Systematics and biogeography of southwest Pacific Bactrocera (Diptera: Tephritidae: Dacini)

Abstract

This study reports the results of a phylogenetic analysis of 30 Pacific Bactrocera species. These 30 species belong to three subgenera — Bactrocera, Bulladacus and Notodacus. Bactrocera and Notodacus were reported by Michaux (1996)to be basal members of a monophyletic group of Dacini subgenera. Six species belonging to four other subgenera ( Afrodacus, Zeugodacus, Parazeugodacus, and Sinodacus), while being part of the Dacini fauna of the southwest Pacific, were excluded because they are not members of the Bactrocera– Notodacus group ( Michaux, 1996). Initially 214 minimal trees were obtained from an analysis using PAUP. Successive approximations weighting of characters to maximise the Rescaled Consistency and Retention Indices resulted in the same subset of three preferred trees. The strict consensus tree showed that informal species complexes previously recognised within Pacific and Australasian Bactrocera are not natural groupings. A supra-specific classification of Bactrocera, in which a number of subgenera are recognised, is broadly supported. The subgenera Bulladacus and Notodacus are monophyletic. The biogeographic analysis of Pacific Bactrocera was based on the strict consensus tree and is interpreted in terms of the tectonic development of the region, with particular reference to the fragmentation of east Gondwana. The need for a centralised database of Pacific taxa is discussed.