Carabidae – ground beetles
The classic ‘starter family’ of beetles. They are a good group to begin with as they are a nice size (about 370 species) and occur in all terrestrial and freshwater habitats from the inter-tidal zone to the highest mountain tops. More or less wherever you look, there will always be a carabid to be found. They are mostly of a size that allows identification with a hand lens or a low-power microscope. They’re not all easy though: the Carabidae includes some identification challenges to test any coleopterist!
Identification
For identification of carabids you’ll need a copy of Martin Luff’s (2007) RES Handbook. This is up-to-date and complete (excluding only 13 species which are occasional introductions, long extinct, or both). Amongst the improvements over the preceding RES Handbook (Lindroth, 1974) are all the line illustrations in the margins of the key, ‘similar species’ text highlighting diagnostic differences where appropriate, and 147 whole-beetle colour photographs at the back of the book.
However, if you are new to carabids, or perhaps working on carabids without access to a reference collection, you may not always find that Luff’s keys get you swiftly and easily to an identification that you can be confident of. So this page aims to help.
1. The field guide approach
Keys such as those in the RES Handbooks series are good for a lot of beetles but there are plenty of species which would be better suited to a field guide treatment. The ideal guide would take people as far as possible towards identification of carabids in the field, using photographs, illustrations and diagnostic text. But field identification is not realistic for all the carabids: a hybrid approach is needed between a field guide treatment where appropriate with traditional keys for the really critical species.
As a step towards this vision, I have been working with John Walters on a series of guides to British and Irish carabids. These guides are deliberately beginner-friendly but they will also be valuable for experts. We believe they are the best available guides to identification for the species they cover.
These first two are available for purchase via John Walters’ website (all profits go to John):
1. Carabus, Calosoma and Cychrus (Carabini and Cychrini)
3. Cylindera and Cicindela Tiger-beetles (Cicindelinae)
The remaining guides are available for download as full-colour PDF files. These are free to download but by downloading any of these guides, you agree to let John and I know of any corrections, improvements or updates that you discover (e.g. leave a Comment below). We’ll update the guide and issue a revised version. It’s best to right-click on these links and choose to save the PDF to your computer.
4. Leistus (part of the Nebriini)
5. Nebria, Eurynebria and Pelophila (the other part of the Nebriini)
6. Notiophilus (Notiophilini): part A and part B
7. Brachinus (Brachininae), Omophron (Omophroninae), Loricera (Loricerini) and Broscus and Miscodera (Broscini)
8. Blethisa and Elaphrus (Elaphrini)
9. Pogonus (Pogonini)
10. Poecilus (Pterostichini)
11. Asaphidion (Bembidiini)
12. Odacantha (Odacanthini), Drypta (Dryptini) and Polistichus (Zuphiini) in preparation.
13. Patrobus (Patrobini)
14. Pterostichus, Stomis and Abax (the remainder of Pterostichini) in preparation.
The plan is to cover the whole of the Carabidae in 24 parts.
These identification guides are introducing English names for carabids, most of which are newly-invented though they draw on existing vernacular names where possible. As this has been a contentious and divisive issue amongst coleopterists, in the past at least, I explain myself here.
2. Corrections and clarifications to Luff’s keys.
Few have achieved the ‘holy grail’ of a key which newcomers to a group can use and get the right answers first time. Luff’s handbook is a tremendous achievement but experience has shown that users (new and old) can and do get stuck when trying to key out specimens. This crib (download PDF below) was started by Roger Key to try to solve real problems encountered by students on Roger’s carabid course at Leeds University, and has been expanded and updated to fix the problems encountered by attendees at the BENHS carabid workshops in March 2010 and March 2011, and any other problems that have come to my attention.
Download the PDF of the carabid crib: Carabid Crib v10 (2011-07-19). Version 10 includes a revised couplet for Harpalus rufipes and H. griseus (thanks Peter Hodge), a revision to the key to Agonum sensu stricto (thanks Dave Murray), a revision to the key to Bembidion subgenera (thanks Clive Washington), and an explanation of ‘pronotal epipleura’ in the key to Leistus (thanks Andrew Duff).
3. Tell us where you get stuck!
The keys should work first time. But only a first-time key-user can really judge whether the keys work first time or not! Experienced coleopterists often fail to spot the problems that would face a first-time user.
So, please ‘Comment’ below on any and all problems you find. Tell us the solution as well if you’ve worked it out, and we’ll update the crib.
4. Supplementary help
Martin Luff’s Provisional atlas of the ground beetles (Coleoptera, Carabidae) of Britain can be downloaded free here. You can see more up-to-date maps of carabid distributions on the NBN Gateway but the Atlas is not badly out of date and Martin’s text is very useful. The Atlas really helps to check whether the carabid you have just identified is common, scarce, rare or outrageous.
Some websites with good reliably-named collections of carabid photos:
Ground Beetles of Ireland (Roy Anderson’s incomparable photos of live beetles)
Udo Schmidt’s beautiful photos (Western Palaearctic species)
Watford Coleoptera Group
The Coleopterist photo gallery (including a lot of John Walters’ photos)
Carabidae of Alsace (NW France, lots of overlap with the British and Irish fauna)
Know of any others? Please let me know your recommendations.
Some detailed online identification guides:
Notiophilus (all 8 species)
Elaphrus (all 4 species)
Trechus obtusus and quadristriatus (see also here)
Bembidion tetracolum, andreae and femoratum
Pterostichus nigrita and P. rhaeticus
Amara communis and A. convexior
Amara ovata and A. similata
Amara apricaria and A. consularis
Philorhizus notatus and P. vectensis.
Online keys to the genera and species of Irish carabids:
Ground Beetles of Ireland ID Keys
Roger Key’s very useful Carabid Glossary: Carabid Glossary v1 (2010-03-01)
Good video footage of Carabus in action!
References
Lindroth, C.H. (1974) Coleoptera, Carabidae. Handbooks for the identification of British insects, volume 4, part 2. London: Royal Entomological Society.
Luff, M.L. (2007). The Carabidae (ground beetles) of Britain and Ireland. Handbooks for the identification of British insects , volume 4, part 2 (2nd edition). St Albans: Royal Entomological Society.
30 Responses “Carabidae – ground beetles”
“where there are some identification tips for Carabidae, amongst other groups.”
Do I have to register and login to be able to get this ?
How do I register ?
Mick, Thanks for your comment. A user’s 1st comment needs moderator’s (my) approval which is why it didn’t appear straight away.
I’ve fleshed out the identification info on the Carabidae page for you. Good luck!
I have trouble with Luff on P. 37 couplet 20. The distinction between a segment that is less pubescent basally, and one that is ‘clearly less pubescent than the 4th segment’ isn’t too clear. I had to look over several museum specimens, and ask advice, before I got the hang of this couplet so perhaps it could be clarified?
Luff p. 145, Amara, Couplet 2. Having found apricaria I checked it against a museum specimen for all in this subgenus. I have to say that I didn’t see a clear distinction between the angle of obliquity (is that a word?) of the pronotal keel in apricaria or consularis. They looked identical. The angle of the elytral sides seemed a much better character.
Luff p.145, Amara, couplet 2. Agreed that the ‘ridge inside pronotal hind angle’ is only very slightly less oblique in apricaria compared to consularis. There is a pore at the pronotal hind angle bearing a long seta. In apricaria that ridge reaches the base of the pronotum and the pore lies outside of the ridge, whereas in consularis that ridge is interrupted before the base by the pore. I think this is the best character to use: ID page added.
Hi,
I notice Luff uses winged and non-winged forms as a diagnostic feature in his description between Trechus obtusus and T. quadristriatus. The german website above suggests at least some specemins of T. obtusus are macropterous. Is this therefore a reliable diagnostic feature in the UK?
Chris, Although macropterous obtusus are known on the continent, I’m not aware that they have ever been found in Britain. Brachyptery in general does tend to be more prevalent towards the range edge I think. So, wing-length can be used as a diagnostic feature in Britain but I bet someone could find a macropterous obtusus if they looked hard enough!
I’m still not happy with Couplet 20 p. 37, If you take e.g. Bradycellus, the 3rd antennal segment has so much less pubescence than the 4th that you are tempted to go to couplet 22. Until I have seen more species I have tentatively pencilled in simply pubescent/glabrous to my copy!
Also there is an error on p. 148 in which the Harpalini are stated to have ‘no seta at pronotal hind angle’ but Dicheirotrichus does in fact have setae and this led me through some considerable pain before I checked up with a colleague!
Thanks Clive. I have tested p.37 Couplet 20 and found that it doesn’t really work for Bradycellus, Trichocellus or Dicheirotrichus. I have composed an alternative couplet and uploaded this within version 4 of the Carabid Crib. Also included is a correction to the statement that Harpalini lack setae at the pronotal hind angle.
Mark,
In the Carabid crib I noticed in the new couplet adjustment from MXG the couplet numbering is awry – the wording matches the key so readers can work it out and the couplet references directly above each are also correct.
cheers
Clive
Having just got my hands on a Patrobus atrorufus I have to take issue with the species description on p. 104 in which the antennomeres are described as parallel-sided. In fact they are only parallel-sided in one viewing direction and are strongly tapered if the antenna is viewed at right-angles to this. Of course sods law will control which face is displayed after they are mounted…
Page 117, couplet 9:
- the size distinction is set at 7mm, but in the text it is 6.5mm, which seems a better match to my specimens
- for Oxypselaphus, most of my specimens have both the head *and* thorax dark, with the elytra paler
- I find it hard to appreciate any darkening of the antennae in Oxypselaphus (and can’t see it on plate 95)
- the easiest distinction for this couplet seems to be something that is only mentioned in the text: Oxypselaphus has punctured striae, Paranchus has unpunctured striae
Carabid crib version 7 now deals with identification issues raised by Clive Washington and Martin Harvey (above) and by Nic Millar on the beetles-britishisles yahoo group. Thanks to all three for their help.
Hi Mark,
Carabid crib v7 page 34 couplet 2, second part says “Apex of tibia with a single large apical spur” (cf. first part of the couplet). This needs to make it clear that you are referring to the front tibia – the mid and hind tibiae of all carabids have two apical spurs I think.
Hi Mark, me again.
Carabid crib v7 page 37 couplet 19 says “elytral margin crossing the epipleuron near the apex”. This needs to reinstate the word “usually” as the elytral margin is not crossed in Pterostichus cristatus (see Luff p. 107).
Carabid crib v7 page 171. Minor typo in Bradycellus distinctus species account: Deal is in East Kent, not West.
Carabid crib v 7 page 187 couplet 7 says for Paradromius “both elytra together at least twice as long as wide”. But if you measure the width : length ratio from Plate 138 you find the length is not quite twice the width (13 : 23 mm). I suggest changing the couplet to “… nearly twice as long as wide”, vs. “… much less than twice as long as wide”.
Luff p. 182 couplet 5 says “Length at least 5 mm” for Badister dilatatus, but the species note (on p. 183) has “Length 4.5-5.4 mm”. The latter is correct according to Kevan (1955) in EMM 91: 207-210. I suggest deleting the length character from both sides of this couplet as there is simply too much overlap.
Thanks Andrew, all those comments now incorporated into Carabid Crib version 8.
Bembidion genera, p. 77 couplet 6. “Sides of pronotum rounded, hind angles not protruding” ought to have the qualifier “although a small tooth may be present at the hind angle”. It’s quite easy to misread this description to mean that the hind angle itself is rounded – which of course is not the case.
The key to Leistus on p. 46 refers to the pronotal epipleura. However this term is not explained in the Morphology section on pp. 1-4 and would be confusing to the uninitiated.
Thanks Clive and Andrew, your comments have now been dealt with in Carabid Crib version 10.
A very minor correction. Luff states that wings are absent in Bembidion tetracolum (p. 93), however I believe this species is usually brachypterous, i.e. with flight wings present but short and non-functional.
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Mark,
I’m just going through v10 to update whats been added since v9. I note alterations are in page order, would it be possible on the next update to add a version number next to the change (i.e. v11) since the last version. Users could then search text on this basis and extract the latest items without going over previous adjustments. It could be missing a trick (been a long day) and I can filter this elsewhere, apologies if so.
all the best
Clive
Clive,
Thanks, I see the problem and I will do as you recommend in v11 (which is overdue).
Hi Mark,
I wondered if you had any advice when seperating Bembidion (Bembidionetolitzkya)? I almost certainly have all three from traps placed on mid-river islands (Scotland) for the last couple of years. However I am never entirely comfortable I have keyed them out correctly. I.e. they never seem to fully fit both the key or species description in Luff.
Are there any diagnostics that might not have been included in the book?
Kind Regards
Chris
Chris, Have emailed you my ID notes. Will try to get these finished and online before too long.
As a beginner I am very thankful for these PDF guides. Would be good to see the months these beetles are around though.
Have you seen the note in Oct 09 edition of beetle news ref Anisodactylus and the colour being an unreliable way of separating poeciloides from other members of the genus?