Epimeria bruuni Barnard, 1961

Lörz, Anne-Nina, 2008, Epimeriidae (Crustacea, Amphipoda) from New Zealand with a description of a new species, Zootaxa 1847, pp. 49-61 : 54-60

Epimeria bruuni Barnard, 1961

( Figs 6–8 )

Epimeria bruuni Barnard, 1961: 103 , fig. 71.

Type material. Holotype: ZMUC CRU- 5922, 7 mm, Galathea st 665, Kermadec Trench, 36°38’S, 178°21’E, 2470 m, 25 Feb1952.

Other material examined. NIWA 4088, female, 25 mm, Young Nicks Seamount, Hikurangi Plateau, 39°22.56'S, 179°50.59'E, 2526–2550 m, TAN0413/200, beam trawl, 20 Nov 2004.

Description. Anterior cephalic margin sinuous, lateral cephalic lobe acutely produced; rostrum same length as head, reaching proximal part of antenna 1 peduncle article 1; eye present, round, 0.5 x head height, set at anterior cephalic lobe margin. Pereonite 1 subequal in length to head (excluding rostrum), pereonite 2 c. 0.75 x length of 1, pereonites 1–4 lacking mid-dorsal or dorsolateral processes; pereonite 5–7 with blunt dorsolateral carina increasing in size, pleonites 1–3 with large, acute mid-dorsal teeth curved posteriorly to overhang following somite. Pereonite 7, pleonite 1 and 2 each one small dorsolateral tooth. Epimera 1–3 antero- and posteroventral angles rounded.

Urosomite 1 with acute cone mid-dorsally, lacking dorsolateral processes; urosomite 2 shortest; lacking mid-dorsal processes, urosomite 3 with small blunt middorsal cone.

Antenna 1 peduncle article 1–3 no processes; article 2 shorter than article 1; article 3 shortest; accessory flagellum scale-like; primary flagellum of 31 articles. Antenna 2 articles 1–5 lacking distal processes, flagellum with 33+ articles.

Mandible: incisor and lacinia mobilis strongly dentate; molar produced and triturative; palp article 3 setose medially, with long stout SS distally. Lower lip (hypopharynx) with wide lobes and groups of setae on distomedial angles. Maxilla 1 medial plate subtriangular, obliquely convex inner margin with 11 stout, plumose SS; lateral plate distal margin oblique, with 14 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 end of carpus, medial plate with a row of long plumose SS on medial, anterior face; palp slightly setose.

Pereopods: Gnathopod 1 coxa 1 long and slender, anterior margin slightly concave, broadly rounded anterodistally to form acute posterodistal corner, posterior margin straight; 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 slightly expanded distally, posterior margin with long SS; propodus subrectangular, anterior margin naked except for distal fringe of short SS, palm slightly oblique, posterior margin with numerous long SS; dactylus slender, slightly curved, posterior margin strongly serrate. Gnathopod 2 slightly longer than gnathopod 1; coxa 2 similar in shape to coxa 1, tapering distally; basis linear, merus anterior margin very short, distal margin obliquely articulating with carpus, with group of 4 SS posterodistally; carpus curved proximally, widened distally, anterior margin naked except for transverse row of SS distally, posterior margin with numerous stout SS distally; propodus 0.8 x carpus length, palm lined with numerous submarginal RS; dactylus large, exceeding palm, posterior margin serrate. Pereopod 3 coxa wider and slightly longer than coxa 2, posterior margin concave; basis linear, extending just further than coxa, anterior margin finely setulose; merus slightly expanded distally, carpus slightly widened distally, anterior margin naked, posterior margin with pairs of RS; propodus same length as carpus, naked anteriorly, posterior margin with pairs of RS; dactylus stout, curved, 0.5 x propodus length. Pereopod 4 coxa much longer than 3, 1.3 x longer than wide, anterior margin straight, produced into stout, acute 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, wider than long; basis linear, scarcely covered by coxa, distal margin two rounded lobes; ischium distal margin also forming two lobes; carpus slightly widened distally, anterior margin with few SS; propodus with 6 pairs of RS; dactylus slightly curved, stout. Pereopod 6 coxa anterior half hidden by coxa 5, posterodistal corner rounded, posterior margin broadly rounded; basis wider than of pereopod 5, posterior margin slightly convex, ischium to dactylus as in pereopod 5. Pereopod 7 coxa small, rounded; basis wider than pereopod 6, posterior margin convex; ischium to dactylus as in pereopods 5– 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 margins naked except for few short RS on peduncle; inner ramus length 1.3 x outer ramus. Uropod 3 peduncle shorter than inner ramus, produced into weak process; outer ramus both margins with row of short RS, inner margin with few short RS along distal 0.5 of length; outer ramus 0.8 x length of inner. Telson weakly tapering to c. 0.8 of basal width proximally, longer than wide, u-shaped emargination 0.2 x length, lobes triangular, broadly rounded apically.

Remarks. The original brief description of E. bruuni was based on a single juvenile specimen, 7 mm in length. Apart from the lateral habitus view, only the gnathopods, the third uropod and the telson were figured ( Barnard 1961). The present redescription is based on an adult specimen of 25 mm length and includes most appendages. The main differences between the juvenile type specimen and the recently collected adult specimen are listed in Table 1 .

Distribution. New Zealand: Kermadec Trench and Young Nicks Seamount, Hikurangi Plateau; 2470– 2526 m.

Coxa 4 (see Fig. 8 ) Strongly attenuated & geniculate Apex blunt Corner more produced

but narrow

Twenty-six species in the amphipod family Epimeriidae are currently known worldwide but they are mainly distributed in the Southern Hemisphere, primarily the Southern Ocean. Few species are known from South America and South Africa, none from Australia and now four from New Zealand waters.

Three of the New Zealand epimeriid species are only known from the deep sea. Epimeria horsti sp. nov. was collected on two seamounts in 970 and 1030 m depth, Epimeria glaucosa Barnard, 1961 and Epimeria bruuni Barnard, 1961 were collected during the Galathea II, Danish Deep Sea Expedition 1950–52, in 3710 m depth in the Tasman Sea and 2470 m depth in the Kermadec Trench, respectively.

The fourth New Zealand species of Epimeriidae , Epimeriella victoria ( Hurley, 1957) occurs in shallower water than New Zealand species of Epimeria . Epimeriella victoria was originally described in Epimeria based on a male collected at 140 m in Cook Strait. Moore (1985) transferred it to the genus Epimeriella and complemented the type description with a female from 130 m depth off Otago, extending the known distribution of this species to the South Island. The large, ridged mandibular molar processes, diagnostic of the genus Epimeria , is replaced in Epimeriella , including E. victoria , by a thin setose lamina ( Moore 1985). Coleman (2007) listed the wide hypopharyngeal gap of the lower lip as the second character separating Epimeriella from Epimeria , the later bearing a “normal” lower lip. The distinction in lower lip morphology between Epimeria and Epimeriella recognised by Coleman (2007), however, requires further study — the hypopharyngeal gap of the lower lip of Epimeriella victoria does not appear to very wide (see Hurley 1957: fig. 5). Clearly, morphological character separation has to be tested more rigorously to resolve whether Epimeriella should be retained. Ongoing studies combining morphological characters and DNA sequence data will test the validity of Epimeriella as distinct from Epimeria . A key to the New Zealand Epimeriidae is given below.

Figures

FIGURE 6. Epimeria bruuni Barnard, 1961; female, 25 mm, NIWA 4088. Habitus lateral. Antenna 1 (A 1). Upper lip (labrum, uL). Lower lip (hypopharynx, LL). Antenna 2 (A 2). Maxilliped (MxP). Mandible (Mnd). Habitus scale bar 10 mm, other scale bars 1 mm.

FIGURE 7. Epimeria bruuni Barnard, 1961; female, 25 mm, NIWA 4088. Maxilla 1 (Mx 1). Maxilla 2 (Mx 2). Gnathopd 1 (G 1). Gnathopod 2 (G 2). Pereopod 3 (P 3). Pereopod 4 (P 4). Scale bars 1 mm.

FIGURE 8. Epimeria bruuni Barnard, 1961; female, 25 mm, NIWA 4088. 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). Coxa 4 (C 4) of holotype ZMUC CRU- 5922 (left) and of 25 mm female, NIWA 4088 (right). Scale bars 1 mm.

Tables

TABLE 1. Major distinguishing features between between Epimeria bruuni Barnard, 1961 and E. horsti sp. nov.

	Epimeria bruuni , 7 mm	Epimeria bruuni , 25 mm
Carina begins Blunt teeth present	Pereon 6 Pereon 7–Epimeron 2	Pereon 5 Pereon 6–Epimeron 3
Coxa 1–3	Similar in shape	Coxa 3 longer and wider than coxa 1–2