Paranchus albipes (Fabricius, 1796)

Occurs throughout England, Wales and Scotland including the isles of Wight, Scilly, Lundy, Anglesey, Man, (most of) the Western Scottish islands, Orkney and Shetland. Common and generally abundant north to the Scottish borders, common further north but records are more scattered (Luff). Typical habitat is the margins of standing or running water where the adults are gregarious; they are abundant in suitable habitats throughout our Watford area with discrete populations along the margins of all rivers and wetlands. We have recorded adults each month between May and September and teneral specimens (very pale and exceptionally soft bodied; they tend to be quite soft even when mature) occur at least until July. They are to some extent active diurnally - splashing water onto to areas of bare soil among vegetation will invariably produce them - but searching at night with a torch will reveal them to be active in numbers, usually among populations of other marginal carabids. At Radlett road they are common among reed litter even where this is waterlogged, throwing a few handfuls onto a sheet will often produce them, under pondside debris they accumulate in large numbers which scatter rapidly when exposed. Adults can 'skim' across the water surface in the manner of some Stenus species by secreting a chemical onto the water which reduces the surface tension and so propels them forward (Lott, 2003). They breed in the spring and occasionally (presumably) in the autumn as larvae have been found in the winter (Luff). All specimens examined have been fully winged but we have yet to record them in flight or at MV.
This medium sized ground beetle soon becomes familiar in the field; colour varies from dark brown or almost black to pale yellowish brown with lighter elytral margins (immature specimens are lighter); in bright sunshine many specimens have a distinct mauve or maroon colour to the elytra. The broad, rather flat and shining elytra and pale, often almost white, appendages are distinctive.

6.5-8.8mm (Luff) A flat, elongate species with long pale appendages, body without any metallic lustre, elytral margins and suture often paler. Head (and to a varying extent the pronotum as well) somewhat dull due to microsculpture which is barely visible at X20. Two setiferous punctures beside eyes. Frontal furrows well developed and with a fine raised ridge from the top of the eye to the base of the mandibles. Mandibles produced and sharp, outer edge excavate. Antennae pale, pubescent from fourth segment. Palps pale; terminal segment of maxillary palps well developed, penultimate segment of labial palps with two fine setae on inner side. Pronotum transverse (16:13) and cordate, lateral margins narrowly explanate and rounded to a short sinuation before sharp, perpendicular hind angles. Front margin gently curved inwards. Basal margin coarsely punctured, fovea wide and shallow, indistinctly delimited. Elytra somewhat shiny, becoming dull towards apex due to microsculpture. Broad oval and evenly rounded, widest behind middle, margins narrowly explanate and epipleurs not crossed. Striae well impressed and unpunctured, interstices flat; with two setiferous punctures (often very weak) in third interstice, generally adjoining third striae. Femora and tibiae long and slender, meso and metatibiae with two apical spurs inside. Protibiae strongly notched on inside in anterior half, beyond this parallel to apex, with a single apical spur on inside. All tarsi with median furrow on upper surface (in some species they are furrowed laterally). Claws smooth. Male protarsi with three basal segments weakly dilated.

Description from 16 Watford specimens at X20