Systematics of moths

Lauri Kaila

The phylogeny of the Lepidoptera is presently poorly resolved. Interrlationships of even major lineages largely remain unknown, and much of the present knowledge is inferred from data relying on few characters, often studied by non-analytical methods. A sound, testable hypothesis on the phylogeny is, however, essential for comparative studies of different species and a necessary component of understanding the behaviour, ecology and evolution of single species. Phylogenies are also the foundation of stable systematics, where different taxonomic levels (e.g. genus, tribe, family, etc.) describe the monophyletic groups of species. Constructing reliable phylogenies is not a simple endeavour and currently it is acknowledged that combining morphological evidence with that derived from DNA markers will give the best estimate of the true relationships of a group of species.

The superfamily Gelechioidea, comprising tens of thousands of species, is among the basal lineages of the Ditrysian Lepidoptera, and thus may prove to be a key group in resolving details of the evolution of herbivory, the suggested key factor of the success of the Ditrysian Lepidoptera. The Gelechioidea contains both saprophagous (presumably an ancestral trait) and herbivorous species.

The objective of the project is to create a testable hypothesis of the phylogeny of the main lineages of the Gelechioidea, and a more detailed study of the assemblage comprising lineages grouped as the family Elachistidae in a broad sense. The results of the phylogeny study will be further used to study the evolution of feeding strategy shifts between saprophagy and herbivory in the Gelechioidea, and the host-plant relationships of the Depressariinae, a subfamily within the Elachistidae, the species of which display a high degree of host-plant fidelity for certain plant families. The aim is to perform a total evidence analysis of the phylogenetic relationships combining morphological character data scored for larval, pupal and adult stages of the terminal taxa with that obtained from selected sequences of nuclear and mitochondrial DNA from the same species. Characters will be scored for a representative selection of species representing a wide spectrum of presumably different phylogenetic lineages within the target groups.

The data obtained will principally be analysed using cladistic methods. Another aim of the project is to resolve the phylogenetic structure and functional anatomy of the genitalia of the Scopulini of the non-related superfamily Geometroidea using the same approach, carried by Pasi Sihvonen.

Selection of these two superfamilies as the target groups is aimed at obtaining detailed experience of groups representing distant lineages of Lepidoptera, thus giving a better insight for the future study on the Order as a whole. This approach will, e.g., provide information of characters applicable across the Order.

Within the project a special effort has been laid on the phylogeny and taxonomy of the elachistid moths (Gelechioidea: Elachistidae s. s.), comprising about 600 named, and perhaps another 150 known but unnamed species. The real number of species is possibly considerably higher, since previously unknown species are regulary discovered even in the more well-known areas of the World - including Finland. In my study I have searched for criteria applicable for species identification and delimitation, and I have proposed a generic classification for the World species of the Elachistidae. The classification is based on a cladistic analysis using 150 characters derived from the morphological and ecological traits of species. It is hoped that the proposed classification where the World elachistid species are placed at three genera will clarify the previoulsy prevailed nomeclatoric mess with 40 generic names inconstistently used and usually without any scientific foundation.

An essential part of the project has been production of an up-to-date taxonomic revision of the World elachistid species. The elachistid fauna of South and North America has been published as several monographs and journal articles, and that of Australia is in preparation.