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136
P.J. Hodge
[The Coleopterist 21(3): 136-139, December 2012]
Bruchidius imbricornis (Panzer, 1795)
(Chrysomelidae) new to the British Isles
Peter J. Hodge
8 Harvard Road, Ringmer, Lewes, East Sussex BN8 5HJ
A mature hedgerow on the eastern side of Buckingham Hill Road, Stanford-le-
Hope, South Essex, TQ671813, forming the western boundary of St Clere’s Golf
Course, was surveyed for insects on 13 May 2012. Special attention was given to
flowering hawthorn Crataegus sp. growing in the hedgerow and a small bruchid
with entirely orange antennae was picked out in the field as something unusual.
From its general form it was clearly a Bruchidius and was certainly not Bruchus
brachialis Fåhraeus which also frequently has orange antennae (Hammond &
Harvey, 2011). A similar British species, Bruchidius varius (Olivier), always has
bicoloured antennae with the elytra strongly variegated, therefore the specimen was
at once suspected to be a species new to the British fauna. Six specimens (five
males and a female) were collected over a period of about half an hour and several
more evaded capture because they flew off the sheet in the warm sunshine.
By referring to the excellent photographs on the Entomologie en Alsace web
site http://claude.schott.free.fr/Bruchidae/Bruchidae_liste_PL.html, the most likely
species was Bruchidius imbricornis (Panzer). Its host plant goat’s-rue Galega
officinalis (Schott, 2004) is an alien vetch that has become established on
brownfield sites and road verges in many places in the London district.
The site was revisited on 22 July 2012 and after a brief search a large area
covered with flowering goat’s-rue was discovered on a steep east-facing bank on
the western side of Buckingham Hill Road, TQ670810, a short distance from the
hedge where B. imbricornis was found two months previously. By sweeping the
vetch a short series of both sexes was collected.
In early August 2012 I sent a low resolution image of B. imbricornis by email
to Dr Henry Callot of Strasbourg who forwarded it to his colleague Claude Schott.
Dr Callot’s reply stated: “I received today a message from Claude Schott. He
thinks that the pictures of your Bruchidius are in excellent agreement with B.
imbricornis and that, if captured on Gallega, it must be imbricornis. On his way to
Scotland he often observed Gallega along motorways near London and wondered if
the Bruchidius was present in the UK. You confirmed his guess!”
B. imbricornis is thought to be a recent arrival in north-west Europe, for
example the earliest record for the region covered by the Société Alsacienne
d’Entomologie is 2002 (Schott, 2004). Hoffman (1945, p77) gives the distribution
of B. varius subsp. imbricornis as central and southern Europe and cites Vosges,
Jura and Alsace-Lorraine in eastern France. There are also a few recent records
from widely scattered locations in Germany.
137
Bruchidius imbricornis new to Britain
[The Coleopterist 21(3): 136-139, December 2012]
Fig. 1 Habitus of B. imbricornis: male Fig. 2 Habitus of B. imbricornis: female
Fig. 3 Habitus of B. varius: male Fig. 4 Habitus of B. varius: female
138
P.J. Hodge
[The Coleopterist 21(3): 136-139, December 2012]
B. imbricornis: Fig. 5 Aedeagus: dorsal view Fig. 6 Aedeagus: lateral view
Fig. 7 Spermatheca Fig. 8 Ovipositor
B. varius: Fig. 9 Aedeagus: dorsal view Fig. 10 Aedeagus: lateral view
Fig. 11 Spermatheca Fig. 12. Ovipositor
Identification
Five Bruchidius species are listed as British by Duff (2012): B. cisti (Fabricius), B.
olivaceus Germar and B. villosus (Fabricius) have entirely black antennae with
black elytra clothed with pubescence that is not variegated; B. incarnatus
(Boheman), an alien species occasionally imported with beans, has entirely reddish
antennae with the elytra either entirely blackish or reddish with a darker base and
suture; and B. varius, which has bicoloured antennae with a variegated pattern of
pubescence on the elytra. B. imbricornis is closest to B. varius and these two
species may separated as follows.
139
Bruchidius imbricornis new to Britain
[The Coleopterist 21(3): 136-139, December 2012]
B. imbricornis and B. varius are approximately equal in size with a body length
of 2.5-3.0 mm. Males are easily separated in the field on antennal colour but
females are more difficult to distinguish, especially if abraded. Figures 1-12 above
show habitus photos and dissected organs of both species. Table 1 below lists the
most useful external differences although some variation must be expected.
Table 1 separation of B. imbricornis and B. varius
Species Antennae Pronotum Elytra Legs
B. imbricornis
male
(Figs. 1, 5, 6)
Entirely yellow,
segments 5-11
transverse.
Pubescence
uniformly
brownish.
Obscurely patterned
with grey and
brown pubescence.
Reddish, base
of hind femora
darkened.
B. varius
male
(Figs. 3, 9, 10)
Segments 5-8
black, 1-4 and
9-11 yellowish,
5-11 quadrate.
Pubescence
white at sides
and base.
Distinctly patterned
with grey and white
pubescence.
Reddish, tarsi
and base of all
femora dark.
B. imbricornis
female
(Figs. 2, 7, 8)
Segments 5-9
dark, 1-4 and
10-11
yellowish.
Pubescence
uniformly
brownish.
Obscurely patterned
with grey and
brown pubescence.
Reddish, hind
tarsi and base
of hind femora
darkened.
B. varius
female
(Figs. 4, 11, 12)
Segments 5-10
dark, 1-4 and 11
yellowish.
Pubescence
white at sides
and base.
Distinctly patterned
with grey and white
pubescence.
Reddish, hind
femora and all
tarsi darkened.
Biology
The host plant of B. imbricornis in the Alsace region of eastern France is goat’s-rue
Galega officinalis. The larvae feed and pupate within the seed pods and emerging
adults make round exit holes in the pods as illustrated on the Société Alsacienne
d’Entomologie web site.
Acknowledgements
I would like to thank Mr Robert Lyon, landowner of St Clere’s Golf Course, for
allowing me to publish this paper, Darren Mann, Oxford University Museum of
Natural History, for providing photographs, Henry Callot and Claude Schott of the
Société Alsacienne d’Entomologie, France for their helpful discussion and Andreas
Herrmann and Frank Köhler for advice on the status of B. imbricornis in Germany.
References
DUFF, A.G. (Ed.) 2012. Checklist of Beetles of the British Isles, 2nd Edition. Iver:
Pemberley Books (Publishing).
HAMMOND, P. & HARVEY, P. 2011. The exotic seed beetle Bruchus brachialis Fåhraeus
(Coleoptera: Chrysomelidae: Bruchinae) established in South Essex. Essex Naturalist
(New Series) 28: 29-33.
HOFFMANN, A. 1945. Coléoptères Bruchides et Anthribides. Faune de France 44: 1-184.
SCHOTT, C. 2004. Catalogue et Atlas des Coleopteres d’Alsace, Tome 14: Bruchidae,
Urodontidae, Anthribidae. Strasbourg: Société Alsacienne d’Entomologie.
