Reproductive biology, species status and taxonomic relationships of four recently discovered galaxiid fishes in a New Zealand river.

Abstract

The reproductive biology of four recently discovered, largely allopatric non-migratory Galaxias species in the Taieri River, New Zealand, was compared with the closely related Galaxias vulgaris. Timing of spawning was similar (late winter/spring) but spawning habitat, spawning behaviour and nest structure differed among the Taieri species and G. vulgaris. Patterns of fecundity also differed among the Taieri species but, with G. vulgaris, they form a distinct group of galaxiids with maxima of 800-1500 eggs having diameters of 2·3-2·8 μn. The different spawning behaviours of the Taieri galaxiids, in particular the differences in spawning orientation, provide evidence for prezygotic isolating mechanisms and support their status as separate species. In cladistics terms, the results indicate that Galaxias anomalus, G. eldoni and G. vulgaris are sister taxa, while G. depressiceps and Galaxias sp. form a second cluster.