Epimeria (Drakepimeria) acanthochelon, 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 : 22-26

Epimeria (Drakepimeria) acanthochelon subgen. et sp. nov.

urn:lsid:zoobank.org:act:B878492E-3294-4449-A17D-DBD502918370

Figs 1–7

Epimeria similis – Coleman 2007: 54, in part, plate 1 fig. e only. — Lörz & Coleman 2009: unnumbered photograph on p. 17. — Rauschert & Arntz 2015: 62, pl. 55 unnumbered photograph.

‘ Clade A similis / macrodonta complex - SI3’ – Verheye et al. 2016a, supplement: 2 (online).

non Epimeria similis Chevreux, 1912: 215 .

Etymology

From the Greek ακανθα, spine; χελώνη, tortoise. The name, which is a noun in apposition, alludes to the toothed and heavily calcified body of the species, which can be compared to a spiny tortoise.

Type material

Holotype

RV Polarstern cruises:

SOUTHERN OCEAN: ♀, cruise CEAMARC, sample CEAMARC 1421, stn 62EV303, Adélie Coast, 66°10ʹ34″ S, 143°20ʹ45″ E, 532–550 m, beam trawl, 4 Jan. 2008 (coll. IPEV-AAD-MNHN, removed from MNHN-IU-2014-4342, now MNHN-IU-2014-7321 ) [extraction M7; Genbank nr, 28S: KU759674 ].

Paratypes

RV Polarstern cruises:

SOUTHERN OCEAN: 4 specs, cruise PS39, ANT-XIII/3, EASIZ I, stn 1, GSN 1, eastern Weddell Sea, 71°03.10ʹ S, 11°25.50ʹ W to 71°02.10ʹ S, 11°19.30ʹ W, 462–481 m, bottom trawl, 5 Feb. 1996 (previously identified as Epimeria cf. similis and used for gut content studies), coll. C. De Broyer and G. Chapelle ( RBINS, INV. 132698); 1 spec., cruise PS39, ANT-XIII/3, EASIZ I, stn 1, GSN 1, eastern Weddell Sea, 71°03.10ʹ S, 11°25.50ʹ W to 71°02.10ʹ S, 11°19.30ʹ W, 462–481 m, bottom trawl, 5 Feb. 1996, coll. C. De Broyer and G. Chapelle ( RBINS, INV. 132699); 1 spec., cruise PS39, ANT-XIII/3, EASIZ I, stn 6, AGT 1, eastern Weddell Sea, 71°31.80ʹ S, 13°34.50ʹ W to 71°31.86ʹ S, 13°35.50ʹ W, 254–261 m, Agassiz trawl, 8 Jan. 1996, coll. C. De Broyer and G. Chapelle, ( RBINS, INV. 132697); 1 spec., cruise PS39,ANT-XIII/3, EASIZ I, stn 6, AGT 1, eastern Weddell Sea, 71°31.80ʹ S, 13°34.50ʹ W to 71°31.86ʹ S, 13°35.50ʹ W, 254–261 m, Agassiz trawl, 8 Jan. 1996, coll. C. De Broyer and G. Chapelle, ( RBINS, INV. 132706); 1 spec., cruise PS39, ANT-XIII/3, EASIZ I, stn 9, AGT 10, eastern Weddell Sea, 71°34.70ʹ S, 12°26.60ʹ W to 71°34.80ʹ S, 12°25.90ʹ W, 560–571 m, Agassiz trawl, 26 Feb. 1996, coll. C. De Broyer ( RBINS, INV. 132696); ca 30 specs of all sizes, cruise PS39, ANT-XIII/3, EASIZ I, stn 29, BPN 4, eastern Weddell Sea, 71°31.50ʹ S, 12°25.50ʹ W to 71°30.30ʹ S, 12°27.80ʹ W, 204–529 m, 28 Feb. 1996, coll. C. De Broyer ( RBINS, INV. 132705);

RV Aurora Australis cruises:

SOUTHERN OCEAN: 1 spec., cruise CEAMARC, sample CEAMARC 300, stn 30EV66, Adélie Coast, 65°59ʹ50″ S, 143°39ʹ00″ E, 421–440 m, beam trawl, 24 Dec. 2007, coll. IPEV-AAD-MNHN (MNHN-IU-2014-4340) [extraction M5; Genbank nr, 28S: KU759672 ]; 2 specs, cruise CEAMARC, sample CEAMARC 1317, stn 51AEV215, Adélie Coast, 66°44ʹ52″ S, 145°26’40″ E, 525–553 m, beam trawl, 30 Dec. 2007, coll. IPEV-AAD-MNHN (MNHN-IU-2014-4279); 1 spec. (possibly ♂), cruise CEAMARC, sample CEAMARC 1383, stn 50AEV220, Adélie Coast, 66°45ʹ09″ S, 145°20ʹ04″ E, 567– 604 m, beam trawl, 30–31 Dec. 2007, coll. IPEV-AAD-MNHN (MNHN-IU-2014-4271); 3 specs, cruise CEAMARC, sample CEAMARC 1384, stn 50AEV220, Adélie Coast, 66°45ʹ09″ S, 145°20ʹ04″ E, 567– 604 m, beam trawl, 30–31 Dec. 2007, coll. IPEV-AAD-MNHN (MNHN-IU-2014-4332); 1 spec., cruise CEAMARC, sample CEAMARC 1384, stn 50AEV220, Adélie Coast, 66°45ʹ09″ S, 145°20ʹ04″ E, 567– 604 m, beam trawl, 30–31 Dec. 2007, coll. IPEV-AAD-MNHN (MNHN-IU-2014-4333) [extraction M8; Genbank nr, 28S: KU759675 ]; 2 specs, in one specimen lateral points of coxa 4 broken, cruise CEAMARC, sample CEAMARC 1421, stn 62EV303, Adélie Coast, 66°10ʹ34″ S, 143°20ʹ45″ E, 532– 550 m, beam trawl, 4 Jan. 2008, coll. IPEV-AAD-MNHN (MNHN-IU-2014-4342); 3 specs, 1 adult and 2 immatures, cruise CEAMARC, sample CEAMARC 1643, stn 31EV268, Adélie Coast, 66°34ʹ30″ S, 145°01ʹ15″ E, 429–451 m, beam trawl, 3 Jan. 2008, coll. IPEV-AAD-MNHN (MNHN-IU-2014-4322) [extraction M9; Genbank nr, 28S: KU759676 ]; 2 specs, cruise CEAMARC, sample CEAMARC 1951, stn 36EV297, Adélie Coast, 66°20ʹ20″ S, 143°41ʹ08″ E, 552–573 m, beam trawl, 1 Jan. 2008, coll. IPEV-AAD-MNHN (MNHN-IU-2014-4280); 1 spec., cruise CEAMARC, sample CEAMARC 2724, stn 71EV447, Adélie Coast, 66°23ʹ60″ S, 140°32ʹ21″ E, 683–791 m, beam trawl, 14 Jan. 2008, coll. IPEV-AAD-MNHN (MNHN-IU-2014-4337).

RV L’Astrolabe cruises:

SOUTHERN OCEAN: 3 specs, cruise REVOLTA III, stn none (Dumont d’Urville Sea), Collect_ID: REVO_449, Field_ID: CE-000002101, Adélie Coast, 66°38ʹ S, 140°42ʹ E to 66°38ʹ S, 140°40ʹ E, 718–729 m, mud, beam trawl, 20 Jan. 2012, coll. G. Lecointre, A. Dettaï, J. Lanshere, C. Gallut and C. Ozouf (MNHN-IU- 2009-2539) [extraction K7 (largest specimen); Genbank nr, 28S: KU759659 ]; 1 spec., cruise REVOLTA III, stn none (Dumont d’Urville Sea), Collect_ID: REVO_449, Field_ID: CE- 000002239, Adélie Coast, 66°38ʹ S, 140°42ʹ E to 66°38ʹ S, 140°40ʹ E, 718–729 m, mud, beam trawl, 20 Jan. 2012, coll. G. Lecointre, A. Dettaï, J. Lanshere, C. Gallut and C. Ozouf (MNHN-IU- 2009-2532) [extraction K6; Genbank nr, 28S: KU759658 ].

Belgian and Belgian-Dutch Antarctic expedition:

SOUTHERN OCEAN: 1 spec., Princess Ragnhild Coast, stn 133, Baie Léopold, 70°19ʹ09″ S, 24°13ʹ05″ E to 70°19ʹ08″ S, 24°12ʹ06″ E, 240 m, trawl, year 1961, coll. A. Capart ( RBINS, INV. 132748); 1 spec., Princess Ragnhild Coast, stn 139, coordinates unavailable, year 1961, coll. A. Capart ( RBINS, INV. 132749); 1 spec. (possibly ♂), Princess Ragnhild Coast, stn 150, Baie Léopold, 70°20ʹ04″ S, 24°13ʹ E, 255 m, dredge, 20 Jan. 1961, coll. A. Capart ( RBINS, INV. 132746); 1 spec., Princess Ragnhild Coast, stn 219, Baie du Glacier, 70°18ʹ05″ S, 23°58ʹ00″ E, 216 m, trawl, 31 Jan. 1965, coll. A. Capart ( RBINS, INV. 132745); 1 spec., Princess Ragnhild Coast, stn 220, Baie du Glacier, exact coordinates unavailable [presumably about 70°18ʹ S, 23°58ʹ E], 414–450 m, 1 Feb. 1965, trawl, coll. A. Capart ( RBINS, INV. 132734).

Description

ROSTRUM. Long, reaching about tip of article 1 of peduncle of antenna 1 (teeth excluded), weakly curved, sharp-tipped in lateral view.

EYE. Very large, elliptic.

PEREION–PLEOSOME TOOTH PATTERN. Mid-dorsal tooth on all segments or from pereionite 2 onwards; pair of non-carinate posterodorsal teeth or swellings on all segments; pereionite 1 often with small but distinct mid-dorsal tooth or scarcely distinct bump, with pair of very low non-carinate dorsolateral swellings; pereionite 2 nearly as broad as pereionite 1, with mid-sized blunt-tipped mid-dorsal tooth and pair of dorsolateral swellings or very blunt teeth; pereionite 3 with well-developed blunt-tipped regularly curved broad, mid-dorsal tooth and pair of dorsolateral blunt teeth; pereionite 3 to pleonite 2 with acute-tipped broad and regularly curved mid-dorsal tooth (nearly same shape and size on all these segments) and pair of small non-carinate acute-tipped dorsolateral teeth (pleonites 1–2 without second pair of dorsolateral teeth); pleonite 3 with dorsal sharp carina with distinct median notch (lobe anterior to notch distinctly curved) and obliquely produced posteriorly into an a broad acute and sharp triangular tooth, and pair of dorsolateral non-carinate acute-tipped teeth.

COXAE 1–3. Strongly carinate and distally sharp.

COXA 4. Anterodorsal and anteroventral border nearly straight, joined by low and blunt angular discontinuity, anterior angle not strongly projecting forward; ventral tooth very long and styliform; lateral carina with lateral long and sharp triangular tooth pointing obliquely backwards, carina very distant from margin of coxa at its deepest point.

COXA 5. With long, sharp and narrowly triangular, carinate, lateral tooth pointing obliquely backwards.

COXA 6. With mid-sized, sharp and narrowly triangular, carinate, lateral tooth pointing obliquely backwards; posteroventral corner produced into a triangular tooth.

COXA 7. With ventral and posterior border straight, with posteroventral angle produced into a strong tooth.

EPIMERAL PLATES 1–3. Posteroventral angle produced into a very long styliform tooth.

UROSOME TOOTH PATTERN. Urosomite 1 with sharp triangular process pointing upwards; urosomite 2 without pair of small posterior dorsolateral teeth pointing upwards.

TELSON. Cleft on 0.3; tips of lobes sharp, slit narrow.

PEDUNCLE OF ANTENNA 1. Article 1 with long lateral and medial teeth reaching mid of article 2 (teeth excluded) and long ventral tooth reaching tip of article 2 (teeth excluded); article 2 with long lateral tooth nearly reaching tip of article 3, with medial tooth slightly overreaching article 3 (ventral tooth excluded), with ventral tooth slightly overreaching tip of article 3 (tooth excluded); article 3 with very long ventral tooth, longer than article itself.

GNATHOPODS 1–2. Carpus and propodus of normal slenderness; propodus not narrowing distally, palm distinct.

PEREIOPODS 5–7. Merus, carpus and propodus very slender; basis of pereiopods 5–6 of normal width, with posteroproximal process rounded and strongly protruding, with posterodistal tooth strong; basis of pereiopod 7 very broad with posterodistal tooth sharp, followed more proximally by small concavity, directed posteriorly.

Colour pattern

Body and appendages white with a pinkish hue on posterior dorsal crests, peduncles of antennae and the distal half of pereiopods; eyes red (photograph of a specimen from Adélie Coast, MNHN-IU- 2009-2539). The specimen from the eastern shelf of the Weddell Sea illustrated by Rauschert & Arntz (2015) under the name of Epimeria similis exhibits a diffuse orange pattern on a whitish background.

Body length

Up to 45 mm.

Distribution

Eastern shelf of the Weddell Sea, Princess Ragnhild Coast, Adélie Coast; depth range 204– 791 m.

Biology

Dauby et al. (2001a) observed the following items in the gut content of Epimeria from the eastern Weddell Sea identified by them as E. similis : cnidocysts of various size and shape, some of them identified as from hydrozoans of the genera Tubularia and Campanula , and others to actiniids. Other items observed were: planktonic cells (diatoms and foraminifers), spicules of sponges and setae of polychaetes. Dauby et al. (2001b) concluded that it is a micropredatory browser. These specimens were presumably Epimeria acanthochelon sp. nov., as that species was collected in large numbers during the cruise EASIZ I, and as the material studied by these authors was largely based on material collected during that cruise. Epimeria similis s. str. is not present in the eastern Weddell Sea.

Remarks

Epimeria acanthochelon sp. nov. (type locality: Adélie Coast) is morphologically extremely similar to E. similis from the tip of the Antarctic Peninsula and South Shetland Islands. However, results of molecular analyses based on 28S rDNA suggest that they would be distinct species ( Verheye et al. 2016a; this paper Fig. 342 ). Specimens from the eastern shelf of the Weddell Sea are also identified as E. acanthochelon sp. nov., albeit on basis of their morphology only. A genetic characterization of specimens from that area would be desirable whenever possible. Epimeria acanthochelon sp. nov. often has a small tooth or a trace of mid-dorsal tooth on pereionite 1, which is absent in E. similis . The dorsal teeth of other segments have a slightly different form, with those of the second and third segments being more developed in E. acanthochelon sp. nov. than in E. similis . The carina of pleonite 3 also has a stronger anterior lobe followed by a deeper median notch in E. acanthochelon sp. nov. than in E. similis . Coxa 7 often has a stronger posteroventral tooth in E. acanthochelon sp. nov. than in E. similis . Finally, the telson notch is also slightly deeper in E. acanthochelon sp. nov. than in E. similis .

The specimen illustrated by a photograph in Coleman (2007: plate 1 fig. e), Lörz & Coleman (2009: unnumbered photograph on p. 17) and Rauschert & Arntz (2015: 62, plate 55) and identified by them as Epimeria similis is probably E. acanthochelon sp. nov. On page 125, Rauschert & Arntz (2015) indicated that it was collected on the eastern shelf of the Weddell Sea and in an early draft of their book made available to the authors, it is specified that it was collected during the cruise ANT-XIII/3, which indeed sampled on the eastern shelf of the Weddell Sea ( Arntz & Gutt 1997). Its morphology matches perfectly with the description of E. acanthochelon sp. nov.: the posteroventral tooth of its coxa 7 is stronger and the anterior lobe of the dorsal crest of pleonite 3 is more developed than in E. similis .

Figures

Fig. 1. Epimeria (Drakepimeria) acanthochelon subgen. et sp. nov. A–B. ♀, holotype, Adélie Coast, CEAMARC 1421, MNHN-IU-2014-7321. A. Lateral habitus. B. Dorsal habitus. C. Sex undetermined, paratype, Adélie Coast, REVOLTA III, Num_Collecte/Collect_ID: REVO_449, MNHN-IU-2009-2539, colour in life, photograph Cyril Galut.

Fig. 2. Epimeria (Drakepimeria) acanthochelon subgen. et sp. nov., ♀, holotype, Adélie Coast, CEAMARC 1421, MNHN-IU-2014-7321. A. Facial habitus. B. Head in facial view.

Fig. 3. Epimeria (Drakepimeria) acanthochelon subgen. et sp. nov., ♀, holotype, Adélie Coast, CEAMARC 1421, MNHN-IU-2014-7321. A. Coxae. B. Urosome and posterior part of pleosome.

Fig. 4. Epimeria (Drakepimeria) acanthochelon subgen. et sp. nov., ♀, holotype, Adélie Coast, CEAMARC 1421, MNHN-IU-2014-7321. A. Head in lateral view. B. Urosome in dorsal view. C. Telson.

Fig. 5. Epimeria (Drakepimeria) acanthochelon subgen. et sp. nov., ♀, holotype, Adélie Coast, CEAMARC 1421, MNHN-IU-2014-7321. A. Gnathopod 1. B. Gnathopod 2.

Fig.6.Epimeria(Drakepimeria)acanthochelonsubgen.etsp.nov.,♀,holotype,AdélieCoast, CEAMARC 1421, MNHN-IU-2014-7321. A. Pereiopod 4. B. Pereiopod 5. C. Pereiopod 6. D. Pereiopod 7.

Fig. 7. Epimeria (Drakepimeria) acanthochelon subgen. et sp. nov., ♀, paratype, Adélie Coast, CEAMARC 1643, MNHN-IU-2014-4322. A. Anterior half in lateral view. B. Head and two first body segments in lateral view.

Fig. 342. Phylogenetic tree obtained by Bayesian analysis of the concatenated COI and 28S sequences, updated from Verheye et al. (2016). Bayesian posterior probabilities and bootstrap values (from the Maximum Likelihood analysis) are indicated above the nodes of interest. Bootstrap values inferior to 50 are not indicated. Besides the species names are indicated the MOTUs codes used in Verheye et al. (2016). The Genbank accession number of the outgroup species: Gnathiphimedia sexdentata (Schellenberg, 1926) are KU870835 (COI) and KU759609 (28S).