Northern Ireland's Priority Species

Haliplus variegatusHaliplus variegatus

 
Haliplus variegatus
Click on map to open large map in new window

Haliplus variegatus Sturm, 1834
Family: Haliplidae

Haliplus variegates is a crawling water beetle mainly associated with stoneworts in small still water sites.

In brief

  • H. variegatus was originally found in Brackagh Moss, County Down, and rediscovered there in 1991. There is an old record for County Armagh
  • It is found in lowland, shallow, vegetated pools with soft bottoms in association with stoneworts
  • Adult beetles can be found in the water throughout the year, with peak numbers in April, and breeding in early summer
  • It is rare and has declined
  • Declining water quality caused by pollution appears to be the main threat
  • H. variegatus is found in relict fenland, sometimes in cutover bog.

Species description
The crawling water beetles are all small and straw-coloured, and this species has black blotches on the wing cases, sometimes concentrated around the midline in the form of a cross. They swim freely under water, alternating the use of legs in dog paddle fashion, unlike diving beetles that synchronise leg movement in a ‘butterfly’ action. H. variegates is 2.5 to 3.5mm long. The larva is elongate with six, short, single-clawed legs on the thorax and a long pointed abdomen.

Life cycle
Eggs are almost certainly laid on stoneworts in early summer, after which most adults die. The larvae complete their development and pupate in midsummer, producing a new generation of adults in August. These adults can overwinter in the water. Adults are probably predators of small animals and the larvae are specialist feeders on stoneworts, perhaps also being able to feed on filamentous algae.

Similar species
The bright markings and shiny appearance of this species should make it stand out from the more common Haliplus species, most of which can be distinguished from it by the notches on the hind edge of the thorax. It is like a small version of Haliplus fulvus (Fab.) (3.5-4.5mm), a more common species of larger waterbodies, and with which it shares the blotches. The ground colour is typically richer, almost tan brown in parts. The larvae have spiny processes, long enough to render it distinct from other Irish species.

How to see this species
H. variegates was originally found in Brackagh Moss, County Down, and rediscovered there in 1991. There is an old record for County Armagh. This beetle is most easily found by netting or sieving aquatic vegetation and sorting the material on a tray. It should be possible to detect this species in an occupied site between April and October, but there is a gap in July and August when adults are scarce. H. variegates is mainly associated with shallow pools on soft peat or clay. Relevant access permissions should always be sought prior to visiting any sites.

Current status
This species was originally detected in Northern Ireland in Brackagh Bog in 1909, and was rediscovered there, in cutover bog, in 1991. The other record is for a single specimen from a peat drain in The Kinnegoe, County Armagh in 1911. In Ireland it has been recorded from nine 10 km squares since 1980, and from six before then. On the basis of the much greater recording effort since the 1980s this indicates an overall decline. H. variegates has been recorded from twenty 10 km squares in England and Wales from 1980 onwards, with evidence of substantial decline and contraction of range in the English Midlands. H. variegates is in decline in Denmark, possibly because of pollution (Holmen 1981).

Why is this species a priority in Northern Ireland?

  • It has declined and is rare
  • The Irish Red List status is provisionally Vulnerable . This is based on IUCN Regional criteria B2 (a) (b) (ii) (iii) (area of occupancy (AOO) estimated to be less than 2,000km² and known to exist at less than ten locations, also with an inferred decline in the AOO and in the area, extent and quality of the habitat).

Threats/Causes of decline
Cutover bog is not generally regarded as an endangered habitat in Ireland, but this species is clearly rare and almost certainly in decline. The reasons for this scarcity are not understood. It must be assumed that they relate to water quality rather than, for example, to disturbance or climate change. Losses in Britain have been greatest in areas subject to agricultural intensification and to lowlands affected by urban and industrial development. The stoneworts on which H. variegates is almost certainly dependent are under threat from fertiliser enrichment and invasive alien plants, and the need to maintain open areas in peat cuttings is particularly emphasised by Stewart and Church (1992).

Conservation of this species

Current action

  • Brackagh Moss is a National Nature Reserve.

Proposed objectives/actions

  • The status of Haliplus variegatus should be surveyed and monitored and appropriate conservation action undertaken if required.

What you can do
Send any records to the organiser of the recording scheme (NBN link) or to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU. Tel: 028 9039 5256, email CEDaR.info [at] magni.org.uk. Get involved in recording aquatic insects.

Further information

Links
NBN Gateway (NBN Gateway has 285k data-set with most records but not all).

Brackagh National Nature Reserve

Literature
Holmen, M. (1981). Status over Danmarks Haliplidae (Coleoptera) med bemœrkninger om Zoogeografi og autøkologi. Entomologiske Meddelelser 49: 1-14.

Holmen, M. (1987). The aquatic Adephaga (Coleoptera) of Fennoscandia and Denmark I. Gyrinidae, Haliplidae, Hygrobiidae and Noteridae. Fauna Entomologica Scandinavica 20>. E.J. Brill/Scandinavian Science Press Ltd, Leiden & Copenhagen, 168 pp.

Stewart, N.F. and Church, J.M. (1992). Red Data Book of Britain & Ireland. The Joint Nature Conservation Committee, Peterborough.

Text written by:
Dr Garth Foster