http://www.collembola.org/slides/setaea03.htm - Last updated on 2001.09.05 by Frans Janssens
Checklist of the Collembola: Morphology of the setae: slide 3 of 14


Fig.3. Setal shaft diameter gradients. Janssens, F. © 1999.
Proximodistal shaft diameter gradients
The setal shaft can have a negative, zero or positive proximodistal diameter gradient. Setae with a negative shaft radius gradient are recorded from all species. It is the typical acuminate shape of the setulae and the microchaetae. Acuminate macrochaetae are recorded from genera such as Isotoma. Cylindric macrochaetae with a zero shaft radius gradient are recorded from genera such as Orchesella. Also trichobothria typically have a cylindric setal shaft. Clublike macrochaetae having a positive shaft radius gradient are recorded from genera such as Cyphoderus.