Cerapus lowryi, Berents, 2023

Berents, Penelope B., 2023, New Species of Cerapus from Australian Waters (Amphipoda: Senticaudata: Ischyroceridae), Records of the Australian Museum (Rec. Aust. Mus.) 75 (4), pp. 381-403 : 395-399

Cerapus lowryi sp. nov.

urn:lsid:zoobank.org:act:A7DA6C97-A751-483E-A82B-3137D838C12D

Figs 14–18

Holotype: Male, 7.2 mm, AM P.51212, east of Port Jackson , New South Wales, Australia, 33°52'S 151°23'E, mud, epibenthic sled, 80 m, FRV Kapala , K 80-20-11, R. T. Springthorpe, 11 December 1980. Paratypes: 1 male, 4.9 mm, AM P.106369; 1 male, 3.8 mm, AM P.106370; 1 male 6.1 mm, AM P.106371; 1 female, 5.1 mm; AM P.51213; all same data as holotype. 1 male, 6.5 mm, AM P.18116; 1 male 5.4 mm, AM P.106366; 2 females, AM P.106367, Bass Strait, Victoria, Australia, 39°S 148°30'E, 126 m, Esso-Gippsland st. 19, C. Phipps, 7 – 9 May 1969.

Additional material examined. 15 specimens, AM P.106373; 1 male AM P.106372; same data as holotype. 1 male, AM P.2525, 3 – 4 km off Botany Bay, New South Wales, Australia, 34°5'S 151°15'E, mud, 91 – 95 m, HMCS “Thetis”, st. 37, E. R. Waite, 11 March 1898; 1 male, 1 female, AM P.106368, 9 – 12 km off Cape Three Points,New South Wales,Australia, 33°32'S 151°32'30"E, sticky mud & shell, 75 – 91 m, HMCS “Thetis”, st.13, E. R. Waite, 25 February 1898; 1 male,AM P.106374, southeast of Broken Bay, New South Wales,Australia, 33°36'S 151°30'E, trawl, 71 – 75 m, FRV “ Kapala ”, 10 February 1986, K86-01-02; 1 male,AM P.106375, east of Port Jackson, New South Wales,Australia, 33°50'S 151°32'E, trawl, 132 – 135 m, FRV “ Kapala ”, K85-21-01, J. K. Lowry & R.T.Springthorpe, 18 December 1985; 6 specimens, AM P.106376, east of Newcastle, New South Wales, Australia, 32°53'S 152°35'E, bottom tow with plankton net, 146 – 165 m, FRV “ Kapala ”, K85-12-23, 15 August 1985; 1 male, AM P.22508, east of Malabar, New South Wales,Australia, 33°58'S 151°16'E, 32 m, Australian Museum Shelf Benthic Survey, 1973; 1 female,AM P.22507, 1 km east of Magic Point, New South Wales,Australia, 33°57'40"S 151°16'10"E, 31 m, Australian Museum Shelf Benthic Survey, Shipek Collection pt. D, 17 May 1972; 1 female ovigerous, 3.4 mm, AM P.22502, east of North Head, New South Wales, Australia, 33°49'S 151°18'E, on sponge Polymastia craticia Hallman, 1912 , 26 m, Australian Shelf Benthic Survey, transect 7, 26 February 1974; many specimens, MV J.75818, 85 km north-east of North Point, Flinders Island, eastern Bass Strait, Tasmania,Australia, 39°02'24"S 148°30'36"E, dredge, 121 m, stn 169D, R. S. Wilson, 15 November 1981; 7 specimens, MV J.75817, 45 km north-east of North Point, Flinders Island, eastern Bass Strait, Tasmania, Australia, 39°31'48"S 148°24'25"E, Smith-McIntyre grab, 40 m, BSS 168G, R. S. Wilson, 15 November 1981; many specimens, MV J.75816, 85 km north-east of North Point, Flinders Island, eastern Bass Strait, Tasmania, Australia, 39°02'24"S 148°30'36"E, Smith-McIntyre grab, 121 m, stn 169G, R. S. Wilson, 15 November 1981.

Type locality. East of Port Jackson, New South Wales, Australia, 33°52'S 151°23'E.

Etymology. Named for Dr Jim Lowry, mentor, colleague, and friend, in recognition of his immense contribution to the study of the Amphipoda .

Description. Male (based on holotype, 7.2 mm, AM P.51212).

Head. Rostrum long, length 0.3 × head, evenly tapered, apically acute; lateral cephalic lobe with ventral corner acute, subocular margin deeply recessed, reaching beyond eye, anteroventral corner subquadrate, ventral margin horizontal, posterior margin sloping. Antenna 1 long, length 0.5 × body length; peduncle with scales; peduncular article 1 shorter than article 3, length 0.7 × peduncular article 3 not produced anterodistally and anteromedially, with strong sub-quadrate projection along posterior margin, posterodistal corner not produced; peduncular article 2 anterodistal corner without distal projection; flagellum 5-articulate; article 1 short. Antenna 2 length 0.7 × antenna 1; flagellum 5-articulate.

Pereon. Pereonite 1 with lateral keel, without sternal keel. Pereonite 2 with sternal keel. Pereonite 3 without sternal keel. Pereonite 5 length 1.6 × depth.

Gnathopod 1 coxa not fused to pereonite 1, length 1.9 × depth, without anteroventral lobe; basis length 2.1 × depth; carpus very broad, length 1.6 × depth with setose posterior lobe; propodus palm extremely acute, robust setae absent. Gnathopod 2 carpochelate; coxa not fused to pereonite 2, length 2.6 × depth, with a strongly produced anteroventral lobe; basis short, broad, length 1.4 × breadth, without anteroproximal group of long slender setae; carpus long, length 1.6 × breadth, broad, posterior margin with small spine, palm deeply excavate, anterodistal tooth extremely produced, located near articulation with propodus, posterodistal tooth well defined, medium length, length 1.4 × width; propodus slender, strongly curved, length 5.6 × width, without tooth on posterior margin, posterodistal corner smooth, without teeth; dactylus, length 0.5 × propodus.

Pereopod 3 coxa with narrow anteroventral lobe, not fused to pereonite 3, length 1.9 × depth; basis, length 1.6 × breadth, evenly rounded, with plumose setal group and simple setae along anterior margin, with patches of denticles along medial surface; ischium long, length 2.5 × breadth; merus length 1.1 × breadth, short; without ridges. Pereopod 4 coxa not fused to pereonite 4, with anterior lobe separated from several small anteroventral lobes; basis length 1.6 × breadth, with plumose setae along entire anterior margin; ischium long, length 3.1 × breadth; merus very long, length 2.2 × breadth. Pereopod 5 coxa, length 1.5 × depth, without patches of small setae, with setae along ventral margin; merus with anterior lobe not extending beyond anterior margin of carpus, posterior lobe with 1 plumose seta; propodus with 2 setae along posterior margin; dactylus short, uncinate with 1 accessory hook.

Pereopod 6 coxa with setal fringe ventrally, without patches of small setae near margins; basis with patch of small setae near anterior margin; merus, length 1.8 × breadth; dactylus short, uncinate, with 1 accessory hook. Pereopod 7 coxa without posterodorsal lobe, with patch of small setae; merus length 2.3 × breadth; dactylus, short, uncinate, with 1 accessory hook.

Pleon. Pleopods 1–3 biramous, decreasing in size. Pleopod 1 inner ramus 7-articulate; outer ramus 5-articulate, article 1 evenly swollen; Pleopod 2 inner ramus reduced, 1-articulate; outer ramus, broad, 1-articulate. Pleopod 3 inner ramus reduced, 1-articulate; outer ramus broad, 1-articulate. Uropod 1 biramous; peduncle, length 1.4 × outer ramus; rami with distoventral fan of robust setae; outer ramus with lateral row of denticles, without medial setae, with 10 lateral setae, with large apical robust seta, without smaller slender setae; inner ramus, length 0.8 × outer ramus, medial setae absent, with 8 lateral setae, with large apical robust seta. Uropod 2 uniramous, peduncle, length 3.2 × breadth, 4.1 × length of ramus; ramus small with 6 denticles and 1 slender apical seta. Uropod 3 uniramous, peduncle length 1.9 × breadth; ramus with 2 curved hooks. Telson broader than long, length 0.4 × breadth, cleft to base, each lobe with 28–29 anteriorly directed recurved spines in 2 rows.

Female (sexually dimorphic characters). Based on paratype female, 5.1 mm, AM P.51213. Antenna 1 peduncle without scales; flagellum 2-articulate. Antenna 2 flagellum 2-articulate. Pereonite 1 without lateral keel. Pereonites 1, 2, 3 without sternal keel. Pereonite 5 length 1.7 × depth. Gnathopod 1 coxa, length 1.7 × depth; basis length 1.9 × depth; carpus, length equal to depth with setose posterior lobe. Gnathopod 2 subchelate; coxa length 1.9 × depth with short anteroventral lobe; basis length 1.1 × depth, with medial line of setae; palm extremely acute. Pereopod 5 coxa, length twice depth. Oostegites from gnathopod 2 to pereopod 5.

Tube. Long slender tube composed of fine grey sediment and detritus.

Habitat. Marine, 26–165 m.

Remarks. Cerapus lowryi and C. chiltoni are the only Australian species of Cerapus with a strongly produced anteroventral lobe on coxa 2. In C. lowryi the lobe becomes more produced in mature males. Cerapus lowryi differs from C. chiltoni in having a long rostrum and in the shape of the palm of gnathopod 2, which is deeply excavate in both, but narrow in C. chiltoni and wide in C. lowryi with the posterodistal tooth long in C. chiltoni and medium length in C. lowryi . The second gnathopod of C. lowryi also changes as males mature. The propodus becomes more curved and elongate in males greater than 7 mm in length. The carpus also becomes elongate with the ratio of length to width changing from 1:1.3 in males 3 mm to 6 mm in length, to 1:1.6 in males greater than 7 mm in length. Cerapus lowryi is the only Australian species with a very broad lobe on the carpus of gnathopod 1 in the male. Pereopod 3 is dimorphic in C. lowryi with all articles except the ischium bearing more setae in the female than the male. The basis of pereopod 7 has a patch of setae, which is unique to C. lowryi and C. yuyatalay .

Distribution. Bass Strait, Tasmania to east of Cape Three Points, New South Wales.