Leiosoma oblongulum Boheman, 1842

Suborder:

Superfamily:

Family:

Subfamily:

Tribe:

Genus:

POLYPHAGA Emery, 1886

CURCULIONOIDEA Latreille, 1802

CURCULIONIDAE Latreille, 1802

MOLYTINAE Schönherr, 1823

MOLYTINI Schönherr, 1823

Leiosoma Stephens, 1829

This very local and generally rare species has a mostly central and southern European distribution; it occurs in upland and mountain areas from the Pyrenees to Ukraine and north to Germany, Poland and the UK although here it is sporadic and missing from many regions. In the UK it is probably under-recorded, it is very local in Kent and Sussex, the West Midlands and Wales, and there are a few more widely scattered records from the West Country, East Anglia and as far north as Cumbria, it is also recorded from Northern Ireland. Here the typical habitats are permanently damp grassland and woodland while on the continent it occurs in upland deciduous forests and wet meadows and is often recorded from moss and vegetation beside mountain streams. The biology is poorly understood but adults occur year-round; they overwinter among moss or leaf-litter and are active from March until November, peaking in abundance from March until June and again in October.  Host plants include various Ranunculaceae, in the UK usually Wood Anemone (Anemone nemorosa (L.) Holub) and various buttercups (Ranunculus L.) while on the continent also on Common Columbine (Aquilega vulgaris L.). Larvae feed on or within roots and probably develop through late spring and early summer to produce new-generation adults in late summer and autumn. Adults may be found during the milder months by sweeping close to damp ground among suitable host material but they are elusive and usually occur in small numbers and so are easily missed, sampling damp moss and litter, especially at sites where the weevil is known to be present, is a better way to find them.

2.5-3.1 mm. Superficially similar to the common L. deflexum, but distinctly narrower and a ventral tooth on the femurs. Convex and discontinuous in outline with separately-rounded pronotum and elytra, shiny black, occasionally with a faint metallic reflection, but for the tarsi (and sometimes the tibial apices) and antennal scape and funiculus which are brown or reddish-brown, body with sparse short pale pubescence. Head transverse and usually retracted into the thorax to the posterior margin of weakly convex eyes, surface punctured and obscurely sculptured, rostrum about as long as the pronotum (compare in lateral aspect) and strongly down-curved, parallel-sided but distinctly broadened towards the apex where the lateral scrobes are narrowly visible. Antennal scape gradually thickened in the apical half or third, funiculus 7-segmented and club broadly oval and pointed. Pronotum slightly transverse, broadest about the middle and smoothly curved to rounded anterior angles, in the basal half almost straight and converging to obtuse posterior angles, surface strongly and discretely punctured. Metepisterna with dense pale scales (obvious in lateral aspect between the middle and hind legs).Elytra elongate, broadest about the middle and evenly curved from sloping shoulders to a continuous apical margin. Legs robust; femora without a ventral tooth, front tibiae with a small incurved apical tooth, middle and hind tibiae only slightly widened apically and without well-developed spurs, tarsi pseudotetramerous. Males may be distinguished by the apex of the front tibia which is strongly incurved and twisted.

Leiosoma oblongulum

Leiosoma oblongulum

All text on this site is licensed under a Creative Commons Attribution 4.0 International License.

For information on image rights, click HERE.

  • Facebook