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Amphipods are extremly diverse, abundant and widespread crustaceans. They are found in nearly all marine and freshwater habitats. They are paticularly important as herbivores, detritivores, micropredators and scavengers in marine environments and they are almost always an important componen
Description. Head free, not coalesced with peraeonite 1; exposed; deeper than long, or much deeper than long; rostrum present, short or moderate or long; eyes present, well developed or obsolescent, or absent; not coalesced; 1 pair; not bulging. Body laterally compressed; cuticle smooth.
Antenna 1 shorter than antenna 2, or subequal to antenna 2; peduncle with sparse robust and slender setae; 3-articulate; peduncular article 1 shorter than article 2, or subequal to article 2, or longer than article 2; antenna 1 article 2 longer than article 3; peduncular articles 1-2 not geniculate; accessory flagellum present; antenna 1 callynophore present, or absent. Antenna 2 present; short, or greater than body length; articles not folded in zigzag fashion; without hook-like process; flagellum longer than peduncle; 5 or more articulate; not clavate; calceoli present, or absent.
Mouthparts well developed. Mandible incisor smooth; lacinia mobilis present on left side only; accessory setal row with distal tuft; molar present, medium, non-triturative; palp present. Maxilla 1 present; inner plate present, weakly setose apically; palp absent, 0 -articulate. Maxilla 2 inner plate present; outer plate present. Maxilliped inner and outer plates well developed or reduced, palps present, well developed or reduced; inner plates well developed, separate; outer plates present, large; palp 4-articulate, article 3 without rugosities. Labium smooth.
Peraeon. Peraeonites 1-7 separate; complete; sternal gills absent; pleurae absent.
Coxae 1-7 well developed, none fused with peraeonites. Coxae 1-4 longer than broad, overlapping, coxae not acuminate. Coxae 1-3 not successively smaller, coxa 1 vestigial. Coxae 2-4 none immensely broadened.
Gnathopod 1 not sexually dimorphic; subequal to gnathopod 2; vestigial, hidden or partially hidden by coxa 2; gnathopod 1 merus and carpus not rotated; gnathopod 1 carpus/propodus not cantilevered; shorter than propodus; gnathopod 1 not produced along posterior margin of propodus; dactylus large. Gnathopod 2 not sexually dimorphic; subchelate; coxa subequal to but not hidden by coxa 3; ischium elongate; merus not fused along posterior margin of carpus or produced away from it; carpus/propodus not cantilevered, carpus elongate, longer than propodus, not produced along posterior margin of propodus.
Peraeopods heteropodous (3-4 directed posteriorly, 5-7 directed anteriorly), none prehensile. Peraeopod 3 well developed. Peraeopod 4 well developed. 3-4 not glandular; 3-7 without hooded dactyli, 3-7 propodi without distal spurs. Coxa well developed, longer than broad; carpus shorter than propodus, produced anteriorly; dactylus well developed. Coxa larger than coxa 3, not acuminate, with well developed posteroventral lobe; carpus not produced. Peraeopods 5-7 with few robust or slender setae; dactyli without slender or robust setae. Peraeopod 5 well developed; subequal in length to peraeopod 6; coxa smaller than coxa 4, without posterior lobe; basis expanded or slightly expanded or linear, subrectangular or subovate or subquadrate, with posteroventral lobe or without posteroventral lobe; merus/carpus free; carpus linear; setae absent. Peraeopod 6 subequal in length to peraeopod 7; merus/carpus free; dactylus without setae. Peraeopod 7 with 6-7 well developed articles; subequal to peraeopod 5; similar in structure to peraeopod 6; with 7 articles; basis expanded, without dense slender setae; dactylus without setae.
Pleon. Pleonites 1-3 without transverse dorsal serrations, without dorsal carina; without slender or robust dorsal setae. Epimera 1-3 present. Epimeron 1 well developed. Epimeron 2 without setae.
Urosome not dorsoventrally flattened; urosomites 1 to 3 free; urosomite 1 much longer than urosomite 2; urosome urosomites not carinate; urosomites 1-2 without transverse dorsal serrations. Uropods 1-2 apices of rami without robust setae. Uropods 1-3 similar in structure and size. Uropod 1 peduncle without long plumose setae, without basofacial robust seta, without ventromedial spur. Uropod 2 well developed; without ventromedial spur, without dorsal flange; inner ramus longer than outer ramus. Uropod 3 sexually dimorphic, or not sexually dimorphic; peduncle short or elongate; outer ramus longer than peduncle, 1-articulate or 2-articulate, without recurved spines. Telson laminar; moderately cleft, or weakly cleft; longer than broad, or as long as broad; apical robust setae absent.
Cite this publication as: 'J.K. Lowry & R.T. Springthorpe (2001 onwards). Amphipoda: Families and Subfamilies. Version 1: 1 September 2001. http://crustacea.net/'. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited.
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