Family PERTHIIDAE Williams & J.L. Barnard, 1988

Perthia acutitelson

© Copyright from Williams & Barnard 1988: fig. 103.

Museums

Regional Maps

Introduction

The Perthiidae are a Southern Hemisphere group of freshwater crangonyctoid amphipods originally established by Williams & Barnard (1988) for two freshwater species known from south-western Australia. Except for Perthia acutitelson Straškraba (1964), no new species have been described since Nicholls (1924), but Bradbury (pers. comm.) has examined undescribed Perthia species from the Mount Lofty Ranges in South Australia and from the western slopes of the Great Divide near the border of New South Wales and Victoria. Bradbury & Williams (1999) provide a key to the two known species.

Diagnosis

Head as long as deep or longer than deep; anteroventral margin concave; anteroventral corner rounded; rostrum short; eyes reniform. Body laterally compressed; smooth; with sparse slender setae. Antenna 1 shorter or longer than antenna 2; peduncular article 1 longer than article 2; article 2 longer than article 3; article 3 shorter than article 1; primary flagellum 5- or more articulate; callynophore absent. Antenna 2 medium length; flagellum shorter than peduncle; 5- or more articulate; calceoli present or absent. Mandible incisor dentate; lacinia mobilis present on both sides; molar non-triturating, a smooth protuberance with large robust setae. Maxilla 1 inner plate weakly setose apically. Maxilliped inner plates well developed; outer plates small or vestigial. Pereonites with sternal gills. Coxae 1–4 longer than broad, overlapping. Gnathopod 1 not sexually dimorphic; smaller (or weaker) than or subequal to gnathopod 2; subchelate; coxa smaller or subequal to coxa 2; carpus/propodus cantilevered on narrow hinge; carpus shorter than propodus. Gnathopod 2 not sexually dimorphic; subchelate; coxa subequal to but not hidden by coxa 3; ischium short; carpus short, shorter than propodus, strongly produced along posterior margin of propodus. Pereopod 3 coxa longer than broad; carpus shorter than propodus, not produced. Pereopod 4 coxa larger than coxa 3, with well-developed posteroventral lobe; carpus shorter than propodus, not produced. Pereopod 5 shorter than pereopod 6; coxa smaller than coxa 4; basis expanded, subovate, with or without posteroventral lobe; carpus linear. Pereopod 6 longer than pereopod 7; basis expanded. Pereopod 7 longer than pereopod 5; basis expanded, subovate. Epimeron 2 setose or without setae. Urosomite 1 subequal to, or longer than urosomite 2. Uropods 1–2 apices of rami with robust setae. Uropod 3 biramous; peduncle short; rami styliform; outer ramus longer than peduncle; inner ramus apically setose. Telson laminar; deeply cleft; longer than broad; dorsal robust setae present or absent; apical robust setae present.

General References

Bradbury, J.H. & Williams, W.D. 1999. Key to and checklist of the inland aquatic amphipods of Australia. Technical Reports of the Australian Museum 14: 1-21

Nicholls, G.E. 1924. Neoniphargus branchialis, a new freshwater amphipod from south-western Australia. Journal of the Royal Society of Western Australia 10(14): 105-111

Straškraba, M. 1964. Perthia n.g. (Amphipoda, Gammaridae) from fresh water of Western Australia, with remarks on the genera Neoniphargus and Uroctena. Crustaceana 7: 125-139

Williams, W.D. & Barnard, J.L. 1988. The taxonomy of crangonyctoid Amphipoda (Crustacea) from Australian fresh waters: foundation studies. Records of the Australian Museum, Supplement 10: 1-180

History of changes