Species Card of Copepod
Monstrilloida ( Order )
    Monstrillidae ( Family )
        Monstrilla ( Genus )
Monstrilla longicornis  Thompson, 1890   (F,M)
Syn.: Monstrilla intermedia Aurivillius,1898;
Monstrilla clavata Sars, 1921 a (p.14, figs.F); Rose, 1933 a (p.341, figs.F); C.B. Wilson, 1950 (p.267)
Ref.:
T. Scott, 1904 (p.244, figs.F,M); Pearson, 1906 (p.33); van Breemen, 1908 a (p.204, figs.F, M); Farran, 1908 b (p.91); A. Scott, 1909 (p.235, figs.F); Pesta, 1920 (p.635, fig.F); Sewell, 1921 a (p.11, figs.F,M); Sewell, 1949 (p.132, 141); Isaac, 1975 (p.3, 6, 7, figs.F,M); McAlice, 1982 (p.46); Huys & Boxshall, 1991 (p.155, 156, 464, figs.F,M); Grygier, 1994 (p.240: Rem.); 1995 a (p.37, 69); Suarez-Morales, 2000 b (p.685: Rem.); Boxshall & Halsey, 2004 (p.836, figs.F,M); Vives & Shmeleva, 2010 (p.180, figs.F,M, Rem.)
Species Monstrilla longicornis - Plate 1 of morphological figuresissued from : R. Huys & G.A. Boxshall in Copepod Evolution, The Ray Society, 1991. [p.161, Fig.2.5.4].
Female (from Norway): A, habitus with two egg masses (lateral); B, urosome with eggs (lateral); C, 5th pedigerous and genital double somites (lateral); D, structures associated with genital aperture (ventral view); E, idem (lateral view).
Arrows show copulotary pore in C-E.


Species Monstrilla longicornis - Plate 2 of morphological figuresissued from : R. Huys & G.A. Boxshall in Copepod Evolution, The Ray Society, 1991. [p.162, Fig.2.5.5].
Male (from Norway): A, A1.


Species Monstrilla longicornis - Plate 3 of morphological figuresissued from : R. Huys & G.A. Boxshall in Copepod Evolution, The Ray Society, 1991. [p.164, Fig.2.5.7].
Male (from Norway): D, urosome (lateral); E, idem (ventral).


Species Monstrilla longicornis - Plate 4 of morphological figuresissued from : G.O. Sars in An Account of the Crustacea of Norway, with short descriptions and figures of all the species, 1921a, 8. [Pl. II].
Female (from Norway). Urs, urosome (ventral).
Nota: Body integuments exhibit everywhere a finely granular or dotted surface.
Cephalic segment occupying about half the length of the body.
Eye imperfectly developed, without any trace of refracting elements, and only replaced by a diffuse yellowish pigment.
A1 apparently 5-segmented, only the 1st distinctly defined, the others being confluent and only indicated by slight constrictions of the antenna; most of the setae attached around the middle of the fusiform terminal segment reachly ramified.
Oral tubule well marked and occurring somewhat behind the middle of the cephalic segment.
natatory legs all of the very same structure and of about equal size; 2nd basal segment (Basis) not very sharply defined from the 2st basal segment (Coxa) and armed inside with 2 small juxtaposed denticles; terminal segment (exopod) having the outer edge divided into 4 very distinctly marked crenulations. Last pair of legs rather broad at the base, but having the outer part abruptly narrowed and provided at the obtusely rounded extremity with 3 ciliated setae, the innermost of which is much smaller than the other 2; inner expansion almost rectangular and carrying a single, but well developed seta.
Genital segment being fully as long as the remaining part of the urosome, and oblong quadrangular in shape, with a well marked transverse suture in the middle of the dorsal face; ovigerous spines about twice the length of the urosome.
Caudal rami about equalling in length the last 2 segments combined and slightly divergent, each provided with 5 strong plumose setae of nearly equal size, the outmost one attached to a well-marked ledge of the outer edge.

The movements of the animal are very rapid, and are performed in abrupt bounds, whereby the body is kept in a more or less erect position. Male specimens seem to occur in nearly same number as the females.
Body in both sexes of a yellowish grey colour.


Species Monstrilla longicornis - Plate 5 of morphological figuresissued from : G.O. Sars in An Account of the Crustacea of Norway, with short descriptions and figures of all the species, 1921a, 8. [Pl. III].
Male.
Nota: Considerably smaller than female and of somewhat shorter and stouter form.
A1 more strongly built than in female and having the segments more distinctly defined, being more over conspicuously hinged, the hinge located between the last 2 segments.
Natatory legs of same structure as in female. Last pair of legs much reduced in size, forming 2 small knob-like prominences issuing from a common base, each prominence tipped by 2 (in some cases only 1) slender setae.
Urosome comparatively more slender than in female, and composed of 4 well defined segments of nearly equal length, the 1st produced below to a club-like copulative appendage terminating in 2 short diverging rami, each armed at the end with a short spine.
Caudal rami of a similar shape to that in female, but with one of the apical setae absent.


Species Monstrilla longicornis - Plate 6 of morphological figuresissued from : G.O. Sars in An Account of the Crustacea of Norway, with short descriptions and figures of all the species, 1921a, 8. [Pl. VI]. As Monstrilla clavata.
Female (from Hvlør, outside the Christiana Fjord).


Species Monstrilla longicornis - Plate 7 of morphological figuresIssued from : A. Scott in The Copepoda of the Siboga Expedition Part I. Siboga-Expeditie XXIX a., 1909. [Pl. LVII, Figs.3-4].
Female (from 1°33' N, 124°47'.5 E): 3,habitus (dorsal); 4, P5.

Nota: A1 2-segmented, equal to two-thirds of the length of the cephalic segment.Abdomen 3-segmented.
Genital segment sub-quadrangular in shape and equal to nearly twice the combined length of the next two segments. It is considerably shorter than the united length of the next two segments and caudal rami. The segment is marked by a well defined suture traversing the middle.
The 3rd segment very short and equal to about half the length of the 2nd segment.
Caudal rami 4 times longer than the anal segment, each ramus with 1 outer marginal seta and 4 apical setae. The 2nd inner seta shorter than the others.
P5 sub-cylindrical in shape with a distinct contraction in the middle. Each foot is furnished with 1 inner marginal seta and 2 apical setae.The only difference between the Siboga's specimens and the illustrations given by Giesbrecht (1893) and by T. Scott (1904), is the absence of a 3rd seta on the apex of P5.

Compl. Ref.:
Vaissière & Séguin, 1980 (p.23, tab.1); Buchanan & Sekerak, 1982 (p.41, Rem.: p.49); Falkenhaug & al., 1997 (p.449, spatio-temporal pattern); Holmes, 2001 (p.62); Bernier & al., 2002 (p.651, tab.1); Dvoretsky & Dvoretsky, 2010 (p.991, Table 2)
NZ: 7

Distribution map of Monstrilla longicornis by geographical zones
Loc:
G. of Maine, ? W Baffin Bay, W Ireland, Man Is., S & W Norway, Malangen fjord, Barents Sea, North Sea (GB), English Channel, W Mediterranean Sea (Alger, Tyrrhénienne), Indien, Indonesia-Malaysia, Philippines, Viet-Nam
N: 16
Lg.:
(5) F: 2,8; (449) F: 3,1-3; M: 2; (663) F: 4,5; (727) F: 3,1; M: 2; 748) F: 4; 3,7; M: 2,7; {F: 2,80-4,50; M: 2,00-2,70}
Rem.: For Sars (1921 a, p.12) this species may be easily distinguished from its nearest allies by the somewhat robust body and the rather coarse and distinctly granular integuments and the structure of the natatory legs by the presence inside the 2nd basal segment of 2 well defined denticles, and the very conspicuous crenulation of the outer edge on the terminal segment of the exopod. These characters are pretty constant and found quite alike in both sexes.
Last update : 27/08/2013
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