INTRODUCTION
The Epimeriidae Boeck, 1871 is an amphipod family with a worldwide distribution. The by far largest genus Epimeria has 46 species, including the new species described below. Twenty-four Epimeria species are known from the Antarctic, 11 from the Atlantic, one from the Indian Ocean and now ten from the Pacific. Examination of material collected north-west of New Zealand in the Tasman Sea revealed one species new to science, which is here described. This paper increases the number of known species of Epimeria from the Pacific to ten, five from the south-west (off New Zealand), three from the north-west (off Japan) and further two from the north-east (off Oregon). All except one species were collected below 1000 m depths. A key to the Pacific Epimeria is provided.
MATERIALS AND METHODS
Amphipods were collected during an RV ‘Tangaroa’ voyage to the Tasman Sea north-west of New Zealand. Specimens were immediately sorted on deck, often pictured alive on board, fixed in 98% ethanol and later transferred to 70% ethanol. Specimens were examined and dissected using a Leica MZ9.5 stereomicroscope and drawn using a camera lucida attachment. Small appendages (mouthparts, uropods and telson) were temporarily mounted in lactic acid and examined and drawn using a Nikon compound microscope fitted with a camera lucida. The body lengths of specimens examined were measured by tracing individual's mid-trunk lengths (tip of the rostrum to end of telson) using a camera lucida. All illustrations were inked electronically using a Wacom Intuous2 Graphics Tablet and Adobe Illustrator CS4 following Coleman (Reference Coleman2003). Setal terminology follows Watling (Reference Watling, Felgenhauer, Watling and Thistle1989).
Type material is held at the Sydney Museum, Australia.
RESULTS
Epimeria norfanzi sp. nov., holotype: adult female 32 mm, P66441; (A) habitus lateral; (B) habitus dorsal; (C) antenna 1; (D) antenna 2. Scale bars A, B: 2 mm; C, D: 1 mm.
Epimeria norfanzi sp. nov., holotype: adult female 32 mm, P66441; (A) gnathopod 2; (B) mandible; (C) maxilla 2; (D) maxilla 1. Scale bars: A–D 1 mm.
Epimeria norfanzi sp. nov., holotype: adult female 32 mm, P66441; (A) gnathopod 1; (B) pereopod 6; (C) pereopod 7; (D) pereopod 5; (E) pereopod 4; (F) pereopod 3; (G) maxilliped; (H) part of hypopharynx. Scale bars A–H: 1 mm.
Epimeria norfanzi sp. nov., holotype: adult female 32 mm, P66441; (A) uropod 1 dorsal and ventral; (B) uropod 2 dorsal and ventral; (C) uropod 3 dorsal and ventral; (D) pleopod 3; (E) telson; (F) egg. Scale bars: A–G 1 mm.
Epimeria norfanzi sp. nov., holotype: adult female 32 mm, P66441; photographed by Karen Gowlett-Holmes (CSIRO) immediately after sampling. Scale bar 5 mm.
TYPE MATERIAL
Holotype: P66441, female 32 mm, TAN0308/145, West Norfolk Ridge, 34°17′50″S 168°25′49″E, depth 1268 m, collected 2 June 2003.
ETYMOLOGY
The species is named after the NORFANZ Expedition—NOrfolk Ridge, France, Australia and New Zealand Expedition during which it was collected on the West Norfolk Ridge.
DIAGNOSIS
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, round, 0.5 × head height. Pereonite 1 shorter than head (excluding rostrum), pereonite 2 ~0.75 × length of 1, pereonites 1 to 6 lacking mid-dorsal or dorsolateral processes; pereonite 7 posterior margin with tooth, dorsolateral carina weakly developed; pleonites 1–3 each with acute mid-dorsal tooth curved posteriorly to overhang following somite. Epimeron 1 antero- and posteroventral angle rounded; epimerons 2 and 3 posteroventral angle produced. Urosomite 1 with a keel-like middorsal process; urosomites 2 and 3 lacking mid-dorsal processes. Coxa 5 strongly produced, reaching posterior margin of second epimeron.
DESCRIPTION
Antenna 1 peduncle article 1 with 3 short processes; article 2 with no process, shorter than article 1; article 3 shortest with 2 short processes; accessory flagellum scale-like; primary flagellum of 32 articles. Antenna 2 articles 1 and 5 with short distal processes, articles 2 and 3 with several setae.
Mandible: incisor and lacinia mobilis strongly dentate; molar produced, not triturative; palp article 3 densely setose medially and distally. Maxilla 1 medial plate subtriangular, inner margin with 11 stout, plumose slender setae; lateral plate distal margin oblique, with 11 medially lobate robust setae; palp strongly exceeding outer plate; palp article 1 short, article 2 slightly curved medially with, stout robust setae distally. Maxilla 2 with long, crenulate setae distally on lateral and medial plates. Maxilliped lateral plate broadly rounded distally, reaching half length of palp, medial plate with nodular robust setae and a row of long plumose slender setae on medial, anterior face; palp medial margin strongly setose. Hypopharynx damaged, not setose.
Pereopods: Gnathopod 1: coxa 1 long and slender, ventrally rounded; basis linear, slender; merus slightly longer than ischium, anterior margin very short, distal margin oblique, posterodistal angle acute, setose; carpus linear, posterior margin with long slender setae; propodus slightly expanded distally, with clusters of robust setae, anterior margin naked except for distal fringe of short slender setae, palm finely crenulate, slightly oblique, posterior margin with numerous long slender setae; dactylus slender, slightly curved, posterior margin strongly serrate. Gnathopod 2: coxa 2 wider than coxa 1, ventrally rounded; basis linear, ischium anterior margin very short, carpus slightly expanded distally, anterior margin naked except for transverse row of slender setae distally, posterior margin with numerous stout slender setae distally; propodus linear, palm almost transverse, convex, finely crenulated, lined with numerous submarginal robust setae; dactylus slightly curved, posterior margin serrate, as long as palm. Pereopod 3: coxa larger than 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 robust setae; propodus almost naked anteriorly, posterior margin with 6 pairs of robust setae; dactylus stout, curved. Pereopod 4: coxa longer and wider than 3, anterior margin straight, produced into posterodistal cusp directed posterodistally, posterior margin straight, ridge parallel to posterior margin; basis to dactylus as for pereopod 3. Pereopod 5 smaller than pereopods 3 and 4; coxa subrectangular, posterodistal corner extremely produced, reaching distal end of epimeral plate 2; basis nearly linear, strong ridge at distal part; merus dorsally expanded; carpus linear, posterior margin with 5 pairs of robust setae; propodus linear, posterior margin with 7 pairs of robust setae; dactylus curved, stout, ~0.3 × propodus length. Pereopod 6: coxa anterior half hidden by coxa 5, pointed process, posterior margin convex; basis similar shape than pereopod 5, with ridge along entire length; ischium to dactylus as in pereopod 5. Pereopod 7: coxa subrectangular; basis expanded midposteriorly; ischium to dactylus as in pereopods 5 and 6.
Pleopod 3 rami with 27 and 35 articles, peduncle about half the length of rami.
Urosome and telson: Uropod 1: peduncle longer than rami, bearing keel, distal margin with row of short robust setae; outer magins of rami with few short setae. Uropod 2: peduncle naked, with keel, produced into acute process, slightly shorter than outer ramus; inner ramus length 1.3 × outer ramus, both margins sparse robust setae; outer ramus, both margins with few short robust setae. Uropod 3: peduncle short, ~0.3 × length of inner ramus, medial and inner margins of both rami with sparse row of short robust setae. Telson 1.2 × wider than long, quadrate, not cleft.
Twenty-four eggs were counted, all having about the same size and oval–roundish in shape.
COLORATION
Freshly captured specimen of Epimeria norfanzi sp. nov. shows distinct orange eyes (Figure 5) and a rose-coloured body.
DISTRIBUTION
Only known from type locality, West Norfolk Ridge, west off northern New Zealand, 1268 m.
REMARKS
The new species, Epimeria norfanzi sp. nov., superficially resembles Epimeria pacifica Gurjanova, Reference Gurjanova1955 but can be distinguished via several characters (Table 1).
Character differences between Epimeria norfanzi sp. nov. and Epimeria pacifica Gurjanova, Reference Gurjanova1955.
KEY TO THE PACIFIC EPIMERIA
1. Pereon segments lacking dorsal carinae… … … … … . .4
— Pereon segments bearing dorsal carinae… … … … . 2
2. Coxa 5 produced; third epimeral plate posterolaterally produced … … … … … … … … … … … … … … … .3
— Coxa 5 not produced; third epimeral plate posterolateral corner rounded … … … … … . . .Epimeria bruuni
3. Dorsal carinae starting on pereon 4; epimeral plates bearing postero-lateral produced corners and at least two produced lateral teeth each… … … … . Epimeria victoria
— Dorsal carinae starting on pereon 6; posterolateral corners of epimeral plates 1 and 2 rounded … … … … … … … … … … … … … … … … …Epimeria horsti
4. Eyes present… … … … … … … … … … … … … . 7
— Eyes absent … … … … … … … … … … … … . 5
5. Coxa 5 produced… … … … … … … … … … … … 6
— Coxa 5 not produced … … … … .Epimeria yaquinae
6. Pleonites 1–3 with dorsal carinae, urosomite 1 dorsally produced, coxa 1–3 ventrally rounded… … … … … … … … … … … … … … … … … … .Epimeria glaucosa
— Pleonites 1–2 smooth, pleonite 3 and urosomite 1 dorsally produced, coxa 1–3 ventrally pointed … … … … … … … … … … … … … … … .Epimeria subcarinata
7. Urosomite 1 bearing dorsally pointed tooth, rostrum expanding beyond first peduncle article of antenna 1 … … … … … … … … … … … … … … … … … … .9
— Urosomite 1 lacking dorsally pointed tooth, rostrum not expanding beyond first peduncle article of antenna 1 … … … … … … … … … … … … … … … … … .8
8. Protrusion of coxa 5 reaching posterior margin of epimeral plate 2, telson not cleft, coxal plates 1–3 ventrally rounded… … … … … … … .Epimeria norfanzi sp. nov.
— Coxa 5 not produced, telson cleft, coxal plates 1–3 ventrally pointed… … … … … … … .Epimeria pelagica
9. Head ventral lobe not produced, coxa 4 ventral protrusion as long as posterior protrusion, coxa 5 protrusion not reaching epimeral plates… … … … … … … … … … … … … … … … … … … … . Epimeria cora
— Head ventral lobe produced, coxa 4 twice as long as wide, coxa 5 protrusion nearly reaching second epimeral plate… … … … … … … … … … …Epimeria pacifica
DISCUSSION
Barnard (Reference Barnard1971) noted that the species Epimeria cora has very close affinities with E. glaucosa J.L. Barnard, Reference Barnard1961 and E. subcarinata Nagata, Reference Nagata1963, and the three entities may be subspecies of a common stem. Even though seven more species of Epimeria are now known from the Pacific, and these were collected more than 80 degrees of latitude and 90 degrees of longitude apart from the north-east, south-west and north-west Pacific, the morphological similarities amongst them are strong. In other words, the morphological differences amongst the species known from the Pacific are minor compared to the morphological differences observed amongst the species from the Antarctic or the species from the Atlantic. I agree with Barnard (Reference Barnard1971) that presumably all Pacific species belong to the same clade.
Synopsis of Pacific Epimeria species
Epimeria bruuni Barnard, Reference Barnard1961
(Figured by Barnard, Reference Barnard1961 and Lörz, Reference Lörz2008, descriptions in English)
The original description of E. bruuni is based on a single juvenile specimen, 7 mm in length from the Danish ‘Galathea’ expedition, Kermadec Trench, 36°38′S 178°21′E in 2470 m. The redescribed material by Lörz, Reference Lörz2008 is based on an adult specimen, 25 mm in length, collected in 2526 m depth from the New Zealand Young Hicks seamount, Hikurangi Plateau.
Epimeria cora J.L. Barnard, Reference Barnard1971
(Figured by Barnard, Reference Barnard1971, description in English)
Epimeria cora is described from the north-east Pacific off Oregon from 2086 m depth.
Epimeria glaucosa Barnard, Reference Barnard1961
(Figured by Barnard, Reference Barnard1961, description in English)
Described from the Kermadec Trench north of New Zealand from 3710 m depth.
Epimeria horsti Lörz Reference Lörz2008
(Figured by Lörz, Reference Lörz2008, description in English)
Described from the New Zealand graveyard seamounts complex, type material is from the Ghoul and Gothic seamounts, east off New Zealand from 970–1030 m.
Epimeria pacifica Gurjanova Reference Gurjanova1955
(Figured by Gurjanova, Reference Gurjanova1955, description in Russian)
Epimeria pacifica is described from 1450–1430 m depth from the slopes of the Japan trench, east of Shikotan.
Epimeria pelagica Birstein & Vinogradov Reference Birstein and Vinogradov1958
(Figured by Birstein & Vinogradov, Reference Birstein and Vinogradov1958, description in Russian)
Described from the Kamchatka Trench off Japan. While all other known epimeriids are regarded as benthic, this species was collected in the water column between 0 and 8000 m depth. Also recorded from Nagata (Reference Nagata1963) in a summary of species from the Japan Trench, south-east of the Kamchatka Trench.
Epimeria norfanzi sp. nov.
(Figured in present paper, description in English)
Described from the Tasman Sea, on the West Norfolk Ridge east off North New Zealand in 1268 m.
Epimeria subcarinata Nagata, Reference Nagata1963
(Figured by Nagata, Reference Nagata1963, description in English)
Nagata (Reference Nagata1963) summarized the species from the Japan Trench, 37–42°N 143–148°E and described E. subcarinata from 2230 m, off Onagawa. According to Nagata (Reference Nagata1963) E. subcarinata is potentially a synonym of E. pacifica.
Epimeria victoria (Hurley, Reference Hurley1957)
(Figured by Hurley, Reference Hurley1957 and Moore, Reference Moore1985, descriptions in English)
Epimeria victoria (Hurley, Reference Hurley1957) is known from shallower waters at 130 m depth, off Otago, South Island New Zealand (Moore, Reference Moore1985) and 140 m in the Cook Strait (Hurley, Reference Hurley1957). Hurley (Reference Hurley1957) described a male specimen, Epimeria victoria, from the Cook Strait. Moore (Reference Moore1985) complemented the description with a female from off Otago, extending the known distribution of this species to the South Island and moved it to the genus Epimeriella Walker, 1906. The diagnostic character of the genus Epimeria, the large, ridged mandibular molar processes, is missing in the victoria specimens and Moore (Reference Moore1985) classified this species as Epimeriella on the basis of the thin setose lamina. Lörz et al. (Reference Lörz, Maas, Linse, Coleman and Bruce2009) synonymized the genus Epimeriella with the genus Epimeria.
Epimeria yaquinae McCain, Reference McCain1971
(Figured by McCain, Reference McCain1971, description in English)
This species is described from two stations on 2800–2862 m depth in the north-east Pacific off Oregon.
ACKNOWLEDGEMENTS
Erika McKay (NIWA) kindly inked the plates. Karen Gowlett-Holmes (CSIRO) took the on-board photograph. Thanks to Jim Lowry of the Australian Museum for the loan of the material. This research was funded by NIWA's (National Institute of Water & Atmospheric research) Biodiversity & Biosecurity programme CO01X0502 of the New Zealand Science Foundation. Funding for the NORFANZ voyage in 2003 was provided by the New Zealand Ministry of Fisheries (contract ZBD2002/16) and National Oceans Office of Australia. Additional funding, equipment and scientific support was provided by NIWA, NIWA Vessel Management, CSIRO Marine and Atmospheric Research; ORSTOM Nouméa, Museum of New Zealand Te Papa Tongarewa: Collection Development fund, and Foundation for Research Science and Technology (FRST) projects: MNZX0203 and CO1X0502 ‘Biosystematics of New Zealand EEZ Fishes’, and CO1X0224 ‘Seamounts: their importance to fisheries and marine ecosystems’.
