British Insects: the Families of Diptera
British Insects: the Families of Diptera |
|
This data set is generated from a DELTA database (Dallwitz 1980; Dallwitz, Paine, and Zurcher 1993). The original intention of the ‘British insects’ suite of packages, of which it forms part, was to present scans of the fine hand-coloured engravings of insects in John Curtis’s British Insects: illustrations and descriptions of the genera of insects found in Great Britain and Ireland (1824–1840), of which the first 12 volumes (up to 1835) are available to us. For further information on this aspect, see Notes on John Curtis’s British Entomology.
In addition to presenting Curtis’s and other early illustrations, all the ‘British Entomology’ subsets incorporate descriptive data organized under the DELTA system, and purport to offer facilities for attempting at least partial identification and for information retrieval, via the interactive program Intkey. The present subset encompasses all the families of British Diptera, described via standard morphological and ecological characters. It is unlikely to achieve its objectives satisfactorily at this early stage of development, but in any case the DELTA data (from which updates of the interactive package are easily generated) are readily accessible for improving, correcting and extending.
Family descriptions were initially compiled for this purpose using Unwin’s (1981) key to the British families and the detailed family descriptions provided by Colless and McAlpine (1970), supplemented from Imms (1950). They were then checked, and greatly improved and extended, with reference to the copious descriptive information and keys provided by Colyer and Hammond (1968); and the rather restricted suite of family illustrations obtained from Curtis has been greatly extended via comprehensive scans of the engravings in Walker’s early, classic work on the British Diptera (1851–1856). Of the present 102 families, 29 have fewer than five species, and 15 are additional to Unwin’s (1981) list; and of the 20 or so families not yet exemplified here by at least one illustration, most comprise taxa relatively recently promoted to family level, many of which are small in terms of numbers of British species and genera.
Assignments to Orders, Families, and sub-familial groupings have been aligned with Chandler (1998), and Curtis’s and Walker’s nomenclature has been laboriously updated with reference to the same work in conjunction with Kloet and Hincks (1945). The few Curtis names not located are indicated by quotation marks in the Intkey displays of descriptions and images, and the plates involved are presented under the pseudo-taxon ‘Unidentified Images’. Some of them may denote adventives or taxa erroneously admitted to the British list, but others may represent names that have never been formally linked with taxa recognised in modern times (cf. Kloet and Hincks).
Curtis’s and Walker’s plates are cited in the Intkey displays of taxon images, and for at least one example in each family illustrated by Curtis, as well as for all the genera and species originally described and illustrated by him in ‘British Entomology’, these are accompanied by scans of his text. As well as legends for the illustrations and formal taxonomic descriptions, the latter offer numerous examples of his entertaining, informative and elegantly expressed notes on sources of specimens, morphological interpretations, classificatory methodology, general biology, etc.
Family assignments of the insects illustrated have been checked at family level to some extent, in effect with reference to the family descriptions in the cited works, by ‘identifying’ the illustrations using the Intkey package. While it has thus been ascertained that the they conform reasonably well with the family assignments, checking on the generic and specific identities of the flies depicted has so far been very limited indeed. Biologists wishing to use the pictures for their own purposes should therefore take the necessary precautions for themselves.