Aristias eden, Stoddart & Lowry, 2010

Stoddart, H. E. & Lowry, J. K., 2010, The family Aristiidae (Crustacea: Amphipoda: Lysianassoidea) in Australian waters, Zootaxa 2549 (1), pp. 31-53 : 32-35

Aristias eden sp. nov.

( Figs 1–3 )

Type material. HOLOTYPE, female with nonsetose oostegites, 4.5 mm, AM P.71815, south-east of Eden , New South Wales, Australia, 37°22’S 150°18’E to 37°14’S 150°19’E, 157 m, 29 October 1979, FRV Kapala , stn K79-17-17 . PARATYPES: male, AM P.71818, same data as holotype; 5 specimens, MV J59366 , south of Point Hicks , Victoria, Australia, 38°21.90'S 149°20.00'E, 1000 m, WHOI epibenthic sled, 23 July 1986, G.C.B. Poore et al., RV Franklin , stn SLOPE 32 ; 3 specimens, MV J59367 and 1 female, 3.0 mm, AM P.81158, south of Point Hicks , Victoria, Australia, 38°19.60'S 149°24.30'E, 930 m, rock, rubble, clay, sand, biogenic sediment, WHOI epibenthic sled, 23 July 1986, M.F. Gomon et al., RV Franklin , stn SLOPE 33 ; 1 female, MV J59368 , off Freycinet Peninsula , Tasmania, Australia, 41°58.60'S 148°38.80'E, 500 m, coarse shell, WHOI epibenthic sled, 27 July 1986, M.F. Gomon et al., RV Franklin , stn SLOPE 47 ; 2 specimens, MV J59369 , off Freycinet Peninsula , Tasmania, Australia, 41°57.50'S 148°37.90'E, 400 m, coarse shell, WHOI epibenthic sled, 27 July 1986, M.F. Gomon et al., RV Franklin , stn SLOPE 48 .

Additional material. Female with nonsetose oostegites, 4.5 mm, MV J59370 , south of Point Hicks , Victoria, Australia, 38°17.70'S 149°11.30'E, 400 m, coarse sand, gravel, mud, many sponges, WHOI epibenthic sled, 24 July 1986, M.F. Gomon et al., RV Franklin , stn SLOPE 40 ; 4 specimens, MV J59371 , and 5 specimens, AM P.71820, 44 km east of Nowra , New South Wales, Australia, 34°55.79'S 151°08.06'E, 429 m, muddy coarse shell, WHOI epibenthic sled, 22 October 1988, G.C.B. Poore et al., RV Franklin , stn SLOPE 56 ; 1 male, 3.4 mm, MV J11251 , 51 km south-south-west of Cape Otway , Victoria, western Bass Strait, Australia, 39°16'S 143°17'E, 90 m, medium sand, 10 October 1980, G.C.B. Poore, HMAS Kimbla , stn BSS- 73 .

Type locality. South-east of Eden , New South Wales, Australia, 37°22’S 150°18’E to 37°14’S 150°19’E, 157 m depth.

Etymology. The species is named for its type locality.

Diagnostic description. Head lateral cephalic lobe broadly triangular, apically blunt; eyes well developed, oval to round. Antenna 1 accessory flagellum 2-articulate. Antenna 2 calceoli not present in male. Epistome and upper lip with central notch. Mandible lacinia mobilis present on left mandible; molar a weakly setose flap. Maxilla 1 inner plate with 4 pappose setae along inner margin; outer plate with 10 setalteeth in an 8/2 arrangement, most with moderate number of cusps. Maxilliped palp 4-articulate, palp article 1 with lateral and medial margins about same length.

Gnathopod 1 parachelate; carpus shorter than propodus, without posterodistal lobe; propodus posterior margin dentate, with 3 robust setae along posterior margin. Gnathopod 2 carpus longer than propodus. Pereopods 5–7 propodus with anterodistal spur. Pereopod 5 coxa posterior lobe deeper than anterior lobe, long, triangular; basis moderately expanded posteriorly, with posteroventral lobe. Pereopod 6 coxa posterior lobe deeper than anterior lobe, long, triangular; basis greatly expanded posteriorly, with posteroventral lobe. Pereopod 7 basis greatly expanded posteriorly, posterior margin evenly curved, with posteroventral lobe, posteroventral corner rounded.

Epimeron 3 posterior margin smooth, posteroventral corner subacute. Urosomite 1 smooth dorsally, without a dorsodistal boss. Urosomite 3 without dorsolateral flanges. Uropod 3 rami with robust setae only on apices of outer ramus article 1; inner ramus longer than article 1 of outer ramus. Telson longer than broad, moderately cleft, without mid-dorsal robust setae, lateral margins curved, uniformly tapering distally, without robust setae on lateral margins, with 1 apical robust seta on each lobe.

Remarks. Aristias eden is very similar to A. tumidus from the boreal North Atlantic and North Pacific Oceans. Both species have cusps on the maxilla 1 setal-teeth and very similar arrangement of the 9 to 10 setal teeth; pereopods 5–7 with a spur on the propodus; pereopod 7 with the posterior margin of the basis evenly rounded; and a moderately cleft telson. Aristias uokonia from New Caledonia shares most of these characters, but has 13 setal-teeth on maxilla 1. Aristias eden can be distinguished from A. tumidus by: lateral cephalic lobe broadly triangular (rounded in A. tumidus ); gnathopod 1 carpus shorter than propodus (longer than propodus in A. tumidus ) and uropod 3 inner ramus longer than article 1 of outer ramus (shorter in A. tumidus )

The specimens from stations BSS-73, SLOPE 40 and SLOPE 48 have a rounder, more distinct and darker eye than the other material but are otherwise indistinguishable.

Distribution. South-eastern Australia in 157–1000 m depth.

Figures

FIGURE 1. Aristias eden sp. nov. Paratype, female, 3.0 mm, AM P.81158.

FIGURE 2. Aristias eden sp. nov. Holotype, female, 4.5 mm, AM P.71815. Scales represent 0.1 mm.

FIGURE 3. Aristias eden sp. nov. Holotype, female, 4.5 mm, AM P.71815. Scales represent 0.1 mm.