Undinula darwini f. typica   Sewell  (Copepod)
Organism information awaits expert curation
Class: Maxillopoda

Image copyrights: Biotech Books

a. Posterior thoracic margin and abdomen, right side (female), b. The 2nd antenna, c. The 2nd maxilla, d. Maxilliped, e. The 1st swimming leg, f. The 2nd swimming leg, g. An abnormal 2nd swimming leg; endopod of two segment only. h. The 3rd swimming leg, i. The 5th leg (female)

Size (female): length 1.66 mm

The proportional lengths of the cephalothorax and abdomen are as 35:9, the abdomen thus being contained 3.9 times in the length of the anterior region of the body.
The head and 1st thoracic segments are fused and together constitute rather more than one-half of the total length of the body. In the middorsal line, marking the level at which the fusion of the head and the next segment has taken place, is a small rounded backwardly directed protuberance. The forehead is uniformly rounded and terminates below in a pair of long rostral spines. The thoracic margin differs on the two sides of the body, that on the right side being for the most part uniformly rounded but at the postero-inferior region it is slightly produced and immediately below this small prominence is an equally small notch; on the left side the thoracic margin is produced in a well-marked and usually square lappet, that covers at least three-fourths of the genital segment of the abdomen. The outline of the lappet is in some cases rounded instead of being square.
The 1st and 2nd free segments are stated to be armed with rows of spines running transversely across the segments near the posterior border, but as already mentioned these spines may be reduced or even absent altogether.
The 1st antenna reaches back to the posterior margin of the 3rd abdominal segment. It consists of twenty-four free segments, segments 8 and 9 being fused. A transverse row of small spinules runs across the surface of segments 6 and 7 near the distal margin. The 2nd antenna and mouth-parts are of the usual Calanoid type.
In case of 4th pair of the swimming legs, the external margin of the distal part of the third segment of the exopod is invariably smooth and shows no signs of any denticulation such as occurs in the 2nd and 3rd legs.
In the 5th pair of swimming legs the marginal spine of exopod 1 is long, much longer than the corresponding spines on the 2nd, 3rd and 4th legs and reaches to the level of the base of the marginal spine of the 2nd segment of the exopod; the inner margin of the 1st basal segment is fringed with a row of small spinules about 40 in number, all of which are of approximately the same size.

Synonym (s)

Common Name (s)
Economic Importance and Threats



• INDIA (Record: 1910-1925)

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

Page last updated on:2009-07-27

Back to Search