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

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.

Mikhail Potapov, Moscow State Pedagogical University, Moscow, 129164, Russia
Anatoly Babenko, Institute of Ecology and Evolution RAN, Moscow, 119071, Russia
Arne Fjellberg, Zoological Museum, Lund University, S-223 62, Lund, Sweden
Frans Janssens, Department of Biology, University of Antwerp, Antwerp, B-2020, Belgium

Preamble

A number of other known species of the Proisotoma complex, especially Nearctic ones, may actually belong to the genus Scutisotoma. They are not included in the key because of insufficient descriptions.

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).   Maxillary outer lobe with a simple palp..................... 2
        Maxillary outer lobe with bifurcate palp.................... 6
 
2(1).   Third thoracic segment with ventral chaetae................. 3
        Third thoracic segment without ventral chaetae.............. 4
 
3(2).   Mucro with 2 teeth................................. fjellbergi
        Mucro with 3 teeth..................................... oirota
 
4(2).   Labial papilla e with 6 guards, e7 absent; prelabral chaetae
          3......................................................... 5
        Labial papilla e with 7 guards; prelabral chaetae 4...........
           ............................................. christianseni
 
5(4).   Dens with 1 anterior and 3-4 posterior chaetae (fig.140);
          ventral tube with 4 + 4 laterodistal chaetae...... indigirka
        Dens with 6-7 anterior and 8 posterior chaetae; ventral tube
          with 3 + 3 laterodistal chaetae.................. subarctica
 
6(1).   Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae........ 7
        Manubrium without anterior chaetae (figs. 122-123, 128).... 22
 
7(6).   Number of sensilla on second thoracic segment to fifth
          abdominal segment as 33/22224 (figs. 6, 46)............... 8
        Number of sensilla on second thoracic segment to fifth
          abdominal segment more than 33/22224..................... 21
 
8(7).   Dens with 1 anterior and 2-3 posterior chaetae (figs. 114,
          115).......................................... dodecocellata
        Dens with more than 1 anterior and 2-3 posterior chaetae.... 9
 
9(8).   Third antennal segment with one laterodistal sensillum
          (fig.101)................................................ 10
        Third antennal segment with two laterodistal sensilla
          (fig.70)................................................. 18
 
10(9).  Dens with fewer than 13 anterior and 13 posterior chaetae;
          furca short.............................................. 11
        Dens with more than 25 anterior and 20 posterior chaetae
          (figs. 36, 37); furca long............................... 16
 
11(10). Dens with 10-13 anterior chaetae; mucro with 3 teeth, proximal
          tooth almost as strong as apical and subapical ones
          (fig.89)................................................. 12
        Dens with 6-8 anterior chaetae; mucro with 2 teeth (fig.111),
          or a third minute proximal tooth may be present
          (figs.105-107)........................................... 13
 
12(11). Dens with 10-13 posterior chaetae : 5-6 basal, 3 inner, 1-3
          outer and 1 subapical (fig.88)...................... schisti
        Dens with 8-9 posterior chaetae : 4-5 basal, 2 inner, 1 outer
          and 1 subapical (fig.99)........................... matalini
 
13(11). Dens with 10-11 posterior chaetae (figs. 110, 111). acorrelata
        Dens with at most 8 posterior chaetae (fig.103)............ 14
 
14(13). Labial papilla e with 6 guards, e7 absent (fig.17); mucro with
          2 teeth; on fifth abdominal segment accp3 and accp4 sensilla
          clearly shorter than medial pair (fig.146, 148).......... 15
        Labial papilla e with full number of guards (fig.15); mucro
          usually with 3 teeth, the proximal one hardly visible (figs.
          106, 107); on fifth abdominal segment accp3 and accp4
          sensilla longer than medial pair of sensilla (fig.108)......
           ............................................ tenuidentifera
 
15(14). Dens with 4 posterior chaetae (fig.144)............. nicksmeti
        Dens with 6-7 posterior chaetae (fig.149)......... tianshanica
 
16(10). Fifth abdominal segment not with 2 anterior and 2 posterior
          sensilla; modified chaetae on third tibiotarsus in males are
          short and chaeta-like (fig.43); second thoracic segment with
          all lateral sensilla in a single group in anterior part of
          the tergite (fig.46); ventral tube with more than 4
          posterior chaetae (fig.47)............................... 17
        Fifth abdominal segment with 2 anterior and 2 posterior
          sensilla (fig.58); modified chaetae on third tibiotarsus in
          males are long and strong (fig.55); second thoracic segment
          with the most lateral sensillum set posterior to other
          sensilla of the lateral group (figs. 59-61); ventral tube
          with 2 posterior chaetae........................... karadagi
 
17(16). Labium usually with 5 basomedian chaetae; males without
          spine-like macrochaetae; dens tuberculated (fig.41); on
          fifth abdominal segment all sensilla set in a line (fig.45).
           .................................................... ladaki
        Labium with 4 basomedian chaetae; males with many spine-like
          macrochaetae on tergites; dens crenulated (fig.37); on fifth
          abdominal segment sensillum accp2 set posterior to others
          (fig.39).......................................... muriphila
 
18(9).  Mucro with 2 teeth......................................... 19
        Mucro with 3 teeth......................................... 20
 
19(18). Tenaculum with 3 + 3 teeth........................... ananevae
        Tenaculum with 4 + 4 teeth....................... millimetrica
 
20(18). Fifth abdominal segment with lateral sensilla set in a
          transverse line (fig.71); dens less than basal 1/3 without
          anterior chaetae (figs. 67, 69); tergal sensilla short and
          slightly thickened................................. kolymica
        Fifth abdominal segment with medial sensilla accp2 moved
          anteriorly (fig.79); dens basal half without anterior
          chaetae (fig.74); tergal sensilla chaeta-like, almost as
          long as ordinary chaetae...................... longisensilla
 
21(7).  Number of sensilla on second thoracic segment to fifth
          abdominal segment as 44/33334 - for third abdominal segment
          (fig.8)............................................ armeriae
        Number of sensilla on second thoracic segment to fifth
          abdominal segment more than 44/33334 (figs. 31, 32).. titusi
 
22(6).  Ocelli 5 + 5............................................... 23
        Ocelli 8 + 8............................................... 24
 
23(22). Dens with 1 anterior and 1-3 posterior chaetae; mucro
          bidentate, sometimes shortened or totally absent. variabilis
        Dens without anterior chaeta (fig.128); mucro usually
          hook-like...................................... stachanoremi
 
24(22). Second thoracic segment with lateral sensilla in a single
          group in front of the macrochaeta........................ 25
        Second thoracic segment with one of the lateral sensilla set
          behind the macrochaeta (figs. 126, 131).................. 26
 
25(24). First to third tibiotarsus with 21-21-25 chaetae; manubrium
          with 8-10 + 8-10 posterior chaetae on the main part.........
           .................................................. stepposa
        First to third tibiotarsus with more than 21-21-25 chaetae
          (figs. 136, 137); manubrium with 17-18 + 17-18 posterior
          chaetae on the main part (fig.133).................... baica
 
26(24). Dens with 1 anterior chaeta; mucro with 2 teeth (figs.
          122-123); tenaculum with 4 + 4 teeth (fig.120)...... montana
        Dens without anterior chaeta; mucro absent; tenaculum with 2 +
          2 teeth............................................ tolerans

Differential diagnoses

acorrelata
Dens with more than 1 anterior and 2–3 posterior chaetae. Dens with fewer than 13 anterior and 13 posterior chaetae. Dens with 6–8 anterior chaetae. Dens with 10–11 posterior chaetae (figs. 110, 111). Furca short. Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Mucro with 2 teeth (fig.), or a third minute proximal tooth may be present (figs.105–107). Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). Third antennal segment with one laterodistal sensillum (fig.).

ananevae
Dens with more than 1 anterior and 2–3 posterior chaetae. Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Mucro with 2 teeth. Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). Tenaculum with 3 + 3 teeth. Third antennal segment with two laterodistal sensilla (fig.).

armeriae
Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Number of sensilla on second thoracic segment to fifth abdominal segment more than 33/22224. Number of sensilla on second thoracic segment to fifth abdominal segment as 44/33334 - for third abdominal segment (fig.).

baica
First to third tibiotarsus with more than 21–21–25 chaetae (figs. 136, 137). Manubrium without anterior chaetae (figs. 122–123, 128). Manubrium with 17–18 + 17–18 posterior chaetae on the main part (fig.). Maxillary outer lobe with bifurcate palp. Ocelli 8 + 8. Second thoracic segment with lateral sensilla in a single group in front of the macrochaeta.

christianseni
Labial papilla e with 7 guards. Maxillary outer lobe with a simple palp. Prelabral chaetae 4. Third thoracic segment without ventral chaetae.

dodecocellata
Dens with 1 anterior and 2–3 posterior chaetae (figs. 114, 115). Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46).

fjellbergi
Maxillary outer lobe with a simple palp. Mucro with 2 teeth. Third thoracic segment with ventral chaetae.

indigirka
Dens with 1 anterior and 3–4 posterior chaetae (fig.). Labial papilla e with 6 guards, e7 absent. Maxillary outer lobe with a simple palp. Prelabral chaetae 3. Third thoracic segment without ventral chaetae. Ventral tube with 4 + 4 laterodistal chaetae.

karadagi
Dens with more than 1 anterior and 2–3 posterior chaetae. Dens with more than 25 anterior and 20 posterior chaetae (figs. 36, 37). Fifth abdominal segment with 2 anterior and 2 posterior sensilla (fig.). Furca long. Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Modified chaetae on third tibiotarsus in males are long and strong (fig.). Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). Second thoracic segment with the most lateral sensillum set posterior to other sensilla of the lateral group (figs. 59–61). Third antennal segment with one laterodistal sensillum (fig.). Ventral tube with 2 posterior chaetae.

kolymica
Dens less than basal 1/3 without anterior chaetae (figs. 67, 69). Dens with more than 1 anterior and 2–3 posterior chaetae. Fifth abdominal segment with lateral sensilla set in a transverse line (fig.). Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Mucro with 3 teeth. Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). Tergal sensilla short and slightly thickened. Third antennal segment with two laterodistal sensilla (fig.).

ladaki
Dens tuberculated (fig.). Dens with more than 1 anterior and 2–3 posterior chaetae. Dens with more than 25 anterior and 20 posterior chaetae (figs. 36, 37). Fifth abdominal segment not with 2 anterior and 2 posterior sensilla. Furca long. Labium usually with 5 basomedian chaetae. Males without spine-like macrochaetae. Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Modified chaetae on third tibiotarsus in males are short and chaeta-like (fig.). Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). On fifth abdominal segment all sensilla set in a line (fig.). Second thoracic segment with all lateral sensilla in a single group in anterior part of the tergite (fig.). Third antennal segment with one laterodistal sensillum (fig.). Ventral tube with more than 4 posterior chaetae (fig.).

longisensilla
Dens basal half without anterior chaetae (fig.). Dens with more than 1 anterior and 2–3 posterior chaetae. Fifth abdominal segment with medial sensilla accp2 moved anteriorly (fig.). Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Mucro with 3 teeth. Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). Tergal sensilla chaeta-like, almost as long as ordinary chaetae. Third antennal segment with two laterodistal sensilla (fig.).

matalini
Dens with more than 1 anterior and 2–3 posterior chaetae. Dens with fewer than 13 anterior and 13 posterior chaetae. Dens with 10–13 anterior chaetae. Dens with 8–9 posterior chaetae : 4–5 basal, 2 inner, 1 outer and 1 subapical (fig.). Furca short. Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Mucro with 3 teeth, proximal tooth almost as strong as apical and subapical ones (fig.). Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). Third antennal segment with one laterodistal sensillum (fig.).

millimetrica
Dens with more than 1 anterior and 2–3 posterior chaetae. Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Mucro with 2 teeth. Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). Tenaculum with 4 + 4 teeth. Third antennal segment with two laterodistal sensilla (fig.).

montana
Dens with 1 anterior chaeta. Manubrium without anterior chaetae (figs. 122–123, 128). Maxillary outer lobe with bifurcate palp. Mucro with 2 teeth (figs. 122–123). Ocelli 8 + 8. Second thoracic segment with one of the lateral sensilla set behind the macrochaeta (figs. 126, 131). Tenaculum with 4 + 4 teeth (fig.).

muriphila
Dens crenulated (fig.). Dens with more than 1 anterior and 2–3 posterior chaetae. Dens with more than 25 anterior and 20 posterior chaetae (figs. 36, 37). Fifth abdominal segment not with 2 anterior and 2 posterior sensilla. Furca long. Labium with 4 basomedian chaetae. Males with many spine-like macrochaetae on tergites. Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Modified chaetae on third tibiotarsus in males are short and chaeta-like (fig.). Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). On fifth abdominal segment sensillum accp2 set posterior to others (fig.). Second thoracic segment with all lateral sensilla in a single group in anterior part of the tergite (fig.). Third antennal segment with one laterodistal sensillum (fig.). Ventral tube with more than 4 posterior chaetae (fig.).

nicksmeti
Dens with more than 1 anterior and 2–3 posterior chaetae. Dens with fewer than 13 anterior and 13 posterior chaetae. Dens with fig.–8 anterior chaetae. Dens with at most 8 posterior chaetae (fig.). Dens with 4 posterior chaetae (fig.). Furca short. Labial papilla e with 6 guards, e7 absent (fig.). Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Mucro with 2 teeth. Mucro with 2 teeth (fig.), or a third minute proximal tooth may be present (figs.105–107). Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). On fifth abdominal segment accp3 and accp4 sensilla clearly shorter than medial pair (fig., 148). Third antennal segment with one laterodistal sensillum (fig.).

oirota
Maxillary outer lobe with a simple palp. Mucro with 3 teeth. Third thoracic segment with ventral chaetae.

schisti
Dens with more than 1 anterior and 2–3 posterior chaetae. Dens with fewer than 13 anterior and 13 posterior chaetae. Dens with 10–13 anterior chaetae. Dens with 10–13 posterior chaetae : 5–6 basal, 3 inner, 1–3 outer and 1 subapical (fig.). Furca short. Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Mucro with 3 teeth, proximal tooth almost as strong as apical and subapical ones (fig.). Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). Third antennal segment with one laterodistal sensillum (fig.).

stachanoremi
Dens without anterior chaeta (fig.). Manubrium without anterior chaetae (figs. 122–123, 128). Maxillary outer lobe with bifurcate palp. Mucro usually hook-like. Ocelli 5 + 5.

stepposa
First to third tibiotarsus with 21–21–25 chaetae. Manubrium without anterior chaetae (figs. 122–123, 128). Manubrium with 8–10 + 8–10 posterior chaetae on the main part. Maxillary outer lobe with bifurcate palp. Ocelli 8 + 8. Second thoracic segment with lateral sensilla in a single group in front of the macrochaeta.

subarctica
Dens with 6–7 anterior and 8 posterior chaetae. Labial papilla e with 6 guards, e7 absent. Maxillary outer lobe with a simple palp. Prelabral chaetae 3. Third thoracic segment without ventral chaetae. Ventral tube with 3 + 3 laterodistal chaetae.

tenuidentifera
Dens with more than 1 anterior and 2–3 posterior chaetae. Dens with fewer than 13 anterior and 13 posterior chaetae. Dens with 6–8 anterior chaetae. Dens with at most 8 posterior chaetae (fig.). Furca short. Labial papilla e with full number of guards (fig.). Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Mucro usually with 3 teeth, the proximal one hardly visible (figs. 106, 107). Mucro with 2 teeth (fig.), or a third minute proximal tooth may be present (figs.105–107). Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). On fifth abdominal segment accp3 and accp4 sensilla longer than medial pair of sensilla (fig.). Third antennal segment with one laterodistal sensillum (fig.).

tianshanica
Dens with more than 1 anterior and 2–3 posterior chaetae. Dens with fewer than 13 anterior and 13 posterior chaetae. Dens with 6–8 anterior chaetae. Dens with at most 8 posterior chaetae (fig.). Dens with 6–7 posterior chaetae (fig.). Furca short. Labial papilla e with 6 guards, e7 absent (fig.). Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Mucro with 2 teeth. Mucro with 2 teeth (fig.), or a third minute proximal tooth may be present (figs.105–107). Number of sensilla on second thoracic segment to fifth abdominal segment as 33/22224 (figs. 6, 46). On fifth abdominal segment accp3 and accp4 sensilla clearly shorter than medial pair (fig., 148). Third antennal segment with one laterodistal sensillum (fig.).

titusi
Manubrium with 1 + 1, rarely 2 + 2, anterior chaetae. Maxillary outer lobe with bifurcate palp. Number of sensilla on second thoracic segment to fifth abdominal segment more than 33/22224. Number of sensilla on second thoracic segment to fifth abdominal segment more than 44/33334 (figs. 31, 32).

tolerans
Dens without anterior chaeta. Manubrium without anterior chaetae (figs. 122–123, 128). Maxillary outer lobe with bifurcate palp. Mucro absent. Ocelli 8 + 8. Second thoracic segment with one of the lateral sensilla set behind the macrochaeta (figs. 126, 131). Tenaculum with 2 + 2 teeth.

variabilis
Dens with 1 anterior and 1–3 posterior chaetae. Manubrium without anterior chaetae (figs. 122–123, 128). Maxillary outer lobe with bifurcate palp. Mucro bidentate, sometimes shortened or totally absent. Ocelli 5 + 5.


References