Epimeria (Hoplepimeria) gargantua, 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 : 78-81

Epimeria (Hoplepimeria) gargantua subgen. et sp. nov.

urn:lsid:zoobank.org:act:E5FDFA56-F77B-46D9-9665-644728A7970C

Figs 145–151

Epimeria robusta Klages, 1988: 73 , unnumbered fig., 76, 82, figs 20a–b.

Epimeria robustoides? Lörz & Coleman in Lörz et al., 2009: 10 , possibly in part, possibly fig. 10A, not figs 2–5 (= E. robustoides ).

Epimeria robusta – Coleman 1994: 560, in part, fig. 5D only.

‘ Clade G robustoides / robusta complex - RO1’ – Verheye et al. 2016a, supplement: 4 (online). non Epimeria robusta K.H. Barnard, 1930: 375 , figs 40a, 41.

non Epimeria robustoides Lörz & Coleman in Lörz et al., 2009: 10 , figs 2–5.

Etymology

Gargantua is a giant and one of the main characters in the tales of François Rabelais, such as ‘La vie très horrifique du grand Gargantua, père de Pantagruel’. The name, which is a noun in apposition, alludes to the huge size of the species, which is the largest known Epimeria species.

Type material

Holotype

RV Polarstern cruises:

SOUTHERN OCEAN: ♀, cruise PS81, ANT-XXIX/3, Bransfield Strait , stn 196-8, 62°47.80ʹ S, 57°5.35ʹ W to 62°47.63ʹ S, 57°5.63ʹ W, 542–580 m, trawl haul with huge stones and a lot of life, Agassiz trawl, 24 Feb. 2013, coll. C. d’Udekem d’Acoz and M. Verheye ( RBINS, INV. 122937A ) [extraction ANT 33; Genbank nr, COI: KU870820 , 28S: KU759592 ].

Paratypes

RV Polarstern cruises:

SOUTHERN OCEAN: 1 medium-sized spec., cruise PS69, ANT-XXIII/8, stn 662-1, between Elephant Island and King George Island, 61°35.91ʹ S, 57°17.04ʹ W to 61°35.41ʹ S, 57°20.60ʹ W, 425–432 m, bottom trawl, 30 Dec. 2006, coll. C. d’Udekem d’Acoz and H. Robert ( RBINS, INV. 122491); 2 large specs, cruise PS69, ANT-XXIII/8, stn 663-1, northeast of King George Island, 61°38.18ʹ S, 57°33.17ʹ W to 61°38.02ʹ S, 57°37.16ʹ W, bottom trawl, 432–434 m, 30 Dec. 2006, coll. C. d’Udekem d’Acoz and H. Robert ( RBINS, INV. 122494); 5 specs, cruise PS81, ANT-XXIX/3, Bransfield Strait, stn 196-8, 62°47.80ʹ S, 57°5.35ʹ W to 62°47.63ʹ S, 57°5.63ʹ W, 542–580 m, trawl haul with huge stones and a lot of life, Agassiz trawl, 24 Feb. 2013, coll. C. d’Udekem d’Acoz and M. Verheye ( RBINS, INV. 122937B); 1 spec., cruise PS81, ANT-XXIX/3, Bransfield Strait, stn 217-6, 62°53.45ʹ S, 58°13.06ʹ W to 62°53.42ʹ S, 58°13.41ʹ W, 461–483 m, rich sponge bottom, Agassiz trawl, 2 Mar. 2013, coll. C. d’Udekem d’Acoz and M. Verheye ( RBINS, INV. 122927) [extraction K37; Genbank nr, COI: KU870869 , 28S: KU759649 ]; 1 spec., cruise PS81, ANT-XXIX/3, Bransfield Strait, stn 217-6, 62°53.45ʹ S, 58°13.06ʹ W to 62°53.42ʹ S, 58°13.41ʹ W, 461–483 m, rich sponge bottom, Agassiz trawl, 2 Mar. 2013, coll. C. d’Udekem d’Acoz and M. Verheye ( RBINS, INV. 122928) [extraction K38; Genbank nr, COI: KU870870 , 28S: KU759650 ]; 7 specs, cruise PS81, ANT-XXIX/3, Bransfield Strait, stn 217-6, 62°53.45ʹ S, 58°13.06ʹ W to 62°53.42ʹ S, 58°13.41ʹ W, 461–483 m, rich sponge bottom, Agassiz trawl, 2 Mar. 2013, coll. C. d’Udekem d’Acoz and M. Verheye ( RBINS, INV. 132957); 1 spec., cruise PS81, ANT-XXIX/3, Bransfield Strait, stn 217- 6, 62°53.45ʹ S, 58°13.06ʹ W to 62°53.42ʹ S, 58°13.41ʹ W, 461–483 m, rich sponge bottom, Agassiz trawl, 2 Mar. 2013, coll. C. d’Udekem d’Acoz and M. Verheye (MNHN-IU-2014-7333, removed from RBINS, INV. 132957); 1 spec., cruise PS81, ANT-XXIX/3, Bransfield Strait, stn 227-2, 62°55.83ʹ S, 58°41.09ʹ W to 62°55.76ʹ S, 58°41.46ʹ W, 562–564 m, mud, Agassiz trawl, 5 Mar. 2013, RBINS, coll. C. d’Udekem d’Acoz and M. Verheye ( RBINS, INV. 122939) [extraction ANT 40; Genbank nr, COI: KU870826 , 28S: KU759599 ].

Description

ROSTRUM. Medium-sized, not reaching tip of article 1 of peduncle of antenna 1, anteriorly distinctly and regularly curved, ventrally straight, fairly narrow and subacute in lateral view; fairly narrow and with very weakly convex converging borders in frontal view.

EYE. Very large, broadly elliptic to more or less reniform. PEREION–PLEOSOME TOOTH PATTERN. Pereionites 1–7 smooth; pleonite 1 dorsally weakly carinate, very weakly convex, with distinct posterior bump; pleonite 2 dorsally distinctly carinate, with extremely low (nearly inconspicuous) proximal rounded lobe followed by extremely weak (nearly inconspicuous) concavity, posteriorly produced into a bluntly triangular tooth projecting backwards; 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 nearly straight (inconspicuously concave), anteroventral border straight, these two borders being joined by blunt but broad, very distinct squared angle (anterior corner), which is slightly projecting forward; ventral corner forming a very obtuse angle (ventral projection very short and very broad); lateral carina absent; posteroventral border nearly straight (inconspicuously convex).

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

COXA 6. With posterior border very weakly concave, 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 weakly rounded.

EPIMERAL PLATES 1–3. Posteroventral angle: angulate in plate 1, produced into a medium-sized tooth in plates 2–3.

UROSOME TOOTH PATTERN. Urosomite 1 with well developed blunt-tipped process of which both the anterior and the posterior borders have an angulate concavity (the anterior deeper); urosomite 3 with dorsolateral borders weakly concave and posteriorly produced into a sharp triangular tooth.

TELSON. Cleft nearly on 0.2; tips of lobes triangular and subacute, 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, very curved, with long unguis; basis of pereiopods 5–6 broad, with posteroproximal process present, sword-like, projecting obliquely, with posterodistal corner produced into a triangular tooth (with tip subacute), projecting backwards; 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 narrowly triangular tooth projecting backwards.

Colour pattern

Body and coxae pure white, gnathopods and oral field purplish; antennae and pereiopods 3–4 pale pink; pereiopods 5–7 and tailfan pure white; eyes red. This colour pattern was very consistent in all specimens examined during ANT-XXIX/3; none had spots or marks on their immaculate body.

Body length

Up to 80 mm.

Distribution

Between Elephant Island and King George Island; northeast of King George Island, Bransfield Strait; 404–580 m (present material; Coleman 1994: “ Epimeria robusta from Elephant Island” (specimen actually collected between Elephant and King George Islands)).

Remarks

Epimeria gargantua sp. nov. is the largest known Epimeria species, both in length and body volume. Epimeria gargantua sp. nov. (tip of Antarctic Peninsula) is morphologically similar to E. robustoides (eastern shelf of the Weddell Sea), but these two species were identified as separate species by methods based on COI and 28S genes ( Fig. 342 ). In E. gargantua sp. nov., the dorsolateral margins of urosomite 3 are less concave and the posterodistal corner of the basis of pereiopods 5–7 sharper than in E. robustoides . The colour pattern of E. gargantua sp. nov. is very constant (body white, without coloured marks), whilst it is more variable in E. robustoides .

Figures

Fig. 145. Epimeria (Hoplepimeria) gargantua subgen. et sp. nov., ♀, type series and probably holotype, Bransfield Strait, ANT-XXIX/3, stn 196-8, RBINS, INV. 122937, colour in life.

Fig. 146. Epimeria (Hoplepimeria) gargantua subgen. et sp. nov., ♀, holotype, Bransfield Strait, ANT- XXIX/3, stn 196-8, RBINS, INV. 122937A. A. Lateral habitus. B. Dorsal habitus.

Fig. 147. Epimeria (Hoplepimeria) gargantua subgen. et sp. nov., ♀, holotype, Bransfield Strait, ANT- XXIX/3, stn 196-8, RBINS, INV. 122937A. A. Facial habitus. B. Head in dorsal view.

Fig. 148. Epimeria (Hoplepimeria) gargantua subgen. et sp. nov., ♀, holotype, Bransfield Strait, ANT- XXIX/3, stn 196-8, RBINS, INV. 122937A. A. Coxae 4–5. B. Coxae 5–7. C. Pleosome and urosomite 1. D. Urosome in lateral view.

Fig. 149. Epimeria (Hoplepimeria) gargantua subgen. et sp. nov., ♀, holotype, Bransfield Strait, ANT-XXIX/3, stn 196-8, RBINS, INV. 122937A. A. Head in lateral view. B. Urosome in dorsal view. C. Telson.

Fig. 150. Epimeria (Hoplepimeria) gargantua subgen. et sp. nov., ♀, holotype, Bransfield Strait, ANT- XXIX/3, stn 196-8, RBINS, INV. 122937A. A. Gnathopod 1. B. Gnathopod 2.

Fig. 151. Epimeria (Hoplepimeria) gargantua subgen. et sp. nov., ♀, holotype, Bransfield Strait, ANT-XXIX/3, stn 196-8, RBINS, INV. 122937A. A. Pereiopod 4. B. Pereiopod 5. C. Pereiopod 6. D. Pereiopod 7.

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).