Systematics of Pamphiliinae feeding on broad-leaved trees and the evolution of their host preference and nest-building behavior

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1. To enrich the material for study, adults and immature stages of Pamphiliine sawflies were collected in various regions of Hokkaido in June to July, 2003 to 2006, in various regions of Honshu and Shikoku in May to September, 2003 to 2006, and in Qinling Mountains, Shaanxi, China, in May to June, 2005. Some undescribed species and new information about the larval hosts and nest-building behavior were obtained.2. Mainly based on adult morphology, phylogenetic relationship of the species of the Pamphiliinae was analyzed using PAUP and MacClade. As a result, the monophyly of each genus and each species-group of Pamphilius as well as the previous hypothesis of their relationships (Shinohara, 2002) were generally supported. By incorporating the information of the host plants and nest-building behavior of each species into the cladogram, the following hypothesis was obtained. In the ancestral condition, larvae do not roll leaves but make a web-nest as in the species of Neurotoma, a genus characterized mainly by ancestral features also in morphology. From this primitive type evolved another type of larval nest, where the larva makes an irregular shelter by roughly folding the margin of a leaf ; this type of larval shelters are known for Onycholyda and some Pamphilius species. In many Pamphilius species, the larva makes a tube-like shelter by regularly and tightly rolling the leaf margin. This is further development. Basically, the eggs are laid on the under surface of a leaf and the larval shelter is made also on the under surface, whereas, in some species of the Pamphilius vafer group, the eggs and shelters are on the upper surface. The latter is a specialized state of oviposition and shelter making behavior.3. Part of new findings during the course of this study have been published in 19 separate papers.