Morphometric and cladistic analyses of the phylogeny of Macropodinium (Ciliophora : Litostomatea : Macropodiniidae)

Phylogenetic studies of the genus Macropodinium were conducted using two methods; phenetics and cladistics. The phenetic study of morphometrics suggested that the genus could be divided into 3 groups attributable mostly to cell size and shape. The cladistic study also split the genus into 3 groups related to cell size but groups were further distinguished by patterns of ornamentation. Reconciliation of both approaches revealed considerable congruence, however, it also suggested the existence of convergences in the phenetic study and a lack of resolution in the cladistic study. The morphological diversity of Macropodinium is probably due to evolutionary trends such as increasing body size, allometry and polymerisation of structures. None of these trends, however, was uniformly directional and differential effects were observed in different regions of the phylogenetic tree. Comparison of the phylogeny of Macropodinium to a consensus phylogeny of the macropodids revealed limited incongruence between the 2 trees. The ciliate groups could be related to 2 host groups; the wallaby genera and the kangaroo and wallaroo subgenera. The association with these host groups may be the result of phyletic codescent, ecological resource tracking or a combination of both. Further studies of both host and ciliate phylogeny are necessary to resolve these effects.

Trichodinids (Ciliophora : Trichodinidae) from native and exotic Australian freshwater fishes

There are very few data on trichodinids of freshwater fishes in Australia. 2003 fishes were surveyed across Eastern Australia to investigate the diversity of trichodinids present, to determine which species have been introduced with exotic fishes and to determine the extent to which these species have crossed into native fish Populations. Twenty-one putative trichodinid species were recovered from the 33 fish species examined. Trichodina heterodentata, T. mutabilis and T. reticulata were the exotic species recovered regularly; a single specimen matched a fourth exotic species, T acuta. All four exotic species are redescribed from Australian material. Trichodina heterodentata was recorded from 17 species of fishes, 15 of which were new host records; this species is identified as one of emerging importance in fish parasitology and a list of its known hosts is presented. Two new native species are also described based on silver stained specimens: T cribbi sp. n. from Hypseleotris galii, H. klunzingeri, and Hypseleotris sp. 5; and T. bassonae sp. n. from Selenotoca multifasciata. Trichodina cribbi is characterised by a large circular central inclusion and approximately 28 denticles, which have a blade length slightly greater than the ray length. Trichodina bassonae is characterised by a small, round, central inclusion and approximately 25 denticles, which have straight, non tapering rays that are in line with the leading edge of the denticle blade. It is estimated that the Australian trichodinid fauna may include up to 150 as yet undescribed species and represents a major source of unexplored biodiversity.

Predator-specific changes in the morphology and swimming performance of larval Rana lessonae

1. We investigated the morphological responses of larval Rana lessonae to the presence of two predators with substantially different prey-detection and capture techniques; larval dragonflies (Aeshna cyanea) and the Pumpkinseed Sunfish (Lepomis gibossus). 2. We also examined the functional implications of any predator-induced morphological variation on their swimming ability by assessing performance during the initial stages of a startle response. 3. We found the morphological responses of larval R. lessonae were dependent on the specific predator present. Tadpoles raised in the presence of dragonfly larvae preying upon conspecific tadpoles developed total tail heights 5.4% deeper and tail muscles 4.7% shallower than tadpoles raised in a non-predator environment, while tadpoles raised with sunfish possessed tails 2% shallower and tail muscles 2.5% higher than non-predator-exposed tadpoles. 4. Predator-induced morphological variation also significantly influenced swimming performance. Tadpoles raised with sunfish possessed swimming speeds 9.5 and 14.6% higher than non- and dragonfly predator groups, respectively. 5. Thus, the expression of these alternative predator-morphs leads to a functional trade-off in performance between the different environments.