Tarsal formula

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Diagram of a typical insect leg

The tarsal formula is the number of segments on the tarsi of arthropods. The tarsus is the bottom part of an arthropod's legs, see diagram.

The formula has 3 numbers a-b-c, starting with the front leg (a), then the middle leg (b), then the hind leg (c). For example, a tarsal formula of "5-5-4" means there are 5 segments in the fore leg's tarsi, 5 segments in the middle leg's tarsi, and 4 segments in the hind leg's tarsi.[1] This character is especially useful at family rank and higher.[2]

The characteristic is useful when identifying insects.

References[change | change source]

  1. Waterbug key. [1]
  2. "tarsus, tarsi, tarsomere, tarsal formula - BugGuide.Net". bugguide.net.