http://www.collembola.org/key/onycidea.htm - Last updated on 2019.08.23 by Frans Janssens
Checklist of the Collembola: Key to the families of Onychiuroidea

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
Frans Janssens, Department of Biology, University of Antwerp, Antwerp, B-2020, Belgium

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). Abdomen with lateral projections (fig.1).... Pachytullbergiidae
      Abdomen without lateral projections........................... 2

Fig.1.
   
2(1). Anterio-median part of fifth abdominal tergum with a glandular
        opening (fig.2); prothoracic tergum with papillae but no
        setae (fig.3)................................ Isotogastruridae
      Anterio-median part of fifth abdominal tergum without a
        glandular opening; prothoracic tergum with setae but no
        papillae.................................................... 3

Fig.2.
  

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

Fig.4.
   
4(3). Pseudocelli absent............................................ 5
      Pseudocelli present, at least on antennal base (fig.5) and/or or
        dorsum of fifth abdominal segment............... Tullbergiidae

Fig.5.
   
5(4). Anal spines 3: bilateral pair and extra middorsal terminal
        spine; clothing plurichaetomic; sixth abdominal segment seta
        a0 present..................... Triacanthellidae:Triacanthella 1
      Anal spines never 3; clothing paucichaetomic; sixth abdominal
        segment seta a0 absent........................... Odontellidae

Endnotes

1 Monogenic family Triacanthellidae nom. nov. (type genus =Triacanthella) with tentative status (infered from D'Haese, 2002, 2003; Greenslade & al., 2011).

Differential diagnoses

Isotogastruridae
Abdomen without lateral projections. Anterio-median part of fifth abdominal tergum with a glandular opening (fig.2). Prothoracic tergum with papillae but no setae (fig.3).

Odontellidae
Abdomen without lateral projections. Anal spines never 3. Anterio-median part of fifth abdominal tergum without a glandular opening. Clothing paucichaetomic. Prothoracic tergum with setae but no papillae. Pseudocelli absent. Sense organ of third antennal segment with at most two or three protective papillae and two inner sensory structures (fig.4b), or with the organ divided into a dorsal and ventral section, each bearing more than 2 structures. Sixth abdominal segment seta a0 absent.

Onychiuridae
Abdomen without lateral projections. Anterio-median part of fifth abdominal tergum without a glandular opening. Prothoracic tergum with setae but no papillae. Sense organ of third antennal segment complex with at least six elements, 4–5 outer papillae and 1–3 inner sense structures (fig.4a).

Pachytullbergiidae
Abdomen with lateral projections (fig.1).

Triacanthellidae:Triacanthella 1
Abdomen without lateral projections. Anal spines 3: bilateral pair and extra middorsal terminal spine. Anterio-median part of fifth abdominal tergum without a glandular opening. Clothing plurichaetomic. Prothoracic tergum with setae but no papillae. Pseudocelli absent. Sense organ of third antennal segment with at most two or three protective papillae and two inner sensory structures (fig.4b), or with the organ divided into a dorsal and ventral section, each bearing more than 2 structures. Sixth abdominal segment seta a0 present.

Tullbergiidae
Abdomen without lateral projections. Anterio-median part of fifth abdominal tergum without a glandular opening. Prothoracic tergum with setae but no papillae. Pseudocelli present, at least on antennal base (fig.5) and/or or dorsum of fifth abdominal segment. Sense organ of third antennal segment with at most two or three protective papillae and two inner sensory structures (fig.4b), or with the organ divided into a dorsal and ventral section, each bearing more than 2 structures.

References