Hyalella azteca

About Hyalella azteca

Hyalella azteca is a small, laterally compressed freshwater amphipod in the family Hyalellidae. The 2008 Atlas of Hawaiian Watersheds & Their Aquatic Resources lists organisms identified as H. azteca among introduced crustaceans in its Wainiha River, Kauaʻi species list (printed p. 111) and marks presence in a Wainiha stream reach (printed p. 113). That is direct Kauaʻi watershed evidence, stronger than the general name glossary previously cited. The atlas compiles sampling from multiple years through 2005; it does not assign this species a precise collection date in the cited pages. González and Watling (2002) redescription from the Mexican type locality explains that H. azteca has long functioned as a cryptic species complex. The Kauaʻi atlas identification therefore documents H. azteca sensu lato; it does not prove that the Wainiha population belongs to the Mexican type-lineage without renewed specimen examination. Adults are gammarid amphipods; enlarged second gnathopods can distinguish males in studied material, but their presence in the Atlas reconstruction is not a diagnostic confirmation of the Kauaʻi population. No claim about current persistence, population size, trend, or island-wide distribution follows from the dated watershed listing.