Species Card of Copepod
Calanoida ( Order )
    Clausocalanoidea ( Superfamily )
        Diaixidae ( Family )
            Xancithrix ( Genus )
Xancithrix ohmani  Markhaseva, 2012   (F,M)
Ref.:
Markhaseva, 2012 (p.305, Descr.F, M; figs.F, M); Laakmann & al., 2019 (p.330, fig. 2, 3, 4, phylogenetic relationships)
Species Xancithrix ohmani - Plate 1 of morphological figuresIssued from : E.L. Markhaseva in Arthropodia Selecta, 2012, 21 (4). [p.297, Fig.1]
Female: 28°01.9'S, 07°18.6'E): A-B, habitus (dorsal and lateral, respectively); C, cephalon (lateral); D, posterior prosome and urosome (dorsal); E, same (lateral), showing dorsolateral seta marked by arrow; F, cephalon anterior ventral view; G, A2; H, exopod of A2.
Scale bars = 0.5 mm (A-B); 0.1 mm remaning figures.
A, D, F: holotype; B; C, E, G, H: paratype.

Nota: Prosome 4.6-5.0 times longer than urosome.
Cephalon and pediger 1, 4th and 5th partly fused.
Rostrum reduced.
Posterior corners of prosome extends as short obtuse-triangular lobes.
Genital double-somite with spermathecae rounded dorsally.
Caudal rami with 4 terminal plus 1 ventral and 1 dorsolateral setae.


Species Xancithrix ohmani - Plate 2 of morphological figuresIssued from : E.L. Markhaseva in Arthropodia Selecta, 2012, 21 (4). [p.298, Fig.2]
Female: A, A1, ancestral segments I-XVII; B, A1, ancestral segments XYIII-XXVIII; C, A1, ancestral segments XXVII-XXVIII (dotted line marks additions after paratype); D, Md (palp); E, Md (mandibular gnathobase); F, Md (cutting edge); G, Mx1.
Scale bars = 0.1 mm.

Nota: A1 of 24 free segments, reaching to the middle of urosome.
Gnathobase Md with 10 teeth and thick dorsal seta; basis with 3 setae; exopod 5-segmented (setal formula 1, 1, 1, 1,, 2, respectively); endopod segment 1 with 2 setae, segment 2 with 9 setae.
Mx1: praecoxal arthrite with 9 terminal, 4 posterior and 1 anterior setae; coxal endite with 5 setae, proximal basal endite with 4 setae and distal basal endite with 5 setae; endopod 3-segmented with 3, 3, 5 setae, respectively; coxal epipodite with 9 setae.


Species Xancithrix ohmani - Plate 3 of morphological figuresIssued from : E.L. Markhaseva in Arthropodia Selecta, 2012, 21 (4). [p.299, Fig.3]
Female: A, Mx2 (praecoxal, coxal, and basal endites, proximal endopodal segment); B, endopod of Mx2 (details); C, Mx2 endopod (details of another view); D, proximal basal endite of Mx2; E, P5.
Scale bars: 0.1 mm.
A, B, D, E: holotype; C: paratype.

Mx2 praecoxal endite bearing 5 setae, coxal (former considered distal praecoxal endite) with 3 setae; basal endites (former considered coxal endites): proximal with 2 sclerotized and 1 sensory setae, distal with 3 setae (2 of them heavily spinulated); lobe of proximal endopodal segment (former considered proximal basal endite) with 2 sclerotized and 2 sensory setae; endopod with 3 long worm-like sensory, 5 brush-like sensory and 1 sclerotized setae.


Species Xancithrix ohmani - Plate 4 of morphological figuresIssued from : E.L. Markhaseva in Arthropodia Selecta, 2012, 21 (4). [p.300, Fig.4]
Female: A, Mxp (syncoxa); B, syncoxa of Mxp (coxal endite); C, Mxp (basis and incorporated endopod segment 1); D, endopod of Mxp; E, P1.
Scale bars: 0.1 mm.
A-E holotype.


Species Xancithrix ohmani - Plate 5 of morphological figuresIssued from : E.L. Markhaseva in Arthropodia Selecta, 2012, 21 (4). [p.301, Fig.5]
Female: A-C, P2 to P4 (posterior views)
Scale bars: 0.1 mm.
A-C: holotype.


Species Xancithrix ohmani - Plate 6 of morphological figuresIssued from : E.L. Markhaseva in Arthropodia Selecta, 2012, 21 (4). [p.302, Fig.6]
Male: A, habitus (lateral); B, cephalon (lateral); C, rostrum (ventral); D-E, posterior prosome and urosome (dorsal and lateral, respectively); F, P5.
Scale bars: 0.1 mm.

Nota: Prosome 3.4 times longer than urosome;
Cephalon and pediger 1 partly fused, 4th and 5th completely fused.
Posterior corners of prosome extend into obtuse lobes.
Rostum rudimentary with a small terminal notch.
Anal segment very small.
Caudal rami with 4 terminal, 1 very small dorsolateral, and 1 ventral setae.
P5 asymmetrical: right coxa plus basis slightly longer than left coxa. Biramous, exopods 3-segmented; endopods rudimentary. Right terminam segment spine-like; left exopod segments 2 and 3 with spinules distally.


Species Xancithrix ohmani - Plate 7 of morphological figuresIssued from : E.L. Markhaseva in Arthropodia Selecta, 2012, 21 (4). [p.303, Fig.7]
Male: A, right A1, ancestral segments I-XV; B, same, ancestral segments XVI-XXVIII; left A1, ancestral segments XXII_XXIII; D, exopod of A2; E, A2 (coxa, basis and endopod); F, Md (palp); G, Mx1.
Scale bars: 0.1 mm.

Nota: A1 longer thanbody; right A1 of 23 free segments.
Mouthparts armaments is rudimentary compared to female.
Md gnathobase with 9 teeth


Species Xancithrix ohmani - Plate 8 of morphological figuresIssued from : E.L. Markhaseva in Arthropodia Selecta, 2012, 21 (4). [p.304, Fig.8]
Male: A, Md (mandibular gnathobase); B, Mx2 (arrow marks sensory setae on basal endites); C, Mxp; D, P1 (arrow marks small lateral seta); E, P2.
Scale bars: 0.1 mm.

NZ: 2

Distribution map of Xancithrix ohmani by geographical zones
Loc:
S Atlant. (G. of Guinea, off W South Africa)
N: 1
Lg.:
(1306) F: 4,50-4,55; M: 4,6; {F: 4,50-4,55; M: 4,6}
Rem.: Abyssopelagic. Above seabed (depth: 5053, 5141, 5058 m)
Last update : 02/04/2019
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