珠母贝（学名：Pinctada margaritifera），中国大陆称作珠母贝，**称作黑蝶真珠蛤，是莺蛤目莺蛤科真珠蛤属的一种。

左右两贝壳不完全相等，左贝壳稍突起；壳顶偏向前方，自壳顶向前后平伸成两耳状突起，全壳略呈斜方形；壳的表面有覆瓦状排列的鳞状薄片，带有苍暗色；内面具有极强烈的珍珠光。

Pinctada margaritifera, commonly known as the black-lip pearl oyster, is a species of pearl oyster, a saltwater clam, a marine bivalve mollusk in the family Pteriidae. This species is common in the Indo-Pacific within tropical coral reefs.

The ability of P. margaritifera to produce pearls means that the species is a valuable resource to humans. The oysters are harvested wild from coral reefs and are also commonly grown in aquaculture, both primarily taking place in the Indo-Pacific region.