Epimeria emma, Lörz, Anne-Nina & Coleman, Charles Oliver, 2014

Lörz, Anne-Nina & Coleman, Charles Oliver, 2014, Amazing new Amphipoda (Crustacea, Epimeriidae) from New Zealand’s deep-sea, Zootaxa 3838 (4), pp. 423-434 : 432-439

Epimeria emma sp. nov.

( Figs 9–14 )

Type material. Holotype: NIWA 84644, 6.5 mm, New Zealand, Challenger Plateau (40.88°S, 170.8555°E to 40.888333°S, 170.8565°E), 529–534 m, beam trawl, TAN0707/119, 6 June 2007.

Paratypes: NIWA 89711, 1 specimen, 11 mm, colour photograph ( Fig. 15 ); NIWA 89712, 1 specimen, 12 mm New Zealand, Chatham Rise (43.535166°S, 174.581833°E to 43.532833°S, 174.578166°E), 494–497 m, epibenthic sledge, TAN1116/31, 6 November 2011; NIWA 86639, 1 specimen, dried and gold coated on scanning electron microscope studs, ( Figs 16 –18), New Zealand, Chatham Rise (43.389333°S, 174.175166°W to 43.388833°S, 174.1705°W), 569–570 m, epibenthic sledge, TAN1116/33, 6 November 2011.

Etymology. Epimeria emma sp. nov. is dedicated to Emma Johanna, daughter of the senior author. The species epithet is used as a noun in apposition.

Description. Rostrum as long as head, reaching distal margin of the first article of antenna 1; eye present, oval, 0.65 × head height. Pereonite 1 subequal in length to head (excluding rostrum), pereonite 2 c. 0.8 × length of 1, pereonites 1–5 lacking mid-dorsal or dorsolateral processes; pereonite 6 and 7 posterior margin with posterodorsal tooth; pleonites 1–3 with strong dorsal carinae. Pereonites 5 and 6 and pleonites 1–2 laterally bearing dorsolateral pocesses and pleonites 1–2 additional posterolateral processes. Epimeron 1 anteroventrally rounded and posteroventral with small point; epimeron 2 posteroventral slightly produced and pointed; epimeron 3 posteroventral angle strongly produced and acute.

Urosomite 1 with a keel-like mid-dorsal process; urosomite 2 shortest, lacking dorsal process; urosomite 3 mid-dorsally bearing small notch.

Antenna 1 peduncle length ratios approximately 3:2:1; accessory flagellum scale-like; primary flagellum broken. Antenna 2 articles 1–2 bearing distal processes, flagellum with 21 articles.

Labrum slightly dentate at both sides of depression. Mandible incisor and lacinia mobilis strongly dentate; molar produced and triturative; palp article 3 densely setose ventrally; palp article 2 with 1 long seta distally. Hypopharynx with broad lobes, distally and medially covered with hair-like setae, lateral processes narrow, pointed; mediodistal group of spines in the hypopharyngeal gap. Maxilla 1 inner plate subtriangular, obliquely convex inner margin with 7 stout, plumose setae; outer plate distal margin oblique, with 10 medially lobate robust setae; palp exceeding outer plate; palp article 1 short, article 2 slightly curved medially with stout setae distomedially, stout setae distally. Maxilla 2 with long, distally serrate setae on apicomedial margin of outer plate. Maxilliped outer plate broadly rounded distally, exceeding distal margin of second article of maxillipedal palp, inner plate with row of long plumose seatae on medial, anterior face; palp medial margin strongly setose; propodus with several plumose setae at terminal end, reaching length of dactylus, which has several teeth on inner curvature.

Pereopods: gnathopod 1 coxa slender and ventrally truncate, with midlateral ridge, basis linear, slender, both margins with numerous fine setae; merus slightly longer than ischium, anterior margin very short, distal margin oblique, posterodistal angle acute, setose; carpus widened distally, posterior margin with groups of long setae, anterior margin naked; propodus palm finely crenulate, slightly oblique, with cluster of robust setae defining rounded distal margin, posterior margin with groups of long setae; dactylus slender, slightly curved, posterior margin strongly serrate, longer than palm. Gnathopod 2 coxa ventrally pointed, with midlateral ridge; basis linear, ischium to dactylus very similar to gnathopod 1. Pereopod 3 coxa slightly longer than coxa 2, with midlateral ridge, ventrally pointed; basis linear; merus slightly expanded distally. Pereopod 4 coxa longer than coxae 1–3, anterior margin convex, produced into posterodistal cusp directed posterodistally, posterior margin divided at mid-point by subacute cusp into two concave sections; basis to merus as for pereopod 3. Pereopod 5 coxa subtriangular, posterodistal corner produced and directed posteroventrally; basis straight, with midlateral ridge; merus constricted proximally. Pereopod 6 coxa with prominent posterior corner, strongly sculptured by ridges, basis linear with midlateral ridge, ischium with robust anteroventral setae, merus linear. Pereopod 7 coxa small; basis broader than those of pereopod 5 or 6, expanded dorso-posteriorly, anterior margin with setae; ischium to dactylus similar to pereopod 6.

Pleopods 1–3 similar; peduncle broad with few plumose setae lateromarginally, with 2 coupling hooks; inner ramus slightly shorter than outer; rami articulated: each article with 1 long plumose setae medially and laterally.

Urosome and telson: uropod 1 peduncle subequal in length to inner ramus, medial margin with 1 robust seta distally; inner ramus lateral margin with spaced row of short robust setae, medial margin with sparse robust setae; outer ramus marginally shorter than inner. Uropod 2 peduncle about half length of inner ramus; outer ramus two thirds length of inner ramus; both margins of both rami with robust setae. Uropod 3 peduncle short, c. 0.3 × length of inner ramus, medial and inner margins of both rami with sparse row of short robust setae. Telson subquadrate with shallow distal notch, 2 plumose setae on both lateral margins.

Colouration. Distinct light rose coloured eye, red to white coloured body ( Fig. 15 ). A red rostrum, light red/ pale orange and rose coloured pereonites, light rose to white coloured pleonites and urosome.

Figures

FIGURE 9. Epimeria emma sp. nov. holotype, 6.5 mm, NIWA 84644; habitus. Scale bar: 1 mm.

FIGURE 10. Epimeria emma sp. nov. holotype, 6.5 mm, NIWA 84644; a) antenna 1; b) abruml; c) antenna 2; d) hypopharynx; e) left mandible; f) incisor and lacinia mobilis of right mandible; g) maxilla 1; h) telson. Scale bars: a, c) 0.2 mm; a, b, d, e, g, h) 0.1 mm.

FIGURE 11. Epimeria emma sp. nov. holotype, 6.5 mm, NIWA 84644; a) inner plates of maxillipeds; b) palp of maxilliped; c) outlines of maxilliped; d) outer plate of maxilliped; e) maxilla 2. Scale bars: a – e) 0.1 mm.

FIGURE 12. Epimeria emma sp. nov. holotype, 6.5 mm, NIWA 84644; a) gnathopod 1; b) palm of gnathopod 1; c) gnathopod 2. Scale bars: a – c) 0.1 mm.

FIGURE 13. Epimeria emma sp. nov. holotype, 6.5 mm, NIWA 84644; a) pereopod 6; b) pereopod 4; c) pereopod 3; d) pereopod 5. Scale bars: a – d) 0.2 mm.

FIGURE 14. Epimeria emma sp. nov. holotype, 6.5 mm, NIWA 84644; a) pereopod 7; b) pleopod 1; c) uropod 1; d) uropod 2; e) uropod 3. Scale bars: a, b) 0.2 mm; c – e) 0.1 mm.

FIGURE 15. Epimeria emma sp. nov. 11 mm, NIWA 89711, photographed on board shortly after sampling.

FIGURE 16. Scanning electron microscope image of Epimeria emma sp. nov., NIWA 86639; a) habitus from pereonite 4; b) coxa 4; c) detail coxa 4; d) pleonites 1 – 3; e) ventral margin of pereonite 2; f) honeycomb and cusp structure on carapace of pereonite 2. Scale bars: a) 200 µm; b) 100 µm; c) 30 µm; d) 200 µm; e) 100 µm; f) 10 µm.