Bembidion properans (Stephens, 1828)

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ADEPHAGA Clairville, 1806

CARABIDAE Latreille, 1802

TRECHINAE Bonelli, 1810

BEMBIDIINI Stephens, 1827

Bembidion Latreille, 1802

Metallina Motschulsky, 1850

This is a widespread and generally common species in Europe, it occurs from lowlands to about 800 m from Portugal to Italy and Greece in the south and north to the UK and southern provinces of Fennoscandia, further east it extends through Asia Minor and Russia into Siberia and it has recently become established in North America; in the United States since the 1940s and in Canada (Nova Scotia) since the 1960s. In the UK it is generally common throughout England and Wales, including the islands, though becoming local and scarce in the north, it is known from only a few sites in southern Scotland and is absent from Ireland. Adults occur year-round; they overwinter among litter and moss etc. usually in sheltered and often marginal situations e.g. arable and woodland borders and hedgerows and are active over a long season from very early in the year. Typical habitats are open sites exposed to the sun, usually on damp clay or peaty soils with medium humidity although they also occur on stony substrates beside rivers and reservoirs etc, they are sometimes found with the widespread and common B. lampros (Herbst, 1784) but unlike that species they are generally absent from dry heaths and wooded areas. They are sometimes quick to colonise new sites and may appear suddenly in well worked sites in spring and early summer, adults are wing dimorphic and there is evidence to suggest that the percentage of winged specimens varies with habitat with the larger proportions occurring on floodplains and other areas prone to flooding and the lower percentages occurring on arable sites away from water. Breeding occurs in the spring and teneral adults occur from late summer but little is known of the biology and the larva is unknown. Adults are diurnal and active in bright sun, they generally occur in numbers and may be very common in the spring and autumn on floodplains and damp agricultural land; they are easily spotted as they run rapidly on the surface but they quickly vanish into crevices or under debris when alarmed. They usually occur in numbers in well placed pitfall traps but are easily pootered or picked by hand, they usually occur along with several other members of the genus as well as other small carabids and so specimens will need to be taken for critical examination. Conversely it is a species that soon becomes familiar in the field with a decent hand lens, especially the coloured forms which seem to occur as frequently as the normal dark ones.

Bembidion properans 1

Bembidion properans 1

Bembidion properans 2

Bembidion properans 2

Bembidion properans 3

Bembidion properans 3

3.5-4.5 mm although smaller specimens occasionally occur, shiny metallic brassy or bronze, sometimes distinctly blue or green, legs dark with the tibiae mostly pale, antennae and palps dark grey. Coloured forms are sometimes referred to in the literature as cyaneotinctum Sharp, 1913 (green) and coeruleotinctum Reitter, 1908 (blue). Head with very large and convex eyes, vertex smooth and only very finely punctured, frontal furrows angled beside the anterior supra-orbital puncture, parallel-sided anteriorly and not extending onto the clypeus, terminal maxillary palpomere diminutive. Pronotum transverse, broadest in front of the middle and rounded to weakly-defined anterior angles and a short and almost parallel-sided margin before perpendicular or slightly obtuse posterior angles, explanate margin well-defined and weakly narrowed to the angles. Surface weakly convex with a longitudinal median impression and a series of small fovea across the base.  Elytra with rounded shoulders, weakly curved or almost parallel-sided laterally and continuously curved apically, each with seven punctured striae which fade beyond the middle and short scutellary striole, the seventh stria about as strongly punctured as the sixth at the base and extending to at least the centre of the margin, interstices unpunctured and almost flat, the third with two setiferous punctures which do not join the striae. Basal elytral border angled with the lateral border and not reaching the scutellum. Legs long and slender, front tibiae with a deep antennal-cleaning notch and all tibiae with paired apical spurs, tarsi 5-segmented. Basal segments of the front tarsi dilated in the male.