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

Image copyrights: Biotech Books

The whole animal from above

Description
Size (female): 3.22 mm.

Female: The proportional lengths of the cephalothorax and abdomen are as 61 to 13, so that the abdomen is contained 4.7 times in the length of the anterior region of the body.

The head and 1st thoracic segment are fused together. The forehead is rounded and is provided with a well-developed central lens. The 4th and 5th thoracic segments are separate. The posterior thoracic margin is rounded and id produced slightly backwards near the dorsal side in a short triangular flap; it also bears at the height of the curve a single hook-like spine. The rostral spines consist of a swollen basal part and a slender terminal portion.

The abdomen consist of four segments.The posterior margins of the 2nd and 3rd segments are fringed with fine spines and the posterior margin of the anal segment is fringed with long hairs. The furcal rami are short and broad and bear five setae, of which the innermost is quite short.

The 1st antenna reaches back to the posterior margin of the 2nd abdominal segment; it consists of 22 segments, segments 8 to 10 and 24 and 25 being respectively fused together.In the 2nd antenna the exopod is nearly twice the length of the endopod. The distal end of the 1st segment of the endopod is swollen and is provided with a tuft of hairs, as also is the outer margin of the distal segment. The endopod consists of 6 segments. The 1st basal segment bears a stout fringed seta at its distal external angle and in addition there is a line of long curved hairs across the inner aspect.

The maxilliped is of the usual type. It bears along the proximal part of the anterior margin of the 1st basal segment a short row of curved spines. The 2nd basal segment is armed with a long row of fine needle-like spines along the anterior margin of the distal fourth of the segment, The endopod consists of five segments of which the 2nd is the longest.

The 1st swimming leg consists of a two-jointed basal part, a three-jointed exopod and a single-jointed endopod. In the exopod the 1st segment is considerably larger than either of the other two and is swollen internally, the internal margin being fringed with hairs; at the distal external angle it bears a delicate seta-like spine that reaches about half-way to the base of the spine on exopod 2, which is of about the same size and delicacy. The 3rd segment of the exopod has a notched outer border and appears to be bent outwards; the marginal spine is twice the length of the spine on the other two segments and the terminal spine is delicate and seta-like.

In the 2nd swimming leg, the exopod is three-jointed and the endopod consists of two segments. The 1st basal segment bears an inner seta and the 2nd basal is produced at its outer distal angle in a spine-like process. The marginal spines on the three segments of the exopod are sub-equal. The 2nd segment of the endopod bears two rows of spines, an outer row of three spines, all of about the same size, and an inner row of two unequal spines, the proximal being much smaller than the distal.

The 3rd and 4th swimming legs each have a three-jointed exopod and endopod. The 2nd basal segment is, as in the 2nd leg, produced in a sharp spine-like process at its distal outer angle. In the exopod the 2nd segment is armed with a row of small spines across the surface near the distal border. The 3rd segment bears U-shaped row of small spines in the middle of its length. The end-spine is of about the same length as the 3rd segment and bears a number of separate teeth along its outer margin; at the proximal end these teeth are reduced in size.
The 5th pair of legs is completely absent.

Male: As in the female the head and 1st thoracic segment are fused and the posterior thoracic margin bears a short stout spine on each side.
The abdomen consists in this sex of five segments, of which the 3rd is much shorter than either the preceding or the following segments. Segments 2 and 3 are armed on their posterior margins with coarse spinules.

The anal segment bears a number of scattered hairs.

The 1st antenna differs on the two sides of the body; on the right it consists of 17 separate segments and on the left of 18. On both sides segment 8 to 13 and 14 and 15 are respectively fused together, as also are segments 24 and 25; and in addition on the right side segments 20 and 21 are fused.

The 2nd antenna and mouth-parts, with the exception of the 2nd maxilla, are similar to those of the female; in the case of the 2nd maxilla the sensory organs on the terminal segment appear all to be of one kind, and are simple and vermiform.

The swimming legs are as in the female.

In the 5th pair of legs, the 2nd basal of the right leg is dilated at its base and bears a long and curved endopod. The exopod possesses two free segments, the 1st apparently being fused with the 2nd basal segment. The fused 2nd basal and exopod 1 is produced in a series of projections and processes on its inner aspect; there is a well developed wing-like projection near the proximal end; about the junction of the middle and distal thirds is a small rounded lobe, and near the distal end there is a club-shaped prominence. The 1st free segment is produced at its base in a strong inwardly-directed blunt process that is about equal in length to the whole segment; the 2nd free segment is imple and sickle-shaped. The left leg consists of a two-jointed exopod; the endopod is curved and bears at its distal end a row of serrations, the distal segment of the exopod terminates in a claw-like process and bears a tuft of hairs.



Synonym (s)

Common Name (s)
Economic Importance and Threats

Ecology

Biogeography


• Andaman and Nicobar Islands, Nicobar, Nankauri Harbour INDIA

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:2011-03-15

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