Nilus radiatolineatus is a species of insect belonging to the family Nilidae. It is commonly known as the radiate-lined water beetle. This insect is characterized by its elongated body, ranging from 10 to 15 millimeters in length, and its distinct radiating lines on its elytra. It is typically found in freshwater habitats, such as ponds and slow-moving streams, where it feeds on small aquatic organisms.