Kyphocalanus atlanticus, Markhaseva, Elena L. & Schulz, Knud, 2009

Kyphocalanus atlanticus sp. nov.

( Figs 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Holotype. Dissected adult female, body length 2.24 mm. ZMH Reg. no. K–41633. Collected on 28 July 2000, above the sea bed at abyssal depths ( 5390m).

The holotype is deposited at the Zoological Museum Hamburg ( ZMH), University of Hamburg.

Type locality. South Atlantic ( 16º18’S 05º27’E).

Description. Female. Prosome 5.2 times as long as urosome.

Rostrum with two strong prong-like rami ( Fig. 1 View FIGURE 1 C–D). Cephalosome and somite 1 and somites 4 and 5 of prosome separate; posterior corners prolonged as triangular lobes ( Fig. 1 View FIGURE 1 A–B, E–F). Urosome of 4 somites. Caudal rami with 4 terminal setae, 1 ventral and a dorsal seta ( Fig.1 View FIGURE 1 E-F).

Antennule ( Fig. 2 View FIGURE 2 A-B) extending to distal margin of pediger 4, of 24 free segments; armature as follows: I–2 s +?, II– IV–6 s + 1ae, V–2 s + 1ae, VI–2 s, VII–2 s + 1ae, VIII–2 s, IX–2 s + 1ae, X– XI-4 s + 1ae, XII–1 s, XIII–1s, XIV–2s + 1ae, XV–1s, XVI–2s + 1ae, XVII–1s, XVIII–1s, XIX–1s, XX–2s, XXI–1s + 1ae, XXII– 1s, XXIII–1s, XXIV–2s, XXV–2s, XXVI–2s, XXVII–XXVIII-5s + 1ae.

Antenna ( Fig. 2 View FIGURE 2 C), coxa with 1 seta, basis without seta; exopod of 8 free segments with 0, 1, 1, 1, 1, 1, 1, and 3 setae, about 1.8 times as long as endopod; first endopodal segment without seta, second with 4 + 6 setae. Mandible ( Fig. 2 View FIGURE 2 D), gnathobase long and slender, cutting edge narrow, with 4 acute and 4 or 3 small teeth plus dorsal seta; basis with 2 setae, proximal with basal part haft-like; exopod 5-segmented with 1, 1, 1, 1, and 1 setae; endopod segment 1 without setae, segment 2 with 9 setae.

Maxillule ( Fig. 3 View FIGURE 3 A), praecoxal endite with 3 terminal setae; coxal endite with 2 setae; proximal basal endite without seta, distal basal endite with 1 seta; endopod with 5 setae; exopod with 7 setae; coxal epipodite with 9 setae.

Maxilla ( Fig. 4 View FIGURE 4 ), proximal praecoxal endite with 2 setae; distal praecoxal endite with 2 setae; proximal coxal endite with 2 setae; distal coxal endite with 2 setae; proximal basal endite with 1 spine; distal basal endite plus endopod with 8 long and thick worm-like sensory setae.

Maxilliped ( Fig. 3 View FIGURE 3 B), syncoxa with 1 worm-like, comparably thin and short sensory seta on proximal praecoxal lobe, 2 long and thick worm-like setae on middle lobe extending to distal part of endopod; distal praecoxal lobe without setae; coxal lobe with 1 seta. Basis with 3 setae. Endopod 6-segmented with 2, 4, 2, 2, 2+1, and 4 setae.

Swimming legs. P1 ( Fig. 5 View FIGURE 5 A–B), basis with medial distal seta nearly straight, or slightly curved with setules; endopod 1-segmented without lateral lobe, outer margin with slight undulation in a proximal half of segment; exopod segments 1 to 3 with 1 lateral spine each, spine of segment 1 the shortest exceeding base of following spine; spine of exopod segment 2 not reaching base of distalmost spine. P2–P4 ( Fig. 5 View FIGURE 5 C), coxa with 1 seta; basis without seta; endopod 2-segmented in P2, 3-segmented in P3–P4; exopods 3-segmented (exopodal segments 2 and 3 of P4 broken); lateral spines of P2–P3 compact, that of exopod segment 1 the shortest. Posterior surface of P4 spinulate.

P5 ( Fig. 3 View FIGURE 3 C) 3-segmented, coxa and basis of equal length; coxa with distolateral row of 6 spinules, basis with patch of spinules distolaterally, exopod ornamented with rare surface spinules and 2 distal spines, terminal spine about 0.6 times length of subterminal inner spine.

Etymology. The species name “ atlanticus ” refers to the type locality of the species in the Atlantic Ocean. The name is an adjective agreeing in gender with the (masculine) generic name.