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Calanoida ( Order ) |
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Clausocalanoidea ( Superfamily ) |
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Scolecitrichidae ( Family ) |
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Scaphocalanus ( Genus ) |
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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) |  issued 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.
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 issued 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 | | |
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Distribution map of Scaphocalanus difficilis by geographical zones
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| | | | 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 | |
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 Any use of this site for a publication will be mentioned with the following reference :
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 April 18, 2024] © copyright 2005-2024 Sorbonne University, CNRS
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