Nephanes titan (Newman, 1834)

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POLYPHAGA Emery, 1886

STAPHYLINOIDEA Latreille, 1802

PTILIIDAE Erichson, 1845

ACROTRICHINAE Reitter, 1909

NEPHANINI Portevin, 1929

Nephanes Thomson, C.G., 1859

Among the smallest of our UK beetles, and outdone in this respect only by Baranowskiella ehnstromi, this ironically-named species is widespread across Central and Northern Europe from the Pyrenees to Italy and Ukraine in the south and north to the UK and into central Fennoscandia. The species is known from Western Russia and is present on most of the Mediterranean islands as well as the Azores and Canary Islands; it is widespread in North Africa and has recently been discovered among specimens collected from the Ivory Coast (Darby, 2020). The species was first described from North America in 1971 from adults and larvae collected in Illinois between 1967 and 1974, and since then it has been found to be widespread and common but whether it is native to that region or an established Old World introduction is not known. This is among the smallest of the world’s non-parasitic insects but despite this it has been the subject of much research; it has a tiny brain and a limited neuronal system but has been found to display cognitive learning behaviour (Polilov et al, 2019). In the UK it is widespread though very local throughout England and Wales, with the possible exception of the West Country, and is known Ireland and from Man but is seemingly absent from the other islands. Adults occur year round, they are active in suitable habitats through the year and peak in abundance from July until the autumn, the phenology might suggest a univoltine development but under suitable conditions the species is more likely to be continuously brooded. The typical habitat is among decaying vegetation but both adults and larvae are more usually associated with dung, manure heaps, and neglected decaying straw and hay, and in such situations both stages may be abundant through the milder months. Little is known of the biology but, typical of the family, females probably mature a single relatively large egg at a time, and larvae, which are definitely not predatory and probably feed on fungal spores, take about three weeks to fully develop. Adults may be sampled by extraction, and here they usually occur in numbers, but they fly well and sometimes swarm about manure or compost, and at least in northern Europe, sometimes over dung pasture or open grassland.

Nephanes titan

Nephanes titan

© U.Schmidt

0.55-0.65 mm. The small size and general habitus is usually sufficient to recognize this species. Body with short pale pubescence, entirely brown, or with the head and pronotum darker, legs a little paler brown, antennae pale at the base and usually darker from the second or third segment. Head narrowed in front of convex and relatively large eyes, temples short and slightly converging, vertex and frons uneven. Antennae 11-segmented; two basal segments long and broad, third segment diminutive, 4-8 elongate and slender, not more than 1.5x longer than wide, and 9-11 elongate-oval, forming an indistinct club. Pronotum transverse, broadest about the middle and evenly curved to obtuse angles, basal margin almost straight and not produced laterally. Pronotal surface impunctate, with wide and shallow cellular microsculpture. Front coxae almost touching, with a short and pointed process at the apex. Mesosternal base slightly projecting laterally, mesocoxae separated by a convex, but not ridged, process which meets the produced median base of the metasternum. Metacoxae widely separated and projecting beyond the metasternal base. Elytra slightly dilated from sloping shoulders to (more or less) truncate apical margins that leave the abdominal apex exposed, surface with finely microsculptured but not (obviously) punctured. Legs short and slender, with unarmed femora and almost parallel-sided tibiae. Tarsi 3-segmented in both sexes, the basal segments short and broad and the terminal segment narrow and very long.