Epimeria (Hoplepimeria) cyphorachis d'Acoz & Verheye 2017, subgen. et sp. nov.

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

urn:lsid:zoobank.org:act: 5A5D8439-3793-4124-A65B-C6EB65A1587E

Figs 138–144

Epimeria georgiana Clade A – Lörz et al. 2011: 1, fig. 1 (triangle), 3, 4, 5, 12.4, 12.5, 12.6, 13 row 1,

14A, 14B, table 3. Epimeria georgiana – Rauschert & Arntz 2015: 61, pl. 54, unnumbered photograph. ‘Clade E georgiana-rimicarinata-rubriequies [sic] complex - GE3’ – Verheye et al. 2016a, supplement: 4

(online).

Etymology

From the Greek, κυφός, humpbacked; ραχις, spine, spinal column. The name, which is a noun in apposition, alludes to the humpbacked silhouette of the species.

Type material

Holotype

RV Polarstern cruises:

SOUTHERN OCEAN: ♀, cruise PS81, ANT-XXIX/3, stn. 249-2, Drake Passage, north of Livingstone Island, 61°56.05ʹ S, 60°5.56ʹ W to 61°56.21ʹ S, 60°5.80ʹ W, 413–421 m, mud, Agassiz trawl, 12 Mar. 2013 (RBINS, INV. 122936) [extraction K25; Genbank nr, COI: KU870859, 28S: KU759637].

Description

ROSTRUM. Medium-sized, overreaching tip of article 1 of peduncle of antenna 1, anteriorly weakly curved, ventrally straight, acute in lateral view; broad and with weakly curved converging borders in frontal view.

EYE. Very large, broadly elliptic.

PEREION–PLEOSOME TOOTH PATTERN. Pereionites 1–3 smooth, pereionites 4 to pleonite 3 with extremely low and extremely blunt mid-dorsal carina; profile of carina of pereionite 4 inconspicuously curved; profile of carinae of pereionites 5 to pleonites 3 straight, those of pleonite 2 with inconspicuous concavity; profile of carina of pleonite 3 straight with anterior low very protrusion followed by shallow notch, then nearly straight, posteriorly blunt; dorsolateral ornamentation absent.

COXAE 1–3. Weakly carinate and distally subacute to narrowly blunt-tipped.

COXA 4. Anterodorsal border nearly straight (very slightly concave), anteroventral border very weakly concave, these two borders being joined by a very large rounded lobe (anterior corner), which is weakly projecting forward; ventral corner forming a sharp squared angle (ventral projection well developed); lateral carina very obtuse, parallel and close to posteroventral border; posteroventral border distinctly concave.

COXA 5. Broad, with surface smooth, with posteroventral corner forming a blunt-tipped nearly squared angle, weakly laterally produced, forming a low very rounded obtuse angle in dorsal view (coxa 5 distinctly visible in dorsal view).

COXA 6. With posteroventral corner broadly rounded, with low projection arising from its surface (forming a distinct lobe in dorsal view).

COXA 7. Posteriorly rounded.

EPIMERAL PLATES 1–3. Posteroventral angle: very obtusely rounded, with indistinct trace of tooth in plate 1; produced into a small tooth in plate 2 and into a medium-sized tooth in plate 3.

UROSOME TOOTH PATTERN. Urosomite 1 with very low dorsal process: anteriorly nearly straight, apically very blunt, posteriorly regularly convex large; urosomite 3 with dorsolateral borders nearly straight.

TELSON. Cleft on 0.2; tips of lobes bluntly triangular, notch narrowly V-shaped.

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

PEREIOPODS 5–7. Merus, carpus and propodus of medium width; dactylus long; basis of pereiopods 5–6 of normal width, with posteroproximal process present, triangular (pereiopod 5) or sword-like (pereiopod 6), parallel to axis of basis, with posterodistal corner obtuse, scarcely projecting posteriorly; basis of pereiopod 7 broad with posterior border distinctly convex, with deep notch on distal 0.8, forming a blunt-tipped squared angle, with posterodistal corner obtuse, scarcely projecting posteriorly.

Colour pattern

Red with a diffuse finely mottled pattern; some parts of the coxae and epimeral plates are white; eyes red.

Body length

Up to 42 mm.

Distribution

South Shetland Islands: north of Livingstone Island, 413–421 m (present material); south of Elephant Island, 463–990 m (Lörz et al. 2011 as Epimeria georgiana Clade A).

Remarks

Epimeria cyphorachis sp. nov. can be easily distinguished from the similar sympatric species E. quasimodo sp. nov. by the shape of the anterior corner of coxa 4: it is broadly rounded in the first species, angulate in the second. Actually, E. cyphorachis sp. nov. (South Shetland Islands) is morphologically more similar to E. xesta sp. nov. (eastern shelf of the Weddell Sea). In E. xesta sp. nov., the rostrum is narrower, the ventral corner of coxa 4 is more blunt, the coxa 5 less projecting laterally and the notch of the basis of pereiopods 5–7 is narrower than in E. cyphorachis sp. nov.