Systematic and Anatomical Studies on Deania calcea (Squalidae), a Deep-Water Shark from New Zealand

Abstract

The deep-water genus Deania is represented in New Zealand waters by a single species, known from the Cook Strait area and the east coast of the South Island. Sixteen local specimens, the subjects of the present study, exhibit wide variation in those characters formerly used to designate the New Zealand population as a separate species, D. kaikourae; it is consequently referred to the synonymy of D. calcea. Evidence from the local specimens indicates that the Japanese D. eglantina should also be synonymized with D. calcea. Anatomical examinations of several systems reveal in D. calcea a number of unusual features imposed upon a fairly generalized squaloid pattern. The urinogenital system, heart, and peripheral nerves all appear somewhat more generalized than they are in Squalus. The brain possesses greatly elongated olfactory tracts and well-developed sensory association centres. The viscera is noteworthy for an unusually elongated duodenum and bile duct; the pyloric stomach is unreverted, and the large cardiac stomach appears to enlarge proportionately with increasing size. The endo-skeleton is characterized by a unique elongation of the neurocranium between the orbits and nasal capsules. The rostrum is tripartite, with a beam-like median cartilage. The large number of free radials in the dorsal fins is remarkable for a squaloid. These and other features suggest that Deania has a long history as a separate genus.