The Hawaiian biota originated from ancestors which arrived accidentally from various directions across open sea. These plants and animals became established in a favorable environment on a young, rapidly changing geological substrate where environmental pressures were limited. Processes of adaptive radiation were thus given much freedom for operation in a sort of "biological vacuum." This condition resulted in an astonishing proliferation of species, species diversification, adaptive morphology, and habitat utilization. The many empty ecological niches have been filled by plants and animals delicately adapted to them and resulting in the development of remarkable differences from their nearest relatives in other areas. This flourishing adaptive radiation would continue today, but its variety and rapidity have been slowed to a disturbing degree by the vastly increased activities of man. The new unfavorable conditions introduced by man have doomed a large fraction of the biota to extermination, and it is doubtful if such an unique biological flowering will ever again be duplicated on earth.1 Prepared during the tenure of a grant from the National Science Foundation. 2 Paper presented as a contribution to the Symposium on Adaptive Aspects of Insular Evolution sponsored by The Association for Tropical Biology and held at the Mayagiiez

The 128 known native Hawaiian species of the tribe Platynini are analysed cladistically. Cladistic analysis is based on 206 unit‐coded morphological characters, and also includes forty‐one outgroup taxa from around the Pacific Rim. Strict consensus of the multiple equally parsimonious cladograms supports the monophyly of the entire species swarm. The closest outgroup appears to be the south‐east Asian‐Pacific genus Lorostema Motschulsky, whose species are distributed from India and Sri Lanka to Tahiti, supporting derivation of the Hawaiian platynines from a source in the western or south‐western Pacific. The biogeographic relationships of the Hawaiian taxa are analysed using tree mapping, wherein items of error are minimized. The area cladogram found to be most congruent with the phylogenetic relationships, and most defensible based on underlying character data is {Kauai[Oahu(Hawaii{Lanai[East Maui(West Maui + Molokai)]})]}. This progressive vicariant pattern incorporates progressive colonization from Kauai, and vicariance of the former Maui Nui into the present islands of Molokai, Lanai, West Maui and East Maui. The evolution of flightlessness, tarsal structure, pronotal setation and bursal asymmetry are evaluated in the context of the cladogram. Brachyptery is a derived condition for which reversal is not mandated by the cladogram, although repeated evolution of reduced flight wings is required. Tarsal structure supports Sharp's (1903) recognition of Division 1 as a monophyletic assemblage, but exposes his Division 2 as a paraphyletic group requiring removal of the genus Colpocaccus Sharp. Pronotal setation is exceedingly homoplastic, and is not useful for delimiting natural groups. Left‐right asymmetry of the bursa copulatrix reversed twice independently, resulting in mirror‐image bursal configurations in B. rupicola and Prodisenochus terebratus of East Maui. The amount of character divergence is greater among species comprising Division 1 than among species of its sister group, the redefined Division 2. Based on superior fit of Division 1 relationships to the general biogeographic pattern, a greater speciation rate coupled with more extensive extinction is rejected as the cause for this greater divergence. Intrinsic differentiation in the processes underlying cuticular evolution appears to be more consistent with the observed biogeographic and morphological patterns.

The historical status of the family Platypodidae is reviewed and the family is revised. Results of a cladistic analysis based on 35 terminal taxa and 80 adult morphological characters show that the current placement of Platypodidae makes the subfamily Scolytinae paraphyletic. Moreover, several important genera included in Scolytinae are shown to be members of Cossoninae (i.e. the placement of Protoplatypus Wood and Phylloplatypus Kato in Cossoninae is confirmed). Based on these results, the status of Platypodidae as a family and subfamily is rejected, Scolytinae thereby becoming a monophyletic taxon. Araucarius groups in Scolytinae instead of Cossoninae in the analysis on a single step only, but it is suggested that it be retained in Cossoninae until this subfamily is submitted to a similar phylogenetic study. Three genera and four species of Cossoninae are described as new: Dobionus Kuschel, gen. nov.: type species D. araucarinus Kuschel, sp. nov. (with the inclusion of D. brachyrhinus (Montrouzier)); Coptonus Kuschel, gen. nov.: type species C. fijianus Kuschel, sp. nov. (with the inclusion of C. papuanus Kuschel, sp. nov.) and Dissostomus Kuschel, gen. nov.: type species D. hornabrooki Kuschel, sp. nov.

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