Description

provided by NMNH Antarctic Invertebrates

“Eclysis similis, n.sp.

Occurrence: St. 123. South Georgia. 1 ♀ 12 mm.

Description. Agreeing in general with Chilton's description and figure of A. australis, 1912, but with the following differences and additions.

Head with antero-inferior corner produced in a short subacute point. Side-plate widening below, lower margin slightly convex, not straight as in Chilton's figure. Side-plate 5, postero-inferior angle rounded as in the 6th side-plate. Dorsal teeth not quite so high as in Chilton's figure ; that on pleon segment 4 more evenly rounded and not so strongly lobed just above the notch. Telson apically incised, lobes subacute, with four denticles (asymmetrical).

Antenna 1, the teeth on 1st and 2nd joints are all short, not at all prominent, accessory flagellum absent. Epistome and upper lip gibbous, with a low median keel, separated by a groove; upper lip broader than long, apically rounded-truncate. Mandible, cutting edge divided into three teeth, bifid or with accessory denticles, separated by deep incisions, no secondary cutting plate in either mandible, spine row well developed, molar a thin tapering setose lamina, palp strong, 3rd joint abruptly narrower than distal end of 2nd. Lower lip, inner lobes absent, outer lobes as in Epimeria cornigera. Maxilla 1 as in cornigera, but palp stronger, 2nd joint ovate-oblong, with eight clavate spines, and a slender spinule at each end on distal margin. Maxilla 2 as in cornigera. Maxilliped, inner plate short, apically truncate, with a few setules, outer plate very large, lamellate, inner margin with clavate spines which pass gradually into slender spines distally, 2nd joint of palp with straight inner margin and quadrate inner apical angle.

Gnathopods 1 and 2, 2nd joint with some fine setules on anterior margin and a few longer setae on hind margin, 5th joint triangular, distally widened, 6th much narrower than distal width of 5th and slightly shorter, palm oblique, ill-defined, except by very fine pectination, dactyl with setules on inner margin.

Peraeopods 3 and 4, 2nd joint evenly oval. Peraeopod 5, znd joint oblong, anterior margin convex, hind margin slightly concave between the upper narrowly rounded angle and the lower, more broadly rounded angle which is obscurely serrulate.

Uropods somewhat mutilated but corresponding with Chilton's description. Peduncle of uropods 3 keeled on both outer and inner upper margins, each keel ending behind in a short acute tooth.

Remarks. This specimen was at first thought to be a small example of A. australis, Chilton, 1912. A specimen of what is undoubtedly the true australis, however, has been studied by Schellenberg, who finds that it is an Iphimediid, and for it has instituted the genus Iphimediopsis (1931, pp. 126, 127, pl. i, fig. c).

The dorsal armature, except for a very slight difference in the shape of the hinder part of the keel on pleon segment 4 is the same in both species ; and in other respects there is great similarity. The main differences as noted above are the shapes of the 5th joints of the gnathopods, and the 2nd joints of peraeopods 3-5, and the telson. Chilton figures the hind margin of the 2nd joint of the gnathopods as markedly spinose, and the 5th joint as cylindrical ; his description of the telson as " . .. emarginate posteriorly " scarcely fits the present specimen. The palp of the maxilliped appears to be longer; the figure here given is drawn from the mounted flattened preparation.

It should be remembered that the Scotia specimen of australis was 35 mm. in length and Schellenberg's ovig. ♀ 45 mm., whereas the present one is much smaller. It is preparing for ecdysis, as the new skin can be seen within the old in the mandibles and other parts. The brood lamellae are well developed though without marginal setae.”

(Barnard, 1932: 182-183)

Depth range

provided by World Register of Marine Species
South Georgia and Weddell Sea: eastern shelf, 230–250 m (De Broyer et al. 2007); Ross Sea, 659– 741 m (Berge & Vader 2005b).
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cc-by-4.0
copyright
WoRMS Editorial Board
bibliographic citation
d'Udekem d'Acoz, C.; Verheye, M. L. (2017). Epimeria of the Southern Ocean with notes on their relatives (Crustacea, Amphipoda, Eusiroidea). <em>European Journal of Taxonomy.</em> 359: 1-553.
contributor
Horton, Tammy, T.