| This study examines the taxonomy, systematics and biogeographic history of the remarkable ant [Hymenoptera: Formicidae] fauna of the Fiji Islands. Chapter One is a synoptic revision of the Fijian ant fauna with a background of the archipelago's geologic history. A total of 186 species representing 42 genera are recognized. Of these species, 68% are endemic to Fiji, 16% are native to the Pacific region, and 12% are introduced into the Pacific region. Taxonomic synopses of each species, keys to most genera, and a species list are given. Chapters Two and Three are detailed studies of the taxonomy, phylogeny, biogeography and conservation of two of the many ant genera that have diversified into endemic radiations within the archipelago. Chapter Two examines the 11 species of Fijian Lordomyrma [Formicidae: Myrmicinae], five of which are described as new. Descriptions of each species are provided, along with distribution maps, images, and a key to workers. The phylogeny of the Fijian taxa and their congeners from across the Pacific is inferred by analyzing the fragments of four nuclear genes 28S, argK, LW Rh, CAD) in order to test alternative hypothesis concerning their taxonomic and biogeographic history. The Fijian Lordomyrma are found to be a monophyletic lineage that split from a sister group in Papua New Guinea approximately 8.8 million years ago (Ma). Chapter Three examines the seven species of the spinescent Pheidole roosevelti group [Formicidae: Myrmicinae], five of which are described as new. Descriptions of each species are provided, along with distribution maps, images, and a key for the identification of workers, majors and queens. The phylogeny of the group, along with congeners from Fiji and across the Pacific, is inferred using two mitochondrial genes (COI, cytb) and two nuclear genes (H3, EF1alpha-F2) from 66 taxa in order to test whether the aberrant spine morphology was inherited from congeners in the subgenus Pheidolacanthinus. The group is monophyletic, and the modern-day clade is estimated to have diverged approximately 7.4--12.2 Ma. The group is more closely related to Fijian Pheidole of conservative morphology than to any Pheidola-canthinus species, suggesting independent acquisition of the spinescent morphology. |
