Mallacoota euroka, Lowry & Springthorpe, 2005

Lowry, JK & Springthorpe, RT, 2005, New and Little-known Melitid Amphipods from Australian Waters (Crustacea: Amphipoda: Melitidae), Records of the Australian Museum 57, pp. 237-302 : 260-261

Mallacoota euroka n.sp.

Figs. 20–22

Mallacoota subcarinata .–J.L. Barnard, 1972a: 247, fig. 144.– Barnard & Barnard, 1983: 632 (in part).

Type material. HOLOTYPE, ♂, 10.1 mm, AM P60561 ; 1 PARATYPE, ♀, AM P 60562 ; 8 PARATYPES, AM P27034 , between Troubridge Light and Cape Jervis , South Australia, [approx. 35°20'S 137°40'E], sponges on mud bottom, 20 m, D. Blake & H. Larsen, 14 March 1978 .

Type locality. Between Troubridge Light and Cape Jervis , South Australia, [approx. 35°20'S 137°40'E], sponge on mud bottom, 20 m.

Description. Based on holotype male, AM P60561 and paratype female, AM P60562.

Head. Lateral cephalic lobes broad, rounded, with anteroventral notch or slit, anteroventral corner rounded. Antenna 1 longer than antenna 2; peduncular article 1 subequal in length to article 2, with 4 or more robust setae along posterior margin; flagellum with about 29 articles; accessory flagellum with 3–4 articles. Antenna 2 peduncular article 2 cone gland reaching at least to end of peduncular article 3; article 4 longer than article 5, or article 4 subequal to article 5; flagellum with about 10 articles. Mandible palp article 3 rectolinear, with setae mostly terminal, longer than article 1; article 2 shorter than article 3; article 1 not produced, subequal to article 2, about twice as long as broad. Maxilla 1 inner plate with setae mainly terminal.

Pereon. Gnathopod 1 coxa anteroventral corner produced, rounded, posteroventral corner notch present; merus without posterodistal spine; propodus palm acute, convex, defined by posterodistal corner, without posterodistal robust setae. Gnathopod 2 sexually dimorphic; subchelate; coxa posteroventral corner notch present; merus with sharp posteroventral spine; carpus compressed; propodus without medial depression, with strong setal bunch, palm acute, straight, sculptured, with sparse robust setae and with group of anterodistal robust setae, without posterodistal robust setae, defined by posteroventral spine; dactylus apically blunt. Pereopod 5 basis posterior margin concave, posteroventral corner narrowly rounded or subquadrate. Pereopod 6 coxa anterior lobe ventral margin slightly produced, rounded; basis posterior margin concave, posteroventral corner narrowly rounded or subquadrate. Pereopod 7 basis posterior margin convex, with posterior margin smooth or minutely castelloserrate, posteroventral corner broadly rounded.

Pleon. Epimeron 1 posteroventral corner with small acute spine. Epimera 1–2 posteroventral margin without spines above posteroventral corner. Epimeron 3 posterior margin smooth, posteroventral corner with strongly produced acute spine. Urosomite 1 dorsally bicarinate. Urosomite 2 posterior margin smooth. Uropod 3 inner ramus subequal in length to outer ramus; outer ramus longer (1.2 to 2× length) than peduncle, 1-articulate. Telson each lobe with 3 or more apical/subapical robust setae, apical conical extension reaching scarcely one third along longest seta.

Female (sexually dimorphic characters). Gnathopod 2 carpus short; setose, smooth, without robust setae, defined by posterodistal robust setae, defined by posteroventral corner; dactylus apically acute/subacute.

Habitat. Marine; littoral; sponges on mud bottom, 20 m depth.

Etymology. Named for the schooner Euroka , built in Brisbane Waters and sunk off the Sandon River mouth, south of Clarence Head, New South Wales, in 1875.

Remarks. This species was originally described as Mallacoota subcarinata phenotype A by J.L. Barnard (1972a). It has a large posteroventral spine on epimeron 3, like M. subcarinata and M. diemenensis . Mallacoota euroka differs from M. diemenensis in having no dorsal spines on pleonites 1 to 3. It differs from M. subcarinata in the number of robust setae on the first peduncular article of antenna 1 (five in M. euroka and one to three in M. subcarinata ), in having posteroventral notches on coxae 1 and 2 and in having a convex posterior margin on the basis of pereopod 7.

Distribution. Victoria: Port Phillip (J.L. Barnard, 1972a). South Australia: Cape Jervis (AM).

Australian geographic areas. Southern Australia.