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Deep-Water Crustacea of the Genus Sergestes (Decapoda, Natantia) from Cook Strait, New Zealand

Colour in Life

Colour in Life

The only specimens seen in a fresh condition were the damaged female from Collection 83 and the undamaged female from Collection 100. Each was examined within a few hours of capture and the following colour notes combine the observations made on both:

Entire body and appendages uniform scarlet, eyes black, organs of Pesta absent, numerous intense purple lens-less photophores (fading to yellow in preservative) arranged as follows:

Carapace: An irregular patch present behind base of antennule and above ventrolateral angle, an irregular row in roof of branchial chamber at level of suprabranchial ridge.

Eyestalk: None.

Antennular Peduncle: 2 distoventrally on 3rd segment.

Antennal Peduncle: 1 distolaterally on penultimate segment, 1 distoventrally on ultimate segment.

Scaphocerite: 1 ventrally at articulation and a longitudinal row of about 9–11 irregularly spaced in distal two-thirds. One long streak and 1 small spot diagonally in proximal third.

Mandible: 1 at distal end of proximal segment of palp.

1st Maxilla: None.

2nd Maxilla: 5 on anterior half of exopodite and a large kidney-shaped one on posterior half.

1st Maxilliped: 1 on the penultimate segment of the exopodite.

2nd Maxilliped: 1 proximally on merus, 1 distally on both carpus and propodus.

3rd Maxilliped: 1 distodorsally on both merus and carpus, and 1 distoventrally on propodus.

1st Pereiopod: 1 proximally on ischium, and 2, one larger than the other, proximally on the merus.

2nd Pereiopod: 1 proximally and 1 distally on ischium, none on merus.

3rd Pereiopod: 2 on ischium as in 2nd pereiopod, row of 8–13 on merus.

4th Pereiopod: 2 on ischium as in 2nd pereiopod, 1 distally on merus, and 2 distally on carpus. 2 internal pigmented patches were visible by reflected light, 1 on ischium and 1 proximally on merus; these were found on dissection to be similar in structure to the externally visible photophores.

5th Pereiopod: 2 on ischium as in 2nd pereiopod, 1 distally on both merus and carpus.

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1st Pleopod: 1 proximally on exopodite.

2nd–5th Pleopods: 2 distolaterally on coxopodite, 1 distally on basipodite, and 1 proximally on exopodite.

Uropod: 1 at proximomedial angle of both endopodite and exopodite, an irregular streak and spot longitudinally on proximal third and an irregularly spaced longitudinal row of about 5 on distal third of exopodite.

Thoracic Sternum: 1 between bases of antennae. 1 large one each side of labrum. 2 between bases of lst-2nd maxillipeds. 1 between bases of 2nd-3rd maxillipeds. 1 between bases of 3rd maxillipeds. 1 between bases of lst-2nd pereiopods. 1 between bases of 2nd-3rd pereiopods. 1 median and 1 pair between bases of 3rd-4th pereiopods. 1 between bases of 4th pereiopods. 1 median and 2 pairs (1 large and 1 small) between bases of 4th and 5th pereiopods. 1 median pair between bases of 5th pereiopods. 1 large one behind base of each 5th pereiopod.

Abdominal Sternum: Each sternite (1st–6th) with one prominent antero-lateral pair and in addition in the midline: 1st sternite, 1 pair behind bases of pleopods. 2nd sternite, 1 pair and 1 unpaired in front of, and 1 pair behind, bases of pleopods. 3rd sternite, 1 pair and 1 unpaired in front of, 1 unpaired between and 1 pair behind, bases of pleopods. 4th sternite, 1 pair in front of, 1 unpaired between, and 1 unpaired behind, bases of pleopods. 5th sternite, 1 unpaired between and 1 unpaired behind, bases of pleopods. 6th sternite, a median longitudinal row of 4–6 irregularly shaped photophores (the posterior one wider than long).

Fig. 19. Sergestes potens. Size frequency histogram for the 47 specimens collected by the Pawley brothers in 1941.

Fig. 19. Sergestes potens. Size frequency histogram for the 47 specimens collected by the Pawley brothers in 1941.