Paradromius Fowler, 1887
Distributed throughout the Palaearctic region, including North Africa and the Atlantic islands, this genus of small carabids includes more than 30 species in 4 subgenera. Of the 16 or so European species most are endemic to certain countries, mostly in Mediterranean or Atlantic regions, and only a very few are at all widespread. Subgenus Trichodromius Bedel, 1907 includes two species and both are endemic to Spain. Subgenus Rugodromius Landin, 1954 (which should probably be included within the subgenus Manodromius Reitter, 1905 but which is often quoted in the literature) includes about 6 species, mostly from Central Asia but none from Europe. Manodromius occurs throughout the range, it includes 22 species of which 12 occur in Europe. Only a few species are widespread e.g. P. linearis (Olivier, 1795) which extends to the UK, and most are very restricted e.g. D. saharensis (Mateu, 1947), known from the Western Sahara, P. strigifrons (Wollaston, 1865) which occurs as 3 subspecies and is endemic to the Canary Islands, or P. insularis (Wollaston, 1854) which is more widespread on the Atlantic islands. Paradromius s.str. includes only two species; P. suturalis is widespread in Asia and extends into Eastern Europe as far as Bulgaria and Ukraine, while P. longiceps (Dejean, 1826) is the more western species, occurring throughout Europe, including the UK, and extending east into Ukraine and Western Russia.
The species are easily recognised by the elongate and narrow form and pale colour. Among our UK carabids only Demetrias, which has the fourth tarsomere bilobed, and a few other genera within the Lebiini, which are superficially similar but broader or differently coloured, might be mistaken for Paradromius. 5.5-6.5 mm. Elongate, narrow and flattened, mostly pale brown or with the forebody and elytral suture or margins darkened. Head quadrate or elongate, with long temples and smooth vertex, frons wrinkled inside the eyes and clypeus and mouthparts produced forward, antennae long and filiform. Pronotum quadrate or slightly elongate, broadest in front of the middle and narrowed to distinct posterior angles, basal margin straight, surface smoothly and weakly convex, lateral margins widened towards the base, basal fovea usually weak. Elytra narrow (parallel-sided or slightly dilated from sloping shoulders to truncate apical margins, striae weakly impressed and variably punctured, basal margin incomplete; visible only towards the shoulders, interstices flat or weakly convex, the seventh with at least two setiferous punctures. Legs long and slender. Front tibiae strongly notched. Tarsi simple, basal segments of front tarsi slightly dilated in males. Our UK species are easily separated:
Paradromius linearis 1
Paradromius longiceps 1
Paradromius linearis 2
Paradromius linearis 3
Third antennomere densely pubescent. Head more elongate, with temples much longer than the eyes and the frons with a single wrinkle inside each eye. Pronotum elongate. 5.0-6.5 mm.
Third antennomere with only the usual fine setae. Head quadrate with temples not longer than the eyes, frons with multiple wrinkles inside each eye. Pronotum quadrate. 4.4-6.0 mm.
Paradromius linearis (Olivier, 1795)
This western Palaearctic species occurs from lowland to low mountain regions throughout Europe to the south of Fennoscandia, extending south to North Africa, including all the Mediterranean islands, Egypt, Caucasus and Russia east to the Ural Mountains; it is common and often abundant across most of its range although in some northern European regions it tends to be more coastal but some northern areas have seen an expansion in recent decades. Here it is abundant throughout lowland England and Wales, rather sparse and mostly eastern-coastal to the north of Scotland, and very local through Ireland. Adults are likely to be encountered in most situations, especially during the warmer months when they are very active on vegetation, but in general they prefer dry situations with plenty of vegetation e.g. grassland, parkland. Dunes, wasteland and road verges etc. and they will often occur in domestic gardens and other disturbed situations. Adults are present year-round and active over a very long season; depending on the season they may be found from February until November although they are also active in mild spells through the winter, during January or February they may be found on fence posts or around the base of trunks, and soon they are active on vegetation, climbing stems and roaming foliage. They are mostly nocturnal but in hot weather they may be swept from vegetation by day or night and may be particularly abundant along arable and woodland margins or occasionally in reed beds. Mating occurs mostly in the spring, during March and April, but also occurs commonly in the autumn, eggs are laid in small batches in the soil around the base of plant stems and larvae develop either in the soil or within hollow stems. Larvae have been recorded in every month; in the winter in plant stems or other sheltered situations, and otherwise in the soil generally, older larvae occur in the summer and these may produce adults that mate in the autumn and either lay eggs that produce overwintering larvae, or overwinter to oviposit in the spring. The majority of new-generation adults appear towards the end of summer, overwinter and mate in the spring but the species may be continuously breeding, at least over parts of its range. Both larvae and adults are predatory on small insects and springtails etc. Sampling adults is simple as they will appear regularly in the sweep net during the warmer months, at night they are likely to be seen on stems etc. at any time of the year; they usually mate on posts or trunks and pairs are easily observed in late winter and spring.
These small beetles, 4.5-5.5mm, are characterized by the pale colour, glabrous and truncate elytra and elongate form. Entirely pale brown, including all appendages, usually with the head, pronotum, elytral apices and suture darker. Head elongate and proportionally large; virtually as wide as and longer than the pronotum, vertex smooth but for longitudinal striations beside each eye, eyes convex and quite prominent anterior to long and tapering temples. Antennae long and slender, second segment shorter than the first and third, all segments elongate, becoming less so and a little broader towards the apex. Pronotum quadrate, broadest behind rounded anterior angles and strongly sinuate and narrowed to sharp and protruding posterior angles, basal margin weakly curved. Elytra very elongate, about 2.5 times longer than wide, with sloping shoulders and a truncate and slightly sinuate apical margin, striae complete to apical fifth or so, weakly-impressed and distinctly punctured, in places consisting only of rows of punctures and not impressed, scutellary stria missing, interstices flat and unpunctured. Legs long and slender, pro-tibiae with an internal antenna-cleaning notch. Tarsi 5-segmented, all segments elongate. Claws serrate. The majority of specimens lack wings.
Paradromius longiceps (Dejean, 1826)
This widespread species occurs in lowland regions throughout Europe from Spain to Italy and east into western Russia, to the north it extends into the UK and southern provinces of Fennoscandia and occasionally occurs further north, it is generally very local and scarce although in some northern countries e.g. Denmark, it has spread considerably in recent decades. In the UK it is a very scarce and more-or-less confined to certain areas of eastern England, mostly in Yorkshire and East Anglia where it occurs on stems and among litter in reed beds, and there are records from a very few eastern and southern coastal localities. Adults occur year-round but are infrequently recorded during the summer; they breed from March until May or June and may persist into the summer but most die-off. The predatory larvae develop through the summer among reed litter etc. and pupate from July or August; new generation adults appear from late summer and will go on to overwinter and breed in the spring. Both adults and larvae may be found in reed beds but they do not, generally, climb stems as does e.g. Demetrias imperialis (Germar, 1824), they usually occur among reed litter (Phragmites australis (Cav.)) or, on coastal dunes, among tussocks or matted foliage of various grasses including Lyme grass (Leymus arenarius (L.)) and Marram (Ammophila arenaria (L.)). In central and northern Europe, where the species also occurs along river and lake margins, adults have been found overwintering under willow bark and among vegetation and litter around the base of trees in marginal situations but much less frequently, unlike with many other reed bed species, within dead reed stems. In the UK adults have been sampled by sweeping reed beds and marginal vegetation, they sometimes climb stems and fly in warm weather and have been sampled in flight-interception traps, but are otherwise mostly nocturnal.
5.0-6.5mm. Elongate and narrow, especially the head and prothorax, head yellowish-brown to chestnut-brown, pronotum and elytra pale brown, the elytral suture and often the apical area darker, appendages pale brown, the antennae often a little darker. Head longer than wide and smooth above, with only a single furrow immediately beside each eye, vertex and frons very finely punctured and sometimes obscurely wrinkled, eyes large and weakly convex, temples much longer than the eyes and converging to the base. Antennae long, slender and pubescent from the third segment. Pronotum elongate, broadest towards the apex and sinuate before rounded posterior angles, lateral margins raised and with a setiferous puncture before the base and apex, surface longitudinally impressed and with shallow and wide basal fovea. Elytra about 3X longer than together wide, gradually broadened from sloping shoulders to rounded apical angles and a truncate apical margin, striae punctured and weakly impressed to the apex, interstices flat impunctate and finely microsculptured. Wings fully developed and usually visible through the elytra. Legs long and slender, front tibiae with a deep antenna-cleaning notch and all tibiae with short but distinct apical spurs. Tarsi long and slender, the front tarsi weakly dilated in the male. Claws smooth.