Antatelson claudei, Krapp-Schickel, 2011

Krapp-Schickel, Traudl, 2011, New Antarctic stenothoids sensu lato (Amphipoda, Crustacea), European Journal of Taxonomy 2, pp. 1-17 : 12-15

Antatelson claudei sp. nov.

Figs 8-9

Holotype

1 ovigerous ♀ 2.5 mm; NHMUK 2011 . 8034. RRS James Clark Ross, cruise JR144 (BIOPEARL I), stn JR 144 SR-EBS-4-E, Shag Rocks, 53°62'S 40°91'W, 11-04-2006, 201- 205 m, gear: epibenthic sledge, 4 Epi-net, (slide deposited at the Natural History Museum, London).

Additional 5 specimens sex? 2.1- 1.2 mm in alcohol, same locality (Natural History Museum, London).

Etymology

Dedicated to Claude De Broyer (Brussels) for his strenuous and tireless effort on the studies of Antarctic amphipods.

Description

HABITUS. Dorsal outline with single tubercles and humps on the mediodorsal body line, with one at the head, some 3-5 irregular ones on the peraeon, and always acute prolongations on all three urosomites. These dorsal body parts are reinforced with knobs. In dorsal view, the body has a nearly right - angled keel laterally along both sides, thus the cross section would be a rhomboid with a much smaller extent in the upper part than in the lower one.

HEAD. A1 subequal to somewhat shorter A2. A1 ped. art. 1 with huge nasiform process, ratio art. 2> art. 3; flagellum with about 10 arts. A2 arts. 2 and 3 short and wide, art. 4 = art. 5, flagellum with 8-9 arts. Mouthparts: No difference found to those in other species of this genus.

GNATHOPODS. Gn1 much smaller than Gn2. Cx1 subquadrate. Basis robust, no setae found; ischium subquadrate, naked. Merus beset with short and stiff setae posteriorly; carpus triangular, on posterior margin beset with few longer setae. Propodus about twice as long as wide, on both margins with a few longer setae, palm weakly rounded without well defined palmar corner, but defined by short spines.

Gn2 larger, but also not strong. Cx2 tongue-shaped, longer than wide, anterior margin somewhat rounded, posterior one straight. Basis more than 5 times longer than wide, anterior margin beset with a few fine setae distally, only few setae on posterior margin; ischium longer than wide, with groups of setae as on merus. Carpus triangular, about as long as wide, distally lobed, without setae. Propodus subrectangular, distally a bit wider than proximally, with few setae on palmar corner; angle of palmar corner about 120°, without tooth, palm without excavation or incisions, beset with small setae. Dactylus short, reaching palmar corner.

PERAEON. P3-7 slender. Cx3 similar to Cx2. P3 basis about twice as wide as propodus and carpus, merus not lengthened anterodistally. Dactylus strong. P4 similar to P3, but ischium longer in P3. Cx4 subtrapezoidal, clearly wider than long. P5-7 again very similar and weak.

Peraeonites 5-7 with single semicircular dorsal humps situated over an acute tooth-shaped prolongation on each segment, partly reaching over the next segment. In some specimens rounded humps also on 2-3 anterior segments, but without this acute overlapping 'fold'.

PLEON. Pl1-3 with regular dorsal triangularly thickened prolongations, with 'double pleat', reinforced with knobs.

Ep1-3 with rounded corners.

Urosomites without dorsal ornaments.

Us2 much narrower than Us1.

U1 peduncle longer than subequal rami, rami with small spines. U2 peduncle longer than longer ramus, rami subwhat unequal, with small spines. U3 peduncle shorter than in U2, but similar in width, without spines; ramus two-articulated, about the same length as peduncle.

TELSON. Enlarged, thickened and vertically inserted.

Remarks

The first impression was that the material studied belonged to A. tuberculatum Andres, 1989 , because, apart from the more numerous humps and tubercles on the body, no difference in the morphology could be found. But in the present material also small specimens of 1.2 mm length show many more tubercles than the holotype of 2.8 mm or paratype of 2.6 mm in Andres' description, thus the idea that the number of humps would increase with body length does not seem justified. And furthermore, Andres stresses in his textual description of A. tuberculatum that the first and second pleon segment carry a pair of tubercles (not visible in the illustrations), and that only the third segment carries a single one. In the specimens of the present study, all segments have a single tubercle in the mediodorsal bodyline.

Figures

Fig. 8. Antatelson claudei sp. nov. Holotype ♀, 2.5 mm. Upper left corner contour of body; Hd = head; Gn1, 2 = gnathopod 1, 2; Cx4 = coxa 4; P3, 4 = peraeopod 3, 4; Pn5-7 = peraeonite 5-7; Pl1-3 = pleonite 1-3; U1-3 = uropod 1-3; T = telson.

Fig. 9. Antatelson claudei sp. nov. a) Body shape of a 2 mm long specimen with mediodorsal outline; b) body shape of the same specimen tipped aside to the lateral crest; c) body shape of a 1.2 mm long specimen with many humps; d) the same specimen seen dorsally.