Leucothoe longimembris Krapp-Schickel & Broyer 2014, sp. nov.

Leucothoe longimembris sp. nov.

urn:lsid:zoobank.org:act: 935721E6-F9D5-4E0A-9AAD-5DEE628627EB

Figs 5, 8-10

Diagnosis

A 1> A 2, eyes absent, Cx 1-5 all ending ventrally at about the same level. Basis P 5-7 slim, broadest not medially but proximally; both margins of bases weakly serrated. Ep 2, 3 posterodistal corner lengthened and pointed. U 1 rami subequal, U 2 rami unequal, ratio 2:1, U 3 rami subequal, about 2/3 of peduncle.

Etymology

Many articles (in Latin membrum, abl. plural membris) like antennae, Gn 1, but especially the bases of the peraeopods 5-7 are unusually elongated (= longis) and this character is different from all other species hitherto known from the Antarctic or sub-Antarctic regions. The chosen specific name is used as non-flexible apposition.

Type material

Holotype ♀ ov. 15 mm (RBINS, I.G. 32565 / INV. 103462), Polarstern ANT XXII-3 (ANDEEP 3); sta. PS67/74-6 EBS; 20 Feb. 2005; eastern Weddell Sea; 71°18.35’S, 13°57.71’W; 1030 m; epibenthic sledge; coll. C. De Broyer & B. Danis.

Description

Length 15 mm.

Head

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

Eyes absent.

Antenna 1 nearly half of body length, flagellum with 21 articles, peduncle art. 1 width proximally less than twice article 2, disto-inferiorly with acute tooth, length art. 1 subequal to 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 shorter than antenna 1, peduncle art. 4> art. 5, flagellum 7 arts.

Mouthparts: Mandibles lacking molars, incisor and lacinia mobilis dentate; palp 3-articulate, art. 2 with many lateral setae of different length, art. 3 with 2 distal setae, more than half length of art. 2. Maxilliped IP small, 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.

Gn 1 basis slender, not inflated, both margins with short setae; ischium smooth; carpus basis about half as long as propodus, distal part linear and extremely narrow, about 10 x longer than wide; propodus straight, about 6 x as long as wide, palm with short setae; dactylus smooth, reaching about 1/3 propodus length.

Cx 2 subquadrangular, about as long as wide, twice as wide as Cx 3, distally smooth; anterior margin and anterodistal corner regularly rounded, inferior margin straight, posteriorly somewhat excavated, facial setae absent.

Gn 2 basis not inflated, on both margins short setae; carpus reaching about 1/3 propodus length, curved, distally serrated, setose; propodus anterodistally with short, acute prolongation, posterior margin with many low humps, palm convex, proximally near dactylus-end no corner; facial setae not seen; dactylus curved, both margins smooth, bare, reaching about 2/3 of propodus length.

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

Cx 4 length shorter than width, smooth, bare, anterior margin nearly straight, distal margin rounded, posterior margin shorter than anterior one, not excavate, facial setae absent.

P 3, 4 basis very narrow, wider than delicate merus; dactylus reaching nearly half length of propodus, all margins naked.

Cx 5-7 facial setae absent.

P 5-7 similar, bases length:width ratio about 2.5 (P 5), 2.3 (P 6) and 2.6 (P 7), both margins with very slight serrations. Merus in P 5-7 with posterodistal corner lengthened.

Pleon

Ep 1-3 bare. Ep 1 distally rounded, Ep 2, 3 posteroventral corner acutely upturned.

Uropods: U 2 the shortest, with very unequal rami (ratio about 1:2), the shorter one shorter than peduncle. U 1 and U 3 with subequal rami.

Telson ratio l:w = 3, tip five-dentate because of four indentations near distal end.

Remarks

The new blind species is similar to the (also blind) deep-sea species L. ayrtonia Bellan-Santini, 1997 (5 mm) and L. atosi Bellan-Santini, 2007 (12 mm), found in the Mid-Atlantic Ridge at 37°N, 31°W at a depth of 850 m, and at the Barbados Trench, 10°N, 58°W at a depth of 1947 m respectively. Differences from L. ayrtonia are in the large rostrum, Cx 4 with posterodistal acute corner, Ep 3 quadrate with small tooth, from L. atosi are in much shorter antennae, blunt posterodistal corner at Ep 2, less unequal U 2 and broader telson. Also L. ushakovi Gurjanova, 1951 (type from Greenland at a depth of 3892 m, specimens from 8-34 mm length; see Krapp-Schickel & Vader 2012) has P 5-7 bases not medially, but proximally widest and is blind; differences with L. longimembris are are the setose bases of Gn 1, 2 and very unequal rami in U 2 in the here described material (vs. naked bases and less unequal rami in L. ushakovi), a longer Gn 1 dactylus and a five-dentate slender telson here (vs. short dactylus and threedentate broader telson in L. ushakovi).