Epimeria (Subepimeria)

d’Acoz, Cédric d’Udekem & Verheye, Marie L., 2017, Epimeria of the Southern Ocean with notes on their relatives (Crustacea, Amphipoda, Eusiroidea), European Journal of Taxonomy 359, pp. 1-553 : 153-155

Epimeria (Subepimeria) sp. 1

Epimeria puncticulata – K.H. Barnard 1932: 175, fig. 104d.

Epimeria sp. n. 1 – Rauschert & Arntz 2015: 60, pl. 53.

non Epimeria puncticulata K.H. Barnard, 1930: 377 , fig. 42.

Material (not examined)

Discovery Investigations 1926–1927:

R.V. Discovery cruises:

SOUTHERN OCEAN: 1 ♀, 13 mm, stn 45, South Georgia, 2.7 miles S 85°E of Jason Light, N 4-T (net with mesh of 4 mm attached to the back of the trawl) and NCS-T (tow-net of coarse silk, with 16 meshes to the linear inch, attached to trawl), 238–270 m, grey mud, 6 Mar. 1926 ( NHM 1936.11.2. 1581– 1590); 3 ♀♀, 11–13 mm, stn 123, South Georgia, off mouth of Cumberland Bay, N 4-T (net with mesh of 4 mm attached to the back of the trawl) and OTL (large otter trawl), 230–250 m, grey mud, 15 Dec. 1926 ( NHM 1936.11.2. 1581–1590); 8 ♀♀, 10–13 mm, stn 140, South Georgia, Stromness Harbour to Larsen Point, N 4-T (net with mesh of 4 mm attached to the back of the trawl), 122–136 m, green mud, stn, 23 Dec. 1926, ( NHM 1936.11.2. 1581–1590); 1 ♂, 10.5 mm, stn 148, South Georgia, off Cape Saunders, N 4-T (net with mesh of 4 mm attached to the back of the trawl) and OTL (large otter trawl), 200–234 m, grey mud, stn, 10 Jan. 1927 ( NHM 1936.11.2. 1581–1590).

R.V. William Scoresby cruises:

SOUTHERN OCEAN: 1 ♂, 7 mm, stn WS 33, South Georgia, 54°59ʹ S, 35°24ʹ W, N 100 H (1 m tow net), 135 m, grey mud, 21 Dec. 1926 ( NHM 1936.11.2. 1581–1590); 1 juv., 5.5 mm, Marine Biological Station, stn MS 71, South Georgia, East Cumberland bay, BTS (small beam trawl) and NCS-T (townet of coarse silk, with 16 meshes to the linear inch, attache to trawl), 60–110 m, 9 Mar. 1926 ( NHM 1936.11.2. 1581–1590).

Description

Description based on the photograph of Rauschert & Arntz (105) and K.H. Barnard’s (1932) account.

ROSTRUM. in lateral view short reaching about tip of article 1 of peduncle of antenna 1, distinctly curved on the proximal half of its anterior border.

EYES. Large, broadly elliptic. PEREION–PLEOSOME TOOTH PATTERN. Pereionites 1–6 totally smooth; pereionite 7 keeled with small blunt posterodorsal tooth; pleonites 1–2 keeled with well developed acute posterodorsal tooth; pleonite 3 keeled with posterodorsal tip forming a very strong blunt protrusion.

COXAE 1–3. Tip blunt.

COXA 4. Of medium width; anterodorsal border proximally nearly straight; anteroventral border straight (transition between anterodorsal and anteroventral border gradual, but with rather distinct anterior corner); the coxa is not projecting forward; ventral corner forming a squared angle, of which the tip is blunt but not rounded; posteroventral border nearly straight (very weakly concave); posterodorsal border as long as posteroventral border.

EPIMERAL PLATES 2–3. Produced into a medium-sized tooth.

UROSOME TOOTH PATTERN. Urosomite 1 with low and blunt triangular dorsal process.

BASIS OF PEREIOPOD 7. Broad; posterior border weakly convex, terminated into a blunt, obtuse (nearly squared) angle.

Colour pattern

“Pale yellow. Each of first 7 segments with a transverse pale brown band dorsally along both anterior and posterior margins. Large side-plate of 4th segment largely red-brown. Posterior segments yellow mottled with brown. Caudal appendages and legs pale yellow. Eyes red” (K.H. Barnard 1932). Whitish with scattered orange dotting and mottling; peduncle of antennae and dorsal process of urosomite 1 red; eyes red (specimen photographed by M. Rauschert).

Body length

13 mm (K.H. Barnard 1932) or 14 mm (specimen photographed by M. Rauschert).

Distribution

South Georgia, 60–270 m (K.H. Barnard 1932 as Epimeria puncticulata ); “Scotia Arc”, 280 m ( Rauschert & Arntz 2015 as Epimeria sp. 1).

Remarks

From discussions with C.O. Coleman and W. Arntz, it transpires that large parts of Rauschert’s collections are not yet registered and thus currently inaccessible. Therefore, the “ Epimeria sp. n. 1” from Rauschert & Arntz (2015) could not be found and its precise collection locality is unknown. An early draft of the book of Rauschert & Arntz (2015) simply indicated that it was collected during the cruise ‘ANT XIX’ in the ‘Scotia Arc’. However, the diagnosis of ‘ Epimeria puncticulata ’ from South Georgia by K.H. Barnard (1932) is in agreement with the photograph of ‘ Epimeria sp. n. 1’: “the 7 th peraeon segment ends in a short medio-dorsal point, the keels on pleon segments 1 and 2 end in slightly more prominent points, and the triangular projection on segment 4 is more sharply pointed than in the Terra Nova specimens.” M. Rauschert took part in cruise ANT-XIX/5, which sampled extensively around South Georgia ( Arntz & Brey 2003). Therefore, there is a high probability that Rauschert’s specimens were collected off South Georgia, just as the specimens of K.H. Barnard (1932). Because of time constraints, it was impossible to borrow and to re-examine K.H. Barnard’s (1932) specimens, deposited in the Natural History Museum in London: NHM 1936.11.2. 1581–1590, six tubes together in the same jar, no specific number allocated to each tube (M. Lowe pers. com.). The species is treated herein as Epimeria (Subepimeria) sp. 1. When examination of specimens will be possible, it will presumably have to be described as a new species.

The dorsal tooth pattern of the Epimeria (Subepimeria) sp. 1 is very different from that of other West-Antarctic Subepimeria examined. It is similar to that of Epimeria adeliae sp. nov. from Adélie Coast. However, the shape of the posterodorsal protrusion on pleonite 3 is different: blunt in Epimeria (Subepimeria) sp. 1 (see Rauschert & Arntz 2015, as Epimeria sp. 1), whereas it forms a squared angle in E. adeliae sp. nov. The anteroventral border of coxa 4 is also more straight and the protrusion on urosomite 1 lower in Epimeria (Subepimeria) sp. 1 than in E. adeliae sp. nov.