Taxonomy and evolution of endemic New Zealand broad-nosed weevils (Coleoptera: Curculionidae: Entiminae)

The broad-nosed weevil (Coleoptera: Curculionidae: Entiminae) fauna of New Zealand is diverse, but the taxonomy of the group has been little studied since the work of Thomas Broun in the late 1800s, despite the economic, evolutionary and conservation interest of the group. This PhD revised the taxonomy of the species described by Broun in the genus Catoptes Schönherr and placed by Guillermo Kuschel in the genus Irenimus Pascoe. Over 7000 specimens were inspected, including type specimens of previously described species, and a combination of museum and fresh collections representing all major New Zealand regions and habitats. It also inferred relationships between species using molecular phylogenetics, determined species' environmental niche space though analysis of geographic ranges, and investigated possible influences on the evolution of particular characters. This was conducted within an overall framework of evaluating the group's fulfilment of four criteria that define adaptive radiations, being: 1) common ancestry, 2) phenotypic-environmental correlation, 3) increased fitness, and 4) rapid speciation. The group of species described by Broun in <i>Catoptes</i> was found to be polyphyletic. <i>Irenimus</i> contains only six species; the characters that define the genus being a complete metanepisternal suture, and a broad bevel at the apex of the hind tibia. Three new genera are proposed to accommodate the remainder of species. <i>Austromonticolus</i> new genus contains five species confined to the alpine regions of Central Otago; these are characterised by having a complete metanepisternal suture, and by females having a single bursal sclerite. <i>Alocommatus</i> new genus, containing eight species, can be distinguished by the presence of a narrow furrow surrounding the eye, strongly declivous frons, and strong basal folds on the pronotum; most species are found in Marlborough and North Canterbury. <i>Chalepistes</i> new genus is the most speciose genus, with 53 species, and including the widespread and occasionally economically important species <i>C. aequalis</i> (Broun), <i>C. compressus</i> (Broun) and <i>C. stolidus</i> (Broun). It is distinguished by the absence of a metanepisternal suture, and by having at most a narrow, unclothed bevel at the apex of the hind tibiae. To infer a phylogeny that gives reliable estimates of relationships and dates of divergence, up to four genes (28S, ArgK, CAD and COI) were sequenced from 316 individuals representing 106 species. A species tree was inferred from these data. Each of the four genera proposed in this research was found to be monophyletic. The genera of the <i>Brachyolus</i> group as proposed by Kuschel form a monophyletic group. Dates of divergence were determined by applying a molecular clock, and these analyses resulted in estimated crown ages of 3.78--6.04 mya for <i>Irenimus</i>, 1.44--3.13 mya for <i>Austromonticolus</i>, 2.21--4.12 mya for <i>Alocommatus</i> and 4.42--7.00 mya for <i>Chalepistes</i>. Analyses of the environmental preferences and distribution of each species showed that <i>Chalepistes</i> occupied the greatest environmental space, and exploited almost all available terrestrial environments in New Zealand. Four sympatric sister species pairs were found; however none of these are considered to be candidates for sympatric speciation due to asymmetrical ranges between the pairs. Little evidence for phenotype--environment correlation was found, the exception being a relationship between metatibial length and ecological habit. Sexually dimorphic species were found to have a significantly increased speciation rate, indicating that a form of sexual selection is occurring. The sexual dimorphism in these weevils is unusual in that it is females, as opposed to males, that possess any of five secondary sexual traits that can be exaggerated: 1) interstria 1 at the top of the elytral declivity prolonged into a tubercle, 2) elytral apex produced posteriorly or ventrally, 3) posterior margin of ventrite 4 developed into a broad lamina, 4) disc of ventrite 5 modified by swellings, tubercles, furrow or concavities, and 5) posterior margin of ventrite 5 being emarginate, with horns surrounding the genital opening in extreme cases. The degree of sexual dimorphism was found to proceed in a progressive fashion, and no correlation between sexually dimorphic traits was detected. Outcomes of this research include greater clarity in the classification of New Zealand Entiminae at the genus level and a modern taxonomic treatment of four genera at the species level. A phylogenetic foundation is produced which, together with the drawing together of geographic and habitat associations, is used here to provide some insights into the macroevolution of Entiminae.