Leucothoe antarctica Pfeffer 1888

Leucothoe antarctica Pfeffer, 1888

Figs 1-5

Leucothoe antarctica Pfeffer, 1888: 54-57, Taf. II: fig. 4.

sub Leucothoe spinicarpa variant 3 – Holman & Watling 1983: 228-229.

Diagnosis

Eyes large, round. Mandibular palp long and narrow, art. 3 about 1/3 length of art. 2. Cx 3 tongue-shaped rounded, smooth. Gn 1 propodus l:w = 4-5, dactylus reaching about 1/3-1/4 of propodus length. P 5-7 basis oval broadened, with regularly rounded hind margin, ratio l:w = 1.5 to 1.2; posterior margin at least in P 7 strongly serrate (not mentioned in Pfeffer’s description). Ep 2 posterodistally with rounded upturned corner.

Type material

Neotype ♀ ov. 5 mm, 2 slides (RBINS, I.G. 31073 / INV. 103461). Polarstern ANT XIX/3 (ANDEEP I), sta. PS61/067-1; 4 Feb. 2002; off Elephant Island, 60°55’53”S, 55°27’38”W to 60°55’09”S, 55°24’50”W; 115-182 m; bottom trawl.

Type locality

South Georgia, Royal Bay, near the Deutsche Polarstation 1882-1883 at Moltke Harbor, approx. 54°30’58”S, 36°00’45”W.

Additional material

Belgian-Dutch Antarctic Expeditions

(RBINS, Brussels, EABN 1966-67, collectors: M. Steyaert & M. Meisch, RBINS I.G. 23694)

EABN 1966-67, sta. 238, 3 Feb. 1967, Breid Bay, Baie Léopold, 70°19’S, 24°14’E; 200 m; bottom trawl: 1 juv.

Polarstern cruises

(RBINS, Brussels, ANT XIII /3 (EASIZ I), coll. C. De Broyer & G. Chapelle, RBINS I.G. 28252; ANT XIX /3 (ANDEEP I), coll. C. De Broyer, P. Dauby & F. Nyssen, RBINS I.G. 31073)

ANT XIII /3 (EASIZ I), sta. PS39/24 MG 26; 21 Feb. 1996; eastern Weddell Sea; 71°08’06”S, 11°31’54”W; 118 m; Multibox Corer: 1 spec. 3.5 mm.

ANT XIX /3 (ANDEEP I), sta. PS 61/047-1; 30 Jan. 2002; off Elephant Island; 61°4.18’S, 54°36.81’W, 189 m, bottom trawl: 1 spec. 4 mm.

ANT XIX /3 (ANDEEP I), sta. PS61/067-1; 4 Feb. 2002; off Elephant Island; 60°55’53”S, 55°27’38”W to 60°55’09”S, 55°24’50”W; 115-182 m; bottom trawl: 1 spec. ♀ ov. 5 mm slide.

Polish Antarctic Expeditions (LPBO-UL, Łódź)

9 th Polish Ant. Exp, sta. OC 412; 11 Jan. 1985; King George Island, Admiralty Bay, Ezcurra Inlet; 62°10’S, 58°32’W; 90 m; Van Veen Grab: 1 spec.

9 th Polish Ant. Exp, sta. OC 520; 3 Nov. 1985; King George Island, Admiralty Bay, section I; 62°09’S, 58°25’W; 335 m; Van Veen Grab: 1 juv.

Victoria Museum, Melbourne

? J 38267 [Aurora Australis AA93 142], off Mac Robertson Land, north of Fram Bank; 66°48’ 46”S- 66°48’52”S, 70°24’59”E- 70°25’32”E; depth:?: 1 spec. 3 mm.

Redescription

Length

4-9 mm [Pfeffer: “ 5 mm ”].

Head

Anterior margin rounded, anterodistal margin rectangular with rounded corner. Mid-cephalic keel not prominent. Rostrum small.

Eyes large, round.

Antenna 1 a quarter of body length, flagellum 10-12-articulate, peduncle art. 1 width proximally less than twice article 2, disto-inferiorly without acute tooth, length art. 1 subequal art. 2, art. 3 about 1/4 of art. 2, acc. flagellum not seen.

Peduncle art. 3 + flagellum shorter than peduncle arts 1+2.

Antenna 2 subequal in length to antenna 1, peduncle art. 4> art. 5, flagellum 7-10 arts.

Mouthparts: Mandibles lacking molars, incisor and lacinia mobilis dentate; palp 3-articulate, art. 2 with 12 long lateral setae, art. 3 with 2 distal setae, 0.35 of art. 2. Maxilliped IP small, ventrally fused, OP reaching about 1/5 of inner margin of palp art. 1; palp articles similar in length.

Peraeon

Cx 1 smooth, length> width; anterior margin smooth, facial setae absent, inferior margin smooth [Pfeffer: “anterodistally rounded corner of about 70°”].

Gn 1 basis scarcely inflated, posterior margin with groups of short setae; ischium smooth; carpus basis more than half as long as propodus, distal part linear and extremely narrow, about 8 x longer than wide; propodus straight, about 4-5 x as long as wide [Pfeffer: “about 4 times”], palm minutely dentate with 8 short setae; dactylus smooth, reaching about 1/3-1/4 propodus length.

Cx 2 subquadrangular, about as long as wide, much wider than Cx 3, distally smooth; anterior margin straight, anterodistal corner rectangular, inferior and posterior margin straight, facial setae absent.

Gn 2 basis not inflated, on both margins up to 6 short or long setae; carpus nearly reaching half propodus length, curved, distally like a finger-tip rounded, densely setose; propodus anterodistally with short, blunt prolongation and a bundle of setae, posterior margin with many low humps, palm convex, proximally near dactylus-end no corner; facial setae medially and submedially present; dactylus curved, both margins smooth, bare, reaching somewhat more than half of propodus length.

Cx 3 length> width, anterior and posterior margin straight, distally rounded, smooth, facial setae absent.

Cx 4 length subequal to width or longer than wide, smooth, bare, anterior margin straight, distal margin rounded, posterior margin shorter than anterior one, not excavate, facial setae absent.

P 3, 4 basis very narrow, a bit wider than merus; dactylus reaching nearly half length of propodus, posterior margins with some short thin spines.

Cx 5-7 facial setae absent.

P 5-7 similar, bases l:w ratio about 1.5 (P 5) to 1.2 (P 7), anterior margins with very slight serrations and small weak spines, posterior margins in P 5, 6 smooth or serrated, in P 7 strongly serrate [not mentioned in Pfeffer]. Merus in P 5-7 with posterodistal corner lengthened.

Pleon

Ep 2 with spines on distal margin, Ep 1, 3 distally bare, but some small setae on posterodistal corner of Ep 3. Ep 1 distally rounded, Ep 2 posteroventral corner not acutely upturned, but produced with rounded corner, Ep 3 posteroventral corner blunt and rectangular.

Uropods: U 2 the shortest, with very unequal rami (ratio nearly 1:2), the shorter one shorter than peduncle.

Telson ratio length:width = 3, tip tridentate because of two indentations near distal end, with a short seta inserted in each one.

No sexual dimorphism known.

Distribution

Circum-Antarctic, from 54° to 71°S, from 11° to 58°W and from 24 to 70°E (type material: 54°S, 36°W).

Depth range

24- 335 m.

Remarks

Pfeffer (1888) compared his new species only with the Atlantic species Leucothoe articulosa (Leach, 1814), insufficiently described and actually kept it – with question marks – as a synonym of L. spinicarpa (Abildbaard, 1789); there is, however, no doubt that it belongs to the “ spinicarpa -group”.

The original description and illustration of the single type are not very helpful (see Fig. 1), but at least the semicircular posterior margin of P 7 and the scarcely upturned rounded posterodistal corner in Ep 2 are visible in the drawing.

Holman & Watling (1983: 228-229, fig. 11d-e) discussed a so-called “ Leucothoe spinicarpa variant 3”; on p. 229 they wrote: “Cx 3 with smoothly rounded ventral margin, Cx 4 not excavate posteriorly. Gn 1 dactyl 1/5 length and approximately equal to width of propodus, latter 6 times as long as wide (here 5x). P 7 basis broadly expanded, Ep 3 with quadrate posterodistal corner. Distribution: tip of Antarctic Peninsula, 210-220 m [about 63°S, 58°W].”

By the combination of the key character states – P 7 basis broadly rounded, Gn 1 dactylus reaching about 1/4 of propodus, Cx 3 distally smooth, Ep 2 posterodistal corner only a little produced and rounded – L. antarctica clearly differs from all other members of the spinicarpa-group.