Bathypsammis polaris Willen & Schulz, 2007, sp. n.

Bathypsammis polaris sp. n. (Figures 1–9)

Description

Female (holotype). Body length: 1221 µm, furcal rami length: 318 µm. Rostrum (figure 1 A) demarcated from cephalothorax, slightly broader than long, rounded, with 1 pair of sensilla apically and 1 subapically.

Body (figures 1A–B, 7B). Long and slender, no distinct separation between prosome and urosome. Cephalothorax square, cephalic shield with sensilla and pores, distal lateral edge with tuft of long spinules. Posterior margin of each body somite (excluding penultimate somite) with sensilla. Urosomal somites with ventrolateral spinule rows on distal margins and the 2 somites preceding the anal one (figure 1A) dorsally with spinule rows on distal margins; body dorsally otherwise without spinule ornamentation, hyaline frills smooth; genital double-somite (free somites 5 and 6) ventrally not completely fused, genital field as in figures 1B, 7B; P6 with 3 setae, innermost longest and middle one short. Anal somite completely divided with 2 dorsal sensilla, anal operculum absent, peudoperculum present (figure 1A). Furcal rami (figures 1A, 7B–C) approx. 14 times longer than broad, furcal seta I absent, II and III damaged, II subapically at outer edge, III slightly displaced ventrad, IV and V well developed, proximally densely ornamented with spinules, distally tapering into long, flexible tendrils, VI damaged, VII biarticulated, subterminally on dorsal surface.

Antennule (figures 1A, 8A, 9D). With 5 segments. Armature: I(1); II(10); III(13+aes); IV(8); V(damaged); IV with enlarged and pinnate seta on terminal margin.

Antenna (figure 9A–C). Allobasis medially with long abexopodal pinnate seta and proximal row of spinules; exp 3-segmented, with 2-1-(1+2) setae (apical setae on exp3 broken off in holotype); proximal segment with tuft of spinules; enp with subapical spinule row, subapical armature consisting of 1 large pinnate and 1 naked spine, 1 geniculate and 1 well developed pinnate seta; apically with 7 setae: 1 large pinnate spine, 4 geniculate setae, the outermost of which fused at base with another minute seta and 1 additional pinnate spine.

Mandible (figure 2A–B). Gnathobase compact with 3 large and several smaller, fine and pointed teeth, inner edge with 1 large, bipinnate seta and 1 naked seta; basis large and compact, with spinule patch and 4 pinnate setae; enp longer than exp, with 3 lateral and 6 terminal setae; exp much shorter, with 1 lateral and 2 terminal, pinnate setae.

Maxillule (figure 3A). Arthrite of praecoxa with 9 apical spines, 1 small and naked seta posteriorly, 2 juxtaposed setae on anterior surface; coxa demarcated from basis, coxal endite with 6 setae; basis with 1 endite bearing 6 setae; exp and enp demarcated, exp with 3 setae, enp cylindrical with 3 setae.

Maxilla (figure 3B). Syncoxa with 3 endites; proximal endite bilobed, proximal lobe with 1 large, pinnate spine and apical row of long spinules, distal lobe with 2 pinnate setae, middle and distal endites each with pinnate spine and 2 more setae; basal endite with 1 pinnate claw fused to basis, accompanied by 1 slender, naked seta on posterior and 2 setae on anterior side (1 shortened); enp 1-segmented, bearing setae.

Maxilliped (figure 3C). Syncoxa narrow, shorter than basis, with 2 spinule rows and 1 enlarged pinnate seta at distal margin; large basis long and narrow, bearing 1 naked seta near distal edge and 2 spinule rows on inner margin; enp with claw, and 1 naked seta.

P1 (figure 2C). Basis with large, pinnate inner spine and elongate, pinnate outer spine reaching to first half of exp 2; terminal margin, anterior surface and base of spines with spinule rows. Exp 3-segmented, outer and terminal margins with spinules; exp1 enlarged, much broader than the other exopodal segments and almost as long as exp 2 + 3 together, exp1 and 2 each with 1 outer, pinnate spine, exp2 with inner seta; exp3 with 3 stout, outer, pinnate spines, 1 stout, outer, terminal spine and pinnate terminal seta; enp 2-segmented, both segments of equal length, enp1 almost as long as exp 1, with spinules along inner, outer and distal margins and 1 strong, inner, pinnate seta; enp2 with spinule rows on outer, inner and distal margins, with 1 inner, pinnate seta and terminally with short, pinnate, outer seta, longer middle and shorter inner, terminal pinnate setae.

P2–P4 (figures 4, 5, 6). Exps and enps 3-segmented. Coxae of almost rectangular shape, except for P4 being subtriangular, with spinule rows on surface, terminal and outer margins. Basis of P2–P4 each with well developed pinnate outer seta, and spinule rows on surface, distal margin and at base of outer setae, inner margin with rounded projection fringed with long spinules.

Armature formulae for swimming legs: following method of Lang (1948).

P5 (figure 7A). Pair of legs not fused medially, rami fused to single elongate large plate, exopodal and baseoendopodal parts not distinguishable, short basal pinnate seta located at proximal outer edge with basal spinule row, otherwise setation displaced distad, from outer to inner side armed with pinnate, slender spine, 2 long, naked seta, 2 short, thick pinnate spines, 1 long, pinnate seta, 2 very short and thick spines ornamented with spinules, 1 inner pinnate seta.

Male— unknown.

Etymology— The species name polaris refers to the type locality in the southern polar region.