Key to the groups of British CARABIDAE

For more information on this family click HERE.

With more than 40000 described species worldwide and about 2700 in Europe it might seem somehow straightforward to deal with the U.K. fauna of about 350 species, but the variation in morphology of the various groups means that even a key to the tribes must be a compromise e.g. on morphology the Zabrini will key out twice, and the Sphodrini and Platynini will key out together because there is no single character to distinguish them, they are generally separated on male genitalia characters which are hardly appropriate when all that is needed is an identification. For a similar reason, and in order to simplify things a little the species Callistus lunatus (Fabricius, 1775) is not included; it is so distinctive among our fauna that the picture to the right is all that is needed.

Part 1: Subfamily Key

Callistus lunatus (Fabricius, 1775)

1.

Habitus rounded, scutellum not visible.

Habitus elongate or oval, scutellum visible

2.

Mandibles with large teeth along the inner surface. Antennae inserted inside the base of the mandibles.

 

Mandibles without large teeth on the inner margin. Antennae inserted outside the base of the mandibles.

3.

Appearance very characteristic; bicoloured red and blue or green. Dorsal surface with short, recumbent pubescence.  Abdomen with 7 or 8 visible sternites. 4.5-9.5mm.

 

Appearance otherwise. Abdomen with 6 visible sternites. Includes the majority of our species.

Part 2: CARABINAE Tribes
 

Pro-tibiae smooth along the inside; lacking an antennal-cleaning notch.

1.

Pro-tibiae with a distinct sub-apical notch on the inside.

2.

Posterior angles of the pronotum produced or rounded, or the elytra have 14 striae.

Posterior angles of the pronotum sharp, elytra with at most 9 striae.

 
3.

Head and mandibles produced forward, posterior angles of the pronotum rounded, elytra smooth and length <20mm

 

Head and mandibles less produced, or >20mm, posterior angles of the pronotum produced backwards.

4.

Eyes very large; occupying most of the lateral margin of the head, and the second elytral interstice much wider than the others.

 

Eyes smaller; second interstice normal.

5.

Eyes smaller, fourth antennomere glabrous.

Eyes larger, fourth antennomere pubescent.

 
6.

Basal antennomeres with numerous long setae.

 

Basal antennomeres with only a few setae.

Scutellum placed on a peduncle between the pronotum and the elytra.

7.

Base of the scutellum in line with the basal elytral margin.

 

Pro-tibiae simple at apex.  ≥6mm.

8.

Pro-tibiae produced into two apical teeth. 2-6mm.

 

Apical segment of the mazillary palpi very small compared with the penultimate segment.

9.
 

Apical segment of the maxillary palpi normally developed.

Head with deep, curved impressions extending to behind the eyes. First elytral stria recurved at the apex.

10.
 

Any impressions on the head not extending behind the eyes, first elytral stria not recurved at the apex.

Outer margin of the mandibles with a setiferous puncture.

11.

Outer margin of the mandibles without a setiferous puncture.

 

Basal margin of the elytra with a strong border.

12.

Basal margin of the elytra without or with only a weak border.

 

Mandibles truncate (view from in front).

13.

Mandibles sharp or rounded at the apex.

 

Elytra truncate at the apex; transverse or oblique, sometimes sinuate. Abdomen often visible beyond the apex.

14.
 

Elytra rounded, sometimes sinuate where they curve. Abdomen normally hidden.

Pronotum strongly transverse; almost as broad as the elytra. Pro-tibiae with a series of short spines along the outer margin towards the apex.

15.
 

Pronotum much less transverse; distinctly narrower than the elytra. Pro-tibiae with at most fine setae or pubescence  along the outer margin towards the apex.

Pronotum cylindrical, without a distinct lateral border.

16.
 

Pronotum flattened, with a distinct lateral margin.

Distinctive metallic blue or green species; basal antennomere as long as the next three combined. Penultimate tarsomere strongly bilobed.

17.
 

Elytra testaceous, dark at the apex.. Basal antennomere much shorter than the next three combined.Penultimate tarsomere not strongly bilobed.

Basal antennomere longer than the next two combined. Pronotum and two basal antennomeres pubescent.

18.
 

Basal antennomere not as long as the next two combined. Pronotum and two basal antennomeres glabrous.

Head with a single setiferous puncture by the inner margin of the eyes.

19.

Head with two setiferous punctures by the inner margin of the eyes.

 

Very distinctive species with prominent eyes and densely punctured and pubescent dorsal surface, unmistakable red and black bicoloured

20.
 

Different.

Small <2.5mm Elytra with pubescent margins and the eighth stria strongly impressed. Mandibles strongly produced.

21.
 

Larger, or without pubescent elytral margins.

Penultimate segment of the labial palpi with three or more setae along the inner margin.

22.
 

Penultimate segment of the labial palpi with two or less setae along the inner margin.

Pro-tibiae strongly broadened towards the apex. Elytral epipleura crossed before the apex, except in Pterostichus cristatus (Dufour, 1820).

23.
 

Pro-tibiae much less strongly bordered. Elytral epipleura always distinct and separate to the apex.

or

24.

Third antennomere as densely pubescent as the fourth.

 

Third antennomere glabrous or very finely pubescent, contrasting with the fourth.

25.

Eighth elytral stria raised into a keel towards the apex.

 

Eighth stria normal.

26.

Dorsal surface glabrous.

 

Dorsal surface punctured and pubescent.

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