http://www.collembola.org/key/agrenia.htm - Last updated on 2017.10.31 by Frans Janssens
Checklist of the Collembola: Key to the species of Agrenia

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.

Arne Fjellberg, Mageroveien 168, N-3145 Tjome, Norway
Ernest C. Bernard, Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996-4560, 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).   Mucro with lateral seta absent.............................. 2
        Mucro with lateral seta present............................. 9
 
2(1).   Ventral tube in adults with six or fewer anterior setae on
          each side................................................. 3
        Ventral tube in adults with ten or more anterior setae on each
          side...................................................... 7
 
3(2).   Subapical seta on dens reaching well beyond tip of mucro
          (fig.1a).................................................. 4
        Subapical seta on dens short, not reaching beyond tip of mucro
          (fig.1b).................................................. 6
 

Fig.1.
 
4(3).   Colour deep greenish black; ventral tube without anterior
          setae........................................... atroviridis
        Colour olive; ventral tube with or without anterior setae... 5
 
5(4).   Claw index in summer specimens 2.1-2.5, in winter specimens
          1.2-1.3; anterior setae on ventral tube usually absent,
          occasionally 1-2 on each side; antennae no more than 1.8
          times the length of head diagonal................... riparia
        Claw index in summer specimens 2.8-4.5, in winter specimens
          2.0-2.7 (fig.2); anterior setae on ventral tube usually with
          4-5 on each side, rarely absent; antennae in adults more
          than 1.8 times the length of head diagonal, in large males
          up to 2.7 times as long............................. parkeri
 

Fig.2.
 
6(3).   Body setae strong, on head and thorax with mixed short and
          long setae; claws short, claw index less than 3.0; outer
          dorsal lamella of mucro high and distinct (fig.3b)..........
           .............................................. tarashchukae
        Body setae thin, sparse, uniform; claws very long and slender,
          claw index 3.0 or more; outer dorsal lamella of mucro not
          prominent (fig.3a).................................. falcula
 

Fig.3.
 
7(2).   Maxilla with long, modified lamellae (fig.4b); mucro short and
          compact, apical tooth not larger than subapical tooth
          (fig.1a)............................................ extrema
        Maxilla with short, unmodified lamellae (fig.4a); mucro
          elongate, apical tooth larger than subapical tooth (fig.5)..
           ......................................................... 8
 

Fig.4.
 

Fig.5.
 
8(7).   Claw index 2.3 or less; claws short, shape normal; head shape
          normal, not markedly prognathous; abdominal setae dense,
          isotomurus-like..................................... cyanura
        Claw index 2.8 or more; claws long and slender; head markedly
          prognathous; abdominal setae of normal density....... agilis
 
9(1).   Frontoclypeal field setae along anterior edge not
          differentiated into a "moustache"; ventral tube with fewer
          than 20 anterior setae on each side...................... 10
        Frontoclypeal field with a distinct "moustache"; ventral tube
          in adults with more than 30 anterior setae on each side.....
           .................................................... pilosa
 
10(9).  Mucro elongate, with broad ventral lamella (fig.6a, b)........
           ................................................. lamellosa
        Mucro short and compact, with narrow ventral lamella....... 11
 

Fig.6.
 
11(10). Large reproductive specimens unmodified; body usually with
          some segments, or parts of segments darker than rest........
           ............................................. bidenticulata
        Large reproductive specimens with modified setae on tip of
          abdomen; body colour uniform, without distinctly darker
          sections......................................... polymorpha


Endnotes

1 The claw index is the length of the claw divided by the length of the tunica (Fjellberg 1986).


Differential diagnoses

agilis
Abdominal setae of normal density. Claw index 2.8 or more. Claws long and slender. Head markedly prognathous. Maxilla with short, unmodified lamellae (fig.4a). Mucro elongate, apical tooth larger than subapical tooth (fig.5). Mucro with lateral seta absent. Ventral tube in adults with ten or more anterior setae on each side.

atroviridis
Colour deep greenish black. Mucro with lateral seta absent. Subapical seta on dens reaching well beyond tip of mucro (fig.1a). Ventral tube without anterior setae. Ventral tube in adults with six or fewer anterior setae on each side.

bidenticulata
Body usually with some segments, or parts of segments darker than rest. Frontoclypeal field setae along anterior edge not differentiated into a "moustache". Large reproductive specimens unmodified. Mucro short and compact, with narrow ventral lamella. Mucro with lateral seta present. Ventral tube with fewer than 20 anterior setae on each side.

cyanura
Abdominal setae dense, isotomurus-like. Claw index 2.3 or less. Claws short, shape normal. Head shape normal, not markedly prognathous. Maxilla with short, unmodified lamellae (fig.4a). Mucro elongate, apical tooth larger than subapical tooth (fig.5). Mucro with lateral seta absent. Ventral tube in adults with ten or more anterior setae on each side.

extrema
Maxilla with long, modified lamellae (fig.4b). Mucro short and compact, apical tooth not larger than subapical tooth (fig.1a). Mucro with lateral seta absent. Ventral tube in adults with ten or more anterior setae on each side.

falcula
Body setae thin, sparse, uniform. Claws very long and slender, claw index 3.0 or more. Mucro with lateral seta absent. Outer dorsal lamella of mucro not prominent (fig.3a). Subapical seta on dens short, not reaching beyond tip of mucro (fig.1b). Ventral tube in adults with six or fewer anterior setae on each side.

lamellosa
Frontoclypeal field setae along anterior edge not differentiated into a "moustache". Mucro elongate, with broad ventral lamella (fig.6a, b). Mucro with lateral seta present. Ventral tube with fewer than 20 anterior setae on each side.

parkeri
Antennae in adults more than 1.8 times the length of head diagonal, in large males up to 2.7 times as long. Anterior setae on ventral tube usually with 4–5 on each side, rarely absent. Claw index in summer specimens 2.8–4.5, in winter specimens 2.0–2.7 (fig.2). Colour olive. Mucro with lateral seta absent. Subapical seta on dens reaching well beyond tip of mucro (fig.1a). Ventral tube with or without anterior setae. Ventral tube in adults with six or fewer anterior setae on each side.

pilosa
Frontoclypeal field with a distinct "moustache". Mucro with lateral seta present. Ventral tube in adults with more than 30 anterior setae on each side.

polymorpha
Body colour uniform, without distinctly darker sections. Frontoclypeal field setae along anterior edge not differentiated into a "moustache". Large reproductive specimens with modified setae on tip of abdomen. Mucro short and compact, with narrow ventral lamella. Mucro with lateral seta present. Ventral tube with fewer than 20 anterior setae on each side.

riparia
Antennae no more than 1.8 times the length of head diagonal. Anterior setae on ventral tube usually absent, occasionally 1–2 on each side. Claw index in summer specimens 2.1–2.5, in winter specimens 1.2–1.3. Colour olive. Mucro with lateral seta absent. Subapical seta on dens reaching well beyond tip of mucro (fig.1a). Ventral tube with or without anterior setae. Ventral tube in adults with six or fewer anterior setae on each side.

tarashchukae
Body setae strong, on head and thorax with mixed short and long setae. Claws short, claw index less than 3.0. Mucro with lateral seta absent. Outer dorsal lamella of mucro high and distinct (fig.3b). Subapical seta on dens short, not reaching beyond tip of mucro (fig.1b). Ventral tube in adults with six or fewer anterior setae on each side.


References