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

Previous Records of Sergestes from the New Zealand Region

Previous Records of Sergestes from the New Zealand Region

The Challenger Expedition collected a larval Sergestes off Wellington in July, 1874. This was described by Bate (1888) with others from the North Pacific and tropical Atlantic as a new species, S. parvidens. Hansen (1896), following Ortmann (1893), regarded this as the young mastigopus of S. vigilax Stimpson. In 1903, Hansen stated that this New Zealand specimen could not be found in the British page 3Museum, but one specimen taken by the Challenger in the Atlantic and recorded as S. parvidens was a larval stage of S. vigilax, while other specimens recorded from off Cape York, Australia, and identified as S. parvidens, but not published by Bate, were larvae of S. edwardsi. However, Sund (1920: 22 footnote) considers that S. parvidens Bate could not possibly be a larval stage of S. vigilax and cannot relate it to an adult species. Thus it appears that Sergestes parvidens must be removed from the New Zealand fauna, as the species is regarded as unrecognizable from the account and the original specimen is lost.

Sergestes kröyeri Bate, the type specimen of which was taken at Challenger Station 170, off the Kermadec Islands, has always been listed in the New Zealand fauna (see Hamilton, 1896; Hutton, 1904), but will not be considered further here, as at present the Kermadec Province is not accepted as truly belonging to the New Zealand (or Maorian) Sub-region (A. W. B. Powell, R. K. Dell, unpublished views).

The Terra Nova Expedition took a number of larval stages of Sergestes, but no adults, off the North Auckland Peninsula in shallow plankton tows. Borradaile (1916) identified numerous mastigopi from this material as S. semiarmis Bate, the types of which Hansen (1903) had not been able to find in the British Museum and which he consequently regarded as unrecognizable. Borradaile states that this New Zealand material was possibly a larval stage of S. corniculum, but he gives no reason for this. In 1924, Gurney recorded five early larval forms of Sergestes (understood by Gurney to consist in reality of "groups of species") from this Terra Nova material. These were named as Elaphocaris dohrni, E. ortmanni, E. hispida, "Acanthosoma of hispida type" and "Acanthosoma of dohrni type". The possibility that these early larval forms could be linked up with adults taken in New Zealand waters must not be overlooked, but the whole question of relating larval stages to adults in this genus is very complex and greatly complicated by the uncertainty of much of the adult systematics as well as the aberrant sequence of larval stages. It should be noted that the common Sergestes arcticus has larvae of the E. dohrni type, and in fact Gurney and Lebour (1940) recorded an Acanthosoma larva from a Terra Nova station south of New Zealand as S. arcticus.

Burkenroad (1940) gave preliminary descriptions of two new species of Sergestes taken by the Dana Expedition at Station 3630, north-east of the Bay of Plenty. These species, S. (Sergestes) disjunctus and S. (S.) index, were taken in bathypelagic hauls made with "open nets" and are the first adult specimens of the genus recorded from the New Zealand area.