Sinechostictus Motschulsky, 1864 

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ADEPHAGA Clairville, 1806

CARABIDAE Latreille, 1802

TRECHINAE Bonelli, 1810

BEMBIDIINI Stephens, 1827
S. inustum (Jacquelin du Val, 1857)

S. stomoides (Dejean, 1831)

Sinechostictus inustus (Jacquelin du Val, 1857)

Two groups, Sinechostictus Motschulsky, 1864 and Pseudolimneum Kraatz, 1888, were formerly included as subgenera within Bembidion Latreille, 1802 and are referred to as such in most of the older literature; subgenus Sinechostictus was recently raised to generic rank and includes, among a further ten European species, S. (Sinechostictus s.str.) stomoides (Dejean, 1831), the present species was also included in Sinechostictus within the subgenus Pseudolimneum Kraatz, 1888, and these are the only UK members of the genus. This is a mostly central and western European species which also occurs on some of the Mediterranean islands; it is most prevalent in lowland and low mountain regions from Spain through northern Italy to Ukraine and north to Germany and the UK, it is generally very local and rare but in some northern areas it seems to be expanding its range. Discovered in the UK in 1996 it is known from only very examples from southern and mid-Wales and has not been recorded recently although this may be due to its lifestyle. Adults have been recorded in the UK during April and July and on the continent they occur through the spring and summer and are generally most common during June. The species occurs among marginal shingle and is probably subterranean, or at least substantially so as adults have also been found climbing vegetation, they are diurnal and fully-winged but flight has not been observed and the biology remains unknown. In some areas of southern Europe it occurs in caves and is synanthropic, occurring in cellars and outhouses.

Sinechostictus stomoides 1

Sinechostictus stomoides 1

Sinechostictus inustus 1

Sinechostictus inustus 1

Sinechostictus stomoides 2

Sinechostictus stomoides 2

5.4-6.0 mm. An elongate, narrow and rather flat species; entirely dark brown, the forebody usually darker than the elytra which often has a faint metallic reflection, appendages entirely pale brown. Head broad with relatively large eyes, strongly converging temples and wide and shallow frontal furrows that only just extend onto the clypeus, surface smoothly convex; uneven and wrinkled beside and behind the eyes but not punctured. Basal maxillary palpomere long and curved, penultimate segment long and expanded towards the apex, terminal segment diminutive. Pronotum transverse, broadest in front of the middle and strongly sinuate before sharp posterior angles, lateral margins narrowly explanate, surface with a fine median longitudinal impression which becomes widely expanded in the basal third (this character is an excellent identification guide), disc otherwise smooth except the basal quarter or so strongly wrinkled, the fovea often indistinct. Elytra only weakly curved laterally, almost parallel-sided, with rounded shoulders and smoothly curved apical margins, basal margin rounded beneath the shoulder, each with seven impressed and punctured striae that fade before the apex and an eighth stria that is present only in the apical third, interstices weakly convex, the third with at least two setiferous punctures that join the third stria. Legs slender and only moderately long compared with many similar species. Basal segments of front tarsi broader in the male.

Sinechostictus stomoides (Dejean, 1831)

This generally rare species has a mostly upland and mountain distribution in Europe, it is mainly in western, central and southern areas, occurring up to 1500m in Bulgaria and above 2000m in Austria, it extends north to the UK but is absent from Denmark and Fennoscandia, it is rare in Germany and Belgium and known only from central mountain areas of Switzerland and from the Alps and Pyrenees in France. Here it is a very local and rare species of northern England and southwest Scotland but there are also a few scattered records from South Wales, Dorset and the Norfolk coast, they typically occur among shingle or under rocks on sparsely vegetated river margins but on the continent in a wider range of wetland habitats from uplands to the sub-alpine regions; usually on shaded and overgrown banks of running water from small streams to larger rivers, and usually on permanently wet soil with at least some loam content. In some areas, e.g. Germany, they are known to have suffered a recent decline as a result of river regulation and are no longer present in many of their former sites. Adults are active from April until September, they are diurnal and fully winged but nothing is known about the flight capacity or dispersal of the species, they probably reproduce in the spring and overwinter as adults.

A large convex and shiny black species with a dark green or blue reflection, sometimes this reflection is present only on the forebody and the elytra may be entirely slightly paler, giving the insect a bicoloured appearance, the legs, palps and elytral apices are reddish-brown and the antennae are dark with two or three basal segments brown. 5.2-6.2mm. Head smooth and only finely punctured between large and convex eyes, frontal furrows single, not deeply impressed or extended onto the clypeus. Terminal maxillary palpomere diminutive. Pronotum quadrate and only slightly wider than the head, cordate, widest in front of the middle and rather strongly constricted to rounded anterior angles and sinuate before weakly-protruding posterior angles. Surface with a fine longitudinal impression and wide, well-impressed and strongly punctured basal fovea. Elytra broadly-oval with seven punctured striae which fade towards the lateral margins and the apex, an abbreviated scutellary stria and a deeply-impressed eighth stria which is present only in the apical third, there are two larger setiferous punctures within the third stria and a fine basal margin that curves smoothly around the shoulder.

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