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Title: A NEW SPECIES OF MEGASTIGMUS DALMAN (HYMENOPTERA: TORYMIDAE) GALLING SEEDPODS OF EUCALYPTUS CAMALDULENSIS DEHNHARDT (MYRTACEAE) IN SOUTH AFRICA AND AUSTRALIA

Author
item Grissell, Edward

Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2005
Publication Date: 3/1/2006
Citation: Grissell, E.E. 2006. A new species of Megastigmus dalman (Hymenoptera: Torymidae) galling seedpods of Eucalyptus camaldulensis Dehnhardt (Myrtaceae) in South Africa and Australia. Arican Entomology. 14:87-94.

Interpretive Summary: Recently a new species of seedpod gall-wasp was discovered in South Africa on river red gum. River red gum, an Australian native tree, is the most widely planted eucalyptus in the world and is an economically valuable species. The wood is used for many purposes, including railway sleepers, flooring, fencing, plywood, veneer, turnery and firewood. The trees are good producers of pollen and nectar, producing first-grade honey. The wasp destroys seed as a result of forming galls in the seedpod. In this paper the wasp is described, illustrated, and its biology is discussed. Its discovery in South Africa suggests that it has been accidentally introduced into that country from Australia. It is likely that transport of river red gum around the world has also distributed its seed-destroying wasp as well. The new species is important to our understanding of the distribution of invasive species.

Technical Abstract: The new species Megastigmus zebrinus Grissell is described based on specimens associated with seed pods of Eucalyptus camaldulensis Dehnhardt, an endemic Australian tree. The wasp has been commonly collected in South Africa, where it was presumably introduced along with its host tree. It has apparently host-shifted to Syzygium cordatum Hochst. ex Krauss, an endemic South African tree in the same family as Eucalyptus (Myrtaceae). Observations on the gall-forming habit of Megastigmus zebrinus are presented based on dissections of Eucalyptus seed pods. This appears to be the first species of the genus that has been positively confirmed as a gall-former based on dissection of seed pods.