Gammaracanthidae Bousfield, 1989

Type genus. Gammaracanthus Bate, 1862 .

Diagnostic description. Body laterally compressed. Eyes well developed, round or ovoid. Antennae 1–2 calceoli absent. Antenna 1 longer than antenna 2; peduncular article 1 subequal to, or longer than article 2; article 2 longer than article 3; article 3 shorter than article 1; peduncular articles 1–2 not geniculate; accessory flagellum short. Antenna 2 peduncular article 1 enlarged, bulbous. Mandible molar triturative; palp symmetrical. Maxilla 1 basal endite setose along medial margin or apically setose; palps symmetrical. Maxilla 2 basal endite with oblique setal row. Coxal gills on pereopods 2–7, not stalked; sternal gills present or absent, if present simple; sternal blisters absent; oostegites fringing setae simple. Gnathopod 1 subchelate; similar in males and females (not sexually dimorphic); smaller (or weaker) than, similar in size to, or larger (or stouter) than gnathopod 2; propodus palm without robust setae along palmar margin. Gnathopod 2 subchelate; dissimilar in males and females (sexually dimorphic); carpus slightly produced along posterior margin of propodus or not produced along posterior margin of propodus, projecting between merus and propodus. Pereopods 3–4 not sexually dimorphic. Pereopod 4 without posteroventral lobe. Pereopod 5 shorter than or subequal in length to pereopod 6; coxa with large anteroventral lobe. Pereopod 7 shorter than pereopod 5. Pleonites 1–3 each with dorsal carina or 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; biramous, with plumose setae; endopod subequal in length to exopod. Telson moderately cleft or notched; dorsal or lateral robust setae absent; apical robust setae present or absent.

Habitat. Freshwater epigean.

Included genera. Gammaracanthus Bate, 1862; Relictacanthus Bousfield, 1989 .

Distribution. Northern Europe including Caspian Sea.