A review of the scarce and threatened Coleoptera of Great Britain. Part 3: Water beetles
Three hundred and eleven taxa were assessed for this review of water beetles of Great Britain.
Jäch & Balke (2008) estimate that there are currently
about 18,000 species of water beetle of which 70% have been
described. About thirty families have aquatic representatives, with
25 of them having at least half of them aquatic. The estimates for
the dominant families are, from October 2005, Dytiscidae with 3,908
species, 5,000 being estimated, Hydraenidae (1,380/2,500),
Hydrophilidae (1,800/2,320), Elmidae (1,330/1,850), Scirtidae
(900/1,700) and Gyrinidae (750/1,000). The Palaearctic (3,350 named
as opposed to 3,900 estimated), the Neotropical (2,510/3,900) and
the Afrotropical (2,700/3,750) regions have the most species,
followed by the Oriental (2,200/3,580) and the Australasian
(1,300/2,100), the Nearctic (1,420/1,550) being by far the poorest
in terms of diversity.
The first step is to identify what is included in the term
“water beetle” for the purposes of this review. Many species of
beetle are obligately associated with water with a continuum from
those that are found throughout their life-cycle under water (reed
beetles in the genus Macroplea and a few
weevils), through the majority, i.e. those that pupate out of the
water but are aquatic as both larvae and adults, and on to those
that live in the water as larvae but are found above and away from
the water as adults. The latter include the Scirtidae, many
plant-feeding species, in particularly most of the reed beetles or
Donaciinae. The current review is concerned with the Hydradephaga
(that is the aquatic members of the suborder Adephaga, the
Gyrinidae, Haliplidae, Noteridae, Paelobiidae and Dytiscidae), with
our sole representative of the suborder Myxophaga (Sphaerius
acaroides), and with several families of Polyphaga (the
Hydrochidae, Helophoridae, Georissidae, Spercheidae, the aquatic
Hydrophilidae, Hydraenidae, Heteroceridae, Dryopidae, Elmidae,
Psephenidae, Limnichidae and the Scirtidae).
The status of leaf beetles and weevils will
not be considered further here, being best addressed for these as
part of an overall review of Chrysomeloidea and Curculionoidea.
Further, the many moisture-loving ground and rove beetles should
also be reviewed as part of their major phylogenetic groups. There
will always be inconsistencies in combining the ecological and
phylogenetic approaches, but the groups covered here have the
virtue of being part covered by a single national recording scheme.
Another peculiar exception is the exotic and largely aquatic family
Ptilodactylidae, represented in Britain by a species confined to
moist soils in greenhouses (Mann 2006).
Three hundred and eleven taxa were assessed
for this Review, four of them regarded as subspecies
(Nebrioporus depressus depressus and N. depressus
elegans, and Ochthebius viridis viridis and
O. viridis fallaciosus), the rest as species.
The area covered in this Review is Great Britain
(i.e. England, Scotland and Wales, excluding the Isle of Man and
the Channel Isles). Northern Ireland and the Republic of Ireland
have produced a joint Red List of water beetles for the whole of
Ireland (Foster, Nelson & O Connor 2009).
You will need the free Adobe Acrobat Reader to view this
Soft back, A4, 142pp.
Please cite as: Garth N. Foster, (August 2010), A review of the scarce and threatened Coleoptera of Great Britain. Part 3: Water beetles, Soft back, A4, 142pp., ISSN 1473-0154