- Last updated on 2004.07.13 by Frans Janssens
Checklist of the Collembola:
Major Morphotypes and Hierarchy Classification Criteria

Frans Janssens, Department of Biology, University of Antwerp (RUCA), Antwerp, B-2020, Belgium
Frank B. Dazzo, Department of Microbiology & Molecular Genetics, Michigan State University, East Lansing, Michigan 48824-4320, USA


Some preliminary thoughts with respect to a first attempt of a classification criteria hierarchy for the major Collembola morphotypes. Only general body shape features are used, currently. Features of appendages have not yet taken into account. They will play a role whenever we start fine tuning the criteria hierarchy to be able to distinguish lower level taxa (families, subfamilies, etc...). Note that Podura aquatica and Lepidocyrtus paradoxus specimens already can be recognised by CMEIAS at species level with the given hierarchy! The classification of the genera is quite subjective and I would welcome any suggestion for reclassification.


Some preliminary remarks:

1. Form versus shape: While form is a physical attribute of an object, shape is the perception of a form. The shape of a form of a 3D object is a 2D projection. Example: an object with cylinder form can have a round shape, a rectangular shape or a rectangular shape with rounded poles depending on the angle of viewing. CMEIAS deals with images, thus shapes, not forms.

2. The anatomical body position is to be taken into account as the reference position of specimens of a sample. Collembola have a bilateral symmetry, therefore the lateral aspect of the body will be most suitable to do measurements.
Length = cephalo-caudal length
Width = dorso-ventral width

3. The body shape is the remaining shape after masking out all appendages, such as antennae, legs, ventral tube, and furca.

4. The image of the sample of specimens is made by scanning a petridish on a flatbedscanner at highest possible resolution. This will make sure that the specimens are not deformed. When mounted on object slides, specimens are usually deformed: the body shape is appearing much more wide then in not mounted specimens.

Hierarchy Classification Criteria

The selected taxa in the current hierarchy are the most common European genera, based on Hopkin (2000). The maximum length (in mm) is indicated after each taxon.
  1. General lateral shape of body = elongated
    (= ratio of length/width much larger than 1)
    1. Cephalo-caudal body axis not curved (Poduromorpha including Metaxymorpha)
      (= quantified curvature about 0)
      1. Body tapered at caudal end only (body widest at cephalic end)
        1. A
          morphotype 1
          Body in middle with constant width
          Anurida 2.0
          Anuridella 1.9
          Micranurida 1.0
        2. B
          Body narrowing in middle at ventral side (Metaxymorpha)
          (narrowest just behind head, due to hypognathic position of head)
          Podura aquatica 2.0
      2. Body tapered at both ends, cephalic end more blunt than caudal end
        1. C
          morphotype 2
          Body middle with constant width
          Ceratophysella 1.8
          Friesea 1.9
          Hypogastrura 2.0
          Mesaphorura 0.7
          Metaphorura 1.3
          Neonaphorura 1.0
          Neotullbergia 0.7
          Paratullbergia 1.2
          Schaefferia 1.5
          Stenaphorura 1.0
        2. D
          morphotype 3
          Body widest at center
          Mesogastrura 1.5
          Paranura 2.5
          Pseudachorutella 2.0
          Pseudachorutes 3.0
          Willemia 0.7
        3. E
          morphotype 4
          Body widest at 2/3 (ratio = indicative)
          (= widest at center of abdomen)
          Archaphorura 1.5
          Kalaphorura 2.0
          Onychiurus 2.2
          Protaphorura 3.5
        4. F
          morphotype 5
          Body widest at 5/6 (ratio = indicative)
          (= widest at 4th abdominal segment)
          Brachystomella 1.0
          Choreutinula 1.0
          Odontella 1.5
          Schoetella 1.2
          Xenylla 1.4
          Xenyllodes 1.0
    2. Cephalo-caudal body axis curved (Entomobryomorpha)
      (= quantified curvature more than 0)
      1. Body "unbranched" (and tapered at both ends)
        1. G
          morphotype 1
          Body middle with constant width
          Anurophorus 1.4
          Cryptopygus 1.2
          Folsomia 3.0
          Folsomides 0.9
          Isotomodes 0.9
          Proctostephanus 1.3
          Pseudanurophorus 0.5
          Tetracanthella 1.7
          Uzelia 1.4
        2. H
          morphotype 2
          Body widest at center
          Entomobryoides 3.0
          Lepidocyrtus 1.6
          Seira 3.0
          Willowsia 1.5
        3. I
          morphotype 3
          Body widest at 2/3 (ratio = indicative)
          (= widest at center of abdomen)
          Agrenia 2.0
          Cyphoderus 1.6
          Heteromurus 3.0
          Orchesella 5.0
          Pachyotoma 1.5
          Pseudosinella 1.8
          Sinella 1.5
          Tomocerus 6.0
        4. J
          morphotype 4
          Body widest at 5/6 (ratio = indicative)
          (= widest at 4th abdominal segment)
          Archisotoma 1.5
          Axelsonia 2.0
          Ballistrura 1.5
          Entomobrya 2.0
          Isotoma 4.0
          Isotomiella 1.1
          Isotomurus 2.5
          Lepidocyrtus (cyaneus, violaceus) 1.5
          Mesentomata 2.0
          Oncopodura 0.8
          Pseudisotoma 1.7
          Proisotoma 1.1
          Vertagopus 1.8
      2. K
        morphotype 5
        Body "branched"
        (thoracic cap over head)
        Lepidocyrtus paradoxus 1.5
  2. General lateral shape of body = round
    (= ratio of length/width about 1)
    1. L
      Body shape "hunched" (Neelimorpha)
      Megalothorax 0.4
      Neelides 0.6
      Neelus 0.7
    2. Body shape subglobular (Sminthuromorpha)
      1. M
        morphotype 1
        Body = concatenation of 2 "kissing" spheroids = head + "fused" great and small body
        Lipothrix 2.0
        Sminthurides 0.5
        Stenacidia 0.5
      2. N
        morphotype 2
        Body = concatenation of 3 "kissing" spheroids = head + great body + small body
        Allacma 3.5
        Bourletiella 1.3
        Caprainea 1.4
        Cassagnaudiella 1.5
        Deuterosminthurus 1.0
        Disparrhopalites 1.0
        Gisinianus 0.7
        Heterosminthurus 1.5
        Sminthurinus 1.0
        Sphaeridia 0.5
        Sphyrotheca 1.3
      3. O
        morphotype 3
        Body = concatenation of 3 spheroids, of which the first 2 are "abridged"
        = head + "neck" + great body + small body
        (species with "neckbuilding")
        Arrhopalites 1.2
        Dicyrtoma 2.0
        Dicyrtomina 3.0
        Ptenothrix 2.7
        Sminthurus 3.0