Australian Amphipoda: Melitae

J.K. Lowry, P.B Berents & R.T. Springthorpe

Melita plumulosa Zeidler, 1989

Melita plumulosa Zeidler, 1989: 329, figs 1-5.

Type material. HOLOTYPE: male, 6.7 mm, AM P37289. PARATYPES: female, 4.7 mm, AM P37290; 9 males and 4 females, SAM C4076.

Type locality. "The Blue Pools", Angourie, New South Wales, from the shallow edges of the northern-most pond (freshwater).

Description. Based on Zeidler, 1989: 329, figs 1-5. Head lateral cephalic lobes broad, rounded, with anteroventral notch or slit, anteroventral corner rounded. Antenna 1 longer than antenna 2; peduncular article 1 not geniculate with article 2, longer than article 2; flagellum with 18 articles (about); accessory flagellum with 3-4 articles. Antenna 2 peduncular article 2 cone gland not reaching to end of peduncular article 3; article 4 longer than article 5; flagellum with 10-11 articles. Mandible palp present, well developed, article 3 rectolinear, with setae mostly terminal, longer than article 1, article 2 longer than article 3, article 1 not produced, subequal to article 2. Maxilla 1 inner plate with setae mainly terminal.

Pereon. Gnathopod 1 not sexually dimorphic; coxa anteroventral corner not produced, coxa posteroventral corner notch absent; merus without posterodistal tooth; carpus about 2 x as long as broad; propodus without anterodistal projection, posterodistal margin swollen (slightly), palm nearly transverse, convex, defined by posterodistal corner, without posterodistal robust setae. Gnathopod 2 sexually dimorphic; subchelate; left and right gnathopods subequal in size; coxa posteroventral corner notch absent; merus with sharp posteroventral tooth; carpus compressed; propodus with medial depression, without strong concentration of setae, palm broadly rounded, convex, smooth, without robust setae, without posterodistal robust setae, without posteroventral corner; dactylus closing across medial surface of propodus, reaching end of palm, apically acute/subacute. Peraeopod 5 basis posterior margin straight, or convex (slighlty). Peraeopod 5 basis posteroventral corner with acute or subacute process (small). Peraeopod 6 coxa anterior lobe ventral margin slightly produced, rounded. Peraeopod 6 basis posterior margin straight, or subsigmoidal (slighlty). Peraeopod 6 basis posteroventral corner with acute or subacute process (small). Peraeopod 6 propodus not expanded posterodistally. Peraeopod 7 basis posterior margin convex. Peraeopod 7 basis with posterior margin smooth or minutely castelloserrate, posteroventral corner narrowly rounded or subquadrate. Peraeopod 7 propodus not expanded posterodistally.

Pleon. Pleonite 1 without dorsal serrations, without dorsodistal spines, not dorsally bicarinate. Pleonite 2 without dorsal serrations, without dorsodistal spines, not dorsally bicarinate. Pleonite 3 without dorsal serrations, without dorsodistal spines, dorsally smooth. Epimeron 1 anteroventral corner without curved spine. Epimera 1-2 posteroventral margin without spines above posteroventral corner. Epimeron 3 posterior margin smooth, posteroventral corner with strongly produced acute spine, posteroventral margin smooth. Urosomite 1 without dorsal carina, without a small dorsal hump, without dorsal serrations, with spines at midline, no conspicuous medial gape, not dorsally bicarinate. Urosomite 1 with posterodorsal spine. Urosomite 2 posterior margin smooth, without dorsolateral robust setae. Urosomite 3 without dorsal robust setae. Uropod 1 peduncle with basofacial robust seta, without distoventral spur. Uropod 3 greatly exceeding uropods 1 and 2; inner ramus scale-like, much shorter than outer ramus; outer ramus long (more than 1.6 x longer than peduncle), 2-articulate. Telson cleft. Telson without robust setae on inner margins. Telson each lobe with 3 or more apical/subapical robust setae, apical conical extension reaching scarcely one third along longest seta.

Habitat. Freshwater, or Estuarine; intertidal sea grass beds and muddy sand up to 25 m depth.

Depth zone. Littoral (0 to 25 m).

Distribution. New South Wales: Angourie (Zeidler, 1989); Richmond River; Hawkesbury River; Careel Bay, Pittwater; Parramatta River; Haslam's Creek, Homebush Bay; Middle Harbour, Port Jackson; Picnic Point, Georges River; Tuross River; Merimbula Lake; Shadrack Creek and Curalo Lagoon, Twofold Bay (all AM).

Australian geographic areas. South-eastern Australia.

Pereon. Gnathopod 2 carpus short; propodus without medial depression, palm acute, straight; dactylus closing along palm. Peraeopod 6 coxa anterior lobe ventral margin strongly produced, rounded.

Pleon. Remarks. Specimens of M. plumulosa from the type locality in northern New South Wales are covered in plumose setae. Specimens, which appear to be the same species, from the Sydney area have simple setae. The only other difference we have seen is that the population in northern New South Wales does not have dorsal setae on urosomite 2, a highly unusual characteristice in the genus Melita.

Melita plumulosa is the only Australian species without dorsal setae on urosomite 2.

Cite this publication as: 'J.K. Lowry, P.B Berents & R.T. Springthorpe (2000 onwards). Australian Amphipoda: Melitae Descriptions, Illustrations, Identification and Information Retrieval. Version: 2 October 2000. https://crustacea.net'.