Photosella mucronata ( Pirlot, 1936 )

Lowry, J. K. & Stoddart, H. E., 2011, The tryphosine genera Photosella gen. nov. and Tryphosella Bonnier, 1893 (Crustacea: Amphipoda: Lysianassoidea: Lysianassidae: Tryphosinae) in Australian waters 2956, Zootaxa 2956 (1), pp. 1-76 : 12

Photosella mucronata ( Pirlot, 1936)

( Figs 5 , 6 )

Tmetonyx mucronatus Pirlot, 1936: 275 , fig. 108. —J.L. Barnard, 1958: 100. —J.L. Barnard, 1962: 30 (key).

Tryphosella mucronata . — Barnard & Karaman, 1991: 537.

Type locality. North-west of Waigeo Island , West New Guinea, Indonesia, 0°3'8''N 130°24'E, 141 m depth .

Material examined. All stations are north-west of Port Hedland, North West Shelf, Western Australia and were collected by the CSIRO on FRV Soela. 1 female and 1 male, AM P.71828, 19°56.8'S 117°53.4'E to 19°56.4'S 117°53.7'E, 42 m, beam trawl, 22 April 1983, stn NWS 02.B2.BT ; 6 specimens, AM P.71829, 19°56.9'S 117°53.7'E to 19°56.4'S 117°53.8'E, 42–43 m, epibenthic sled, 22 April 1983, stn NWS 02.B2.S ; 1 specimen, AM P.71830, 19°05.4'S 118°53.3'E to 19°05.428.2'S 118°54.1'E, 82 m, epibenthic sled, 27 April 1983, stn NWS 02.B4.S; 1 ovigerous female, AM P.71831, 19°56.4'S 117°53.9'E to 19°56.8'S 117°53.6'E, 44 m, epibenthic sled, 25 June 1983, stn NWS 03.B2.S ; 3 specimens, AM P.71832, 19°56.8'S 117°53.5'E to 19°56.4'S 117°53.9'E, 44 m, beam trawl, 25 June 1983, stn NWS 03.B2.BT ; 1 male, AM P.71833, 19°56.6'S 117°54.1'E to 19°56.3'S 117°53.9'E, 44 m, beam trawl, 26 August 1983, stn NWS 04.B2.BT ; 1 male, AM P.71834, 19°56.7'S 117°53.6'E to 19°56.4'S 117°54.0'E, 41 m, epibenthic sled, 26 October 1983, stn NWS 05.B2.S ; 1 male, AM P.71835, 19°29.7'S 118°52.0'E to 19°29.4'S 118°52.5'E, 39 m, epibenthic sled, 25 October 1983, stn NWS 05.D3.S ; 1 female, AM P.71836, 19°29.6'S 118°51.7'E to 19°29.9'S 118°51.0'E, 40–41 m, epibenthic sled, 25 October 1983, stn NWS 05.D7.S ; 1 male, AM P.71837, 19°04.1'S 118°47.8'E to 19°04.7'S 118°47.2'E, 82 m, beam trawl, 23 October 1983, stn NWS 05.B10.BT .

Diagnostic description. Head lateral cephalic lobe subtriangular, apically rounded; eyes (fading in alcohol), large, subtriangular with ventral concave lens. Antenna 1 flagellum with strong 2-field callynophore, robust setae absent from proximal articles; calceoli absent. Antenna 2 peduncular articles 4 and 5 not enlarged; flagellum short, calceoli absent. Epistome/Upper lip epistome less produced than upper lip, straight. Mandible molar with asymmetrically reduced column, proximally setose, distally triturating. Maxilla 1 setal-tooth 7, left and right symmetrical, cuspidate along most of straight inner margin; palp distal margin with apical robust setae. Maxilliped outer plate with 2 short apical robust setae.

Gnathopod 1 subchelate; coxa large (length 1.9 x breadth), subrectangular, distally subovate; basis moderately setose along anterior margin; ischium short (length 1.6 x breadth); carpus long (length 2 x breadth), shorter than propodus, without posterior lobe; propodus margins subparallel, palm moderately acute. Gnathopod 2 propodus palm moderately obtuse. Pereopod 4 coxa without distinct lateral ridge. Pereopod 5 coxa with distinct lateral ridge; basis about as long as broad, with photophore.

Epimeron 3 posterior margin smooth, posteroventral corner broadly rounded. Uropod 3 outer ramus article 2 short, with plumose setae on both rami. Telson deeply cleft, with dorsal robust setae, with 2 to 3 apical robust setae on each lobe.

Male (sexually dimorphic characters). Antennae 1 and 2 calceoli present. Antenna 2 peduncular articles 4 and 5 enlarged.

Remarks. When Pirlot first described this species he recognised its similarity to the species now known as Photosella miersi but noted the lack of a ridge on coxa 5 of Stebbing's species. Photosella mucronata differs from P. miersi in having a ridge on the coxa of pereopod 5. In Australia it is currently known only from the North West Shelf of Western Australia.

Distribution. Eastern Indonesia and north-western Australia, 39–141 m depth.

Figures

FIGURE 5. Photosella mucronata (Pirlot, 1936). Female, 14.2 mm, AM P.71831; male, 15.2 mm, AM P.71834; North West Shelf. Scales for A1, A2 represent 0.5 mm; remainder represent 0.2 mm.

FIGURE 6. Photosella mucronata (Pirlot, 1936). Female, 14.2 mm, AM P.71831, North West Shelf. Scales represent 0.5 mm.