Mapping an unusual Staphylinid in Cheshire

Figure 1. Hadrognathus longipalpis

On 19th July 2020 Don Stenhouse and I were hunting for beetles in Danebridge, Staffordshire. We were on a mission to find new sites for Bromius obscurus (we didn’t) but like most beetlers, couldn’t resist a bit of rotten wood. I lifted bark on a fallen branch of oak and found a small brown beetle which I didn’t recognise. On returning home it was clearly Staphylinidae, Omaliinae, but had unusual long hooked mandibles. These enabled me to identify it as Hadrognathus longipalpis using Mike Hackston’s online keys.

H. longipalpis is a newcomer to the UK, initially being found in a quarry in Cumbria, and was subsequently found to be widespread in peatlands in South Wales. A few isolated records have also been reported, leading to a puzzling and rather scattered distribution map. The nearest prior location to Danebridge was Cannock Chase in 2015.

On 29th July 2020 I visited Macclesfield Forest which is approximately 4 miles north of Danebridge, not particularly looking for H. longipalpis, but just generally surveying litter and decay environments. Having previously thought my single specimen was an isolated case, I was surprised to find a total of twelve H. longipalpis over two separate sites. Wondering how widespread it was, I returned on 6th August and collected material from four more locations in the forest; H. longipalpis was present in two of them.

The samples were taken from sufficiently distant locations to suggest that H. longipalpis was probably present throughout the forest, but give little indication of any habitat preference. The initial two sites were mixed established woodland in the lower region of the forest near Ridgegate reservoir. The later records were from a mixed area on the edge of Trentabank reservoir, and from a wholly coniferous plantation area.

Figure 2. Records of H. Longipalpis in the Cheshire/Staffordshire/Derbyshire border region. Records are indicated by open circles.

On 20th August 2020 Gary and Leanna had organised a survey event at Errwood Hall and Reservoir, a mixed woodland site, and again I located two H. longipalpis specimens in litter and decaying timber. This site is a further 5 miles north-east of Macclesfield forest, in the Goyt Valley, and lies virtually on the Cheshire-Derbyshire border, being within administrative Derbyshire but in VC58 from a vice-county perspective.

The observed distribution of H. longipalpis is shown in Figure 2, although there are numerous other woodlands not yet studied in the area, which may well yield specimens. The ease with which it was found suggests that it is well established in the Staffordshire/Cheshire/Derbyshire border area, and beetle recorders in the north west should look out for it, particularly in the east of the region.

 

 

 

References

HOLMES, P.R., BOYCE D.C. & REED D. K. 1990. Hadrognathus longipalpis (Mulsant & Rey) (Coleoptera: Staphylinidae) in South Wales. British Journal of Entomology and Natural History 3: 192.

LOTT, D. A. 1989. Hadrognathus longipalpis (Mulsant & Rey) (Coleoptera: Staphylinidae) new to the British Isles. Entomologist’s Gazette 40: 221-222.