Uracanthus is a large group of longicorn beetles in the Australian Region. The larvae of this genus are borers of at least 31 genera of trees and parasitic plants, including some economically important crops such as citrus, litchi, peach, plum, and apricot. Several species are important pests of orchards. Adults visit flowers of various tree species and are attracted to the light. In this thesis, I undertook a thorough taxonomic revision, analysed the phylogeny using morphological and molecular characters, and appraised biogeographic distribution of the genus. In the taxonomic revision, I redefine the scope of the genus, describe and illustrate new and previously known species, and provide a key to all species. The revised Australian Uracanthus includes 39 species, eight of which are established as new to science: U. pseudogigas sp. nov., U. maculatus sp. nov., U. griseus sp. nov., U. bicoloratus sp. nov., U. perthensis sp. nov., U. punctulatus sp. nov., U. quadristriolatus sp. nov., and U. bistriolatus sp. nov. Six new synonyms are proposed (senior synonyms last): U. multilineatus McKeown with U. ventralis Lea, U. dentiapicalis McKeown with U. parvus Lea, U. marginellus Hope and U. inermis Lea (not Aurivillius) with U. bivittatus Newman, U. fuscostriatus McKeown with U. lateroalbus Lea, and U. daviumbus Gressitt with U. longicornis Lea. Dorsal views of all species are presented as photographs, terminalia of both sexes illustrated, and distributions mapped. Brief comments are also given on the biology of this genus. In the full morphological phylogenetic analyses of all 39 species, I use 55 informative characters and cladistic method to test the monophylies of Uracanthus and its species groups. My results show that the monophylies of the genus and seven species groups are confirmed. However, several species groups still need additional steps to become monophyletic and are currently considered paraphyletic. In the molecular phylogenetic studies, due to the situations beyond my control (difficulties of extracting DNA from some old species and prohibitions of extracting DNA from type specimens), I analyse only 21 species. I extract and amplify the cytochrome oxidase I (COI) region of the mtDNA from 21 species and perform a phylogenetic analysis using molecular characters. To make the molecular phylogeny comparable to the morphological phylogeny, I also cladistically analyse the phylogeny of these 21 species using morphological and combined morphological-molecular characters. A comparison of trees obtained from morphological, mtDNA and combined data shows that the relationships of several closely related taxa remain constant, for example, the sister relationships of U. gigas + pseudogigas, U. insignis + punctulatus, and U. acutus + loranthi. However, the placement of U. insignis and U. punctulatus on the phylogenetic trees varies from the most basal in the full morphological analysis to the highly derived in the combined and molecular analyses. Considering the amount of available data is more limited in the molecular analysis than in the morphological analysis, the molecular phylogeny presented in this study should be interpreted with caution. The Uracanthus fauna can be divided into five subregions: the Kosciuskan, Western and Eyrean in southern and central Australia, and the Torresian and Timorian in northern Australia. The fauna are richest with highest endemism in the Kosciuskan and Western. The Kosciuskan and Western are similar in faunal composition and closely related; the Eyrean has probably acted as a faunal exchange transit area between the Kosciuskan and Western, and the two northern Australian subregions have no endemic species. When the areas of endemism of each species are attached to the phylogenetic tree generated from the full morphological analysis, a clear picture of the distribution patterns of species groups in relation to phylogeny is obtained. It is suggested that the speciation and species radiation of Uracanthus may have occurred first in the Kosciuskan, then in the Western, and finally in the Eyrean, Torresian, and Timorian.
| Identifer | oai:union.ndltd.org:ADTP/282811 |
| Date | January 2007 |
| Creators | Thongphak, Duangrat |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
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