Gaussia princeps   (Scott T,  1894) (Copepod)
Organism information awaits expert curation
Taxonomy
Kingdom:Animalia
Phylum:Arthropoda
Class: Maxillopoda
Order:Calanoida
Family:Metridinidae

Image copyrights: Biotech Books

Showing the arrangement of the cutaneous pores

Description
Size (male): length 8.0-9.5 mm; (female): length 9.0-9.5 mm.

The coloration of this species is particularly striking. The anterior part of the head is devoid of pigment, but the rest of the cephalothorax is colored a dense black, the degree of pigmentation varying, however, in different individuals. A black pigmented mass is present on each side of the genital segment of the female; the abdomen of the male is however; devoid of pigment. The 1st antenna is colorless in its proximal half but the terminal segments, from the 16th to the 25th, are all pigmented black. The 2nd antenna is free from pigment and so is the mandibular palp, but the rest of the mouth-parts and the four pairs of swimming-legs are heavily pigmented. The 5th pair of legs are heavily pigmented in the female, but in the male only traces of this pigmentation are present. The immature forms are not nearly so heavily pigmented as the adults.
Female: The proportional lengths of the cephalothorax and abdomen are as 36 to 15, so that the abdomen is contained 2.4 times in the length of the anterior region of the body.
Anteriorly the forehead is continued forwards in a stout spine and the rostrum consists of two long tapering spines, fringed with short hairs. The 4th and 5th segments of the thorax are fused together and the lateral angles of the latter segment are produced backwards in stout spinous processes.
The abdomen consists of three segments, having with the furca the proportional lengths of 52; 9; 18; 21. The 1st or genital segment is symmetrical and in all the mature females obtained by me bears a dense black mass laterally; The anal segment bears on each side a backwardly directed process that extends as far as the base of the outer furcal seta; between the furcal rami on the dorsal aspect the segment bears a bluntly rounded anal plate.
The furcal rami are as broad as long, and there is a tuft of long hairs on the outer margin near the base and proximal to the outermost seta. The inner accessory dorsal seta is very slender.
The 1st antenna reaches well beyond the tip of the furcal ramus and consists of 23 free segments. Of these the terminal segment is quite short and is articulated to the penultimate one by an oblique joint that is somewhat difficult to see; the 7th, 8th and 9th segments are fused together into a single joint; the degree of fusion varies, however, in different specimens; in some examples it is nearly complete, but in others, although there appears to be no actual jointing between the segments, the limit of each component can clearly be made out.
In the 1st antenna, 1st, 2nd and 4th to 6th segments all carry short stout spines on their anterior margins.
The maxilliped is of the usual type and is armed with a row of delicate spines along the margin of the 2nd basal segment.
In the 1st pair of swimming legs, the 1st basal segment carries a stout inner marginal seta. The 2nd basal segment bears an S-shaped seta at its inner distal angle, a delicate external seta and a tuft of long hairs on the distal part of the inner margin. Both rami consist of three segments. Exopod 1 bears a long marginal spine that is fringed with hair on its inner side and reaches to the base of the spine on exopod 2; the outer margin is armed distally with a few small claw-like teeth; the distal margin of the anterior surface bears a row of lancet-like spines and the inner margin is fringed with hair and bears a single seta. Exopod 3 bears two marginal spines, that are also finely serrated on both borders, and the whole of the outer border is fringed with hair; the inner margin carries four plumose setae. The terminal spine is finely serrated externally and its length is equal to the combined lengths of the two last segments of the ramus. Endopod 1 bears a single eta; the outer margin is fringed with hair and there is a row of hairlike spines on the anterior aspect. Endopod 2 bears a single seta and is clad on its anterior aspect and outer border with fine hair. Endopod 3 carries five setae.
In the 2nd swimming leg, basal 1 bears an inner seta. Basal 2 bears an inner seta and presents a rounded projection on its inner margin that is fringed with long hair; on its external anterior aspect it is armed with a scattered group of small denticles. Both rami are three jointed. Exopod 1 carries a broad marginal spine that is leaf-shaped and has finely serrated edges; the inner margin is fringed with hair and bears a single seta; there are some small spinules on its inner anterior aspect near the base. Exopod 2 bears a single marginal spine similar to that on the proximal segment. The outer margin is fringed with a row of small hair-like spines; the inner border is fringed with hair and carries a single seta. Endopod 3 bears three leaf-like marginal spines and the outer margin is fringed with minute spines, which, however, do not extend along the extreme distal part of the margin; the inner border carries five setae. The terminal spine is short and broad, and is only one-third the length of the terminal segment; it is finely serrated along its outer border. The 1st segment of the endopod bears the characteristic double, recurved hooks on its inner margin and a single one near the base; the outer margin is fringed with hair along its distal three-fourths. Endopod 2 bears two inner setae and the outer margin is fringed with hair. Endopod 3 is also fringed with hair on its outer margin and bears eight setae.
The 3rd and 4th swimming legs are similar; the minute spines that are present on the external margin of the exopod in the more anterior legs are here replaced by short hairs; the end-spines are quite short and are less than half the length of the terminal segment of the exopod.
The 5th legs are symmetrical and are composed of a basal part and four free segments that have the following proportional lengths; 33; 33; 22; 12. The 3rd free segment bears a single long seta on its inner aspect, and the 4th or terminal segment bears two setae of which the inner is the longer. The third free segment clearly corresponds to the last two in the present species
Male: The proportional lengths of the cephalothorax and abdomen are as 34 to 13, so that in this sex the abdomen is contained 2.6 times in the length of the anterior region of the body.
The 4th and 5th thoracic segments are fused together and the posterior thoracic margin is produced backwards in a spinous process.
The abdomen consists of five segments with the furcal rami.
In males, the 1st antennae are asymmetrical; that of the left side resembles that of the female and consists of 23 free segments.
The right antenna is modified to form a grasping organ, the knee-joint being, as usual, situated between segments 18 and 19.
Segments 1 and 2 are fused together completely. Segments 7, 8 and 9 are separate; segments 19, 20 and 21 are fused but in certain specimens traces of the division between segments 19 and 20 can be made out; segments 22 and 23 are also fused. The 17th segment bears on its anterior aspect a lamellar crest, that is produced distally over the following segment. The 18th segment bears a lamellar plate that is equal to the length of the segment itself. The fused mass of the 19th-21st segments carries two lamellar plates and is produced distally in a short spine; segment 22-23 bears a short spine at its distal end.
The 2nd antenna, mouth-parts and swimming legs 1 to 4 are similar to those of the female.
In the 5th pair of legs, that on the left side consists of a basal part and 4 free segments. Segment 1 is narrow at the base but widens out considerably at the distal end; it bears a single small seta near the distal external angle. Segment 2 is produced at its distal internal angle in a small rounded process. Segments 3 and 4 appears to be partially fused but a clear line of demarcation can be traced between them. Segment 3 bears a long and narrow spine near its inner proximal angle. Segment 4 bears a long narrow spine on its inner aspect at the junction of the proximal and 2nd quarter of its length and a smaller , but otherwise similar, spine about half-way along its inner margin; the extreme tip of the segment is narrowly rounded. In the right leg the 1st free segment bears a small seta at its distal outer angle. Segment 2 is devoid of any setae. Segment 3 is produced on its inner aspect in two digitiform processes, of these the proximal overlaps the 2nd segment by half to the whole of its length, the distal process is directed distally and extends as far as the end of the segment. The retroverted process and the inner margin of the segment is clad with a band of hairs, that at its distal end curves round across the surface of the segment. Segment 4 presents a low rounded lobe on its inner surface and bears a short spine about the middle of its length.

The spermatophore which is carried by the breeding female is torpedo-shaped and is about 3 mm in length; it is attached by a narrow pedicle to the under aspect of the genital segment near the genital aperture.




Synonym (s)
Pleuromma princeps T. Scott, 1894
Metridia scotti Giesbrecht, 1897
Gaussia melanotica Wolfenden, 1905
Gaussia scotti Wolfenden, 1905
Gaussia scotti Wolfenden, 1911
Metridia scotti Sewell, 1913
Gaussia scotti (Giesbrecht, 1897)
Pleuromamma princeps (Scott T., 1894)

Common Name (s)
Economic Importance and Threats

Ecology

Biogeography


• Bay of Bengal (Lat: 15) (Long: 90) INDIA
• Bay of Bengal INDIA (Record: 21/10/1911)
• 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)
• Arabian Sea (Lat: 16) (Long: 62) INDIA (Record: 12/09/1991-23/09/1991) (Depth: 200-500 mts)
• Arabian Sea (Lat: 23) (Long: 73) INDIA (Record: 12/09/1991-23/09/1991) (Depth: 200-500 mts)
• Bay of Bengal (Lat: 7.35) (Long: 85.12) INDIA (Record: 21/10/1911)

Literature Source(s)
  • Manakadan, R and Pittie, A (2002) Standardized english and scientific names of the Indian subcontinent-2002 Newsletter for Birdwatchers S. Sridhar 42 p 35
  • Madhupratap, M and Haridas, P (1986) Epipelagic calanoid copepods of the Northern Indian Ocean Copepod 105-117 Available at - NIO, RC Kochi
  • 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
  • Fernandes, V (2008) The effect of semi-permanent eddies on the distribution of mesozooplankton in the central Bay of Bengal Journal of Marine Research Sears Foundation for Marine Research 66 465–488 Available at - NIO,Goa
  • 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
  • Goswami, SC and Srivastava, Y (1996) Zooplankton standing stock, community structure and diversity in the northern Arabian Sea Proceedings of the Second Workshop on Scientific Results of FORV Sagar Sampada Department of Ocean Development, New Delhi, India 127-137p Available at - http://drs.nio.org/drs/handle/2264/2147

Page last updated on:2011-03-16

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