Lepidepecreoides stoddartae, Hughes, 2020

Hughes, Lauren Elizabeth, 2020, Lepidepecreoides stoddartae sp. nov. from the Falkland Islands (Amphipoda: Tryphosidae), Zootaxa 4816 (1), pp. 108-114 : 109-113

Lepidepecreoides stoddartae sp. nov.

( Figs 1 , 2 )

Type material. Holotype female, dissected, 11.0 mm, NHMUK 2018.903 , North Falkland Basin , Falkland Islands, South West Atlantic (49°21’31.701”S, 59°8’21.478”W), 341 m, Brown silty clay occasional pebble, 24 December 2012, Box Corer, RRS Ernest Shackleton, Sea Lion Field Development Environmental Baseline Survey (43 MFC) . Paratypes: 1 specimen unsexed, 7.1 mm, NHMUK 2018.755 , North Falkland Basin , Falkland Islands, South West Atlantic (49°21’29.380”S, 59°3’24.061”W), 434 m, Brown silty clay occasional pebble, 14 April 2012, Box Cor- er, RRS Ernest Shackleton, Sea Lion Field Development Environmental Baseline Survey (46 MFB); 3 gravid female specimens, all 10 mm, NHMUK 2018.899 , North Falkland Basin , Falkland Islands, South West Atlantic (49°19’21.438”S, 59°6’44.668”W), 450 m, Brown silty clay occasional pebble, 15 April 2012, Box Corer, RRS Ernest Shackleton, Sea Lion Field Development Environmental Baseline Survey (33 MFC) ; 1 juvenile specimen, 5.0 mm, NHMUK 2018.900 , North Falkland Basin , Falkland Islands, South West Atlantic (49°20’27.670”S, 59°10’1.713”W), 436 m, Brown silty clay occasional pebble, 15 April 2012, Box Corer, RRS Ernest Shackleton, Sea Lion Field Development Environmental Baseline Survey (37 MFA) ; 1 juvenile specimen, 5.0 mm, NHMUK 2018.901 , North Falkland Basin , Falkland Islands, South West Atlantic (49°21’32.428”S, 59°10’0.6200”W), 434 m, Brown silty clay occasional pebble, 14 April 2012, Box Corer, RRS Ernest Shackleton, Sea Lion Field Development Environmental Baseline Survey (42 MFA) ; 2 specimens unsexed (7.0 mm, 8.5 mm), NHMUK 2018.902 , North Falkland Basin , Falkland Islands, South West Atlantic (49°21’32.428”S, 59°10’0.620”W), 434 m, Brown silty clay occasional pebble, 14 April 2012, Box Corer, RRS Ernest Shackleton, Sea Lion Field Development Environmental Baseline Survey (42 MFC) ; 1 juvenile specimen, 4.0 mm, NHMUK 2018.1005 , North Falkland Basin , Falkland Islands, South West Atlantic (49°18’15.113”S, 59°3’27.771”W), 453 m, Brown silty clay occasional pebble, 15 April 2009, Box Corer, RRS Ernest Shackleton, Sea Lion Field Development Environmental Baseline Survey (29 MFA) ; 1 specimen unsexed, 8.0 mm, NHMUK 2018.754 , Falkland Islands, South West Atlantic Ocean , no GPS, RPS North Falklands Drill Site seafloor mining lease (Rhea 1), depth unknown, 26 August 2015, Box Corer, RRS Ernest Shackleton (ENV11 FC) ; 1 juvenile specimen, 4.1 mm, NHMUK 2018.699 , Falkland Islands, South West Atlantic Ocean , no GPS, RPS North Falklands Drill Site seafloor mining lease (Rhea 1), depth unknown, 26 August 2015, Box Corer, RRS Ernest Shackleton (ENV11 FC) .

Type locality. North Falkland Basin , Falkland Islands, South West Atlantic (49°21’31.701”S, 59°8’21.478”W) .

Etymology. Named in honour of Helen Stoddart for her significant contribution to lysianassoid taxonomy.

Comparative material examined. Lepidepecreoides xenopus K.H. Barnard, 1931 , Holotype male, 9.0 mm, BMNH 1936.11 .2.334, Palmer Archipelago , Antarctica. Non-type Female, 11.0 mm, BMNH 1936.11 .2.335, South Shetland Islands.

Description. Head with lateral cephalic lobe subtriangular, apically subacute; eyes apparently absent. Pereonites 1–7 without mid-dorsal carina. Pleonites 1–2 mid-dorsal carina produced as small hump. Pleonite 3 mid-dorsal carina as small hump, posterodorsal margin produced. Urosomite 1 with recurved, apically rounded produced boss. Antenna 1 peduncular articles 1 and 2 without anterodistal lobe; accessory flagellum 3-articulate, terminal article small, offset; flagellum with strong 2-field callynophore; robust setae present on proximal articles; calceoli absent. Antenna 2 flagellum short, calceoli absent. Epistome rounded. Mandible molar columnar with oval, fully triturating surface; palp attached distally, article 3 with proximal A3-seta. Maxilla 1 outer plate with left and right setal-tooth 11 symmetrical, cuspidate distally along inner margin; palp distal margin with 12 apical robust setae. Maxilliped not observed (?damaged). Gnathopod 1 subchelate; coxa large, about as long as coxa 2, subrectangular; basis sparsely setose along anterior margin; ischium short; carpus long, length 4 times breadth, longer than propodus, without posterior lobe; propodus small, margins subparallel, palm angle acute, defined by robust seta. Gnathopod 2 parachelate, palm convex. Pereopod 4 coxa with small posteroventral lobe (posterior margin concave). Pereopod 5 coxa with distinct lateral ridge; basis about as long as broad, posterior margin with well developed mid-central spine, spine longer than broad, apically rounded, posteroventral lobe rounded. Pereopod 6 basis posterior margin serrate. Pereopod 7 basis posterior margin serrate, posterodistally rounded, produced, not reaching merus. Epimeron 3 posterior margin smooth, posteroventral corner broadly rounded. Uropod 3 outer ramus article 2 short; with plumose setae on each ramus. Telson deeply cleft, with 2–3 apical robust seta on each lobe.

Remarks. Lepidepecreoides stoddartae sp. nov. can be distinguished from other species in the genus by the acute palm of gnathopod 1 and the more elongate posterior projection on the basis of pereopods 5. The presence of the pereopod 5 projection is a defining character for the genus, the dorsal and ventral margins of the projection and its more proximal position along the posterior margin of the basis in L. stoddartae sp. nov. is most similar to L. xenopus . The serrations along the posterior margin of pereopods 6 to 7 in L. stoddartae sp. nov., is similar to L. bassi and L. xenopus however in the latter two species the serrations are not as well-developed. The pleonite 3 dorsal projecting boss is more recurved and apically rounded in L. stoddartae sp. nov. compared with L. bassi and L. xenopus which have a more acute boss projection with a straight posterior margin.

Both L. stoddartae sp. nov. and L. xenopus are recorded from the South Atlantic, currently L. stoddartae is known only from areas around the Falkland Islands, while L. xenopus has been more extensively within the Antarctic region ( Table 1). Lepidepecreoides xenopus is the type species for the genus with the type locality South Georgia, it is perhaps not particularly remarkable that the two most morphologically similar species, L. stoddartae sp. nov. and L. xenopus , also have geographically proximate distributions.

Lepidepecreoides stoddartae sp. nov. was collected at 341 to 453 m depth, which is similar to previous records of Lepidepecreoides ( Table 1).

The collection here includes 12 individuals from eight sampling events. This is a particularly high number of specimens. Most Lepidepecreoides species are known from only one or few specimens across six expeditions (one specimen— L. bassi , L. nubifer , L. talboti , L. torresi ; three specimens L. chincui and L. xenopus eight specimens). Other studies have recorded a maximum of three specimens from the same sample ( L. xenopus USNM306582 Weddell Sea, Lowry & Stoddart, 2002) ( Table 1).

Figures

FIGURE 1. Lepidepecreoides stoddartae sp. nov. holotype female, 11.0 mm, NHMUK 2018.903, North Falkland Basin, Falkland Islands. Scale 0.5 mm.

FIGURE 2. Lepidepecreoides stoddartae sp. nov. holotype female, 11.0 mm, NHMUK 2018.903, North Falkland Basin, Falkland Islands. Scale 0.5 mm.