Hydrovatus subtilis

Hydrovatus subtilis, is a species of predaceous diving beetle found in India, Andaman & Nicobar Islands, Sri Lanka, Indonesia, Japan, Laos, Malaysia, and Thailand.

Body larger with a typical length of about 2.4 to 2.8 mm. Male antenna with joints 7 to 8 broader than adjacent joints. Head between eyes is not margined. Male with stridulation apparatus on metacoxal plates along suture close to metathorax.