Scottocalanus dauglishi   Sewell,  1929 (Copepod)
Organism information awaits expert curation
Taxonomy
Kingdom:Animalia
Phylum:Arthropoda
Class: Maxillopoda
Order:Calanoida
Family:Scolecitrichidae

Description
Size (male): 4.6 mm.
Size (female): Length 5.3 mm.

Female: The proportional lengths of the cephalothorax and abdomen are as 69 to 16, so that the abdomen is contained 4.3 times in the length of the anterior region of the body. The head and 1st thoracic segment are fused together and thoracic segments 4 and 5 are also partially fused. The head is furnished with a high, almost triangular crest and the rostrum consists of two stout, sharply pointed spines. The posterior thoracic margin is produed backwards in a rounded lappet on each side. The abdomen consists of four segments with the furca.The 4th segment is very short. Both segments 2 and 3 are armed with a row of short spines across the dorsal part of the posterior margin. The genital segment exhibits a prominent protuberance on the ventral aspect which slightly overlaps the following segment. The furcal rami are as broad as long; they bear only four normal setae, the 5th seta being so reduced as to be hardly noticeable. The accessory seta is also considerably reduced.

The 1st antenna reaches back to the end of the furcal ramus and consists of 24 separate segments, segments 8 and 9 being fused together.
In the 2nd antenna, the endopod is about one-half the length of the exopod. The 1st basal segment bears a row of curved setae on its inner aspect proximally and a single seta distally. The mandible is well-developed and the two branches of the palp are of approximately equal length.
The 2nd maxilla is of the characteristic type; the 5th lobe is larger than the others and the terminal joint bears the usual characteristic appendages of two kinds.

In the maxilliped, the 1st basal joint bears a single sensory appendage about the middle of the length of the anterior margin. The 2nd basal segment is armed with a row of needle-like spines along the proximal two-thirds of the length of the anterior margin. The endopod consists of five segments, of which the 2nd is by far the longest.The 1st pair of swimming legs each consist of a three-jointed exopod and an unjointed endopod. The 1st and 2nd segments of the exopod bear slender marginal spines, while the marginal spine on the terminal segment is considerably stouter and equals the segment in length.

In the 2nd swimming leg, the exopod is three-jointed and the endopod consists of two segments. The distal segment of the endopod is armed with three pairs of spines, that are much stronger and coarser. The 2nd segment of the exopod bears a curved row of spines across the distal part of its surface and, in addition, a short row of three minute spines a little beyond the middle of its length.

In the 3rd and 4th swimming legs both rami consist of three segments.
In the 5th pair of legs, towards the end of the terminal spine the spinules become crowded together to form a definite comb.
Male: The proportional length of the cephalothorax and abdomen are as 27 to 10, the abdomen being contained 2.7 times in the length of the anterior region of the body.

In its general shape and in the characters of the head and crest the male very closely resembles the female. The abdomen consists of five segments of which the 5th is very short.The 2nd and 3rd segments are each fringed across the dorsal part of the posterior margin with a row of minute spines.
The 1st antenna reaches beyond the posterior thoracic margin to the 3rd abdominal segment. The number of free joints in the antennae is considerably reduced by the fusion of a number of segments in the middle of its length. On the right side segments 8 and 9 are fused completely, and so also are segments 10, 11 and 12 and each of these composite joints are again fused together and segment 13 is also partially fused to the 12th; segments 14 and 15 are also fused together. On the left side the fusion of the segments is as on the right side with the additional fusion of segments 20 and 21.

The 2nd antenna and mouth-parts closely resemble those of the female with the single exception of the maxilliped, which in this sex is slightly reduced in size, the reduction specially affecting the 2nd basal and the segments of the endopod.The swimming legs are the same as in the female.In the 5th pair of legs, the endopod of the right leg reaching only to about three-fourths of the length of the 1st segment of the exopod and it is straight instead of being sickle-shaped. The exopod consists of three segments, of which the 2nd and 3rd are sub-equal in length; the 2nd segment is curved and stout, but the terminal segment is flattened and spear-shaped and bears a small spine on its outer margin.



Synonym (s)

Common Name (s)
Economic Importance and Threats

Ecology

Biogeography


• INDIA (Record: 23-04-1924)
• INDIA (Record: 23/04/1924)
• Kerala, Off Kochi (Lat: 10) (Long: 68.05) INDIA (Record: 14/11/1983-17/11/1983)
• Kerala, Off Kochi (Lat: 11.5) (Long: 73.11) INDIA (Record: 14/11/1983-17/11/1983)

Literature Source(s)
  • Sewell, RBS (1999) The copepoda of Indian seas Biotech Books, Delhi, India 407 pp Available at - NIO, Goa
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at - http://www.marinespecies.org
  • Madhupratap, M and Haridas, P (1990) Zooplankton, especially calanoid copepods, in the upper 1000m of the south-east Arabian Sea Journal of Plankton Research Oxford University Press 12 305-321 Available at - http://drs.nio.org/drs/handle/2264/2432

Page last updated on:2011-03-15

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