The recently described buprestid genus Petersonia Hawkeswood, 2007 is proposed as a new subjective junior synonym of the large Australasian genus Castiarina Gory & Laporte, 1838. A brief discussion about male antennal modifications in Buprestidae is given. A list of criteria and considerations on erecting genus-group names from an earlier paper by Holm & Schoeman (1999) is repeated verbatim.