Ancyronyx
genus of insects
Ancyronyx, commonly known as spider water beetles or spider riffle beetles, is a genus of aquatic riffle beetles from North America, South Asia, China, and Southeast Asia. They are small beetles with extremely long legs ending in strong claws. Both the adults and the larvae are found underwater in the shallow riffles of streams and rivers, clinging to rocks or submerged wood. They feed on algae and decaying wood tissue. The genus contains twenty-one species, eleven of which are endemic to the Philippines.
Taxonomy
The genus Ancyronyx was established in 1847 by the German entomologist Wilhelm Ferdinand Erichson based on the type species Macronychus variegatus first described in 1824 by the German coleopterologist Ernst Friedrich Germar. It was regarded as a monotypic species until the French entomologist Antoine Henri Grouvelle described the second species, A. acaroides in 1896. It is the sole member of the tribe Ancyronychini, and is classified under the subfamily Elminae of the riffle beetle family, Elmidae.
Description
Members of Ancyronyx superficially resemble spiders and are aquatic, hence their common name, "spider water beetles". They are typically very small, with an average body length (without legs) of 1 to 2 mm (0.039 to 0.079 in).
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The date and method of observation matter as much as the stated conclusion, especially where classification or consensus has changed. The source revision retrieved here is dated May 18, 2026. The linked authority identifier is Q15077417. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1847, 1824 and 1896.
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This entry incorporates text from “Ancyronyx” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.