Amphipoda: Families and Subfamilies

J.K. Lowry & R.T. Springthorpe

Eusiridae Stebbing, 1888

Description. Head free, not coalesced with peraeonite 1; exposed; as long as deep, or longer than deep, or deeper than long; anteroventral margin weakly recessed or moderately recessed or concave or rounded or notched or straight or oblique, anteroventral margin shallowly excavate, anteroventral corner rounded or subquadrate or hooked; rostrum present or absent, short or moderate or long; eyes present, well developed or obsolescent, or absent; coalesced, or not coalesced; 1 pair; bulging, or not bulging. Body laterally compressed, or dorsoventrally flattened; cuticle smooth, or processiferous.

Antenna 1 shorter than antenna 2, or subequal to antenna 2, or longer than 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, or absent; antenna 1 callynophore present, or absent. Antenna 2 present; short, or medium length, or long, or greater than body length; articles not folded in zigzag fashion; without hook-like process; flagellum shorter than peduncle, or as long as peduncle, or longer than peduncle; less than 5-articulate, or 5 or more articulate; not clavate; calceoli present, or absent.

Mouthparts well developed. Mandible incisor dentate; lacinia mobilis present on both sides; accessory setal row without distal tuft; molar present, medium, triturative; palp present. Maxilla 1 present; inner plate present, strongly setose along medial margin or weakly setose apically; palp present, not clavate, 2 -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, small; 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 or as long as broad, overlapping, coxa 1 anteroventrally acuminate or coxae not acuminate. Coxae 1-3 not successively smaller, none vestigial or coxa 1 reduced. Coxae 2-4 none immensely broadened.

Gnathopod 1 not sexually dimorphic; smaller (or weaker) than gnathopod 2, or subequal to gnathopod 2; smaller than coxa 2, or subequal to coxa 2; gnathopod 1 merus and carpus not rotated; gnathopod 1 carpus/propodus cantilevered on narrow hinge, or carpus/propodus not cantilevered; shorter than propodus, or subequal to propodus, or longer than propodus; gnathopod 1 slightly produced along posterior margin of propodus, or not produced along posterior margin of propodus; dactylus large. Gnathopod 2 sexually dimorphic, or not sexually dimorphic; simple, or subchelate; coxa subequal to but not hidden by coxa 3; ischium short; merus not fused along posterior margin of carpus or produced away from it; carpus/propodus cantilevered on narrow hinge or carpus/propodus not cantilevered, carpus short or elongate, shorter than propodus or subequal to propodus or longer than propodus, strongly produced along posterior margin of propodus or slightly produced along posterior margin of propodus or 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 or as long as broad or broader than long; carpus shorter than propodus or subequal to propodus, not produced; dactylus well developed. Coxa subequal to coxa 3 or larger than coxa 3, not acuminate, with well developed posteroventral lobe or without posteroventral lobe; carpus not produced. Peraeopods 5-7 with few robust or slender setae; dactyli without slender or robust setae. Peraeopod 5 well developed; shorter than peraeopod 6, or subequal in length to peraeopod 6; coxa smaller than coxa 4 or subequal to coxa 4, equilobate or with ventrally produced posterior lobe or with posterodorsal lobe or without posterior lobe; basis expanded or slightly expanded, subrectangular or subovate, with posteroventral lobe or without posteroventral lobe; merus/carpus free; carpus weakly expanded, or linear; setae absent. Peraeopod 6 shorter than peraeopod 7, or subequal in length to peraeopod 7; merus/carpus free; dactylus without setae. Peraeopod 7 with 6-7 well developed articles; subequal to peraeopod 5, or longer than peraeopod 5; similar in structure to peraeopod 6; with 7 articles; basis expanded or slightly 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 setose, or without setae.

Urosome dorsoventrally flattened, or not dorsoventrally flattened; urosomites 1 to 3 free; urosomite 1 longer than urosomite 2, or much longer than urosomite 2; urosome urosomite 1 carinate, or urosomites not carinate; urosomites 1-2 without transverse dorsal serrations. Uropods 1-2 apices of rami with robust setae, or 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 subequal to outer ramus, or longer than outer ramus. Uropod 3 not sexually dimorphic; peduncle short or elongate; outer ramus shorter than peduncle or longer than peduncle, 1-articulate, without recurved spines. Telson laminar; deeply cleft, or moderately cleft, or weakly cleft, or notched, or emarginate, or entire; longer than broad, or as long as broad; apical robust setae present, or absent.

Habitat. freshwater or marine or estuarine.

Habitat. benthic or demersal.

Remarks. The Eusiridae is maintained as a family separate from Calliopiidae based on the cleft condition of the telson. This is done entirely to reduce the number of genera available for identification and has no phylogenetic significance.


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 (see References).

Index