Species Status No. 3 A review of the scarce and threatened flies of Great Britain Part 3: Empidoidea by Steven J. Falk and Roy Crossley Further information on the JNCC Species Status project can be obtained from the Joint Nature Conservation Committee website at http://www.jncc.gov.uk/species Copyright JNCC 2005 ISSN 1473-0154 This publication should be cited as: Falk, S.J. & Crossley, R. 2005. A review of the scarce and threatened flies of Great Britain. Part 3: Empidoidea. Species Status 3: 1-134. Joint Nature Conservation Committee, Peterborough. This is version 1.4. Dryodromia testacea (Rondani) see page 63 I.F.G. McLean del. after Collin (1961) Contents 1. Introduction........................................................................................................................ 3 2. Format of the data sheets.................................................................................................... 3 3. Information on the data sheets ........................................................................................... 3 4. Methods and sources of information.................................................................................. 5 5. Criteria for including species in the review ....................................................................... 6 6. Species not included......................................................................................................... 13 7. Taxonomic list of species previously given Red Data Book or Notable status but excluded from this review................................................................................................ 17 8. The future......................................................................................................................... 21 9. Acknowledgements.......................................................................................................... 21 10. Species listed by status category...................................................................................... 23 11. Taxonomic list of Red Data Book and Nationally Scarce species................................... 28 12. Criteria used for assigning species to threatened categories............................................ 35 13. The data sheets ................................................................................................................. 37 Hybotidae ............................................................................................................. 37 Atelestidae............................................................................................................ 61 Empididae ............................................................................................................ 61 Dolichopodidae .................................................................................................... 83 14. References...................................................................................................................... 111 15. Index............................................................................................................................... 125 1 2 1. Introduction The first account of threatened British Diptera was included in Shirt (1987). This listed 827 Diptera, 270 as Endangered, 226 as Vulnerable, 328 as Rare and 3 as Appendix (extinct). Data sheets were included for 82 species (35 Endangered, and 47 Vulnerable), of which two were Empidoidea (Syneches muscarius (F.) and Poecilobothrus ducalis (Loew)). This was followed by the publication of A review of the scarce and threatened flies of Great Britain (Part 1) (Falk 1991). This presented species accounts of threatened species from the better-known families of British Diptera, together with a list of all British flies provisionally assigned to Red Data Book and Nationally Notable (now termed Nationally Scarce) categories. This present volume deals with the Superfamily Empidoidea as defined by Chvála (1983), which total 673 British species in the latest Diptera check list (Chandler 1998a), now increased to 677 species (as of March 2003; Stubbs (2003)). The Empidoidea comprise five families (Atelestidae, Dolichopodidae, Empididae, Hybotidae, and Microphoridae), the species included representing approximately 10% of our Diptera fauna. The remaining families of Diptera outside of the Empidoidea that were not dealt with by Falk (1991) are reviewed in three further parts within the JNCC Species Status Review series. Although less well-known than some of the more popular families of Diptera, the Empidoidea has attracted the interest of a growing number of dipterists in recent years. This has resulted in greatly increased recording effort, which is continuing under the auspices of the national recording scheme for Empidoidea (see the Biological Records Centre website at: www.brc.ac.uk). The Empidoidea are found as adults throughout the spring, summer and autumn, with the greatest number of Empididae and Hybotidae found in early June (Plant 2003). The phenology can differ greatly between individual species and is summarised in the identification guides, but is not considered in this review. The adults are typically predators of other small insects, but they may also feed at flowers, with some species apparently showing preferences for certain plants (for instance, see Allen, 1994). Stark (1994) reviewed the prey composition and hunting behaviour of Platypalpus species. Pollet and Grootaert (1994) investigated the consequences of using different colours and heights of water traps upon the species collected. The status of many species as proposed by Falk (1991) has been revised during the preparation of this volume. Initially, the Red Data Book and Notable categories (as defined by Parsons 1993) were used for this revision. Subsequently, following the adoption of the revised IUCN Guidelines (IUCN 1994) by JNCC in 1995, a further revision of the status for all species was carried out by Ian McLean (JNCC) in 2003. At the same time the nomenclature was brought up to date in accordance with the latest checklist for British Diptera (Chandler 1998a) and recent literature up to 2004 has been incorporated within the introductory sections and in the species accounts. 2. Format of the data sheets Information on each species is given in a standard form. The data sheets are designed to be self-contained in order to enable site managers to compile species-related information on site files; this is the reason for the repetition that occurs between the species accounts. 3. Information on the data sheets 3.1. The species’ name Nomenclature is intended to be as up to date as possible. Where the name differs from that used by Shirt (1987) or Falk (1991) or from the most recent Diptera check list (Chandler 1998a) the previous name is indicated, with citation of any relevant references. 3 3.2. Identification The latest or most convenient work from which the identity of the species can be determined is stated. In the case of the former Empididae (now comprising Hybotidae, Atelestidae and Empididae), the principal identification work has been Collin (1961), which is now supplemented by the treatment in Chvála (1975, 1983 and 1994), together with papers by other dipterists. The remaining family of Empidoidea, the Dolichopodidae, was dealt with by d’Assis-Fonseca (1978), also now supplemented by papers by other dipterists. 3.3. Distribution Ideally the Watsonian Vice-counties (Dandy 1969) should form the basis of the distribution statements, but this has not been practicable as most records, especially those for England, do not specify the smaller divisions into which the larger-sized historic counties were split by H.C. Watson. To have attempted to trace them throughout would have been too time-consuming and therefore in many cases the statement has been based on modern counties. All these have, however, been listed in ascending Watsonian numerical order. Where records are fewer in number, as for the more threatened species, then fuller details are provided where these are available. 3.4. Habitat Few habitat descriptions are available, and the majority of records merely refer to a place name. In some instances the known recording preferences of dipterists can be of some help, but caution must always be exercised. For example, “Aviemore”, so beloved of generations of dipterists, probably refers to the shrub-fringed banks of the River Spey in the majority of cases; however, it could on occasions refer to the area now within Craigellachie NNR or even to a guesthouse garden! Inevitably, many statements in this section are vague, and in some cases no attempt has been made to compile a description due to lack of information. It is hoped that by drawing attention to these obvious gaps in our knowledge in this way, dipterists will be encouraged to quote habitat details when presenting future records. Fortunately, in the case of some species there is sufficient information to enable reasonable inferences to be made. 3.5. Ecology Considering the small size of most species, it is surprising that the life histories of some of the commoner Empidoidea are known, at least in outline. However, this is not so for the majority of species in this review. Consequently there is often little information given under this heading, but in cases where information on related species is available and considered relevant, this is cited. 3.6. Status It is upon this statement that the status category is based. This can be assessed in two ways: first, the perceived scarcity