(syn. Tadorna Ϯ Paradise Shelduck T. variegata) Portmanteau of Zealand (i.e. New Zealand) and genus Casarca Bonaparte, 1838, shelduck; "The genus Casarca Bp., 1838, haplotype Anas ferruginea Pallas, has always held the Paradise Duck (Anas variegata Gm.)  Both species should not be in the same genus. To see both forms alive indicates that. At Mr. Ezra's place, in 1934, no ornithologist there would agree to this New Zealand Duck being placed in the genus Casarca.   Zesarkaca sub-gen. nov.   Type Anas variegata Gm.   The type of this new sub-genus differs from the type of Casarca in being a different colour and in having the nails on the toes of quite a different character. The nails in ferruginea are pointed, curved and narrow, those of variegata are wide and blunt" (Mathews 1937)  (OD per Mark Brown).   Var. Zekarkaca.

Search for more names on the Key to Scientific Names in Ornithology by James A. Jobling.
Recommended citation
Jobling, J. A. (2019). Key to Scientific Names in Ornithology. In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.) (2019). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from www.hbw.com on 19 January 2019).