http://www.collembola.org/key/isotomur.htm - Last updated on 2024.10.31 by Frans Janssens
Checklist of the Collembola: Key to the species of Isotomurus, partim Western Europe

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.

Antonio Carapelli, Department of Evolutionary Biology, University of Siena
F. Frati, Department of Evolutionary Biology, University of Siena
P.P. Fanciulli, Department of Evolutionary Biology, University of Siena
R. Dallai, Department of Evolutionary Biology, University of Siena
Arne Fjellberg, Mageroveien 168, N-3145 Tjome, Norway
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).   Trunk colour concentrated in distinctive patterns........... 2
        Trunk colour distributed uniformly......................... 12
 
2(1).   Pigment pattern in irregular patches........................ 3
        Pigment pattern in regular bands............................ 5
 
3(2).   Pigmentation as irregular stripes on posterior part of third
          to fifth abdominal segments............................... 4
        Pigmentation as irregular symmetrical patches on tergites.....
           ................................................. maculatus
 
4(3).   Mesochaetae ciliate; body with darker ribbon-like patches of
          pigmentation on the margins of tergites; legs uniformly
          coloured like tergites; dentes are dorsally covered by many
          setae, each one inserted in a papilla-like cuticular
          structure; furca: retinaculum with 10-15 ordinary setae.....
           ................................................. aetnensis
        Mesochaetae smooth; body with thin violet drawings mostly
          present on last abdominal tergites; legs whitish; dentes
          dorsally with many short setae, which are longer on lateral
          margins; furca: retinaculum with 14 to 32 ordinary setae....
           ................................................. nebulosus
 
5(2).   Pigment pattern longitudinal................................ 6
        Pigment pattern transversal................................ 10
 
6(5).   Lateral flaps of ventral tube with 11 + 11 to 20 + 20 setae;
          longitudinal middorsal pattern very wide, about 1/3 width of
          tergites.......................................... alticolus
        Lateral flaps of ventral tube with 3 + 3 setae; longitudinal
          middorsal pattern less than 1/5 width of tergites and
          sometimes absent on the last abdominal tergites........... 7
 
7(6).   Longitudinal middorsal pattern continuous and very pronounced,
          sometimes absent on fifth and sixth abdominal segment..... 8
        Longitudinal middorsal pattern interrupted or fainter,
          especially on third abdominal segment, with net-like
          ornaments on lateral parts of each tergite................ 9
 
8(7).   Dorsolateral pigmentation absent or very limited. unifasciatus
        Dorsolateral pigmentation abundant brownish...................
           ........................................... pseudopalustris 1
 
9(7).   Abdominal setae all smooth; mucro without lateral seta;
          unguiculus with inner corner tooth................ palustris
        Abdominal setae some smooth and some weakly feathered having 3
          to 5 ciliae laterally near the base of the seta, especially
          abundant on third abdominal segment; mucro with lateral
          seta; unguiculus without inner tooth............... plumosus 2
 
10(5).  Pigmentation dark on all tergites of second thoracic segment
          to second abdominal segment, completely covered...... rabili
        Pigmentation dark only on anterior parts of tergites....... 11
 
11(10). Macrochaetae multilaterally ciliate; ordinary setae abundant;
          trichobothrial formula: 3 + 3 + 1; lateral flaps with 3 + 3
          setae; retinaculum with 12-16 ordinary setae.... ghibellinus
        Macrochaetae unilaterally slightly ciliate; ordinary setae
          reduced if compared with species of the palustris group;
          trichobothrial formula: 0 + 1 + 1; lateral flaps with 5 + 5
          setae; retinaculum with 2 ordinary setae........... gallicus
 
12(1).  Background colour dark brownish or black................... 13
        Background colour light greenish or yellowish.............. 15
 
13(12). Colour black...................................... hadriaticus
        Colour brownish............................................ 14
 
14(13). Accp1-5 + as1 and 4 on abdominal segment iv; accp1-5 + as1 on
          abdominal segment v; accp1 and accp2 equally long as other
          accp setae on abdominal segment v; postantennal organ/dca:
          0. 8-1; l/antennae: 3. 5-4. 0.................... cassagnaui
        Accp1-5 + as1, 2 and 4 on abdominal segment iv; accp1-5 +
          as1-2 on abdominal segment v; accp1 and accp2 longer than
          the other accp setae on abdominal segment v; postantennal
          organ/dca: 1. 5; l/antennae: 2. 2................. fucicolus
 
15(12). Collophore with 3 + 3 lateral setae; dens dorsally crenulate;
          mucronal seta absent............................... graminis
        Collophore with up to 20 + 20 lateral setae; dens dorsally
          tuberculate; mucronal seta present................. prasinus

Endnotes

1 This key does not apply to the population of I. unifasciatus from Siena, where specimens resemble those of I. pseudopalustris.

2 This feathering is usually visible only under great enlargement, and on preparations of the tergits cut off and made transparant under the influence of KOH (Stach, 1947:462).

References