Stephonyx arabiensis Diffenthal & Horton, 2007

Lowry, J. K. & Kilgallen, N. M., 2014, A generic review of the lysianassoid family Uristidae and descriptions of new taxa from Australian waters (Crustacea, Amphipoda, Uristidae), Zootaxa 3867 (1), pp. 1-92 : 63-66

Stephonyx arabiensis Diffenthal & Horton, 2007

( Figs 40–41 )

Stephonyx arabiensis Diffenthal & Horton, 2007: 33 , figs 1–4.— Narahara et al., 2012: 1505 (key).— Corrigan et al., 2013: fig. 5.

Types. Holotype female, 26.7 mm, NHM 2007.799. Paratypes: male, 24.9 mm, NHM 2007.800; 6 large mature females, NHM 2007.801–806; 31 males, NHM 2007.807–816; 14 immature females, NHM 2007.817–826; 14 juveniles, NHM 2007.827–836.

Type locality. Off the coast of Pakistan in the northern Arabian Sea (22º51.067'N 65º59.916'E), 1864 m depth, mean bottom temperature = 3.53ºC .

Material examined. New South Wales. 1 specimen, AM P.96589, northeast of Coffs Harbour (30º10.88’S 153º32.22’E), 1000 m, baited trap, 12–13 August 1993, P.B Berents & R. T . Springthorpe , MV Cheryl Lee [NSW-877] ; 2 specimens, AM P.96590, off Wollongong (34º32.4’S 151º22.8’E), 1000 m, baited trap, 28–29 March 1994, J.K. Lowry & K. Dempsey, MV Robin E [NSW-972]; 4 specimens, AM P.96591, off Wollongong (34º32.4’S 151º22.8’E), 1000 m, baited trap, 28–29 March 1994, J.K. Lowry & K. Dempsey, MV Robin E [NSW-971]; 7 specimens, AM P.96592, off Wollongong (34º32.4’S 151º22.8’E), 1000 m, baited trap, 28–29 March 1994, J.K. Lowry & K. Dempsey, MV Robin E [NSW-973]; 7 juveniles, AM P.48101, north-east of Coffs Harbour (30°10.93’S 153°32.26’E), 963 m, baited trap, 11–12 August 1993, P.B. Berents, R. T . Springthorpe & W. Vader, MV Cheryl Lee [NSW-862] ; 2 specimens, AM P.52661; 2 specimens, AM P.49815, north-east of Coffs Harbour (30°10.88’S 153°32.22’E), 1000 m, baited trap, 12–13 August 1993, P.B. Berents, R. T . Springthorpe & W. Vader, MV Cheryl Lee [NSW-876] ; 1 specimen, AM P.43430, off Wollongong (34°32.4’S 151°22.8’E), 1000 m, baited trap, muddy sand, 27–28 March 1994, J.K. Lowry & K. Dempsey, MV Robin E [NSW-953]; 9 specimens, AM P.43496, off Wollongong (34°32.4’S 151°22.8’E), 1000 m, baited trap, Globigerina ooze, 27–28 March 1994, J.K. Lowry & K. Dempsey, MV Robin E [NSW-954]; 3 specimens, AM P.43446, off Wollongong (34°32.4’S 151°22.8’E), 1000 m, baited trap, 28–29 March 1994, J.K. Lowry & K. Dempsey, MV Robin E [NSW-971]; 15 specimens, AM P.43372, north-east of Coffs Harbour (30°10.93’S 153°32.26’E), 1000 m, baited trap, Globigerina ooze, 8–9 September 1994, J.K. Lowry & K. Dempsey, MV Carrie Ann [NSW-1000] ; 1 specimen, AM P.50071, north-east of Coffs Harbour (30°10.93’S 153°32.26’E), 1000 m, baited trap, 9–10 September 1994, J.K. Lowry & K. Dempsey, MV Carrie Anne [NSW-1021] ; 6 specimens, AM P.50080, north-east of Coffs Harbour (30°10.93’S 153°32.26’E), 1000 m, baited trap, 9–10 September 1994, J.K. Lowry & K. Dempsey, MV Carrie Ann [NSW-1022] .

Queensland. Male 22.7 mm, AM P.96587, 2 specimens, 8.1–12.5 mm, AM P.96588, east of Flynn Reef, Queensland, Australia (16º37.82’S 146º23.08’E), 1000 m, baited trap, 6–7 June 1993, J.K. Lowry & P. Freewater, RV Sunbird [QLD-931]; 30 specimens, AM P.96593, off Flynn Reef (16º37’S 146º23’E), 1000 m, baited trap, 7–8 June 1993, J.K. Lowry & P. Freewater, RV Sunbird [QLD-950]; 6 specimens, AM P.50235, east of Flynn Reef (16°37.82’S 146°23.08’E), 1000 m, baited trap, 6–7 June 1993, J.K. Lowry, P. Freewater & W. Vader, RV Sunbird [QLD-931/ SEAS]; 6 specimens, AM P.50244; 4 specimens, AM P.57607, east of Flynn Reef (16°37.82’S 146°23.08’E), 1000 m, baited trap, 6–7 June 1993, J.K. Lowry, P. Freewater & W. Vader, RV Sunbird [QLD-932/ SEAS]; 11 specimens, AM P.50297; 3 specimens, AM P.57614, east of Flynn Reef (16°37.82’S 146°23.08’E), 1000 m, baited trap, 7–8 June 1993, J.K. Lowry, P. Freewater & W. Vader, RV Sunbird [QLD-949/ SEAS]; 3 specimens, AM P.58069, east of Flynn Reef (16°37.82’S 146°23.08’E), 1000 m, baited trap, 7–8 June 1993, J.K. Lowry, P. Freewater & W. Vader, RV Sunbird [QLD-950/ SEAS]; 2 specimens, AM P.57611; 2 specimens, AM P.49520, east of Flynn Reef (16°37.82’S 146°23.08’E), 1000 m, baited trap, 7–8 June 1993, J.K. Lowry, P. Freewater & W. Vader, RV Sunbird [QLD-948/ SEAS]; 6 specimens, AM P.47889, due east of Mooloolaba (26°36.23’S 153°50.23’E), 1006 m, baited trap, 2–3 August 1994, J.K. Lowry & K. Dempsey, MV Capricorn I [QLD-1140] .

Tasmania. Many specimens, AM P.73709, Hill V, south-southeast of South East Cape (44°23.6’S 147°10.7’E), 1400 m, baited trap, 30 January 1997, CSIRO party on FRV Southern Surveyor , [SS01/97/61] .

Description. Based on male, 22.7 mm, AM P.96587. Head, lateral cephalic lobe subtriangular, apically subacute. Antenna 1 peduncular article 1 without anterodistal lobe; accessory flagellum not forming cap, 8- articulate, terminal article not offset; primary flagellum with strong 2-field callynophore; calceoli absent. Antenna 2 peduncular article 3 short; articles 3 to 5 not enlarged, brush setae present; calceoli present. Labrum, epistome and upper lip separate, with weak suture; epistome broadly rounded; upper lip produced, subacute apically. Mandible molar setose with vestigial triturating surface; palp attached about midway, article 2 not strongly broadened distally, article 3 blade-like. Maxilla 1 outer plate setal-tooth 7 present, cuspidate along most of straight inner margin; palp distal margin with apical robust setae. Maxilliped outer plate with 9 apical robust setae.

Gnathopod 1 chelate; coxa reduced, significantly shorter than coxa 2, subquadrate; basis moderately setose along anterior margin, or sparsely setose along anterior margin; ischium very long (length 4 × to 6 × breadth); carpus very long (length more than 4 × breadth), subequal in length to propodus, without posterior lobe; propodus margins subparallel, palm obtuse, entire, slightly concave; dactylus simple. Gnathopod 2 propodus palm transverse, slightly concave. Pereopod 4 coxa with a well-developed posteroventral lobe. Pereopod 5 coxa without distinct lateral ridge; basis broader than long, posterior margin not serrate. Pereopod 7 basis posterodistally produced less than halfway along merus.

Pleonite 3 without mid-dorsal carina, not produced dorsodistally, posterodorsal margin not produced. Epimeron 3 posterior margin smooth, posteroventral corner subquadrate, producing minute spine. Urosomite 1 not projecting over urosomite 2, with anterodorsal notch and slightly rounded boss. Uropod 2 inner ramus without constriction. Uropod 3 peduncle without dorsolateral flange; outer ramus article 2 short, with strong plumose setae on both rami. Telson deeply cleft , with 1 apical robust setae on each lobe.

Habitat. Marine.

Feeding strategies. Scavenger ( Diffenthal & Horton 2007).

Depth range. 963 – 1864 m.

Remarks. Our material agrees very well with the description of Diffenthal & Horton (2007). This is the first record of S. arabiensis outside the type locality in the Arabian Sea. This remarkable range extension from the north-western Indian Ocean into the South Pacific Ocean indicates a wide range for the species. There is no other species of Stephonyx known from this vast area except for the S. biscayensis of J.L. Barnard (1961) and Ledoyer (1986) from Kenya and Madagascar, which appears to be an undescribed species (see remarks under S. biscayensis ).

Distribution. Australia. Off the east coast from Flynn Reef, Queensland, to South East Cape, Tasmania (this study). Pakistan. Northern Arabian Sea ( Diffenthal & Horton 2007).

Figures

FIGURE 40. Stephonyx arabiensis Diffenthal & Horton, 2007, male, 22.7 mm, AM P. 96587, from east of Flynn Reef, Queensland, Australia. Scale bars: 0.5 mm.

FIGURE 41. Stephonyx arabiensis Diffenthal & Horton, 2007, male, 22.7 mm, AM P. 96587, from east of Flynn Reef, Queensland, Australia. Scale bars: 0.5 mm.