GENETIC-VARIATION AND PHYLOGENETIC-RELATIONSHIPS OF 7 OREO SPECIES (TELEOSTEI, OREOSOMATIDAE) INFERRED FROM ALLOZYME ANALYSIS

Fishing pressure on deepwater oreosomatids has increased recently in A ustralian and New Zealand waters, and yet little is known about these fish. Genetic variation and phylogenetic relationships among Australia n species was examined. Allozyme variation at 26 loci was examined in seven species: six from Australasia (Allocyttus niger, black oreo; A. verrucosus, warty oreo; Neocyttus rhomboidalis, spiky oreo; Oreosoma a tlanticum, oxeye oreo; Pseudocyttus maculatus, smooth oreo; and a new species Neocyttus sp., rough oreo, infrequently captured with the smoo th oreo and black oreo) and one from the North Atlantic (N. helgae). T wo phenetic trees were constructed: an unweighted pair-group method wi th arithmetic averaging (UPGMA) tree derived from Nei's unbiased genet ic distances and a distance-Wagner tree derived from Rogers' distances . A maximum parsimony cladistic analysis, with loci as characters and alleles as unordered states, was also performed. Outgroup species came from three related families: Acanthuridae, Berycidae, and Zeidae. Mea n heterozygosity per locus for the seven oreo species was relatively h igh for teleosts (11.8%), with O. atlanticum having the lowest value ( 8.3%) and N. sp. having the highest value (18.1%). Oreosoma atlanticum was the most divergent, with a mean genetic identity (I) of 0.371. Th e two most closely related species--N. rhomboidalis and N. helgae (I=0 .973)--did not have any diagnostic allozyme loci, although the muscle protein patterns, after Coomassie blue staining, were distinctive. The re was little evidence to support the inclusion of A. niger and A. ver rucosus in the same genus; these two species had a genetic identity of 0.695. Allocyttus niger appeared to be more closely related to member s of the genus Neocyttus than to A. verrucosus. Phenetic analyses reve aled only minor differences in the Oreosomatidae grouping with respect to the three outgroups, whereas cladistic analyses revealed the Zeida e as the most closely related family.