Hydrophilus palpalis is a species of water scavenger beetles belonging to the Hydrophilinae subfamily.
Some authors have included this species in a distinct genus (Diboloceus), but most of them consider Diboloceus just a subgenus of Hydrophilus (Hydrophilus (Dibolocelus) palpalis).
This large species has an oval and moderately convex body. The basic color of the body is dark brown or black. Antennae are 9-segmented. Prosternum is well developed, divided into two lobes. Elytra show ten extremely fine striae. Hind femora are glabrous.
These beetles are adapted for aquatic life. The first-stage larvae and the adults are excellent swimmers. Adults are mainly vegetarian while the larvae are carnivorous and have a preference for molluscs.
This species can be found in South America in aquatic habitat, especially in rice cultivations (Oryza sativa).