Nehemitropia lividipennis (Mannerheim, 1831)
Native to the Palaearctic region this tiny rove beetle has been widely transported with agricultural products and now occurs in many countries worldwide, it is generally common throughout Europe, extending north into the UK and to northern latitudes of Fennoscandia, and north Africa including the Atlantic islands, in Asia it reaches to the far east of Russia, India, China and Japan and extends south into the Australasia, it is recorded from South Africa and many south and central American countries and has become established and widespread across North America since the early 20th century. It is common and often abundant across Wales and England north to Yorkshire, though mostly absent from the West Country, and more local and rare further north to the Scottish Highlands and the Outer Hebrides. Adults are active between late March and September, peaking in abundance during June and July and again in the autumn, although they usually vanish during the warmest part of the summer, they are generally common among horse and cattle dung but may occur in decomposing vegetation and are sometimes common in decaying fungi, they often occur in most habitats and have been recorded under accumulated decaying seaweed and occasionally from carrion. Both adults and larvae predate small insects and their early stages and in warmer climates they are considered important in controlling crop pests. Little is known of the life-history, larvae develop in dung etc. in through the summer and adults have been recorded in December and February but it is not known if this is the primary overwintering stage. Adults fly well and will often be netted when sweeping dung pasture in warm weather.
3.0-3.5 mm. Elongate and fusiform, head and pronotum black, appearing matt due to dense fine punctures and pale pubescence, elytra pale brown with a large triangular dark mark around the scutellum, abdomen shiny black to dark brown with two or three apical segments entirely or partly paler, legs pale brown, antennae dark brown with several basal segments paler. Pronotum and elytra without long marginal setae. Head transverse and much narrower than
Nehemitropia lividipennis 1
Nehemitropia lividipennis 2
© Lech Borowiec
Nehemitropia lividipennis dissections
the pronotum, eyes large and weakly convex, temples evenly rounded and slightly longer than the eyes, surface evenly convex and pubescent above, the pubescence directed forward along the centre but otherwise oblique, lateral margin with a distinct border that continues under the eyes. Maxillary palps with four segments, the penultimate segment moderately expanded from the base and the terminal segment short and slender. Antennae 11-segmented, three basal segments elongate; the third distinctly longer than the second, the remainder shorter and thicker, almost quadrate, and closely approximated, the links usually not visible, terminal segment longer and pointed; almost as long as the previous three segments combined. Pronotum transverse, broadest in front of rounded posterior angles and smoothly rounded anteriorly, basal margin almost straight across the centre and sinuate before the angles, surface smoothly covex, the pubescence oblique from the midline, in places almost perpendicular. Mesosternum with a distinct median keel from the anterior margin extending to between the coxae which are separated posteriorly by a metasternal process. Scutellum triangular with curved lateral margins, surface punctured and pubescent as the pronotum. Elytra transverse and weakly dilated from rounded shoulders to acute posterior angles, basal margins separately curved and strongly sinuate before the outer angles, surface finely punctured throughout, these often forming tansverse patterns, and with fine backwardly directed pubescence. Abdomen strongly bordered and gradually narrowed from the base, shiny and finely and moderately densely punctured and pubescent throughout, posterior margin of basal tergites finely crenulate. Legs long, with robust femora and narrow tibiae, the middle tibiae usually with a single long seta half way along the external margin. Tarsi 4-5-5 (but these are notoriously difficult to count) with all segments simple, the hind tarsi, including the claws, about as long as the hind tibiae, with the first four segments about equal in length and the terminal segment longer.
Aleocharine rove beetles are generally not easy to identify but the present species may be recognized by the form of the head – the lateral border which extends under the eye and the form of the temples – the antennae, pronotal and elytral form and pubescence and, until the species becomes familiar, the form of the pro- and metasternum. The overall form and colour will soon become familiar when working dung pasture. The aedeagus and spermatheca are also distinctive and should be dissected out to provide reference specimens.