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

Size

Size

A size frequency graph of the 25 males and 22 females in the Pawley brothers 1941 collection is given in Fig. 19. In it males and females have been treated together, as they both reflect the same trends. This graph shows that the majority of the specimens, 73%, are in the restricted size range of 23 to 26 mm (carapace length). If we can assume that the sample reflects the size composition of the shoals on which page 17
Fig. 10. Sergestes cf. S. seminudus, carapace, lateral view (anterior organ of Pesta represented by broken circle) ♀. Figs. 11–18. Sergestes potens. Fig. 11—Carapace, lateral view, ♂. Fig. 12—Left scaphocerite, ventral view (setae omitted), ♀ 27 mm. Fig. 13—Left uropod, ventral view (setae omitted), ♀ 27 mm. (Figs. 11–13 drawn to same scale. Photophores represented in black.) Fig. 15—Right petasma, posterior view, ♂ 24 mm. Fig. 16—as preceding, anterior view. Fig. 17—Anterior part cephalothorax, lateral view (setae omitted), ♂ 23 mm. Fig. 18—Diagrammatic view ventral surface to show photophore distribution. (Bases of appendages open circles, photophores in black.)

Fig. 10. Sergestes cf. S. seminudus, carapace, lateral view (anterior organ of Pesta represented by broken circle) ♀.
Figs. 11–18. Sergestes potens. Fig. 11—Carapace, lateral view, ♂. Fig. 12—Left scaphocerite, ventral view (setae omitted), ♀ 27 mm. Fig. 13—Left uropod, ventral view (setae omitted), ♀ 27 mm. (Figs. 11–13 drawn to same scale. Photophores represented in black.)
Fig. 15—Right petasma, posterior view, ♂ 24 mm. Fig. 16—as preceding, anterior view.
Fig. 17—Anterior part cephalothorax, lateral view (setae omitted), ♂ 23 mm. Fig. 18—Diagrammatic view ventral surface to show photophore distribution. (Bases of appendages open circles, photophores in black.)

page 18 the fish were feeding, the uniformity of size range within these shoals should be noted.

The following measurements were taken from mature specimens of both sexes (mm):

Male. Female.
Length entire 87.5 113
Length carapace 24 32
Length rostrum 1.5 2
Length abdomen 51 66
Length 3rd somite abdomen 9 11
Length 6th somite abdomen 12 15
Length telson 11 13
Length 3rd maxilliped 32.5 45
Length 1st pereiopod 24.5 34
Length 2nd pereiopod 35 48
Length 3rd pereiopod 38.5 60
Length 4th pereiopod 28.5 37
Length 5th pereiopod 16.5 21

The male was chosen from the commonest size range (carapace length 24 mm) while the female is the largest specimen in the collection (length entire about 113 mm). This female is, as far as I can ascertain, only surpassed in size by one other specimen of the genus Sergestes recorded in the literature. This is the type male of the closely related S. (Sergia) maximus Burkenroad, 1940, with a length of about 136 mm (carapace length 41.5 mm). The type female of S. (Sergia) inous Faxon, 1893, is also given as 113 mm in length. The length entire is measured from the tip of the rostrum to the posterior tip of the telson and is inaccurate, due to the difficulty in extending the abdomen.