Leucothoe antarctica Pfeffer 1888
- Dataset
- Revision of Leucothoe (Amphipoda, Crustacea) from the Southern Ocean: a cosmopolitanism concept is vanishing
- Rank
- SPECIES
Classification
- kingdom
- Animalia
- phylum
- Arthropoda
- class
- Malacostraca
- order
- Amphipoda
- family
- Leucothoidae
- genus
- Leucothoe
- species
- Leucothoe antarctica
description
Figs 1 - 5
description
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.
diagnosis
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.
discussion
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. 11 d-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 5 x). 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.
distribution
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.
materials_examined
Type material Neotype ♀ ov. 5 mm, 2 slides (RBINS, I. G. 31073 / INV. 103461). Polarstern ANT XIX / 3 (ANDEEP I), sta. PS 61 / 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. PS 39 / 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. PS 61 / 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 AA 93 142], 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.
Name
- Synonyms
- Leucothoe spinicarpa (Abildgaard 1789)
- Homonyms
- Leucothoe antarctica Pfeffer 1888