Cannon, 1940a
Diagnosis
Carapace fragile and ovoid (G. dracontovalis Habitus 1, G. dracontovalis Habitus 2, G. dracontovalis Habitus 3, G. dracontovalis Habitus 4). Gape between valves extends along over three quarters of the carapace (G. dracontovalis Habitus 2, G. dracontovalis Habitus 4). The rostrum small but with distinct incisure (G. dracontovalis 1). Newly caught specimens translucent and tinged with a violet-red pigment; any eggs/embryos in the brood pouch violet. Naupliar eye with some interference colour but is otherwise pale; probably as a result of daylight rapidly bleaching the visual pigment. Poulsen (1962) showed that the most reliable characters for distinguishing this species from its congeners apart from the shape of the carapace, are the numbers of spines in the vicinity of the rostrum and the incisure. There are 44-70 "a" spines on the anterior region of the rostrum from the dorsal point of coalescence of the shell to the base of the incisure. Two "b" spines occur along the lower edge of the incisure number, and 4-6 "c" spines occur where the lower edge of the incisure merges with the ventral edge. The structure of the seventh limb is long and worm-like as is characteristic of Gigantocypris ; armed with about 80 setae and fewer comb teeth (<30) than its congeners; it continually writhes within the carapace, presumably keeping it clean.
Remarks
Distinguished from G. muelleri (Gigantocypris muelleri)by its smaller size, the disposition of setae in the region of the rostrum, its paler colouration and very much deeper bathymetric range. Skogsberg, 1920 described a variety of G. muelleri, var. minor, on the basis of two females from a haul at 29°08'N 25°16'W, which included the type form. Skogsberg stated "it is not impossible that we are dealing with specimens. . .whose development has been checked by unfavourable conditions". Cannon, 1940a designated the species on the basis of a single female from the Indian Ocean off Somalia. Poulsen, 1962 described a further five specimens, all females, three from the Atlantic, one from the central Pacific and another from the Eastern Indian Ocean, all from latitudes <30°. Discovery Collections contain many specimens from samples in which the sampling depth exceeded 3000m.
Distribution
Probably ubiquitous at deep abyssopelagic depths. Particularly abundant in the benthopelagic zone 1.
Type specimens
None designated; status of original material uncertain.
Type locality
6°59'N 55°41'E, John Murray Expedition Station 98, date 29/12/29; depth probably about 1400m (2800 metres of wire out); gear 2m tow net.