Australian Amphipoda: Melitae

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

Quadrivisio sarina Lowry & Springthorpe

Type material. HOLOTYPE: female, 7.4 mm, AM P60482. PARATYPE: male, 8.1 mm, AM P60484.

Type locality. Armstrong Beach, Sarina, Queensland (21º 46'S 149º 29'E), sand beach, midtide level.

Description. Based on holotype female, AM P60482 and paratype male, AM P60484. Head lateral cephalic lobes broad, rounded, with anteroventral notch or slit, anteroventral corner rounded. Antenna 1 shorter than antenna 2; peduncular article 1 not geniculate with article 2, longer than article 2, with 2 robust setae along posterior margin; flagellum with 14 articles; accessory flagellum with 6 articles. Antenna 2 peduncular article 2 cone gland reaching at least to end of peduncular article 3; article 4 subequal to article 5; flagellum with 15 articles. Mandible palp present, well developed, article 3 rectolinear, with setae mostly terminal, longer than article 1, article 2 subequal to article 3 or article 2 shorter than article 3, article 1 produced distally, shorter than article 2, about as long as broad. Maxilla 1 inner plate setose along entire inner margin.

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 not swollen, palm nearly transverse, convex, without posterodistal corner, defined by posterodistal robust setae. Gnathopod 2 sexually dimorphic; subchelate; left and right gnathopods subequal in size; coxa posteroventral corner notch absent; merus with rounded posteroventral corner, or with subquadrate posteroventral corner; carpus compressed; propodus with medial depression, without strong concentration of setae, palm extremely acute, convex, smooth, lined with robust setae, defined by posterodistal robust setae, without posteroventral corner; dactylus closing along palm, reaching end of palm, apically acute/subacute. Peraeopod 5 basis posterior margin convex. Peraeopod 5 basis posteroventral corner narrowly rounded or subquadrate. Peraeopod 6 coxa anterior lobe ventral margin not produced ventrally. Peraeopod 6 basis posterior margin convex. Peraeopod 6 basis posteroventral corner narrowly rounded or subquadrate. 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 small acute spine, posteroventral margin smooth. Urosomite 1 without dorsal carina, without a small dorsal hump, without dorsal serrations, without spines or gape, not dorsally bicarinate. Urosomite 1 with posterodorsal spine. Urosomite 2 posterior margin smooth, with two groups of 1-3 small dorsolateral robust setae. Urosomite 3 without dorsal robust setae. Uropod 1 peduncle with basofacial robust seta, without distoventral spur. Uropod 3 exceeding uropods 1 and 2; inner ramus subequal in length to outer ramus; outer ramus long (more than 1.6 x longer than peduncle), 1-articulate. Telson cleft. Telson without robust setae on inner margins. Telson each lobe with 3 or more apical/subapical robust setae, apical conical extension absent.

Habitat. Marine; sand beach, midtide level

.

Depth zone. Littoral.

Remarks. This is the first record of Quadrivisio in Australian waters. It is most similar to Q. bengalenis Stebbing, 1907, in having robust setae on the inner margins of the telson. Quadrivisio sp.differs from that species in the shape of the basis of peraeopod 7 and in the shape of the palm of gnathopod 2. The antennae and rami of uropod 3 are generally less setose in Quadrivisio sp.

Distribution. Queensland: Armstrong Beach, near Sarina (AM).

Australian geographic areas. North-eastern Australia.

Pereon. Gnathopod 2 merus with sharp posteroventral tooth, or with subquadrate posteroventral corner; propodus without medial depression, defined by posteroventral corner or without posteroventral corner.

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'.