- Last updated on 2001.11.28 by Frans Janssens
Checklist of the Collembola: Keys to the species of Pseudosinella Schäffer, 1897

Kenneth A. Christiansen, Department of Biology, Grinell College, PO Box V3, Grinell, IA 50112-0806, USA
Frans Janssens, Department of Biology, University of Antwerp (RUCA), Antwerp, B-2020, Belgium


Based on the work of Dr Christiansen et al. (1990) on the computer assisted identifications of specimens of Pseudosinella in the DEscription Language for TAxonomy (DELTA) of Mike J. Dallwitz, two different versions of keys are presented here: a conventional dichotomous key and an inter-active key. Both versions of the key are web-enabled, in other words they can be used on-line through using a web browser.

Inter-active key

For historical reasons, the original inter-active key BUGS DELTA of 1990 is described shortly. This key could be accessed on-line through telnet by contacting the Grinnell college system "telnet://" When the system was contacted, it was possible to logon with username "BUGS" and password "DELTA". Then some information was asked for and subsequently the following menu options were offered:

"Go Online" allowed to interactively identify any species.
N.B. Entering "FINI" at any time returned to the main menu.

In 1999, the VAX system that provided for the original inter-active key was put out of service. The interactive version of the key is now provided through NaviKey. In order to use the new interactive version of the key to the species of Pseudosinella you have to contact the www.wEB page at: The menu this offers will present you with several options. The Pseudosinella program includes Examine the Species ; View the Delta Database files for Pseudosinella; and Computer Assisted Identification of specimens.

To show an abbreviated description of any species click on Display Individual Pseudosinella species. Pull down menu will be exposed and scroll down the menu to the desired species . Click on this and then click on display Taxon The characters will be listed and the state present in that species shown under it. If you have questions concerning these features turn to the illustrations and listings of the features shown on pages 239-243 of Christiansen, Bellinger & da Gama (1990). If you wish to see a listing of the characters and the character states click on Character File. If you wish to find the character states present for a particular species click on Items file and either scroll down until the species is reached or use a find and type out the species name with a / mark at the end. You can also use the find to locate all species with a particular character state. For example to find all with Character state 2 for character 32 use find 32,2 and the find again until all the species have been covered.

The interactive species identification presently only works with Internet Explorer 4.5 on the Mac and Netscape 4.0+ on the Windows platform. If one of these is available open the box and then click on the characters of the species at hand in the upper left hand box . The species having this character state will be displayed until only one or no species are presented in the lower right hand box. Continue adding features until only one species or no species are left in the box. Presenting the characters in differing order will be useful in showing relationships between your species and others.

The inter-active key for Pseudosinella offers more than the conventional dichotomous key: such as a list of all species, descriptions of the species, a list of all used characters, etc.

Convential dichotomous key

In 1996, with the cooperation of Dr Christiansen, a HTML-ised conventional dichotomous version of the key was made. With some minor adaptations of the original DELTA files and some additions of missing character states of particular species, kindly provided by Dr Christiansen, a conventional printed key could be generated. All species listed in the original work can be keyed out, except for Pseudosinella virei and P. subvirei. Based on the currently available character states for these species they cannot be keyed out seperatly.

Some species apear more then once in the key due to the unavailability of character state data :

aggtelekiensis            3 times
binoculata                2
encrusae                  2
fallax                    2
goughi                    2
handschini                8
imparipunctata            2
joupani                   3
lleidensis                2
marteli                   7
passauri                  3
picta                     2
propinqua                 3
stachi                    8
styriaca                  2
subduodecima              4
subilliciens             10
tarraconensis longicorni  3

This conventional Pseudosinella key only affords a key to the species. Due to the hyperlink capabilities of HTML, it is possible to move smoothly through the tree. By clicking on the key reference numbers of choice you will be positioned automagically at the next character state selection list in the key.

All the DELTA input files required to generate the key are packed into an archive, and with the kind permission of Dr Christiansen, this archive file can be downloaded here.

Keys to the species of Pseudosinella Schäffer, 1897 (sensu Christiansen et al., 1990)

Check the original paper of Christiansen et al. (1990) for a detailed description of the characters and character states that are used in this key. A copy of the original paper showing illustrations of the various taxonomical characters used in the key may be obtained from Kenneth Christiansen.


Dr Christiansen was so kind to provide all the original DELTA files of the inter-active key of the species of Pseudosinella.


Christiansen, K.A., Bellinger, P.F. & da Gama, M.M. 1990. Computer assisted identification of specimens of Pseudosinella (Collembola: Entomobryidae). Rev. Ecol. Biol. Sol 27, p.231-246.