Grouped Species Action Plan

This action plan covers six beetle species, three in the family Carabidae (Perileptus areolatus, Bembidion testaceum and Lionychus quadrillum), one in the family Hydrophilidae (Hydrochus nitidicollis), and two in the family Staphylinidae (Thinobius newberyi and Meotica anglica). The species share a specific and, in some instances, more or less exclusive association with exposed riverine sediments, mostly of the shingle type. As a consequence of high fidelity to their particular riparian habitats, each of the six species has a restricted, patchy and (generally) western distribution in Great Britain. Most of the six species also appear to have suffered losses of or declines in some populations during this century, with the result that their British ranges have contracted.

All six species covered have known ranges in Great Britain that are western or have a western bias; for most of them recorded occurrences are scattered.

Perileptus areolatus is a predaceous species exclusively associated with exposed riverine sediments of shingle or sand, mostly near to the water`s edge. Older UK records for the species are scattered but extend from Cornwall north to southern Scotland and eastwards to the Isle of Wight in the south and Yorkshire in the north. However, there are no recent records for a number of the areas where the species was once found; most post-1970 records are for Wales and the Welsh borders. There are also recent records for southern Scotland and for south Devon. The species is widely distributed in Europe.

Bembidion testaceum is a predaceous riparian species associated with sand and gravel by slow-running or standing water. The species may be overlooked as it can be difficult to distinguish from some other British species of Bembidion. Old records may be unreliable, but the species undoubtedly once had a fairly wide, if very scattered and mainly western, distribution in England, Wales and southern Scotland. There are recent records for only 4 ten km squares, two in northern England, one in south Wales and one in the Welsh borders. The species is widely distributed in mainland Europe and is at the northern and western limit of its range in Britain.

Lionychus quadrillum was long considered to be not only a very localised but also a largely coastal species in Britain. Old British records are scattered around the east, south-east, south and south-west English coasts. The species has suffered losses of many of its former coastal populations during this century, mostly through loss of suitable habitat due to construction of coastal defences, seaside resorts and other developments, and agricultural intensification. There are recent records for just a few coastal English sites in the east (Suffolk and north Essex) and in the south-west. However, in recent years the species has also been shown to be well established inland in association with shingle and sand banks at a number of sites on Welsh rivers (Rheidol, Tywi, Ystwyth, Usk). In continental Europe the species is widespread both on the coast and inland, mostly in association with riverine shingle and sand, but is known to occur also on bare, shingly ground away from water, for example in south Sweden where the species has recently been expanding its range.

Hydrochus nitidicollis, like other members of its genus, is essentially aquatic as both adult and larva, but may be found in wet substrates above as well as below high water levels. It favours clean and mostly running water. Adults have been collected in pitfall traps on shingle bars, but it is also known to occur in association with exposed riverine sediment substrates that are relatively fine-grained. The species has a very restricted UK distribution, confined to the south-west peninsula of England, and has never been known to occur more widely in Britain. It has been recorded from a total of 10 ten km squares in Devon and Cornwall, six of which are in the Dartmoor district. There are several post-1970 records, covering three areas: Lothwithiel in west Cornwall, Falmouth, and the Rivers Teign and Bovey in Devon. There is no clear evidence of recent decline in the UK, but at least some of the sites where the species has occurred are under threat from development. The continental distribution of the species is markedly western, with the species quite widely recorded in the Iberian peninsula and found southwards as far as Morocco.

Thinobius newberyi is a small and easily overlooked species that appears to be of largely subterranean habits. Like other species of Thinobius it probably feeds on decaying plant material or algae and is associated with shingle banks. There are old records for streamside situations in Cumberland and the Aviemore district of the Scottish Highlands, but the only recent records for the species are for the banks of the Rivers Rheidol, Tywi and Ystwyth in Wales. Although probably of very localised distribution, the species is undoubtedly under-recorded, and this is likely to account for its current status as a putatively endemic British species. Specialist collecting in suitable parts of mainland Europe may be expected to reveal its presence.

Meotica anglica is a tiny and probably much overlooked species of possibly predaceous habits associated with riparian gravel and sand. Like Thinobius newberyi, it appears to be largely subterranean and rarely seen on the surface of the substrates that it inhabits. There are old records for scattered localities from southern Scotland to southern England, mostly in the west. Recent records cover some 4 ten km squares in southern Scotland, three localities in England, the banks of the Rivers Taf, Usk and Severn in Wales, and the Mole in Surrey. Although very similar species occur in Scandinavia, these are apparently distinct, and so far the species has not been found outside of Britain. However, it is likely to occur in other parts of western Europe.

In Great Britain the species covered here are now classified as Rare (Lionychus quadrillum and Hydrochus nitidicollis), Indeterminate (Thinobius newberyi), or Nationally Scarce (Perileptus areolatus, Bembidion testaceum, and Meotica anglica). In addition, Thinobius newberyi and Meotica anglica are classified as Endemic.

Factors likely to affect the habitats used by these species include:

River engineering, eg straightening, dredging, or grading of river banks.

Level regulation and control of flow by damming and flood alleviation schemes.

Livestock encroachment on riverside shingle and other river-bank features.

Water abstraction.

Agricultural improvement resulting in drainage and nutrient enrichment.

Land use changes and development (eg urban) that impinge on riparian habitats.

Colonisation of river banks by Himalayan balsam Impatiens glandulifera and other invasive plant species.

EA, CCW and NE have recently joint-funded programmes aimed at improving knowledge of the UK distribution and characteristics of the specialist invertebrate species associated with exposed riverine sediments. Surveys have taken place in a wide range of catchments across England and Wales.

SNH funded an extensive survey of exposed sediments in the catchments of the Carron, Spey, Nith and Tweed in 1996 and 1997. The aim was to survey the habitat resource and to characterise the sediment types favoured by the specialist invertebrate fauna.

Surveys of exposed riverine sediment (ERS) features in several Welsh river systems, including the Rheidol, Ystwyth and Mawddach, have been undertaken during the past decade by or in conjunction with CCW.

In connection with a Public Enquiry in 1998, EA (Devon Area) commissioned a report on the ERS beetles of sections of the Rivers Teign and Bovey (near their confluence), where two of the species considered here were found.

A number of the sites where one or more of the six species are known to occur are designated as SSSIs, fall within ESAs, or benefit from some form of protected status. Several rivers supporting one or more of these species, including the Tywi, Usk and Wye in Wales, are candidate SACs.

Mike Williams, Environment Agency Tel:01392 316033

The following LBAPs are working on Grouped plan for river shingle beetles:

Originally published in: UK Biodiversity Group Tranche 2 Action Plans - Volume VI: Terrestrial and freshwater species and habitats (October 1999, Tranche 2, Vol VI, p49)

ARKive Visit the ARKive website to view images and further information relating to Hydrochus nitidicollis

ARKive Visit the ARKive website to view images and further information relating to Lionychus quadrillum

ARKive Visit the ARKive website to view images and further information relating to Meotica anglica

ARKive Visit the ARKive website to view images and further information relating to Perileptus areolatus

ARKive Visit the ARKive website to view images and further information relating to Thinobius newberyi