- Last updated on 2008.10.26 by Frans Janssens
Checklist of the Collembola: Restoration of body parts after ecdysis in Tomocerus vulgaris (Collembola: Tomoceridae)

Frans Janssens, Department of Biology, University of Antwerp, Antwerp, B-2020, Belgium
Ab H. Baas European Invertebrate Survey - Nederland, Postbus 9517, 2300 RA Leiden, Nederland



It is known that Collembola are stimulated to moult in case of a damaged appendage, such as a broken antenna. We present here a case of Tomocerus vulgaris that moulted in a culture after severely being damaged while collecting it alive.

Materials and methods

On October 5, 2008, a humus sample was taken, by the junior author, from Hardenberg, the Netherlands, at the Collendoornerdijk 100m away from the roundabout of the Jachthuisweg, at the right side between the trees (UTM 32U 337059.80 m E 5828396.14 m N). The sample was placed in a plastic culture box with a floor made of a mix of plaster of Paris and charcoal. The plaster was moisted and the culture was fed dried aquarium fish food. The culture was kept at room temperature. The sample contained several specimens of Orchesella cincta and one specimen of Tomocerus.


Fig.2. Tomocerus vulgaris
Just after 1st moult
Specimen from Hardenberg, the Netherlands
2008.10.06 © Baas, A.H.
Fig.1. Tomocerus vulgaris
Just before moulting
Specimen from Hardenberg, the Netherlands
2008.10.05 © Baas, A.H.
The scale cover of the Tomocerus specimen was severely damaged. It was damaged up to the point that it was not possible anymore to use the scale cover characteristics as a diagnosis for a definitive identification at species level based on a habitus inspection. The specimen was tentatively identified by the senior author as Tomocerus minor, based on the subcylindric antennae and the fact that in previously collected samples from the same region other Tomocerus minor specimens have been found.

On October 5, 2008, the specimen remained immobile for several hours. Apparently, it was in apolysis stage, a pre-moulting stage in which the epidermis separates from the cuticle of the previous instar. An instar in such a state is said to be in pharate state, refering to an instar cloaked within the cuticle of the previous instar, just before moulting. In the early pharate state, the instar is immobile.
On October 6, 2008, the specimen was moulted. It turned out to be Tomocerus vulgaris, not Tomocerus minor.


Fig.3. Tomocerus vulgaris
Just after 2nd moult
Specimen from Hardenberg, the Netherlands
2008.10.10 © Baas, A.H.
The Tomocerus vulgaris specimen was damaged in several ways (see fig.1):
1. the scale cover was almost removed completely. As such the specimen is treathened by dehydration.
2. except for the collar, all the dorsal setae have been lost. In this way the specimen is severely handicapped in its contact with the environment.
3. the right antenna is broken: the fourth antennal segment and the apical part of the third antennal segment is lost. In this way the specimen lost half of its food tasting capabilities.
4. the right proleg is missing.
These conditions will stimulate the specimen to shorten the normal intermoult period and to go in an early pre-moulting stage. This in order to restore the lost bodyparts and capabilities as soon as possible.

In the moulted specimen (fig.2),
1. the scale cover is completely restored,
2. all dorsal setae are restored,
3. the right antenna is partly restored: the third antennal segment has become longer then before the moult, an indication of a kind of fused third and fourth antennal segment,
4. the right proleg is partly restored.

After a second moult, 4 days later, the right proleg is restored completely (fig.3).


In Tomocerus vulgaris, damaged body parts are restored by the regeneration of these damaged body parts in a series of subsequent moults. A habitus inspection of Tomocerus specimens that have a severely damaged scale cover is insufficient to identify the specimens at species level.