally FWS and JDS thank Helen Hemmes for her hospitality during our trips to Hawaii.