Epimeria ashleyi, Lörz, Anne-Nina, 2012

Lörz, Anne-Nina, 2012, First records of Epimeriidae and Iphimediidae (Crustacea, Amphipoda) from Macquarie Ridge, with description of a new species and its juveniles, Zootaxa 3200, pp. 49-60 : 51-56

Epimeria ashleyi sp. nov.

( Figs 2–7 )

Type material. Holotype: gravid female 22.6 mm, AM P87291, Hjort Seamount, Macquarie Ridge, 56°14'46.788"S, 158°30'20.1594"E, 676–750 m, “seamount sled”, TAN0803/98, 16 April 2008.

Paratype: juvenile from marsupium of holotype, 2.3 mm, NIWA 77689, same data as holotype; female 20.2 mm, with juveniles, NIWA 41025, Hjort Seamount, Macquarie Ridge, 56°14'31.8012"S, 158°27'42.0012"E, 790– 1025 m, TAN0803/102, “seamount sled”, 16 April 2008.

Additional material. NIWA 40497, 1 specimen, “seamount 7” ( Fig. 6 ), Macquarie Ridge, 53°42'54.5976"S, 159°07'49.8"E, 770–810 m, “seamount sled”, TAN0803/79, 12 April 2008 (specimen lost at sea).

Etymology. Epimeria ashleyi sp. nov. is named after Dr Ashley Rowden, one of the organisers of the Tangaroa expedition to the Macquarie Ridge. Dr Rowden’s devotion to seamount research is greatly advancing the scientific knowledge of deep sea biology in the New Zealand region.

Description. Rostrum as long as head, reaching distal margin of the first article of antenna 1; eye present, oval, 0.4 × head height. Pereonite 1 subequal in length to head (excluding rostrum), pereonite 2 c. 0.8 × length of 1, pereonites 1–4 lacking mid-dorsal or dorsolateral processes; pereonites 5–7 posterior margin with tooth; dorsolateral teeth on pereonites 6 and 7; pleonites 1–3 with acute mid-dorsal teeth; double carinae and three lateral bumps on each epimeral plate. 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 mid-dorsal process; urosomite 2 shortest, lacking dorsal process; urosomite 3 lacking mid-dorsal processes.

Antenna 1 peduncle length of articles 1:2:3 approximately 3:2:1; accessory flagellum scale-like; primary flagellum of 28 articles. Antenna 2 articles 1–3 bearing distal processes, flagellum broken off.

Mandible: incisor and lacinia mobilis strongly dentate; molar produced and triturative; palp article 3 densely setose medially, with 3 long stout setae distally. Maxilla 1 inner plate subtriangular, obliquely convex inner margin with 7 stout, plumose setae; outer plate distal margin oblique, with 11 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 crenulate setae distally on lateral and medial plates. Maxilliped outer plate broadly rounded distally, reaching mid length 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 2 plumose setae at terminal end, reaching length of dactylus. Labrum with several terminal setae and slightly dentate at both sides of depression. Hypopharynx has broad lobes, distally and medially covered with hair-like setae, lateral processes narrow, rounded; mediodistal group of spines in the hypopharyngeal gap.

Pereopods: Gnathopod 1 coxa slender an pointed, mid lateral 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 linear, posterior margin with groups of long setae, anterior margin naked except long setae at distal end; propodus anterior margin with few short setae, palm finely crenulate, slightly oblique, with cluster of robust setae defining rounded distal margin, posterior margin with 7 groups of long setae; dactylus slen- der, slightly curved, posterior margin strongly serrate. Gnathopod 2 coxa slightly wider than coxa 1, with lateral ridge, pointed; basis linear; ischium to dactlylus very similar to gnathopod 1, except propodus longer in gnathopod 2; oostegite on gnathopod 2 longer than basis and longer than gill. Pereopod 3 coxa larger than coxa 2, with midlateral ridge; basis linear; merus slightly expanded distally; carpus slightly shorter than merus, anterior margin naked, posterior margin with 5 pairs of robust setae; propodus naked anteriorly, posterior margin with 6 pairs of robust setae; dactylus stout, curved with hook on anterior side. Pereopod 4 coxa same length as coxa 1–3, 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 with a depression mid posterior margin; merus constricted proximally; carpus slightly widened distally; propodus linear, posterior margin with 7 pairs of robust setae; dactylus curved, stout, c. 0.3 × propodus length. Pereopod 6 coxa with prominent posterior corner, strongly sculptured by ridges, ventral marging with setae; basis expanded dorso-posteriorly, anterior margin with setae; ischium to dactylus similar to pereopod 5. Pereopod 7 coxa small; basis broader than pereopod 5 or 6, anterior margin with setae; ischium to dactylus similar as in pereopods 5 and 6.

Pleopods 1–3 similar; peduncle broad with few plumose setae lateromarginally, 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 naked, 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. 0.6 × length of inner ramus, medial and inner margins of both rami with sparse row of short robust setae. Telson 1.2 × longer than wide, u-shaped emargination 0.2 × length, lobes triangular, broadly rounded apically, with 2 small setae apically on each lobe.

Colouration. Distinct, light rose- coloured eyes ( Fig. 6 ) and a rose-coloured body. The rostrum, mouthparts and the proximal parts of the pereopods, from merus to dactylus, are dark red.

Remarks. Epimeria ashleyi sp. nov., superficially resembles E. horsti in having a pronounced dorsal carina starting on the sixth pereonite. Epimeria horsti , however, lacks the double dorsal carinae, lacks the lateral projections on pereonites 6 and 7, its coxa 4 is smaller and coxa 5 more laterally pointed than in E. ashleyi . Biology. The stomach contents of the paratype did not reveal distinct food items. Some muscle and collagen fibres were clearly visible, as were what appeared to be plant tissues. The plant material, confirmed by experts as not algal, most likely came from sunken wood.

Distribution. Macquarie Ridge, Hjort Seamount, 676–1025 m and “seamount 7”, 770– 810 m.

Figures

FIGURE 2. Epimeria ashleyi sp. nov. Holotype, 22.6 mm, AM P 87291: A) habituts lateral, B) habitus dorsal, C) antenna 1, D) antenna 2. Scale A – B 1 mm, C – D 0.5 mm.

FIGURE 3. Epimeria ashleyi sp. nov. Holotype, 22.6 mm, AM P 87291. A) left mandible, B) molar view of left mandible, C) hypopharynx, D) labrum, E) maxilliped, F) right mandible, H) maxilla 1, G) maxilla 2. Scale 0.5 mm.

FIGURE 4. Epimeria ashleyi sp. nov. Holotype, 22.6 mm, AM P 87291. A) gnathopod 1, B) gnathopod 2, C) pereopod 3, D) pereopod 5, E) pereopod 6, F) pereopod 7. Scale 1 mm.

FIGURE 5. Epimeria ashleyi sp. nov. Holotype, 22.6 mm, AM P 87291. A) pleopod 1, B) telson, C) uropod 1, D) uropod 2, E) uropod 3. Scale: A, C – E 1 mm; B 0.5 mm.

FIGURE 6. Epimeria ashleyi sp. nov. NIWA 40497 photographed on board shortly after sampling. Scale bar 5 mm.

FIGURE 7. Juvenile of holotype of Epimeria ashleyi sp. nov. AM P 8729. A) habitus, B) maxilla 1, C) maxilla 2, D) maxilliped, E) mandible. Scale: A 0.5 mm, B – E 0.1 mm.