Deep-Water Crustacea of the Genus Sergestes (Decapoda, Natantia) from Cook Strait, New Zealand
The work of the Victoria University Zoology Department in the deep-waters of Cook Strait has produced four adult species of Sergestes, three of these being new to the fauna. S. arcticus, recorded from the New Zealand area before as a larval stage, was found to be abundant at about 100 fathoms during the night, but apparently sank to deeper waters during the day. This species, well known in the Atlantic from the coast of Greenland to off South Africa, has been recorded from only two other areas in the Indopacific, south of Australia and off the coast of Chile. Observations on the colour of this species in life confirm that it belongs to Sergestes s.s., organs of Pesta being present. A single female of another species with organs of Pesta, the specific identity of which is doubtful, is recorded as S. cf. S. seminudus.
A large, uniform scarlet, partially benthic species, S. potens, with dermal lens-less photophores, was taken twice with a beam trawl, but occurs in large numbers in the stomachs of groper and ling caught commercially in the area. This species, of which only a preliminary description had been previously published, is described here and its photophore distribution given in detail. It has hitherto been recorded only from off South Africa.
Another large, uniform scarlet species, S. japonicus, was taken bathypelagically between about 500 and 600 fathoms on a few ocasions and though well known in the North Atlantic and recorded from Philippine and Japanese waters, this is its first occurrence in the Southern Hemisphere.
The subgeneric division of Sergestes, suggested by Burkenroad but never systematically defined, is discussed in detail and formally established. Those species possessing organs of Pesta and lacking cuticular pigmentation, are referred to the subgenus Sergestes s.s., and those without organs of Pesta, with cuticular pigmentation and often possessing dermal photophores, to the subgenus Sergia Stimpson.
All previous records of Sergestidae from the New Zealand region are discussed, and finally a checklist of the species, now recognised from New Zealand waters, is given.