[reference: Dipterist's Digest (Second Series), 2001]

A further sighting of Thecocarcelia acutangulata (Macqart, 1850) (Diptera, Tachinidae)
and a brief revue of its status in the UK

CHRIS M. RAPER
[postal address withheld]
email chris.raper@tachinidae.org.uk

Summary

Details of the 4th UK record for Thecocarcelia acutangulata (Macquart, 1850) (Tachinidae) and a review of previous UK records, its life history and current UK status are given.

In the summer of 2000 I ran a Malaise trap on the Warburg nature reserve along the edge of a broad chalk downland ride bordering young, mixed, broad-leaved/coniferous woodland (SU7201887929 ±5m). In the catch dated 23rd August to 3rd September I found two female Thecocarcelia acutangulata and this determination was later confirmed by Peter Chandler and Martin Harvey. I have retained one specimen, the other has been donated to the BENHS collection at Dinton Pastures.

The Warburg nature reserve is located in south Oxfordshire, between Nettlebed and Henley-on-Thames (v.c. 23). The reserve is owned and managed by BBOWT, the Wildlife Trust for Berkshire, Buckinghamshire and Oxfordshire. The reserve occupies over 270 acres with a varied choice of habitats including chalk downland and stands of both young and ancient woodland.

In subsequent investigations I have found data for the following additional UK specimens:

• 21-22 July 1954 (published Wyatt, 1986 and repeated in Belshaw, 1993): Hadleigh Wood, Essex (TQ 8287), 1x male, coll.: D.J. & J.A. Clark, det.: Nigel Wyatt. Specimen now in the NHM collection. [Nigel's 1986 article added this species to the UK list.]
• 29.vi.94 (published Dipterist's Digest, 1998): Brent reservoir, East SSSI (TQ 2187), 1x female, coll.: John Dobson, det. confirmed by Nigel Wyatt.
• 10-17 August 1995 (Smith, 2001): Buckingham Palace Gardens (TQ 289796), 1x female, coll.: David Carter & Colin Plant, det.: Nigel Wyatt. Malaise trap run as part of a survey of flora and fauna carried out at Buckingham Palace Garden by the London Natural History Society. Specimen now in the NHM collection.

In the UK T. acutangulata is currently rated RDB2, "Vulnerable" (Chandler). In Carl (1968) the distribution was stated as being no further north than the Vienna Baisin and Versailles. Wyatt (1986) comments that it has a primarily southern European and Afrotropical distribution with few records north of the Alps - the most northerly being in the Somme and Stuttgart regions. Belshaw (1993) gives the distribution as southern England, though I think he only had Wyatt's record to base that on. Tschorsnig & Herting (1994) say it is very rare with a mainly Southern European distribution, scattered colonies existing in warm, dry areas as far north as Southern England. Given this information it is likely that the species is moving very slowly northwards but remains rare wherever it exists.

The hosts are listed as Thymelicus lineola & Parnara mathias (Carl, 1968) and Halpe varia (Tschorsnig & Herting, 1994), all Lepidoptera, Hesperidae but only T. lineola occurs in the UK. T. acutangulata is double brooded (Tschorsnig & Herting,1994 and Carl, 1968) but T. lineola is single brooded so it is almost certainly using alternate hosts. It is thought that this, in combination with the narrow range of potential hosts may be a factor in its rarity (Carl, 1968).

Acknowledgements

I am very grateful to Peter Chandler, Martin Harvey and Nigel Wyatt for tracking down records and to PC & MH for providing advice regarding the content of this article. Material from the Garden at Buckingham Palace was collected as part of an in-depth survey into the flora and fauna there, with gracious permission of Her Majesty The Queen, by the London Natural History Society and the Natural History Museum.

References

• Belshaw, R. 1993. Tachinid Flies - Diptera: Tachinidae. Handbooks for the Identification of British Insects Vol. 10, Part 4a(i)
• Carl, K.P., 1968, Thymelicus lineola (Lepidoptera: Hesperidae) and its parasites in Europe, Can. Ent., 100: 785-801.
• Dobson, J. 1998. Dipterists Day Exhibits. In Dipterist's Digest. 5: 24-26.
• Falk, S.J and Pont, A.C. (in preparation). A review of the scarce and threatened flies of Great Britain. Part X: Calyptratae. JNCC.
• Smith, D. A., 2001 (in press) in Plant, C. W. (ed.). The natural history of Buckingham Palace Garden, London. Part 2. Lond. Nat. 90, (Suppl.).
• Tschorsnig, H.P. and Herting, B. 1994. Die Raupenfliegen (Diptera: Tachinidae) Mitteleuropas: Bestimmungstabellen und Angaben zur Verbreitung und Ökologie der einzelnen Arten. Stutt. Beitr. Naturk. (A) 506: 1-170.
• Wyatt, N.P. 1986. Thecocarcelia acutangulata (Macquart) (Diptera: Tachinidae), new to Britain. Entomologist's Monthly Magazine. 122: 203-204.

All text and photographs on this web site are (c) copyright Chris Raper ( 26 July, 2002 ), unless otherwise stated.