There is no substitute for using the correct key

Dichotomous keys are wonderful things. In addition to increasing your vocabulary with words like piceousfistulous, and about 7,000 different words for plant hairs (e.g. dolabriform); dichotomous keys can give one the ability to identify any species with certainty… almost. Some keys are written with characters that don’t provide much separation (e.g. structure length is 5 – 7 mm or 6 – 8 mm – and your organism’s structure is 6.5 mm), or with relativistic characters (e.g. species X tends to be shinier than species Y – and of course you have only one), or uses male characters only (and you only have female specimens), but most keys work amazingly well.

An important activity after arriving at an identification from a key is to read about the species identified and ask: does this information fit what I know about my specimen? In other words don’t blindly accept that just because you have struggled through a key, you have reached the correct conclusion. I have found that when you are right, it feels right. If you are unsure, better double check or (better still) get an expert to confirm your identification if one is handy. 

I have been collecting dung beetles for a while and have tried to force scarabs (or near scarabs) into the wrong key before. This never works. Well today I discovered I was doing it again. After forcing this 2013-12-10 11.35.17-1little guy again and again into Gordon and Skelley (2007) Aphodiini of the United States and Canada with unhappy results, I finally went to American Beetles Vol. 2 and found the reason I was getting such poor results was that this beetle is in the tribe Eupariini, not Aphodiini. If I had used the key in the front of Gordon and Skelley (2007) I would have discovered this right off the bat. The cool thing is the correct key is available for download from the Smithsonian – alleviating this problem for all sorts of folk throughout the country. Tomorrow I hope to enjoy this key…

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3 thoughts on “There is no substitute for using the correct key

  1. George Sims

    I don’t “DO” plants; however, when I must, I use the following key, which is the result of YEARS of planning and modification. It tells me all I need to know:

    1. Short…………………………………………………..2
    1a. Not very short……………………………………………3

    2. Shorter than your knees………………………………Grass, lawn type, probably needs mowing
    2a. Taller than your knees, but shorter than your head……………..Bush/shrub or tall grass

    3. Real tall, with needles and pine cones……………………………..Pine tree
    3a. Real tall, but not as above………………………………………………Not pine tree

    Reply
  2. Pingback: Dung beetle battle royale | biologistsoup

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