This is a small genus of tiny cerylonids that are known from tropical regions worldwide; largely ignored and until recently including five or six species but a recent revision has added many new species from various tropical regions and now the greatest diversity seems to be in Neotropical areas, see Jaloszynski & Slipinski, 2022. The genus has an interesting taxonomic history, having been placed in various families, and now it seems to be part of the Murmidiidae, formerly a subfamily of the Cerylonidae. Little is known of the biology of the genus but adults of a few species are sometimes imported to temperate regions in bulk grain and cereal products etc. from the tropics and under artificial conditions large populations may quickly build up. M. ovalis (Beck, 1817), which seems to be native to the Australasian and possibly Afrotropical regions, is occasionally reported from the Palaearctic, Nearctic and Oriental regions and may become established under artificial conditions. The species was quoted by Fowler (1889) as occurring among leaf-litter and grass cuttings but there are no accurately dated records and the species is now only very rarely recorded here. M. segregatus Waterhouse, 1876, which seems to be of Afrotropical origin, is very rarely recorded; it has been found in the UK among imported cocoa beans etc. and it was reportedly taken from the wild in Cambridgeshire in 1831, but there are no other records from Europe and outside Africa the only other records are from the Oriental region.

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The beetles are tiny, 1.1-1.4 mm, broadly-oval and entirely brown or reddish brown in colour, usually with the appendages paler. The dorsal surface is rather dull and very finely punctured and pubescent throughout. Head deflexed, weakly convex between prominent eyes and with short and strongly converging temples. Antennae inserted laterally beneath the anterior margin of the eyes, 10-segmented with a broad, almost round single segmented club. Basal antennomere produced externally to a sharp tooth. Pronotum broadest across obtuse posterior angles and narrowed to dorsal antennal-cavities on the anterior angles, anterior margin straight, basal margin sinuate and produced backwards medially, surface evenly convex or with short grooves from the antennal cavities. Elytra evenly rounded from sloping shoulders to a continuous apical margin, surface rather strongly convex and with variously-developed longitudinal rows of larger punctures. Legs short with femora hardly visible in normal setting. Tibiae broadened from the base; front tibiae strongly narrowed and excavate towards the apex, middle and hind tibiae broadest behind the middle and curved or angled externally. All tarsi with 4 simple segments in both sexes. Claws smooth and not toothed at the base. Easily recognised among our UK fauna by the antennal cavities which are obvious from above. The two species recorded from the UK may be separated as follows (although other species may also occur).