Species Card of Copepod
Calanoida ( Order )
    Clausocalanoidea ( Superfamily )
        Scolecitrichidae ( Family )
            Scaphocalanus ( Genus )
Scaphocalanus difficilis  Roe, 1975   (F)
Ref.:
Roe, 1975 (p.315, Descr.F, figs.F, Rem.); Park, 1982 (p.76); Schulz, 1987 (p.108: Rem.); Bradford & al., 1983 (p.93)
Species Scaphocalanus difficilis - Plate 1 of morphological figuresissued from : H.S.J. Roe in Bull. British Mus. (Natural History) Zool., London, 1975, 28 (7). [p.316, Fig.11].
Female: a, habitus (dorsal); b, urosome and last thoracic segment (right lateral side); c, forehrad and rostrum (left lateral view); d, rostrum (ventral); e, A2; f, Mx1; g, Mx2; h, Mxp; i, P1; j, P2; k, P3; l, P3 (first basipodite segment of paratype); m, P4; n, P5.
Bar scale 0.1 mm unless indicated.


Species Scaphocalanus difficilis - Plate 2 of morphological figuresissued from : H.S.J. Roe in Bull. British Mus. (Natural History) Zool., London, 1975, 28 (7). [p.316, Fig.11].
Female: a, habitus (dorsal); b, urosome and last thoracic segment (right lateral side); c, forehrad and rostrum (left lateral view); d, rostrum (ventral); e, A2; f, Mx1; g, Mx2; h, Mxp; i, P1; j, P2; k, P3; l, P3 (first basipodite segment of paratype); m, P4; n, P5.
Bar scale 0.1 mm unless indicated.
Nota : Cephalothorax 3.5 times as long as the 4-segmented abdomen.
Head and 1st thoracic segment fused, 4th and 5th fused..
Rostrum with 2 tapering filaments.
Urosomal segments and caudal rami have the following proportional lenghts 30 : 19 : 19 ; 13 : 19 = 100.
Caudal rami twice as long as wide.
Endopodite of A2 1.4 times longer than the exopodite.
In the Mx1 the 1st inner lobe has only two surface setae and the 3rd inner lobe has only 3 setae.
Endopod of Mx2 with 5 brush-like, of which two are enlarged, and 3 flattened worm-like setae.
P5 with a single segment on each side carrying 2 spines ; the inner spine is 1.8 times longer than the terminal one.

Compl. Ref.:
Vives, 1982 (p.292)
NZ: 1

Distribution map of Scaphocalanus difficilis by geographical zones
Loc:
NE Atlant (Cape Verde Is.)
N: 2
Lg.:
F: 1,44-1,29; {F: 1,29-1,44}
Rem.: Mesopelagic (specimen caught between 500-600 m).
This form shows strong similarities with S. longifurca and S. subbrevicornis, but of small size and some differences.
According to Roe (1975, p.316-317) this species shows slight differences with S. longifurca (Giesbrecht, 1888) and S. subbrevicornis (Wolfenden, 1911). Wether or not these differences merit separation into three species is questionable. It may be necessary to amalgamate two or all of them in future but for the moment at least they can remain separate.
Mx1 of S. difficilis differs from Bradford’s (1973) definition of the genus in having only two surface setae on the 1st inner lobe and 3 setae on the 3rd inner lobe. This last character is shared with other scaphocalanids.
Last update : 31/01/2015
    to add your remark
  

 Any use of this site for a publication will be mentioned with the following reference :

Razouls C., de Bovée F., Kouwenberg J. et Desreumaux N., 2005-2019. - Diversity and Geographic Distribution of Marine Planktonic Copepods. Sorbonne University, CNRS. Available at http://copepodes.obs-banyuls.fr/en [Accessed July 20, 2019]

© copyright 2005-2019 Sorbonne University, CNRS

Webmaster
CNRS   Observatoire Océanologique de Banyuls sur Mer - Laboratoire Arago
Sorbonne Université

 

Version française
English version

 

Search

On the WEB of CNRS

 


Marine Planktonic Copepods

Marine Planktonic Copepods

 

Imprimer Contact Accueil Plan du site Accès restreint Retour Une du Labo Imprimer Contact Plan du site Crédits Téléchargez les Plug-Ins