by Mark G. Telfer incorporating a major contribution from Steve A. Lane
With about 291 species on the British and Irish list, the seed and leaf beetles form the fourth biggest group of beetles (after Staphylinidae with c.1,132, weevils with c.635 and Carabidae with c.372 species). The group includes many of the most striking and beautiful beetles to be found in Britain but also some of the most difficult identification challenges. I think it is fair to say that seed and leaf beetles have not been as popular with British coleopterists as you might think, certainly in comparison to the carabids. I’ve shied away from them to an extent just because there have been some genera (Longitarsus, Chaetocnema, Galerucella and Altica in particular) that I’ve found very hard to identify with any confidence. But for those who want to identify British and Irish seed and leaf beetles, things have recently got a whole lot better with the publication of Dave Hubble’s AIDGAP guide: an essential purchase.
The other major leap forward of recent years has been the excellent Atlas of the Seed and Leaf Beetles of Britain and Ireland by Mike Cox published in 2007. It is another essential purchase, available from the all the usual booksellers. In writing the text for this atlas, Mike Cox committed a vast amount of information to paper, more than could be published in the Atlas without turning it into a very expensive publication. So the overflow was made available as an electronic document and can be downloaded here (click on supplementary material).
It is only within the last decade or so that British coleopterists have recognised the two small families Megalopodidae and Orsodacnidae. Both were formerly included within the Chrysomelidae, and in those simpler times one could just refer to “the chrysomelids” and everyone would know what you meant. Here, I’m going to use “seed and leaf beetles” to mean the members of the three families Chrysomelidae, Megalopodidae and Orsodacnidae. Megalopodidae includes one genus (Zeugophora) with three species. Orsodacnidae includes one genus (Orsodacne) with two species. To the human eye, neither Zeugophora nor Orsodacne look especially unusual compared to the remaining Chrysomelidae, whereas the subfamilies Bruchinae (seed beetles) and Cassidinae (tortoise beetles) are both visually very distinctive groups (and were both formerly regarded as separate families in their own right, e.g. by Joy (1932)).
There is a national recording scheme for seed and leaf beetles organised by Dave Hubble under the wing of the Biological Records Centre: contact details here. See also the page on Dave’s website here which includes a very useful bibliography of key works on seed and leaf beetles.
Dave Hubble’s (2012) AIDGAP “Keys to the adults of seed and leaf beetles of Britain and Ireland” is the best single publication on the group. Using Hubble (2012) as the starting point, this webpage aims to highlight any problems and provide additional help. There is a danger that this webpage is going to look like a catalogue of criticisms of Dave’s keys but more than anything, Dave is to be praised for filling an important gap in British beetle literature, and for not allowing the vain quest for perfection to hold things up.
Lech Borowiec’s website on the Chrysomelidae of Europe and the Mediterranean is an extremely useful library of images of carded beetles and with many aedeagi photographs.
A general issue
Many of the drawings in Hubble (2012) are curiously out of proportion, having been squashed in the vertical plane or stretched in the horizontal plane. On most, the elytra should be half as elongate again to nearly twice as elongate. For example, compare the photo of the tortoise beetle Cassida nebulosa below with the illustration from Hubble. Other examples include: p24 Fig. 16 (Donaciinae figure), p41 Fig. 90, p51 Fig. 128, p64 Fig. 171, p103 Fig. 315, p104 Fig. 322, p112 Fig. 357, p113 Figs 361 and 362 and p114 Fig. 365.
Subfamilies Bruchinae and Amblycerinae Seed Beetles (Hubble pp. 27 – 34)
This excellent paper by Mike Cox (2001) is still well worth referring to:
- Cox, M.L. (2001). Notes on the natural history, distribution and identification of seed beetles (Bruchidae) of Britain and Ireland. The Coleopterist, 9, 113 – 147.
Note that Bruchus brachialis has been added to the British list since Cox (2001) but in time to be included by Hubble. However, for identification of Peter Hodge’s latest addition to the British list, see the following paper:
- Hodge, P.J. (2013). Bruchidius imbricornis Panzer, 1795) (Chrysomelidae) new to the British Isles. The Coleopterist, 21, 136 – 139.
Subfamily Donaciinae (Hubble pp. 35 – 41)
Photographs of the pronota of Plateumaris discolor and P. sericea would be useful to show the usually distinctive differences in the nature of the central furrow and the degree of adjacent wrinkling towards the front of the pronotum.
For a more detailed identification guide to all the British “reed beetles” (Donaciinae: Donacia (15 spp), Plateumaris (4 spp) and Macroplea (2 spp)) with colour photos of 16 of the species, see this paper:
- Menzies, I.S. and Cox, M.L. (1996). Notes on the natural history, distribution and identification of British reed beetles. Journal of British entomology and natural history, 9, 137 – 162. [Available as a scan from the Biodiversity Heritage Library and should also be available as a colour reprint from the BENHS]
Oulema melanopus and rufocyanea (Hubble p. 42)
This pair of species can only be identified by dissection and were not recognised as distinct until Mike Cox’s publication in 1995. Unless you are already familiar with the male and female genitalia of this pair, Hubble’s illustrations (Figs 93 – 96) are likely to leave you baffled, so reference to the original paper is advised.
- Cox, M.L. (1995). Identification of the Oulema ‘melanopus’ species group (Chrysomelidae). The Coleopterist, 4, 33 – 36.
And BEWARE: part of the text in Hubble’s couplet 2 is transposed. In the first part of the couplet, where it reads “short, its length approximately the same as”, that should read “long, clearly longer than”. And vice versa for the second part of the couplet.
Genus Chrysolina (Hubble pp. 54 – 57)
Couplet 11 does not really work. It depends on the interpretation of colour which is too subjective and ambiguous to reliably separate the species concerned. Chrysolina hyperici should be a fairly simple species to key out as it has highly characteristic and diagnostic elytral puncturation which is even evident in the field to the naked eye and can, with practice, be used to identify the species straight away. No other Chrysolina species exhibits elytral puncturation like this. However, to run Chrysolina hyperici through Hubble requires a very difficult, if not impossible, decision to be made as to whether or not it is “conspicuously dark”.
The distinguishing features between Chrysolina brunsvicensis and C. hyperici are stated to be the overall depth of colour and features of the pronotum. In reality, C. hyperici is most easily distinguished from C. brunsvicensis on the elytral puncturation. In C. hyperici, this consists of two paired series of crater-like punctures that run down the elytra between the shoulder and the suture (there is a single smaller row adjacent to the suture). These punctures can be seen to display a metallic field around their rims under magnification (x20 upwards). Between these rows are micro-punctures. The crater-like punctures are around 50 times larger than the micro-punctures. In C. brunsvicensis, there are still two paired series of larger punctures running lengthways along the elytral disc, but these are very much smaller than those of C. hyperici, perhaps only 5-10 times larger than the micropunctures that are also present in this species. Colour is probably reliable as a first indication in the field of which species is present. C. brunsvicensis has a much warmer often coppery-tinged hue, but this observation can only come from experience and comparison.
Chrysolina varians can occasionally exhibit bicolouration where the central area of the pronotum and the elytra are the same colour but the margins of the pronotum are a different metallic colour (e.g. centre of pronotum and elytra pinkish-copper and edges of pronotum bronze). A characteristic which this species shares with a few others in the genus but which might be useful in distinguishing it from C. brunsvicensis (which occurs on the same host plant (Hypericum)) is that it lacks the partially elevated pronotal side margins which are marked at the pronotal base by strong linear furrows.
Chrysolina herbacea and C. graminis. The difference given by Hubble is potentially unreliable and should only be used with caution to distinguish these species. Better characters are those referred to in Oxford et al. (2003). In C. graminis the puncturation on the elytra is coarse, giving the surface a distinctly pitted appearance which obviously differs from the finely punctured thorax. In C. herbacea these two areas are similarly strongly punctured and pitted. Also, in C. graminis there is a smooth lip running the entire length of the lateral margin of the elytra. In C. herbacea this lip is present only along the anterior half of the elytral margin.
- Oxford, G., Sivell, D., Dytham, C. and Key, R. (2003) The jewel of York – ecology and conservation of the Tansy Beetle. British Wildlife, June 2003.
Tribe Galerucini (Hubble’s Key Ha, pp. 64 – 66)
Couplet 3: note that in Galerucella nymphaeae/sagittariae, the 4th hind tarsal segment appears to be as long as the first, and size may reach 8.0 mm. So the second part of this couplet should read: “4th hind tarsal segment longer than, or as long as, the first. 3.0 – 8.0 mm.” It would be better to look at photos of the two Galeruca species: Galeruca tanaceti and Galeruca laticollis.
Couplet 6: The three species of Lochmaeae should key out via the second part of this couplet but many specimens will fail to do so, either because their colouration is not “yellowish, brownish or greyish” or because they do have “dark spots or lines”. A replacement for the second part of this couplet might read: “Elytra yellowish, brownish, greyish, orange, red-brown or blackish-brown. Elytra plain OR with a dark sutural line OR with small, indistinct markings OR with one or two black stripes or elongated spots. 3.0 – 7.0 mm.” As this would turn it into a horrible and confusing couplet, it might be better just to look at photos of the two distinctive species which key out via the first part of the couplet: Phyllobrotica quadrimaculata and Diabrotica virgifera.
Genus Galerucella (Hubble pp. 68 – 69)
A very difficult genus though only comprising six species. Steve Lane considers that this key does not work in its present form and would probably lead to misidentifications. Steve has written a new key to these species which will appear on Richard Wright’s CD-ROM guide to British beetles in due course. Until then, it’s a case of building your own reference collection of dissected specimens (or using a reliable museum collection) and collating other useful references:
- Hincks, W.D. (1950). The British species of the genera Pyrrhalta Joannis and Galerucella Crotch (Col., Chrysomelidae). Journal of the Society for British Entomology, 3, 150 – 156. [Illustrates the aedeagi of all species. Illustrates the female’s last abdominal sternite of five species but frustratingly there is no legend to ascribe two of the five illustrations to a species!]
- Mohr, K-H. (1966). Familie: Chrysomelidae. Pp. 95 – 280 in Freude, H., Harde, K.W. and Lohse, G.A. (eds). Die Käfer Mitteleuropas, Band 9. Cerambycidae, Chrysomelidae. Krefeld: Goecke & Evers. [Includes different and rather less good illustrations of the aedeagi of all British species on pp. 194 and 196.]
Genus Altica (Hubble pp. 80 – 82)
As Hubble notes, “reliable identification of Altica species requires dissection of males and careful examination of the aedeagus”. This statement particularly applies to oleracea, carinthiaca, helianthemi and palustris which should probably only ever be identified by dissection and study of the aedeagus, although with practice and with a reliable reference collection it should be possible to separate out typical helianthemi without dissection. This is a very difficult genus and to learn them it would be prudent to form a reference collection of dissected specimens and to get hold of copies of the other identification works mentioned here. Note that the aedeagus illustrations in Hubble are all more or less distorted.
- Kangas E. and Rutanen, I. (1993). Identification of females of the Finnish species of Altica Müller (Coleoptera, Chrysomelidae). Entomologica Fennica, 4, 115 – 129. [A potentially very useful approach to identification but sadly the paper is missing two species that occur in Britain: brevicollis and helianthemi. Present in the BENHS library.]
- Kevan, D.K. (1963). The British species of the genus Haltica Geoffroy (Col., Chrysomelidae). Entomologist’s monthly magazine, 98 (for 1962), 189 – 196. [This is still an essential reference but note that carinthiaca has been added to the British list since, and also that Kevan treats ericeti and britteni as distinct species, now lumped together under the name longicollis. Also note that “Haltica” is the old name for Altica.]
- Mohr, K-H. (1966). Familie: Chrysomelidae. Pp. 95 – 280 in Freude, H., Harde, K.W. and Lohse, G.A. (eds). Die Käfer Mitteleuropas, Band 9. Cerambycidae, Chrysomelidae. Krefeld: Goecke & Evers. [Includes fine illustrations of the aedeagi of all British species on pp. 232 and 234. Note again that this publication uses Haltica rather than Altica.]
- Photographs of all British Altica species, including photographs of the aedeagi can be viewed on Lech Borowiec’s site.
Altica brevicollis. Steve Lane comments that the character of small bumps and bulges on the elytra used in the couplet separating brevicollis and lythri is hard to appreciate if present at all. Separation of this pair has since been covered in some detail by Lane (2013):
- Lane, S.A. (2013). A history of Altica brevicollis Foudras (Chrysomelidae) in Warwickshire (VC 38) with notes in identification. The Coleopterist, 21, 109 – 111.
Genus Longitarsus (Hubble pp. 86 – 101)
The key to Longitarsus is a revolutionary improvement over anything previously available for the largest and most difficult chrysomelid genus, largely thanks I believe to Steve Lane’s input to the keys during the AIDGAP testing process. Hubble prefaces his key with some words of warning which should be heeded: excellent though it is, this is still a key which is best used to help identify specimens alongside a reference collection.
A couple of specific comments on the Longitarsus key:
- The sutural stripe in Longitarsus curtus is extremely narrow and can often be very hard to detect. In fact, to key it out, one must choose “without a clearly defined and contrasting sutural stripe” at couplet 16. So, if you manage to reach couplet 46 with a specimen of L. curtus, rely on size to distinguish it from exoletus rather than the presence or absence of a sutural stripe.
- Figures of the spermathecae would be useful for some of the Longitarsus species where the differences in aedeagi between species in a couplet are more subtle and comparative than the differences between spermathecae, e.g. Longitarsus pratensis and reichei.
There’s quite a lot more that could be said to make Hubble’s Longitarsus key easier and more reliable to use, and I’ll try to work on this in the coming months. Actually, the concise format of the AIDGAP guides is basically just never going to give enough room to cover the identification of Longitarsus properly. What this genus really needs is a detailed identification paper with plenty of photographs and illustrations to show the full range of variation in each species. Anyone?
One species of Longitarsus has been added to the British list since Hubble (2012): L. minusculus, added by Cox and Duff (2013). It resembles a small L. luridus and has been added on the basis of two specimens, both from chalk grassland in Dorset. Cox, M.L. and Duff, A.G. (2013). Longitarsus minusculus (Foudras, 1860) (Chrysomelidae) new to the British Isles. The Coleopterist, 22, 55 – 61.
The following paper was the best thing for identifying Longitarsus before Hubble (2012) was published and is still well worth referring to:
- Kevan, D.K. (1967). The British species of the genus Longitarsus Latreille (Col., Chrysomelidae). Entomologist’s monthly magazine, 103, 83 – 110. [A valuable set of genitalia and front tarsus illustrations of all British species, if rather stylised. Note that obliteratoides, flavicornis and symphyti have been added to the British list since Kevan’s paper, and that Longitarsus bearei Kevan, 1967 has been synonymised with L. pratensis. The great conundrum of this paper was always how to distinguish between Sections II and Sections IV/V when Kevan describes them almost identically! It hardly matters any more now that Hubble (2012) has superseded it, but there is an answer: Kevan’s Section II is a clumsy amalgamation of the Sections III and V of Tomlin and Sharp (1911-12: Ent. mon. Mag) in which it all makes a lot more sense!]
Genus Sphaeroderma (Hubble p. 110)
The illustrations of the whole beetles (Fig. 350) and their pronota (Fig. 351) are mis-shapen and very misleading, though the text is fine, relying as it does on the very useful and reliable pronotal puncturation as the primary character. The pronotum of Sphaeroderma testaceum is significantly less transverse than that of rubidum. The pronotal diagram of rubidum is fairly accurate, but the one of testaceum is too transverse and the side margins should be longer relative to the hind margin. Although it is hard to put the shapes of the respective pronota into words, the difference in this character is quite distinct and easily appreciated when the two species are observed side by side.
Subfamily Cassidinae Tortoise Beetles (Hubble pp. 110 -114)
For an excellent overview of the species in this sub family, see this tortoise beetle gallery on flickr.
At couplet 7, Hubble goes to great lengths to separate Cassida vittata and C. nobilis. This is a difficult pair of species to separate with dried, carded specimens but they are easily distinguished by looking at the underside, a feature which I have tested on several specimens on both species and have not found any exceptions. Black markings are much more extensive on the abdomen and hind femora of nobilis compared to vittata. On the upperside, the metallic stripes on the elytra are much narrower on nobilis, mostly restricted to the 3rd interval and base of 2nd (often also with a trace of a stripe on the 7th interval too); vittata typically has a stripe covering the 3rd and 4th intervals and parts of the 2nd and 5th at the base, and also tending to a more emerald green colour than the golden-green of nobilis. The metallic stripes vanish soon after death.
Some of the Cassida species have extraordinary spermathecae: I have a photocopy of an excellent set of illustrations but I don’t know where they came from [can anyone help?]. They are worth dissecting in cases of doubt over the identification, especially so for females.
Acknowledgements and a request for help
I owe a great debt of thanks to Steve Lane for his input to this page. I would also like to thank Malcolm Storey and Caroline Uff. If you would like to share information that would make the identification of seed and leaf beetles easier for everyone, please let me know and I will add it to this page and make sure you get the credit for it. Thanks!