Epimeria (Hoplepimeria) robustoides, d’Acoz & Verheye, 2017

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 : 99-101

Epimeria (Hoplepimeria) robustoides subgen. nov. Lörz & Coleman in Lörz et al., 2009

Figs 212–219

Epimeria robustoides Lörz & Coleman in Lörz et al., 2009: 10 , figs 2–5, possibly fig. 10A [it might also be E. gargantua sp. nov.].

Epimeria robusta – Coleman 1994: 560, in part, figs 5A–B, 5E–G, 6–8 (not figs 5C–D). — Klages & Gutt 1990: 73, fig. 1A, 4A–D.

‘ Epimeria robustoides 2ʹ – Rauschert & Arntz 2015: 62, pl. 55, unnumbered photograph.

‘Clade G robusta / robustoides complex - R02ʹ – Verheye et al. 2016a, supplement: 4 (online).

non ‘ Epimeria robustoides 1’ – Rauschert & Arntz 2015: 62, pl. 55, unnumbered photograph (= Epimeria

(Hoplepimeria) sp.).

Material examined

RV Polarstern cruises:

SOUTHERN OCEAN: 3 specs, dorsally opened for gut content analysis, cruise PS14, ANT-VII/4, EPOS 3, stn 290 (AGT 24), 71°05.9ʹ S, 12°34.0ʹ W to 71°06.5ʹ S, 12°42.3ʹ W, 522–531 m, 19 Feb. 1989, coll. C. De Broyer ( RBINS, INV. 132944); 1 ♀, cruise PS69, ANT-XXIII/8, stn 603-5, eastern Weddell Sea, 70°30.99ʹ S, 08°48.08ʹ W to 70°30.40ʹ S, 08°48.13ʹ W, 274–297 m, sponge bottom, Agassiz trawl, 7 Dec. 2006, coll. C. d’Udekem d’Acoz and H. Robert ( RBINS, INV. 132985); 1 juv., cruise PS71, ANT- XXIV/2, ANDEEP-SYSTCO, stn 48-1, eastern Weddell Sea, 70°23.94ʹ S, 8°19.14ʹ W to 70°23.89ʹ S, 8°18.67ʹ W, 595–602 m, bryozoan bottom (exceptional bryozoan diversity), Rauschert dredge, 12 Jan. 2008:, coll. H. Robert ( RBINS, INV. 132969) [extraction I8; Genbank nr, COI: KU870852 , 28S: KU759629 ]; 1 ♀, cruise PS77, ANT-XXVII/3, CAMBIO, stn 265-2, eastern Weddell Sea, 70°47.34ʹ S, 10°40.39ʹ W to 70°47.13ʹ S, 10°40.54ʹ W, 500–600 m, 22 Mar. 2011, coll. C. Havermans and H. Robert ( RBINS, INV. 122894) [extraction Ex114; Genbank nr, COI: KU870834 , 28S: KU759608 ].

Description

ROSTRUM. Medium-sized, nearly reaching tip of article 1 of peduncle of antenna 1, anteriorly straight, ventrally straight, narrow and subacute in lateral view; of medium width and with straight converging borders in frontal view.

EYE. Very large, narrowly elliptic.

PEREION–PLEOSOME TOOTH PATTERN. Pereionites 1–6 smooth; pereionite 7 with weak posterior bump; pleonite 1 dorsally distinctly carinate, straight, with distinct posterior bump or small very blunt tooth; pleonite 2 dorsally distinctly carinate, with very low proximal rounded lobe followed by weak concavity, posteriorly produced into a bluntly triangular tooth projecting obliquely upwards; pleonite 3 dorsally distinctly carinate with median very low rounded lobe, followed by distinct concavity, terminated by a blunt tooth directed upwards.

COXAE 1–3. Not carinate, apically subacute.

COXA 4. Anterodorsal border very weakly sigmoid, anteroventral border nearly straight (extremely weakly convex), these two borders being joined by very broad blunt, very distinct squared angle (anterior corner), which is slightly projecting forward; ventral corner forming an obtuse sharp angle (ventral projection short and fairly broad); lateral carina absent; posteroventral border straight.

COXA 5. Broad, with surface smooth, with posterior border straight, with posteroventral corner forming a very blunt tooth (shape: acute triangle) projecting backwards and not laterally (no tooth or corner visible in dorsal view).

COXA 6. With posterior border straight, with posteroventral corner forming a blunt tooth (shape: narrow acute triangle) projecting backwards and not laterally (no tooth or corner visible in dorsal view).

COXA 7. Posteriorly very weakly rounded.

EPIMERAL PLATES 1–3. Posteroventral angle: angulate with tiny tooth in plate 1, produced into a mediumsized tooth in plates 2–3.

UROSOME TOOTH PATTERN. Urosomite 1 with well developed blunt-tipped process of which the anterior border is distinctly concave and the posterior border is straight; urosomite 3 with dorsolateral borders strongly concave and posteriorly produced into a sharp triangular tooth.

TELSON. Cleft on 0.25; tips of lobes triangular and blunt, notch very broadly V-shaped and subacute at its deepest point.

GNATHOPODS 1–2. Carpus and propodus very broad; propodus expanding distally, palm distinct.

PEREIOPODS 5–7. Merus, carpus and propodus fairly broad; dactylus small, normally curved, with unguis normally developed; basis of pereiopods 5–6 broad, with posteroproximal process present, swordlike, projecting obliquely, with posterodistal corner produced into a rounded lobe projecting obliquely backwards (pereiopod 5) or a blunt triangular tooth projecting obliquely backwards (pereiopod 6); basis of pereiopod 7 broad; posterior border with proximal 0.4 with weak concavity, with distal 0.6 deeply concave, with posterodistal corner forming a blunt triangular tooth projecting obliquely backwards.

Colour pattern

Body and coxae either pure white, or white with two pairs of small yellow spots transversally ordered on some body segments; gnathopods and oral field deep purple; antennae yellowish; pereiopods 3–4 pink; pereiopods 5–7 with basis white and distal articles pale yellowish to orange; tailfan white or whitish; eye red.

Body length

Up to 40 mm.

Distribution

Eastern shelf of the Weddell Sea, 274–605 m ( Lörz et al. 2009; present data).

Biology

According to Klages & Gutt (1990), the digestive tract of specimens identified as E. robusta (but presumably belonging to E. robustoides as they were collected in the eastern Weddell Sea) contained mainly (42%) miscellaneous organic matter. Only in some specimens were siliceous sigma and other types of microspiculae of Demospongiae and calcareous spiculae of Calcispongiae found among sediment particles and organic material. In all the E. robusta stomachs examined by them, some 10% of the contents consisted of tentacles and body wall sclerites of holothurians. The tentacle sclerites of Abyssocucumis cf. liouvillei [i.e. Staurocucumis cf. liouvillei (Vaney, 1914)] ( Holothuroidea: Dendrochirotida ) in one single specimen were identified. On the other hand, Dauby et al. (2001a) recorded a wider range of organisms in the digestive tract of the species (also specimens from the Eastern Weddell Sea identified as E. robusta ): ophiuroids, plankton remains, sponges, cnidarians, polychaetes and crustaceans. Dauby et al. (2001b) concluded that E. robustoides would be an opportunistic predator. Klages (1991, as Epimeria robusta ) indicates that the species is sometimes parasitized by cryptoniscin isopods. Klages (1991, as E. robusta ) also observed that hatchlings of E. robustoides climb on the back of their mother and remain there for a short period of time.

Remarks

Epimeria robustoides is extremely similar to E. gargantua sp. nov., but the two species appear to have allopatric distributions. Epimeria robustoides has been recorded from the eastern shelf of the Weddell Sea, whilst E. gargantua sp. nov. has been found around the tip of the Antarctic Peninsula. Rauschert & Arntz (2015) do not indicate the coordinates of their illustrated ‘ Epimeria robustoides ’, but the origin of the specimens was listed in an early draft of their book made available to the authors. The specimen 2 of Rauschert & Arntz (2015) was collected during the Polarstern cruise ANT-XIII/3 (EASIZ 1), which sampled on the eastern shelf of the Weddell Sea; hence it is presumably E. robustoides . The specimen 1 of Rauschert & Arntz (2015) was collected on the Bruce Ridge (a small isolated shallow bank situated midway between the South Orkney Islands and the South Sandwich Islands) and presumably belongs to an undescribed species, which is referred herein as Epimeria (Hoplepimeria) sp. subgen. nov.

Figures

Fig. 212. Epimeria (Hoplepimeria) robustoides subgen. nov. Lörz & Coleman in Lörz et al., 2009, colour in life. A. ♀, eastern Weddell Sea, ANT-XXVII/3, stn 265-2, RBINS, INV. 122894. B–C. ♀, eastern Weddell Sea, ANT-XXIII/8, stn 603-5, RBINS, INV. 132985.

Fig. 213. Epimeria (Hoplepimeria) robustoides subgen. nov. Lörz & Coleman in Lörz et al., 2009, ♀, eastern Weddell Sea, ANT-XXVII/3, stn 265-2, RBINS, INV. 122894. A. Lateral habitus. B. Facial habitus.

Fig. 214. Epimeria (Hoplepimeria) robustoides subgen. nov. Lörz & Coleman in Lörz et al., 2009, ♀, eastern Weddell Sea, ANT-XXVII/3, stn 265-2, RBINS, INV. 122894. A. Pereiopod 5. B. Pereiopod 6. C. Pereiopod 7.

Fig. 215. Epimeria (Hoplepimeria) robustoides subgen. nov. Lörz & Coleman in Lörz et al., 2009, ♀, eastern Weddell Sea, ANT-VII/4, stn 290, RBINS, INV. 132944. A. Lateral habitus. B. Segments 2 and 3 of urosome.

Fig. 216. Epimeria (Hoplepimeria) robustoides subgen. nov. Lörz & Coleman in Lörz et al., 2009, ♀, eastern Weddell Sea, ANT-VII/4, stn 290. RBINS, INV. 132944. A. Facial habitus. B. Head in facial view.

Fig. 217. Epimeria (Hoplepimeria) robustoides subgen. nov. Lörz & Coleman in Lörz et al., 2009, ♀, eastern Weddell Sea, ANT-VII/4, stn 290. RBINS, INV. 132944. A. Coxae 1–7. B. Pleon.

Fig. 218. Epimeria (Hoplepimeria) subgen. nov. robustoides Lörz & Coleman in Lörz et al., 2009, ♀, eastern Weddell Sea, ANT-VII/4, stn 290. RBINS, INV. 132944. Head in lateral view and coxae 1–3.

Fig. 219. Epimeria (Hoplepimeria) robustoides subgen. nov. Lörz & Coleman in Lörz et al., 2009, ♀, eastern Weddell Sea, ANT-VII/4, stn 290. RBINS, INV. 132944. A. Basis of pereiopod 6. B. Basis of Pereiopod 7.