Species Card of Copepod
Calanoida ( Order )
    Clausocalanoidea ( Superfamily )
        Scolecitrichidae ( Family )
            Rythabis ( Genus )
Rythabis atlantica  Schulz, 1995   (F)
in Schulz & Beckmann, 1995 (p.202, Descr.F, figs.F); Boxshall & Halsey, 2004 (p.194: figs.F)
Species Rythabis atlantica - Plate 1 of morphological figuresissued from : K. Schulz & W. Beckmann in Sarsia, 1995, 80. [p.200, Fig.1].
Female (from N Greenland Sea): A, habitus (dorsal); B, idem (lateral right side); C, forehead (lateral); D, rostral cone (ventral view); E, posterior part of metasome and urosome (lateral right side); F, idem (ventral; G, A1; H, A2.
Scale bars = 0.100 mm.
Nota: Cephalosome and pediger 1 as well as pedigers 4 and 5 separated except ventromedial edge of the latter.
- Posterior corner of prosome rounded and covering 1/2 of genital double-somite.
- Ratio of length of prosome to length of urosome 3.8 : 1.
- Urosome of 4 somites.
- Genital double-somite only slightly dilated laterally, ventral swelling only weakly produced. Spermathecae curved dforwatd, elongate, digitiform.
- Anal somite as long as preceding somite.
- Caudal rami slightly longer than wide, armed with 4 distal setaze and a fine ventral seta implanted about 2/3 along medial margin.
- Rostrum a simgle cone-shaped knob lacking filaments.
- In lateral view, labrum and paragnaths considerably protrudent ventrally (of similar appearance as in Tharybis) and equipped with setules distally.
- A1 24-segmented, reaching to end of genital double-somite.
- A2 coxa with 1 inner seta; basis bearing 2 unequal setae at inner distal corner; endopod 2-segmented, 1st segment with 2 subterminal inner setae, distal compound segment shorter than preceding , with 8 inner setae on proximal lobe and 6 setae on apical lobe; exopod barely triple length of endopod, 6-segmented, terminal segment longer than endopod , bearing 1 inner seta at 1/4 length and 3 apical setae; setal formula: 0, 1, 1, 1, 1, 4.

Species Rythabis atlantica - Plate 2 of morphological figuresissued from : K. Schulz & W. Beckmann in Sarsia, 1995, 80. [p.201, Fig.2].
Female: A, right Md (mandibular blade); B, left Md (cutting edge); C, Md (mandibular palp); D, Mx1; E, Mx2; F, Mxp; G, P1; H, P2; I, P3; J, P4; K, P5.
Scale bars = 0.100 mm.
Nota: Md gnathobase elongate with cutting edge of 3 large, acute teeth ventrally and about 5 smaller teeth and 1 strong setose seta dorsally. Both anterior and posterior sides equipped with needle-like spines. Basis comprising 2 relatively long and curved setae; endopod 2-segmented and slightly larger than exopod, 1st segment with 2 unequal inner setae, and terminal segment bearing 9 setae; exopod indistinctly 5-segmented, 1st to 4th each beraing 1 seta and 5th segment with 2 setae.
- Mx1 with praecoxal arthrite with 14 large elements (of these 4 setae located posteriorly); coxal epipodite with 7 large and 2 smaller proximal setae; coxal endite with 5 setae; proximal basal endite bearing 4 and distal endite 5 setae; proximal basal endite with 4 and distal endite 5 setae; exopod with 4 setae and hairs distally; endopod with 3, 6, 3 setae.
- Mx2 composed of comparatively short praecoxa and endites carrying 4 and 3 setae. Both coxal endites each with 3 setae; basal endite having 1 robust falcate spine, 2 moderately long spine-like setae and 1 aesthetasc ; Endopod unsegmented with 2 short brush-like filaments proximally (their terminal heads with stiff hairs), and 3 moderately long and 3 long vermiform filaments distally.
- Mxp of slender appearance; praecoxa and coxa each with 1 long vermiform seta, 2 long setae and 1 short brush-like aesthetasc proximally and 3 weak setae on distal coxal lobe. Brush-like aesthetasc similar to those of maxillar endopod. Basis comparatively long, of more or less uniform width. Endopod of 6 segments , 1st and 2nd as well as 4th and 5th segments of usual length, 3rd and terminal segment of considerable length.
- P5 uniramous, coxae fused to form common base; basis more or less globular; endopod lacking; exopod 1-segmented, slender and slightly longer than basis, with 1 lateral spine at midlength (the shortest), all ornamented with denticles; latral spine about half the length of inner spine; outer distal spine slightly longer than inner distal spine. Posterior surface particularly distally, and inner margins aof all 3 segments armed with numerous spinules.

NZ: 1

Distribution map of Rythabis atlantica by geographical zones
S Iceland.

Type locality: 59°13' N, 20°50' W.
N: 1
(594) F: 1,14-1,12; {F: 1,12-1,14}
Rem.: ? hyperbenthic (depths: 2860 m).
Last update : 31/03/2016
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Razouls C., Desreumaux N., Kouwenberg J. and de Bovée F., 2005-2024. - Biodiversity of Marine Planktonic Copepods (morphology, geographical distribution and biological data). Sorbonne University, CNRS. Available at http://copepodes.obs-banyuls.fr/en [Accessed July 22, 2024]

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Marine Planktonic Copepods

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