Greek mikros—small, anthos—flower.

Plants grown under this name include the recently introduced M. densiflorus Buining & Brederoo which is possibly better placed in Arrojadoa where it would be closely related to A. polyantha (Werderm.) D.R. Hunt (which is also sometimes placed in Micranthocereus).

Source: Thompson, A, ; Forbes, S.; Spencer, R. (1997). Cactaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.