Eatoniella fuscosubucula is a species of marine gastropod mollusc in the family Eatoniellidae.[1] It was first described by Winston F. Ponder in 1965. It is endemic to the waters of New Zealand.
Eatoniella fuscosubucula has a small conical shell, with a large D-shaped aperture in the shell. The shells are white, with an inner brown layer also visible. The species measures 1.4 millimetres by 0.95 millimetres.[2]
The species is similar in appearance to Eatoniella dilatata, but distinguishable by its colour and larger size, ad to Eatoniella verecunda by its smaller size, thinner shell and brown inner layer.
The species is endemic to New Zealand.[1] The holotype was collected by E.C. Smith in January 1950 from Paterson Inlet, Stewart Island. The species is found in the waters of the lower South Island, Stewart Island and the Auckland Islands.