Mordellistena rayi is a species of beetle in the family Mordellidae. It was first described as Mordellistena humeralis in 1937 by Eugene Ray from Puerto Rico, but this name was preoccupied by Mordellistena humeralis (Linnaeus, 1758), and the replacement name Mordellistena rayi was created by Karl Ermisch in 1965. This beetle measures in length, or when including the anal stylus. The antennae are long. References rayi Beetles of North America Insects of Puerto Rico Endemic fauna of Puerto Rico Beetles described in 1965