Family TRISCHIZOSTOMATIDAE Lilljeborg, 1865

Trischizostoma richeri

© Copyright from Lowry & Stoddart 1994: fig. 46.

Museums

Regional Maps

Introduction

The trischizostomatids are an interesting group of deep-water lysianassoid amphipods with a highly derived morphology. Some members are ectoparasites on demersal sharks and deep-water bony fishes (Sars 1890). Other species occur inside sponges (K.H. Barnard 1925). Only one genus, Trischizostoma, is currently recognised, with about nine species.

Diagnosis

Head as long as deep or longer than deep; rostrum long; eyes ventrally tapered or subrectangular. Body laterally compressed; smooth. Antenna 1 shorter than antenna 2; peduncular article 1 longer than article 2; article 2 shorter than, subequal to, or longer than article 3; article 3 shorter than article 1; primary flagellum 5- or more articulate; callynophore present. Antenna 2 short; flagellum longer than peduncle; 5- or more articulate; calceoli present or absent. Mandible incisor smooth; lacinia mobilis absent; molar absent. Maxilla 1 inner plate weakly setose apically or without setae. Maxilliped inner plates well developed; outer plates large or small. Coxae 1–4 longer than broad or as long as broad, overlapping; coxa 1 vestigial. Gnathopod 1 not sexually dimorphic; larger (or stouter) than gnathopod 2; subchelate; coxa vestigial, hidden or partially hidden by coxa 2; merus and carpus rotated, propodus and dactylus inverted in adult; carpus shorter than propodus. Gnathopod 2 not sexually dimorphic; subchelate; coxa subequal to but not hidden by coxa 3; ischium long; carpus long, longer than propodus; dactylus minute. Pereopod 3 coxa longer than broad; carpus subequal to, or longer than propodus, not produced. Pereopod 4 coxa smaller than or subequal to coxa 3, with well developed posteroventral lobe; carpus shorter than propodus, not produced. Pereopod 5 subequal to pereopod 6; coxa smaller than or subequal to coxa 4, with or without ventrally produced posterior lobe; basis expanded, shape variable, with or without posteroventral lobe; carpus linear. Pereopod 6 subequal to pereopod 7; basis expanded. Pereopod 7 subequal to pereopod 5; basis expanded. Pleonite 3 with or without dorsal carina. Urosomite 1 subequal to, or longer than urosomite 2. Uropods 1–2 apices of rami without robust setae. Uropod 3 biramous; peduncle short; rami lanceolate; outer ramus longer than peduncle; inner ramus not apically setose. Telson laminar; deeply, moderately or weakly cleft, emarginate or entire; longer than broad or as long as broad; dorsal and apical robust setae absent.

General References

Barnard, K.H. 1925. Contributions to the crustacean fauna of South Africa. 8. Further additions to the list of Amphipoda. Annals of the South African Museum 20: 319-380

Bousfield, E.L. 1987. Amphipod parasites of fishes of Canada. Canadian Bulletin of Fisheries and Aquatic Sciences 217: 1-37

Lilljeborg, W. 1865. On the Lysianassa magellanica H. Milne Edwards and on the Crustacea of the suborder Amphipoda and subfamily Lysianassina found on the coast of Sweden and Norway. Uppsala : Royal Academic Press 38 pp. 5 pls.

Lowry, J.K. & Stoddart, H.E. 1993. Crustacea Amphipoda: Lysianassoids from Philippine and Indonesian water. pp. 55-109 in Crosnier, A. Résultats des Campagnes MUSORSTOM, Vol. 10. Mémoires du Muséum national d'Histoire naturelle, Paris [1936-1950] 156: 1-491

Lowry, J.K. & Stoddart, H.E. 1994. Crustacea Amphipoda: Lysianassoids from the tropical western South Pacific Ocean. pp. 127-223 in Crosnier, A. Résultats des Campagnes MUSORSTOM, Vol. 12. Mémoires du Muséum national d'Histoire naturelle, Paris [1936-1950] 161: 1-520

Sars, G.O. 1890. An Account of the Crustacea of Norway, with Short Descriptions and Figures of all the Species. Vol. 1 Amphipoda. Pts 1–3. Christiania & Copenhagen : Alb. Cammermeyer pp. 1-68, pls 1-24.

History of changes