[1] Gammarus hyalelloides is the smallest freshwater amphipod in North America.

[3] Gammarus hyalelloides makes up more than 70% of the diet of Gambusia nobilis in the Phantom Lake Spring refuge (30°56′5″N 103°50′58″W / 30.93472°N 103.84944°W / 30.93472; -103.84944) in Jeff Davis County, Texas.

[4] Other biota found in the Phantom Lake Spring include the snails Pyrgulopsis texana and Lyrodes cheatumi.

[3] The absence of Hyalella azteca may have allowed speciation to take place in the genus Gammarus, with one species entering the vacant niche, and reducing in size to become G.

[3] The amphipods were originally thought to be the common and widespread Hyalella azteca, but were later recognized as a new and distinct species of Gammarus.