British Insects: Hoverflies (Syrphidae: Hymenoptera)

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L. Watson and M. J. Dallwitz

Introduction

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 primarily to present scans of the fine hand-coloured engravings of insects in John Curtis’s British Entomology: illustrations and descriptions of the genera of insects found in Great Britain and Ireland (1824–1840). The first 12 volumes of the first edition (up to 1835) were directly available to us, and pages issued from 1836–1840 have been accessed from other sources (see Notes on John Curtis’s British Entomology). In addition to presenting Curtis’s and other early illustrations, however, all the ‘British Entomology’ subsets incorporate descriptive data organized under the DELTA system, and purport to offer at least partial identification and information retrieval via the interactive program Intkey.

The present subset is itself a subset of the one dealing with all the families of British Hymenoptera (http://delta-intkey.com/britin/hym/index.htm). The very numerous illustrations of Hoverflies additional to John Curtis’s beautiful plates mainly comprise numerous line drawings adapted from Walker (1851) and Verrall (1901), plus some adaptations from Hammond’s (1968) coloured plates, all with the nomenclature updated mainly with reference to Chandler (1998). The draft generic descriptions have been prepared with resort to works listed in the References, in particular Verall (1901), Walker (1851) and Coe (1953), cross referenced with the modern treatments of Stubbs and Falk (2002) and van Veen (2010). Sadly, the two 21st Century publications exemplify an unfortunate modern tendency; viz., to pretend that identifications can be satisfactorily pursued in the absence of adequate comparative taxon descriptions. It is an elementary requirement of competent taxonomic practice that ‘identifications’ derived via printed keys must be confirmed with reference to detailed descriptive information additional to that used in the keys: a few lines of pseudo-diagnostic text supplemented by illustrations simply will not suffice. In this important respect, the modern offerings compare very poorly indeed even with the succinct generic and species descriptions offered by Walker in 1851, let alone with Verrall’s detailed, professional treatment of 1901.

This package is inevitably unsatisfactory, given the absence or relative inaccessibility of adequate descriptive data to account for changes in generic circumscriptions and additions to the British list that have occurred over the past hundred years, but it should suffice to demonstrate the superiority of interactive identification and information retrieval over hard copy. Similar considerations apply to most of the compilations in this ‘British Insects’ series, all of which are readily accessible for extending, improving and making corrections. Organization under the Delta system ensures that all of them are readily accessible for corrections and improvements. Informed criticism and constructive input are of course welcome, and will be appropriately acknowledged. Alternatively, complete Delta data sets can be donated if required for teaching purposes, or to any professional or amateur entomologist or organization interested in developing them further.

Edited 10 October 2011


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