| Gammarus hyalelloides | |
|---|---|
 | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Malacostraca |
| Order: | Amphipoda |
| Family: | Gammaridae |
| Genus: | Gammarus |
| Species: | G. hyalelloides |
| Binomial name | |
| Gammarus hyalelloides Cole, 1976 | |
Gammarus hyalelloides, the diminutive amphipod is a species of amphipod crustacean in the family Gammaridae. It is endemic to four springs in Jeff Davis County and Reeves County, Texas, and is listed as a vulnerable species on the IUCN Red List. [1]
Gammarus hyalelloides is the smallest freshwater amphipod in North America. Males are 5.8–7.8 mm (0.23–0.31 in) long, while sexually mature females are 5.0–7.3 mm (0.20–0.29 in). [3] They live in beds of Chara at the mouth of Phantom Lake Spring. [3]
Gammarus hyalelloides makes up more than 70% of the diet of Gambusia nobilis in the Phantom Lake Spring refuge ( 30°56′5″N103°50′58″W / 30.93472°N 103.84944°W ) 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. hyalelloides. [3]
The first collections of G. hyalelloides were made in 1967 at the Phantom Lake Spring. [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 . [3]
The type specimens were deposited in the United States National Museum (holotype male: USNM 151957; paratype female: USNM 151958). Further paratype series were deposited at the same museum, and at the National Museum of Canada. [3]
G. hyalelloides is part of the Gammarus pecos species complex, alongside Gammarus pecos and Gammarus desperatus ; all three species are restricted to the Pecos River basin of Texas and New Mexico. [5]
