http://www.collembola.org/key/entomobr.htm - Last updated on 2017.10.31 by Frans Janssens
Checklist of the Collembola: Key to the species of Entomobrya, partim Britanica

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.

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).   Third abdominal segment enterily pigmented dorsally......... 2
        Third abdominal segment not enterily pigmented dorsally..... 4
 
2(1).   Third thoracic segment, first abdominal segment, and second
          abdominal segment all enterily pigmented dorsally (fig.1)..
           ................................................ albocincta
        Third thoracic segment, first abdominal segment, and second
          abdominal segment not enterily pigmented dorsally......... 3
 

Fig.1.
 
3(2).   Fourth abdominal segment with band along posterior border
          (fig.2); labral appendages as in (fig.3b); sixth abdominal
          segment without pigment; empodial appendage ciliated along
          posterior border.................................. pulchella
        Fourth abdominal segment without band along posterior border
          (fig.4); labral appendages as in (fig.3a); sixth abdominal
          segment with some pigment laterally; empodial appendage not
          ciliated along posterior border.................. corticalis
 

Fig.2.
 

Fig.3.
 

Fig.4.
 
4(1).   Third abdominal segment with distinct pattern markings...... 5
        Third abdominal segment without pigment, or, if present, very
          poorly developed and diffuse.............................. 9
 
5(4).   Third abdominal segment with a well-marked pattern, consisting
          of two triangular spots, one each side of mid-dorsal line,
          often joined by a band along posterior margin of the
          segment................................................... 6
        Third abdominal segment with diffuse pigment dorsally, formed
          by the extension of the lateral bands on to the
          dorso-lateral surface of the segment, which never reaches
          the mid-dorsal line of the segment (fig.5)........ nicoleti 3
 

Fig.5.
 
6(5).   Sixth abdominal segment not pigmented; fifth abdominal segment
          with a well marked triangular pigment spot lying along
          mid-dorsal line of the segment, the base running along
          posterior margin of the segment (fig.6)........... muscorum
        Sixth abdominal segment partly pigmented; fifth abdominal
          segment rarely with pigment along mid-dorsal line of the
          segment, where the pigment does extend to mid-dorsal line,
          then the pigment on sixth abdominal segment is well
          developed................................................. 7
 

Fig.6.
 
7(6).   Fourth abdominal segment with a pair of clearly marked
          triangular patches of pigment, one each side of mid-dorsal
          line, and with the base of the triangle lying along the
          posterior margin of the segment, where the patches are
          joined to the anterior cross band of the segment, then the
          connectives are poorly developed, and run only from the apex
          of the triangular patches (fig.7)............ multifasciata
        Fourth abdominal segment with a pair of parallel, longitudinal
          bands of even thickness lying on each side of mid-dorsal
          line, and running from posterior margin of the segment to a
          point in the centre of the segment, where the bands
          terminate, and a branch runs diagonally forward, to connect
          with the lateral bands in the anterior margin of the
          segment, a second band may run across the mid-dorsal line of
          the segment, to connect with its opposite number.......... 8
 

Fig.7.
 
8(7).   Fourth abdominal segment always with an inverted v-shaped mark
          in mid-dorsal line of the segment, the apex of this mark
          lying near the anterior border of the segment, the pair of
          longitudinal bands may be joined through this band, but are
          never joined by a band running directly over the mid-dorsal
          line of the segment (fig.8)..................... intermedia
        Fourth abdominal segment without inner cross band running over
          mid-dorsal line between the pair of parallel bands, or if
          this band is present it runs directly between the
          longitudinal bands, and never into the anterior half of the
          segment (fig.9).................................... nivalis
 

Fig.8.
 

Fig.9.
 
9(4).   Fourth abdominal segment with one pair of black pigment spots
          laterally on posterior border of the segment (fig.10).......
           ................................................... nivalis 4
        Fourth abdominal segment without one pair of black pigment
          spots laterally on posterior border of the segment....... 10
 

Fig.10.
 
10(9).  Fourth abdominal segment with no pigment or with two pairs of
          pigment spots, frequently partly fused, lying laterally on
          posterior margin of the segment, and a distinct pigment spot
          on mid-dorsal line in the posterior half of the segment
          (fig.11); fifth abdominal segment without pigment band on
          posterior margin 2................................... maritima
        Fourth abdominal segment with two pairs of distinct pigment
          spots, on posterior margin of the segment, but no pigment
          spot on mid-dorsal line in the posterior half of the segment
          (fig.12); fifth abdominal segment with a pigment band along
          posterior margin................................... nicoleti

Fig.11.
 

Fig.12.
 


Endnotes

1 The pigment pattern referred to in the key is the pattern formed of purple or purple-black pigment; no reference has been made to the ground or general body colour.

2 A few specimens of E. maritima have been taken with traces of faint diffuse pigmentation on the posterior border of the fifth abdominal segment. These specimens were, however, rather strongly pigmented and could be distinguished from E. nicoleti by the presence of pigment on the posterior dorsal surface of the head, which is absent in heavely pigmented E. nicoleti specimens.

3 Dark form of E. nicoleti.

4 Pale form of E. nivalis.


Differential diagnoses

albocincta
Third abdominal segment enterily pigmented dorsally. Third thoracic segment, first abdominal segment, and second abdominal segment all enterily pigmented dorsally (fig.1).

corticalis
Empodial appendage not ciliated along posterior border. Fourth abdominal segment without band along posterior border (fig.4). Labral appendages as in (fig.3a). Sixth abdominal segment with some pigment laterally. Third abdominal segment enterily pigmented dorsally. Third thoracic segment, first abdominal segment, and second abdominal segment not enterily pigmented dorsally.

intermedia
Fifth abdominal segment rarely with pigment along mid-dorsal line of the segment, where the pigment does extend to mid-dorsal line, then the pigment on sixth abdominal segment is well developed. Fourth abdominal segment always with an inverted v-shaped mark in mid-dorsal line of the segment, the apex of this mark lying near the anterior border of the segment, the pair of longitudinal bands may be joined through this band, but are never joined by a band running directly over the mid-dorsal line of the segment (fig.8). Fourth abdominal segment with a pair of parallel, longitudinal bands of even thickness lying on each side of mid-dorsal line, and running from posterior margin of the segment to a point in the centre of the segment, where the bands terminate, and a branch runs diagonally forward, to connect with the lateral bands in the anterior margin of the segment, a second band may run across the mid-dorsal line of the segment, to connect with its opposite number. Sixth abdominal segment partly pigmented. Third abdominal segment not enterily pigmented dorsally. Third abdominal segment with distinct pattern markings. Third abdominal segment with a well-marked pattern, consisting of two triangular spots, one each side of mid-dorsal line, often joined by a band along posterior margin of the segment.

maritima
Fifth abdominal segment without pigment band on posterior margin$note2. Fourth abdominal segment without one pair of black pigment spots laterally on posterior border of the segment. Fourth abdominal segment with no pigment or with two pairs of pigment spots, frequently partly fused, lying laterally on posterior margin of the segment, and a distinct pigment spot on mid-dorsal line in the posterior half of the segment (fig.11). Third abdominal segment not enterily pigmented dorsally. Third abdominal segment without pigment, or, if present, very poorly developed and diffuse.

multifasciata
Fifth abdominal segment rarely with pigment along mid-dorsal line of the segment, where the pigment does extend to mid-dorsal line, then the pigment on sixth abdominal segment is well developed. Fourth abdominal segment with a pair of clearly marked triangular patches of pigment, one each side of mid-dorsal line, and with the base of the triangle lying along the posterior margin of the segment, where the patches are joined to the anterior cross band of the segment, then the connectives are poorly developed, and run only from the apex of the triangular patches (fig.7). Sixth abdominal segment partly pigmented. Third abdominal segment not enterily pigmented dorsally. Third abdominal segment with distinct pattern markings. Third abdominal segment with a well-marked pattern, consisting of two triangular spots, one each side of mid-dorsal line, often joined by a band along posterior margin of the segment.

muscorum
Fifth abdominal segment with a well marked triangular pigment spot lying along mid-dorsal line of the segment, the base running along posterior margin of the segment (fig.6). Sixth abdominal segment not pigmented. Third abdominal segment not enterily pigmented dorsally. Third abdominal segment with distinct pattern markings. Third abdominal segment with a well-marked pattern, consisting of two triangular spots, one each side of mid-dorsal line, often joined by a band along posterior margin of the segment.

nicoleti
Fifth abdominal segment with a pigment band along posterior margin. Fourth abdominal segment without one pair of black pigment spots laterally on posterior border of the segment. Fourth abdominal segment with two pairs of distinct pigment spots, on posterior margin of the segment, but no pigment spot on mid-dorsal line in the posterior half of the segment (fig.12). Third abdominal segment not enterily pigmented dorsally. Third abdominal segment without pigment, or, if present, very poorly developed and diffuse.

nicoleti 3
Third abdominal segment not enterily pigmented dorsally. Third abdominal segment with distinct pattern markings. Third abdominal segment with diffuse pigment dorsally, formed by the extension of the lateral bands on to the dorso-lateral surface of the segment, which never reaches the mid-dorsal line of the segment (fig.5).

nivalis
Fifth abdominal segment rarely with pigment along mid-dorsal line of the segment, where the pigment does extend to mid-dorsal line, then the pigment on sixth abdominal segment is well developed. Fourth abdominal segment without inner cross band running over mid-dorsal line between the pair of parallel bands, or if this band is present it runs directly between the longitudinal bands, and never into the anterior half of the segment (fig.9). Fourth abdominal segment with a pair of parallel, longitudinal bands of even thickness lying on each side of mid-dorsal line, and running from posterior margin of the segment to a point in the centre of the segment, where the bands terminate, and a branch runs diagonally forward, to connect with the lateral bands in the anterior margin of the segment, a second band may run across the mid-dorsal line of the segment, to connect with its opposite number. Sixth abdominal segment partly pigmented. Third abdominal segment not enterily pigmented dorsally. Third abdominal segment with distinct pattern markings. Third abdominal segment with a well-marked pattern, consisting of two triangular spots, one each side of mid-dorsal line, often joined by a band along posterior margin of the segment.

nivalis 4
Fourth abdominal segment with one pair of black pigment spots laterally on posterior border of the segment (fig.10). Third abdominal segment not enterily pigmented dorsally. Third abdominal segment without pigment, or, if present, very poorly developed and diffuse.

pulchella
Empodial appendage ciliated along posterior border. Fourth abdominal segment with band along posterior border (fig.2). Labral appendages as in (fig.3b). Sixth abdominal segment without pigment. Third abdominal segment enterily pigmented dorsally. Third thoracic segment, first abdominal segment, and second abdominal segment not enterily pigmented dorsally.


References