http://www.collembola.org/key/collembo.htm - Last updated on 2024.08.31 by Frans Janssens
Checklist of the Collembola: Key to the families of Collembola

This key is still under construction. Note that missing figures will be provided as soon as possible. Currently, the key is in the feasibility study phase to find out how to integrate in the checklist in a modular way a key that has been generated with DELTA.

Kenneth A. Christiansen, Department of Biology, Grinnell College, PO Box V3, Grinnell, IA 50112-0806, USA
Penelope Greenslade, Division of Botany and Zoology, Australian National University, Australian Capital Territory 0200, Australia
Louis Deharveng, Laboratoire d'Ecologie Terrestre, UMR 5552 du CNRS, UPS, Toulouse Cedex 4, 31062, France
Romuald J. Pomorski, Zoological Institute, Wroclaw University, Sienkiewicza 21, Pl-50-335 Wroclaw, Poland
Frans Janssens, Department of Biology, University of Antwerp, Antwerp, B-2020, Belgium

Acknowledgements

The authors wish to thank Jesus Romero Napoles and Cvenkel Miran for their constructive comments. And to Jesus Romero Napoles for providing a Spanish translation of the key.

Rationale

The rationale for taxa used and not used as well as subtaxonomic classification for some taxa is to be provided.

Key

Note that no distinction between subtaxa and taxa is made in the key.

    
1(0).   Body divided into two: a head and a large mass consisting of
          the abdomen or abdominal segments 1-4 and smaller piece
          consisting of abdominal segments 5 and 6 (fig.1c) and the
          more or less fused thorax................................. 2
        Body elongate with at least abdominal segments 2-4 separated
          by dorsal sutures (fig.1a&b)............................. 12

Fig.1.
   
2(1).   Antennae longer than head, and/or eyes usually present...... 3
        Antennae shorter than head, and eyes absent.......... Neelidae
 

3(2).   Body ellipsoidal; dens with 3 setae (fig.2).. Mackenziellidae
        Body more or less globular (fig.1c); dens with many setae... 4

Fig.2.
   
4(3).   Hollow sacs arising ventrally from cervical region and
          encircling the neck........................... Spinothecidae
        Hollow sacs in cervical region absent....................... 5
 

5(4).   Fourth antennal segment much shorter than third.. Dicyrtomidae
        Fourth antennal segment subequal to or longer than third.... 6
 

6(5).   Females with subanal appendages; males without modified second
          and third antennal segments............................... 7
        Females without subanal appendages; males with second and
          third antennal segments modified in clasping organ (fig.3).
           ........................................... Sminthurididae 13

Fig.3.
   
7(6).   Ocelli four or fewer per side............................... 8
        Ocelli six or more per side................................. 9
 

8(7).   Ocelli four per side............................ Collophoridae
        Ocelli two or fewer per side................... Arrhopalitidae
 

9(7).   Trochanteral organ absent.................................. 10
        Trochanteral organ present (fig.4)........................ 11

Fig.4.
   
10(9).  Thick tenent hairs (fig.5) on all feet....... Bourletiellidae
        Thick tenent hairs absent........................ Sminthuridae 3

Fig.5.
   
11(9).  Tenent hairs clavate and slender, three to six on each leg....
           ............................................... Katiannidae
        Tenent hairs not clavate........................... Sturmiidae
 

12(1).  Protergite distinct (fig.6a)............................... 13
        Protergite not visible (fig.6b)............................ 26

Fig.6.
   
13(12). Dentes absent or vestigial or when present relatively shorter
          and not ringed (fig.7b).................................. 14
        Dentes more than 3 times as long as manubrium, with distal
          rings of granules (fig.7a)........................ Poduridae

Fig.7.
   
14(13). Apical organ of fourth antennal segment absent or without many
          blunt projections........................................ 15
        Apical organ of fourth antennal segment with many blunt
          projections (fig.8).......................... Gulgastruridae

Fig.8.
   
15(14). Sense organ of third antennal segment complex with at least
          six elements, 4-5 outer papillae and 1-3 inner sense
          structures (fig.9a)...................................... 16
        Sense organ of third antennal segment with at most two or
          three protective papillae and two inner sensory structures
          (fig.9b), or with the organ divided into a dorsal and
          ventral section, each bearing more than 2 structures..... 18

Fig.9.
   
16(15). Abdomen with lateral projections (fig.10).....................
           ....................................... Pachytullbergiidae 11
        Abdomen without lateral projections........................ 17

Fig.10.
   
17(16). Postantennal organ absent..................... Hypogastruridae 1
        Postantennal organ present....................... Onychiuridae
 

18(15). Pseudocelli absent or visible only under the scanning electron
          microscope............................................... 19
        Pseudocelli present, at least on antennal base (fig.11) and/or
          or dorsum of fifth abdominal segment.......... Tullbergiidae

Fig.11.
   
19(18). Prothoracic tergum with papillae but no setae (fig.12).........
           .......................................... Isotogastruridae
        Prothoracic tergum with setae but no papillae.............. 20

Fig.12.
   
20(19). Mandible absent............................. Brachystomellidae
        Mandible present........................................... 21
 

21(20). Molar plate on mandible absent (fig.13b&c).................. 22
        Molar plate on mandible present (fig.13a)................... 23

Fig.13.
   
22(21). Between stipe and fulcrum of maxilla there is an
          individualized cardo (fig.13b); mucro never trilamellate.....
           ................................................ Neanuridae
        Between stipe and fulcrum of maxilla there is no
          individualized cardo (fig.13c); mucro often trilamellate
          (fig.14)........................................ Odontellidae

Fig.14.
   
23(21). Postantennal organ minute - about 4. 6 micra - or absent... 24
        Postantennal organ present, normal size.................... 25
 

24(23). Postantennal organ absent; abdomen semi-ovoid; sixth abdominal
          segment shorter than fifth (fig.15a). Hypogastruridae 11
        Postantennal organ minute; abdomen cylindrical; sixth
          abdominal segment longer than fifth (fig.15b)...............
           ........................................ Paleotullbergiidae

Fig.15.
   
25(23). Postantennal organ elongate (fig.16)..........................
           ....................................... Pachytullbergiidae 11
        Postantennal organ not elongate.............. Hypogastruridae 11

Fig.16.
   
26(12). Head hypognathous and some abdominal segments fused
          (fig.17a&b).............................................. 27
        Head prognathous (fig.17c) and/or all six abdominal segments
          clearly separate......................................... 28

Fig.17.
   
27(26). Abdominal segment 3 & 4 fused (fig.17a).......... Coenaletidae
        Abdominal segment 4-5 fused, segment 6 reduced to anal valves
          (fig.17b)....................................... Actaletidae
 

28(26). Mucro absent.................................. Microfalculidae
        Mucro present.............................................. 29
 

29(28). Apical antennal segment at least half as long as subapical;
          mucro with few setae (fig.18b)........................... 30
        Apical antennal segment less than half as long as third; mucro
          hairy (fig.18a)................................. Tomoceridae 6

Fig.18.
   
30(29). Dentes with large ciliate fringed scales (fig.19).............
           .............................................. Cyphoderidae
        Dentes without large ciliate fringed scales................ 31

Fig.19.
   
31(30). Dental spines dentate or ciliate (fig.20a); mucro subequal in
          length to dens or longer...................... Oncopoduridae
        Dental spines simple (fig.20b) or absent; mucro much shorter
          than dens................................................ 32

Fig.20.
   
32(31). Dens dorsally crenulate and curving upward, basally in line
          with manubrium (fig.21a)................................. 33
        Dens straight and usually forming an obtuse basal angle with
          manubrium (fig.21b), usually not crenulate..... Paronellidae

Fig.21.
   
33(32). Antennae with five or six subdivisions.......... Orchesellidae
        Antennae with four subdivisions............................ 34
 

34(33). Third abdominal segment clearly shorter than fourth........ 35
        Third abdominal segment longer to slightly shorter than
          fourth................................................... 37
 

35(34). Trochanteral organ absent or rudimentary................... 36
        Trochanteral organ present (fig.22)............. Entomobryidae

Fig.22.
   
36(35). Trochanteral organ absent......................... Isotomidae 11
        Trochanteral organ rudimentary with few, four or five, setae,
          and none of these short and straight........................
           ......................................... Praentomobryidae 14
 

37(34). Scales absent.............................................. 38
        Scales present.................................... Tomoceridae 8
 

38(37). Postantennal organ usually absent; trochanteral organ present
          on inner surface of trochanter (fig.22a)....................
           ............................................. Entomobryidae 9
        Postantennal organ usually present; trochanteral organ absent.
           ........................................................ 39
 

39(38). Third and fourth antennal segments annulate...................
           .............................................. Tomoceridae 10
        Third and fourth antennal segments not annulate...............
           ............................................... Isotomidae 11

Endnotes

1 Acherongia will key out here.

3 One species (Sminthurus sylvestris) has thick, clavate tenent hairs.

6 Subfamily Tomocerinae.

8 Subfamily Lepidohorellinae, ad partem.

9 Tribus Corynothricini.

10 Subfamily Lepidophorellinae, ad partem.

11 ad partem.

12 Sensiphorura will key out here.

13 Males of some species of Nasosminthurus may key out here, but are easily distinguished by the large thick tenent hairs.

14 Extinct family.

20 The genus Millsia is impossible to be placed in any family. The only specimen is the holotype which is young and in poor condition.

References