The seven "oddities" of Pacific Odonata biogeography 1997

The existing literature on the Odonata inhabiting the three large divisions of the Pacific Ocean (Micronesia, Melanesia, Polynesia) is revised taking into consideration earlier discussions on the species origin, historical faunistic records, various palaeogeographical models proposed for the area, general data on the biology and ecology of this insect order. Special emphasis is paid on the incomplete data set for the region and inconsistency of the exploration of this vast area. The taxonomy and fauna of the Pacific Odonata is far from complete which makes it very difficult to provide any plausible hypothesis on the biogeographical pattern that we observe today. The widely accepted view of long distance dispersal from a centre of origin as the only possible means for species to occupy remote oceanic island archipelagos is critically reviewed. There are seven phenomena in the current Odonata distribution that cannot be explained only by random gene transfer mediated by wind dispersal. Those are called “oddities”, however, they are believed to be regularities of past geological events and modern day human associated activities within the Pacific. The rationale for each of them is explained in details and illustrated with distribution maps following the current taxonomy of the group. A new approach is suggested to tackle the question of the origin of the Pacific Odonata by relating the higher taxa distribution to the geological events and palaeontology of the families. It is not intended to be a new hypothesis yet before more systematic studies of the taxonomy and fauna of the group. Therefore, it is believed that the new method suggested here will increase the attention of the scientific community and will boost studies on this insect order within the Pacific Ocean. Discussion on its applicability is provided with attention to details that are difficult to be explained with the Pacific Odonata palaeontology as we know it for the moment.