Valdiviella oligarthra   Steuer,  1904 (Copepod)
Organism information awaits expert curation
Class: Maxillopoda

Size (male): 6.2 mm.

The proportional lengths of the cephalothorax and abdomen are as 53 to 25, so that the abdomen is a little less than half the length of the anterior region of the body.The rostrum consists of two stout divergent points. The head and 1st thoracic segment are fused together but the line of fusion can be seen running across the dorsal aspect. The 4th and 5th segments are also fused. The posterior thoracic margin is rounded and bears a small backwardly-directed spine.

The abdomen consists of five segments.

Segment 5 is almost completely telescoped into segment 4. Segments 2, 3 and 4 are all armed with a row of small spines that runs across the posterior margin on the dorsal side.

In the 1st antenna the length of the various segments differs slightly on the two sides of the body, as also does the degree of fusion of certain of the segments.

In both cases the 8th and 9th segments and the 24th and 25th respectively are fused, and on the right side the 20th and 21st are fused in addition.
In the 2nd antenna, the endopod bears 6 setae on its inner lobe and 7 on its outer.

The mandible is devoid of any biting edge. The endopod bears 6 setae and the exopod carries 9 setae, of which two are very short, on its second segment and none on its first.

The 1st maxilla is much reduced. The outer lobe bears 11 setae of which the 11th is very short, and the endopod 3 setae; all the other parts are devoid of setae.

The 2nd maxilla is also vestigial; in the basal segment the first three lobes are reduced to mere prominences devoid of setae; the 4th and 5th lobes bear two setae each. The endopod carries 5 setae.

In the maxilliped, basal 1 bears a short spine-like seta situated on a round prominence at the distal end and the base of this prominence is beset with small spines. Basal 2 bears three setae on its anterior margin and one at its distal end; the row of needle-like spines along the proximal part of the anterior margin, that is seen in the female, has completely disappeared. The segments of the endopod bear the same number of setae, namely 3, 2, 2, 2 and 3 on the five segments respectively.

In the 1st swimming leg there is a distinct line of demarcation between segments 1 and 2 of the exopod, though the jointing appears to be incomplete. In the exopod there is a gland opening on the margin of both the 2nd and 3rd segments. The endopod consists of a single segment and a series of glands open along the ridge of the swelling on the posterior aspect.

In the 2nd swimming leg the 1st and 2nd segments of the exopod are fused; the endopod consists of a single segment and in the distal third a gland opens on the posterior aspect, the opening being surrounded with short hairs.

In both the 3rd and 4th swimming legs the 1st and 2nd segments of the exopod are fused; the endopod consists of two joints, the 1st and 2nd segments being fused; the 3rd segment bears a gland opening on its posterior aspect and the surface is beset with short hairs.

In the 5th pair of leg, the endopod of the right leg reaches well beyond the triangular lamella and extends even beyond the joint between the 1st and 2nd segments of the exopod of the left leg.

Synonym (s)
Valdiviella oligarthra Steuer, 1904
Valdiviella oligarthra Wolfenden, 1911
Valdiviella oligarthra Sewell, 1913

Common Name (s)
Economic Importance and Threats



• Bay of Bengal INDIA (Record: 21-10-1911)
• INDIA (Record: 28/04/1925)

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 -
  • Boltovskoy, D (Ed.) Zooplankton of the South Atlantic Ocean Marine Species Identification Portal Available at -

Page last updated on:2011-09-12

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