Spider-water-beetle
Guides
Ancyronyx
spider water beetles, spider riffle beetles
Ancyronyx is a genus of aquatic riffle beetles in the family Elmidae, commonly known as spider water beetles or spider riffle beetles. The genus comprises 21 described species distributed across North America, South Asia, China, and Southeast Asia, with the Philippines recognized as a center of diversity containing 11 endemic species. Members are obligate inhabitants of lotic freshwater environments, where both adults and larvae cling to submerged substrates using their elongated legs and strong claws. The genus is notable for its potential use as a bioindicator of water quality due to its sensitivity to pollution and oxygen levels.
Ancyronyx variegata
Spider Water Beetle
Ancyronyx variegata is a riffle beetle (Elmidae) commonly known as a Spider Water Beetle, characterized by extremely long legs and often a cross-like elytral color pattern that gives it a spider-like appearance. It inhabits clean, pristine running waters in lotic environments and has been studied for its life history and energetics in Northwest Arkansas and Southeast Texas. The species exhibits a univoltine life cycle with adults present year-round.