Pseudocoremia (Lepidoptera: Geometridae: Ennominae): systematics, biogeography and host plant associations

Abstract

A phylogenetic hypothesis of Pseudocoremia an endemic genus of 29 species is determined and related to the biogeography and host plant associations. Five new species are described, and one of the synonymies of Dugdale (1988) is reversed. A cladistic analysis of all New Zealand members of the Boarmiini tribe (including Pseudocoremia) gave four most parsimonious trees with a length of 43 and a CI value of 0.7209, and a 50% majority rule bootstrap consensus tree was obtained. All trees indicated that Pseudocoremia cineracia and Chalastra ochrea are not members of their respective genera. The genera Cleora and Chalastra were determined to be suitable outgroups for a cladistic analysis of Pseudocoremia. The cladistic analysis of Pseudocoremia used of 37 characters producing 21 most parsimonious trees with 161 characters state changes and a CI value of 0.2891. Strict and 50% majority rule trees were produced. Biogeographic patterns of the genus are dominated by a large number of widespread taxa. It is argued that the most likely reason for the number of widespread patterns in the genus is dispersal following speciation events. The structure of the tree also indicates that dispersal has played a large part in the determination of the patterns evident in Pseudocoremia. The occurrence of Pseudocoremia on both Norfolk Island and the Chatham Islands is likely to be the result of dispersal. Host plant relations vary widely within the genus from species which feed upon a wide range of unrelated host plants to those which are restricted to a single genus. Hypotheses for the evolution of host plant relations are debated. Trade-offs in performance on different hosts is likely to be the primary determinant with predation or other ecological factors playing a secondary role, and possibly being a determinant of the level of generalisation shown by a species.