Pachyschesidae Kamaltynov, 1999

Type genus. Pachyschesis Bazikalova, 1945 .

Diagnostic description. Body laterally compressed. Eyes well developed, poorly developed or absent, if present then round, ovoid, reniform, ventrally tapered or subrectangular. Antennae 1–2 calceoli absent. Antenna 1 longer than antenna 2; peduncular article 1 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 or minute. Antenna 2 peduncular article 1 enlarged, bulbous. Mandible palp symmetrical. Maxilla 1 basal endite apically setose; palps symmetrical. Maxilla 2 basal endite without oblique setal row. Labium inner lobes vestigial or absent. Coxal gills on pereopods 2–6, not stalked; sternal gills absent; sternal blisters absent; oostegites fringing setae simple. Gnathopod 1 subchelate; similar in males and females (not sexually dimorphic); similar in size to gnathopod 2; propodus palm without robust setae along palmar margin. Gnathopod 2 subchelate; similar in males and females (not sexually dimorphic); carpus 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 subequal in length to pereopod 6; coxa with large or with small anteroventral lobe. Pereopod 7 subequal in length to pereopod 5. Pleonites 1–3 without dorsal carinae. Urosomites 1–3 free; with 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 shorter than exopod. Telson deeply cleft; dorsal or lateral robust setae absent; apical robust setae absent.

Habitat. Freshwater, epigean.

Included genera. Pachyschesis Bazikalova, 1945 .

Distribution. Lake Baikal.