Priacanthus gracilis sp. nov., an eastern Australian bigeye (Perciformes: Priacanthidae) previously misidentified as Priacanthus macracanthus Cuvier 1829, is described as new based on its morphological and genetic distinctiveness. The new species is characterized by the following combination of characters: dorsal-fin soft rays 12–14 (modally 13); anal-fin soft rays 13 or 14 (14); scale rows above lateral line 9–12 (11); gill rakers on lower limb 23–25 (23); body slender, its depth at sixth dorsal-fin spine base 29.5–36.0% (mean 32.7%) of standard length (SL); orbit diameter large, 13.2–17.5% (15.1%) of SL and 45.3–51.4% (47.7%) of head length; body tapering gently from close behind head; preopercular spine reaching opercular margin; dark brown blotches on dorsal and pelvic fins (preserved specimens); no large black blotch on pelvic-fin base. The new species is endemic to eastern Australia, whereas P. macracanthus is distributed in the eastern Indian and western Pacific oceans, including off eastern Australia. Priacanthus junonis De Vis 1885 and Priacanthus benmebari Temminck and Schlegel 1843 are regarded as junior synonyms of P. macracanthus.

gracilis sp。 nov. 是一种澳大利亚东部大眼鱼（鲈形目：Priacanthidae），之前被误认为是Priacanthus macracanthus Cuvier 1829，但由于其形态和遗传的独特性，被描述为新物种。该新种具有以下特征组合：背鳍软条12-14（模态13）；臀鳍软条 13 或 14 (14);侧线 9-12 上方的鳞片行 (11)；下肢有鳃耙 23-25 (23)；体细长，第六背鳍棘基部深度为标准长度（SL）的29.5-36.0%（平均32.7%）；眼眶直径大，为 SL 的 13.2–17.5% (15.1%) 和头长的 45.3–51.4% (47.7%)；身体从紧靠头部后方逐渐变细；前鳃盖骨棘到达鳃盖边缘；背鳍和腹鳍上有深棕色斑点（保存标本）；腹鳍基部无大的黑色斑点。该新物种是澳大利亚东部特有的物种，而P. macracanthus则分布在东印度洋和西太平洋，包括澳大利亚东部海域。Priacanthus junonis De Vis 1885 和Priacanthus benmebari Temminck 和 Schlegel 1843 被认为是P. macracanthus的初级同义词。