Kyphocalanus

Markhaseva, Elena L. & Schulz, Knud, 2009, A new family and genus of calanoid copepods (Crustacea) from the abyss of the Atlantic Ocean, Zootaxa 2304, pp. 21-40 : 34

Kyphocalanus sp. 2.

( Figs 9–10 )

Material examined. Dissected adult female, body length 2.10 mm. Collected in 1998 above the sea bed at abyssal depths (4800 m) on Porcupine Abyssal plain (48º 58’N 16º 30’W).

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

Description. Female. Prosome 5.3 times as long as urosome.

Rostrum with two strong rami ( Fig. 9 C). Cephalosome and somite 1 and somites 4 and 5 of prosome separate; posterior corners as triangular lobes ( Fig. 9 A–B). Caudal rami with 4 terminal setae, 1 ventral seta, dorsal seta not located ( Fig.9 B).

Antennule entirely lost.

Antenna, attributes of type species.

Mandible ( Fig. 10 A), gnathobase with 4 acutely pointed and 4 very small teeth plus dorsal seta; basis with 2 setae, proximal one larger and with proximal part haft-like; exopod 4(?)-segmented with 5 setae; endopod segment 1 without setae, segment 2 with 9 setae.

Maxillule, shape similar and setation identical to that of type species.

Maxilla ( Fig. 10 C-D), 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. 9 D), 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; 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. 9 E), basis with medial distal seta only slightly curved, with setules; endopod 1- segmented without lateral lobe; exopod segments 1, 2 and 3 with lateral spines, proximal spine is the shortest; spine of exopod segment 1 exceeding base of following spine, spine of exopod segment 2 not reaching base of following spine.

Intact segments of P2–P4 as in type species, except for P4 surface not spinulated.

P5 ( Fig. 9 F) 3-segmented, similar to type species, but exopod surface spinules absent.

Remarks. Kyphocalanus sp. 2 differs from K. atlanticus in the shape of rostrum, its rami being more closely spaced ( Figs. 1 C, 9C) and in the presence of 3 setae on inner lobe of antenna endopod segment 2 (vs 4 setae in K. atlanticus ). From all congeners it is distinct in that spinules are absent on the posterior surface of P5; from Kyphocalanus sp. 1 it can be distinguished by the ratio of the lengths of P5 exopodal spines.

It shares with the type species the following characteristics that differentiate both from Kyphocalanus sp.1: i) its larger size (2.10–2.24 mm vs 1.82 mm in Kyphocalanus sp.1); ii) a longer endopod of antenna (ratio of exopod and endopod lengths as 1.8 vs 2.3 in Kyphocalanus sp.1); iii) presence of 2 setae on maxilla proximal coxal endite (vs 1 seta); iv) and P1 lateral spine of exopod segment 1 shorter than spines of exopod segments 2 and 3 (this spine is the longest in Kyphocalanus sp.1).

Figures

FIGURE 1. Kyphocalanus atlanticus gen. et sp. nov. Female, holotype. A, habitus, dorsal view; B, habitus, lateral view; C, rostrum, anteroventral view; D, rostrum, lateral view; E, posterior prosome and urosome, dorsal view; F, posterior prosome and urosome, lateral view. Scale bars: A-B, D 0.5 mm, C, E-F 0.1 mm.

FIGURE 9. Kyphocalanus sp. 2. Female. A, habitus, lateral view; B, posterior prosome and urosome, lateral view; C, rostrum, anteroventral view; D, maxilliped; E, P 1; F, P 5. Scale bars: A, 0.5 mm, other figures, 0.1 mm.

FIGURE 10. Kyphocalanus sp. 2. Female. A, mandible, palp; B, mandible, gnathobase; C, maxilla, praecoxal, coxal and proximal basal endite; D, maxilla, basal endites and endopod. Scale bars 0.1 mm.