Epimeria horsti, Lörz, Anne-Nina, 2008

Lörz, Anne-Nina, 2008, Epimeriidae (Crustacea, Amphipoda) from New Zealand with a description of a new species, Zootaxa 1847, pp. 49-61 : 50-54

Epimeria horsti sp. nov.

( Figs 1–5 )

Material examined. Holotype: NIWA 34938, female 16.5 mm, Ghoul Seamount, 42°47.85'S, 179°59.26'E, 970–1140 m, TAN0604/111, sled, 7 June 2006.

Paratype: NIWA 34939, female 16.0 mm, Gothic Seamount, 42°43.61'S, 180°6.03'E, 1030–1156 m, TAN0604/106, sled, 5 June 2006.

Etymology. The species is dedicated to Prof. Dr. Horst Lörz with thanks for his continued support.

Description. Anterior cephalic margin sinuous, lateral cephalic lobe slightly produced; rostrum same length as head, reaching proximal part of antenna 1 peduncle article 1; eye present, oval, 0.5 x head height. Pereonite 1 subequal in length to head (excluding rostrum), pereonite 2 c. 0.75 x length of 1, pereonites 1 to 5 lacking mid-dorsal or dorsolateral processes; pereonite 6–7 posterior margin with tooth, dorsolateral carina weakly developed; pleonites 1–3 with acute mid-dorsal teeth curved posteriorly to overhang following somite and distinct, dorsolateral processes on pleonites 1–2.

Epimeron 1 antero- and posteroventral angle rounded; epimeron 2 similar to 1, posteroventral angle less rounded; epimeron 3 posteroventral angle produced.

Urosomite 1 with a keel-like middorsal process; urosomite 2 shortest with pointed middorsal process; urosomite 3 lacking mid-dorsal processes.

Antenna 1 peduncle article 1 with 2 short processes; article 2 with 1 slight process, slightly shorter than article 1; article 3 shortest; accessory flagellum scale-like; primary flagellum of 33 articles. Antenna 2 articles 1–5 lacking distal processes, flagellum with 45 articles.

Mandible: incisor and lacinia mobilis strongly dentate; molar produced and triturative; palp article 3 densely setose medially, with long stout SS distally. Maxilla 1 medial plate subtriangular, obliquely convex inner margin with 11 stout, plumose SS; lateral plate distal margin oblique, with 11 medially lobate RS; palp strongly exceeding outer plate; palp article 1 short, article 2 slightly curved medially with stout SS distomedially, stout RS distally. Maxilla 2 with long, distally crenulate setae distally on lateral and medial plates. Maxilliped lateral plate broadly rounded distally, reaching beginning of propodus, medial plate with nodular RS and a row of long plumose SS on medial, anterior face; palp medial margin strongly setose; merus distally expanded; dactyl with serrate medial margin.

Pereopods: Gnathopod 1: coxa 1 long and slender, basis linear, slender, both margins with numerous fine SS; merus slightly longer than ischium, anterior margin very short, distal margin oblique, posterodistal angle acute, setose; carpus linear, distal half of posterior margin with long SS; propodus slightly expanded distally, anterior margin naked except for distal fringe of short SS, palm finely crenulate, slightly oblique, with cluster of RS defining rounded distal margin, posterior margin with numerous long SS; dactylus slender, slightly curved, posterior margin strongly serrate. Gnathopod 2: coxa 2 wider than coxa 1, basis linear, ischium anterior margin very short, distal margin obliquely articulating with carpus, carpus linear, anterior margin naked except for transverse row of SS distally, posterior margin with numerous stout SS distally; propodus linear, palm almost transverse, rounded, finely crenulated, lined with numerous submarginal RS; dactylus large, exceeding palm, posterior margin serrate. Pereopod 3: coxa similar to coxa 2, basis linear, anterior and posterior margin finely setulose; merus slightly expanded distally, carpus slightly shorter than merus, anterior margin naked, posterior margin with 5 pairs of RS; propodus naked anteriorly, posterior margin with 6 pairs of RS; dactylus stout, curved. Pereopod 4: coxa longer than 3, anterior margin straight, produced into posterodistal cusp directed posterodistally, posterior margin divided at mid point by subacute cusp into two concave sections; basis to dactylus as for pereopod 3. Pereopod 5: coxa subrectangular, posterodistal corner produced; posterior margin straight; basis nearly linear; merus constricted proximally; carpus slightly widened distally; propodus linear, posterior margin with 7 pairs of RS; dactylus curved, stout, c. 0.3 x propodus length. Pereopod 6: coxa anterior half hidden by coxa 5, anterior margin weakly concave, posterior margin straight; basis wider than in pereopod 5; ischium to dactylus as in pereopod 5. Pereopod 7: coxa subrectangular; basis expanded midposteriorly; ischium to dactylus as in pereopods 5 and 6.

Urosome and telson: Uropod 1: peduncle subequal in length to inner ramus, medial margin with 1 RS distally, distal margin with close row of short RS; inner ramus lateral margin with spaced row of short RS, medial margin with sparse RS; outer ramus marginally shorter than inner. Uropod 2: peduncle naked, produced into acute process; inner ramus length 1.3 x outer ramus, both margins sparse RS; outer ramus, both margins with few short RS. Uropod 3: peduncle short, c. 0.3 x length of inner ramus, medial and inner margins of both rami with sparse row of short RS. Telson 1.2 x longer than wide, U-shaped emargination 0.2 x length, lobes triangular, broadly rounded apically.

Colouration. Freshly captured specimen of Epimeria horsti show distinct orange eyes (fig. 5) and a slightly rose-coloured body.

Remarks. Epimeria horsti sp. nov., superficially resembles Epimeria bruuni in the produced dorsal carinae starting on pereonite 6. Epimeria horsti , however, lacks carinae or hooks on the third urosome, and the posterolateral corner of the third epimeron is pointed.

Distribution. New Zealand, Graveyard Seamount complex, 970–1156 m.

Figures

FIGURE 1. Epimeria horsti sp. nov. Holotype, female, 16.5 mm, NIWA 34938. Habitus lateral; Antenna 1 (A 1); Antenna 2 (A 2); Maxilla 1 (Mx 1); Mandible (Mnd). Habitus scale bar 10 mm, other scale bars 1 mm.

FIGURE 2. Epimeria horsti sp. nov. Holotype, female, 16.5 mm, NIWA 34938. Maxilliped (Mxp). Pereopod 4 (P 4). Pereopod 3 (P 3). Upper lip (uL). Maxilla 2 (Mx 2). Scale bar 1 mm.

FIGURE 3. Epimeria horsti sp. nov. Holotype, female, 16.5 mm, NIWA 34938. Gnathopod 1 (G 1). Gnathopod 2 (G 2). Scale bar 1 mm.

FIGURE 4. Epimeria horsti sp. nov. Holotype, female, 16.5 mm, NIWA 34938. Pereopod 5 (P 5). Pereopod 6 (P 6). Pereopod 7 (P 7). Uropod 1 (U 1). Uropod 2 (U 2). Uropod 3 (U 3). Telson (T). Scale bar 1 mm.

FIGURE 5. Epimeria horsti sp. nov. Paratype, 16.0 mm, NIWA 34939. Photographed immediately after sampling on the New Zealand Graveyard seamount complex, 1030 m.