Corophium colo, Lowry, J. K., 2004

Lowry, J. K., 2004, A new species of Corophium from eastern Australian estuaries (Crustacea: Amphipoda: Corophiidae: Corophiinae: Corophiini), Zootaxa 754, pp. 1-10 : 2-7

Corophium colo sp. nov.

Corophium cf. volutator . — Jones, Watson­Russell & Murray, 1986: 531, table 1, appendix 1. — Jones, 1987: 615, table 3, appendix 1.

Corophium sp. — Surtikanti et al., 1998: 85. —Hyne & Everett, 1998: 26. — Hyne, 1999: 94. — Surtikanti & Hyne, 2000: 11. — MacFarlane & Booth, 2001: table 2. — Hyne et al., 2002: 30. —McCready, 2004: ch. 4, p. 2. —McCready et al., 2004: 53.

Type material. Holotype male “a”, 11.7 mm, AM P67529. Paratypes: female “b”, 9.6 mm, AM P67534; 3 females, 2 males, 3 juveniles, AM P35139; all about 200 m from Sentry Box Reach, Hawkesbury River, New South Wales (33°29'S 151°04'E), 9 January 1977, 18 m depth, clay; 2 females, 1 male, 9 juveniles, AM P47696, Upper Mangrove, Hawkesbury River, New South Wales (33°21'S 150°03.30'E), 4 February 1996, silty mud; 31 females, 26 males, 35 juveniles, AM P47694, Colo River, New South Wales (33°26'S 150°51.30'E), 1995.

Other material examined. 1 female, QM W5694, 12.5 km from mouth, north bank of Logon River, Queensland (27°41'S 153°13'E), 10 June 1974. 8 females, NMV J18302 , Port Franklin, Victoria (38°41'S 146°16'E), 21 November 1983, low tide mark, mud, mangroves.

Diagnosis. Head rostrum subacute in male, acute in female. Antenna 1 peduncular article 1 with many setae. Antenna 2 peduncular article 4 without spine near middle of article, male with 1 large and 1 small posterodistal spine, female with 1 posterodistal spine. Urosomites 1–3 separate. Uropod 1 peduncle with broadly triangular distoventral spur. Uropod 2 peduncle without distoventral spur. Uropod 3 peduncle broader distally, ramus ovate.

Description. Male Holotype. Head rostrum present, subacute, length about 0.5 x head; lateral cephalic lobes rounded; eyes well developed. Antenna 1 peduncular article 1 without plumose setae, length 1.3 x peduncular article 2, posterior margin with slight proximal bulge, smooth, with many setae, without teeth, with 1 robust seta, medial margin not expanded, smooth, with many simple setae, lateral margin without robust setae; peduncular article 2 posterior margin without robust setae, without posterior flange; flagellum of about 16 articles, aesthetascs short. Antenna 2 peduncular article 2, gland cone well developed, without robust setae; peduncular article 3 almost square, without posterior robust setae, without processes, anterior margin without robust setae; peduncular article 4, length about 3 x height; anterior margin very setose, without robust setae, medial margin without robust setae, posterior margin setose, without processes, without posterior robust setae, with 1 large and 1 small posterodistal tooth; peduncular article 5 without crenulate flange, posterior margin without robust setae, with many long simple setae, without processes; flagellum of 3 articles, posterior margin of flagellar article 1 with many long setae, without processes, flagellar article 3 without processes, posterior margin of flagellar articles without robust setae, tip of the flagellum without very long setae. Mandibular palp lower distal process on article 2 strongly produced.

Gnathopod 1 coxa with 3 plumose setae; propodus length 2.6 x width; palmar margin of propodus nearly transverse, convex, with about 9 robust setae; dactylus extending to corner of palm. Gnathopod 2 basis without acute tooth; merus subequal in length to basis; carpus distinctly shorter than basis; dactylus posterior margin with 4 robust setae. Pereopod 3 basis rectangular; merus broader distally; propodus length about 2.8 x width; basis and merus anterior margins with long, plumose setae; carpus length about 1.2 x width; carpus and propodus anterior margins without long plumose setae; dactylus shorter than carpus and propodus combined. Pereopod 4 carpus and propodus anterior margins without long plumose setae. Pereopod 5 basis and merus with few plumose setae. Pereopod 6 posterior margin of basis lined with long, plumose setae; merus without plumose setae. Pereopod 7 basis length about 1.5 x width, longest plumose seta distinctly shorter than basis; carpus not protuberant medially, length about 4 x width; propodus about 3.5 x length of dactylus.

Pleopod 1 peduncle with 8 plumose setae. Urosomites 1–3 separate; posterior margins without robust setae; lacking distinct lateral marginal ridge. Uropod 1 peduncle with broadly triangular distoventral spur, with subacute distolateral process, 6 robust setae on medial margin, without simple setae on lateral margin, with 5 robust setae on lateral margin, not confined to distal half, without robust setae on the dorsal surface; rami with apical robust seta not differing in size. Uropod 2 peduncle without distoventral spur, without lateral and dorsal robust setae; outer ramus with 4 robust setae on lateral edge, without robust setae on medial edge, and 3 apical robust setae; inner ramus with 4 robust setae on lateral edge, without robust setae on medial edge, and 1 apical robust setae. Uropod 3 peduncle broader distally, without robust setae, without plumose setae; ramus subequal in length to peduncle, ovate, length subequal to width, without robust setae. Telson with 1 lateral recurved spine on each side.

Female (sexually dimorphic characters). Paratype “b”. Head rostrum acute, length 0.3 x head. Antenna 1 peduncular article 1 with a few plumose setae; medial margin with 2–3 robust setae. Antenna 2 gland cone with 1 robust seta; article 3 with 2 posterior robust setae; article 4 length about 2.5 x height, with 5 single robust setae along posterior margin, with 1 posterodistal spine with 2 robust setae; article 5 posterior margin with 1 robust seta, with a distal acute process.

Habitat. Fresh water and estuarine. Substrate silty mud and clay. Depth range intertidal to shallow subtidal.

Remarks. Corophium colo is the only known species in Australian waters with an unfused urosome. It shows similarities to Corophium intermedium Dang, 1965 an estuarine and freshwater species from Vietnam, but in C. colo the antennae are more setose and the uropod 1 peduncle has significantly more robust setae.

Specimens of Corophium colo from brackish water in the Hawkesbury River and from Nooramunga, Corner Inlet are larger than specimens from fresh water rivers such as the Colo .

Distribution. Logon River, Queensland; Colo River and Hawkesbury River New South Wales; Corner Inlet, Victoria.