Ootypus globosus (Waltl, 1838)
POLYPHAGA Emery, 1886
CUCUJOIDEA Latreille, 1802
ATOMARIINAE LeConte, 1861
ATOMARIINI LeConte, 1861
Ootypus Ganglbauer, 1899
This western Palaearctic species has a rather sporadic distribution through Europe; it occurs from Spain to the Black Sea and into western parts of Russia but is absent from the Balkans and only really common in some southern and central areas, it extends north as far as the UK and central Sweden but is absent from some of the Baltic countries and otherwise generally rare e.g. in Poland and northern Germany. Here it is widespread though very local throughout England and Wales, including the islands, north to the Humber and very local and scarce further north into southern Scotland and across Ireland. Adults occur year-round and are active from early spring until late autumn, they peak in abundance from May until July and may often be found active during the winter. Typical habitats are grassland and dung pasture where they often occur in numbers in herbivore dung but more generally they are associated with compost and decaying vegetation in a wide range of damp or not too dry habitats, and they have been recorded from stored straw etc. in sheds and cellars. Little is known of the life-cycle but larvae are probably saprophagous rather than mould feeders which more general for the family. Adults often occur in numbers, especially in cattle and horse dung that is not too wet, and are easily obtained by extraction or tapping samples over a sheet, more generally they will often be encountered when sieving compost or well-decayed litter in open woodland, during the winter they sometimes appear among extraction samples e.g. from old bird or mammal nests or decaying sporophores, and may be common among flood refuse. Despite their tiny size and obscure habits they soon become obvious in the field and should be regularly recorded.
Ootypus globosus 1
© U.Schmidt https://www.kaefer-der-welt.de/index.htm
Ootypus globosus 2
© Lech Borowiec http://www.cassidae.uni.wroc.pl/Colpolon/index.htm
1.0-1.7 mm. Elongate-oval and very convex, broadest about the middle and more-or-less continuous in outline, body glabrous, entirely dark brown to black, appendages pale brown. Head transverse from above and mostly retracted into the thorax and so without obvious temples, surface smoothly convex and virtually impunctate, produced and deflexed anterior to the antennal insertions. Antennae inserted close together, by about the width of the globose basal segment, segments two and three elongate, four to eight quadrate or slightly elongate and nine to eleven forming an elongate and very gradual club. Pronotum broadest across the base and narrowed to obscure anterior angles, basal margin gradually produced medially, surface evenly convex, finely and sparsely punctured and with extremely fine reticulate microsculpture throughout. Scutellum broadly triangular or with slightly angled lateral margins. Elytra smoothly curved from rounded shoulders to a continuous apical margin, without striae and punctured as the pronotum or little finer, sutural margins divergent just before the apex. Legs short and slender, the hind tibiae not exceeding the elytral apex. Tarsi –segmented, basal segments short and weakly lobed, terminal segment long and curved. Claws smooth and with a very small basal tooth. The form and proximity of the antennae will distinguish Ootypus from many other small species e.g. corylophids or phalacrids, and the non-striate elytra and general habitus are distinctive features. The most likely confusion might be with various similarly-shaped species of Atomaria Stephens, 1829, but these are much less convex and have the scutellum quadrate or transversely oblong.