Ontogenetic changes in morphology of flathead galaxiid fishes (Osmeriformes: Galaxiidae) in South Island, New Zealand

Abstract

We examined ontogenetic changes in morphology of four non-migratory flathead galaxiid fishes and interspecific differences. Geometric analyses were used to determine where ontogenetic shifts occur, examine growth trajectories between taxa and compare interspecific differences with taxa standardised to each of three sizes. Ontogenetic changes in all taxa were mostly associated with the pelvic and anal fins developing slower than overall length. Growth trajectories differed between all taxa except Galaxias southern and G. northern, with the largest interspecific differences occurring in the overlap between the anal fin and the caudal flange. This overlap discriminated taxa at each of the three size classes despite ontogenetic changes. Morphological shifts suggest that habitat use changes with size. Interspecific differences shown in geometric shape require structural linkages before suggestions can be made on identification or systematics. © 2011 Copyright The Royal Society of New Zealand.