Hyalellidae Bulycheva, 1957

Type genus. Hyalella S.I. Smith, 1874 .

Diagnostic description. Body laterally compressed. Eyes well developed or absent, if present then round or ovoid. Antennae 1–2 calceoli absent. Antenna 1 shorter than, subequal in length to, or longer than antenna 2; peduncular article 1 longer than article 2; article 2 subequal to or longer than article 3; article 3 shorter than article 1; peduncular articles 1–2 not geniculate; accessory flagellum absent. Antenna 2 peduncular article 1 enlarged, bulbous. Mandible molar triturative; palp absent. Maxilla 1 basal endite apically setose; palp present or absent, symmetrical. Maxilla 2 basal endite without oblique setal row. Labium inner lobes vestigial or absent. Coxal gills on pereopods 2–7, not stalked; sternal gills present, simple; sternal blisters absent; oostegites fringing setae curltipped. Gnathopod 1 similar in males and females (not sexually dimorphic); smaller (or weaker) than or similar in size to gnathopod 2; propodus palm without robust setae along palmar margin. Gnathopod 2 carpus slightly produced along posterior margin of propodus. Pereopods 3–4 not sexually dimorphic. Pereopod 4 with small posteroventral lobe. Pereopod 5 shorter than pereopod 6; coxa equilobate or with posteroventral lobe. Pereopod 7 longer than pereopod 5. Pleonites 1–3 each with dorsal carina or carinae (small) or without dorsal carinae. Urosomites 1–3 free; without slender or robust dorsal setae. Urosomite 1 without large distoventral robust seta. Urosomite 2 without dorsal setae. Uropod 1 without basofacial robust setae. Uropod 3 not sexually dimorphic; uniramous, without plumose setae. Telson entire; dorsal or lateral robust setae absent; apical robust setae present or absent.

Habitat. Freshwater, epigean.

Included genera. Hyalella (Austrohyalella) Bousfield, 1996; Hyalella (Hyalella) S.I. Smith, 1874; Hyalella (Mesohyalella) Bousfield, 1996 .

Remarks. Hyalellids differ from all other talitridirans in the swollen first peduncular article of antenna 2 and the presence of a coxal gill on pereopod 7.

Distribution. North and South America.