Autor: Backeberg
• ETYMOLOGY
≪Candle with small flowers≫, referring to the usually tiny flowers of the species in this genus.
• DESCRIPTION
A genus of solitary plants or sometimes with branched stems from the base, erect to decumbent, not woody, presenting a hypertrophic growth of spines on the basal areoles, but woody and lacking hypertrophic growth rate of spines on the basal areoles in the subgenus Austrocephalocereus. Ribs narrow, densely spiny, with close-set areoles. Pseudocephalium superficial to somewhat sunken (sunken in Austrocephalocereus). Flowers diurnal-nocturnal self-sterile, rather small, produced in a lateral pseudocephalium (an area modified on a
side of the stem where the areole develops additional bristles), tubular and numerous), often bi-coloured, with outer tepals pink or red and inner tepals yellow or white to creamy-white, with a foetid smell in M. purpureus, pollinated by bats (Aona & al. 2006 in Emerson 2007), the other species are pollinated by hummingbirds (Chlorostilbon aureiventris, C. lucidus, Phaethornis pretrei, P. squalidus, Eupetomena macroura), bees (Trigona spinipes) or
butterflies (Phoebis philea, Vettius sp.). Fruits small, turbinate, red when ripe, pulpy, floral remains persistent (Austrocephalocereus) or eventually falling (Micranthocereus). Seeds blackish-brown, smooth in Micranthocereus, with a striped and tuberculate cuticle in
Austrocephalocereus. Dispersal ensured by birds and bats.
• HABITAT
The genus Micranthocereus is endemic to Brazil, and grows in the ≪campo rupestre≫, (mountainous subtropical savanna), among bushes and shrubs, on quartzic, rocky soils or between rocks, between 375 m and 1685 m in altitude (M. purpureus), together with other cacti (eg. Discocactus).
• DISTRIBUTION
Brazil (Bahia, Minas Gerais).
Currently 8 recognised species (A = Austrocephalocereus) + with one (or more)
subspecies:
– Micranthocereus (A.) albicephalus* (Burning & Brederoo) F.Ritter 1979
– Micranthocereus auriazureus Burning & Brederoo 197
– Micranthocereus flaviflorus* Burning & Brederoo 1974 (= M. densiflorus)
– Micranthocereus flaviflorus subsp. alvinii (M.Machado & Hofacker) J.Lode 2014
– Micranthocereus hofackerianus (P.J.Braun & Esteves) M.Machado 2006 (ex Arrojadoa)
– Micranthocereus polyanthus (Werderm.) Backeb. 1942
– Micranthocereus [A.) purpureus (Gurke) F.Ritter 1968
– Micranthocereus streckeri Van Heek & Van Criekinge 1986
– Micranthocereus (A.) violaciflorus Burning 1969
References: "TAXONOMY of the CACTACEAE" - ISBN 978-84-617-3692-8 (Vol. 2)