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This article presents uses of Identification Key s in Taxonomy . KEYS VERSUS DESCRIPTIONS An Identification Key is only a guide to what a Plant , Animal or Fossil might be. Full identification requires comparison with a full and accurate description preferably in a Monograph . This is often difficult in practise; many monographs being expensive, hard to obtain, and often out of print. Many are in foreign languages; Russian , German and Japanese being the most common and the most difficult for those with English as a first language. Many monographs are more than fifty years old and do not include all species. POINTERS
COMMON ERRORS #Distribution is not a character. Do not assume that because a species is not listed for your region that it does not occur there and can be therefore be discounted. Very few regions have complete lists. Also, the Organism may have been transported. It may also have a new range due to Global Warming . Moreover, new indoor species are being imported all the time. For Europe and, probably, North Africa a Palaearctic key is advisable. Expect surprises near ports and airports. #Rarity is not a character. An identification may be correct even though a species is very rare. #Many keys contain brief descriptions to allow more certain identification. These should not be used as an alternative to full descriptions. #Some keys identify only males (or, more rarely females). Make sure you are working with the right sex. Keys to larvae usually work only for the final Instar . There are important exceptions however some larval Diptera of Forensic relevance being notable exceptions. #Some keys exclude difficult groups. Such exclusions are usually mentioned in the title, but read the introduction carefully). PROBLEMS WITH KEYS #Lighting and magnification - very few keys give details of how the specimen was viewed (the magnification, lighting system, angle of view etc.). This can cause problems. The author may, for instance refer to tiny bristles, hairs or Chaetae --but how tiny?. #Language - almost no keys are multilingual and translations may be incorrect or misleading. Many keys contain vague words that do not translate. #Hopeless keys - some keys are chaotic and do not work. #Out of date keys present a problem since they do not include more recently described species. Also, in such works the Nomenclature is out of date, causing problems of Synonymy . CONSEQUENCES A high error rate in identification renders much Ecological and both pure and applied biological work virtually worthless. This may be of great importance as in the case of medical, Pest control or Forensic work. Error rates in insect identification are discussed by Steve Marshall {Link without Title} . SEE ALSO |
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