The Palaearctic region includes both
temperate
and cold parts of Eurasia and North Africa, and several archipelagos and islands in the Atlantic
and Pacific oceans. There are a number of different views concerning the position of the
southern border of this region (Semenov-Tien-Shansky 1936, Emel'anov 1974, Kryzhanovsky
1983, Lopatin 1989). In our guide we have followed the
definition of Lopatin (1989). Accordingly, the Palearctic region does not include the southern
part of the Arabian peninsula. On the south eastern side of the Palearctic, the border runs along
the northern edge of the subtropical forests. The southern Japanese islands (Shikoku, Kyushu
and south part of Honshu) belong to the Oriental region. These boundaries correspond to the
floristic realms recognized by Walter and Breckle (1985). At the same time, we acknowledge
that the border between the Palearctic and Oriental regions is a wide transition zone, where
Palearctic and Oriental faunistic complexes mix together.
The Palearctic flea beetle fauna consists of more than 1,000 species classified in 59 genera (Table 1). The genera can be separated into several groups based
on their presumed center of origin. The
"true Palearctic" group consists of genera which are exclusively Palearctic (Anthobiodes,
Apteropeda, Arrhenocoela, Mniophila, Novofoudrasia, Oedionychis (s.str.), Orestia,
and probably Ochrosis), or which have only a few additional species in the Oriental
region (Batophila, Lythraria, Minota ).
Another group can be termed "true Oriental genera" based on the distribution of their species
(Aphthonaltica, Aphthonoides, Argopus, Clitea, Horaia, Lipromima, Liprus, Manobia,
Meishania, Nonarthra, Ogloblinia, Omeisphaera, Ophrida, Pentamesa,
Podagricomela, Podontia, Sangariola, Sinaltica, Trachyaphthona, Xuthea, Zipangia). Two of
these genera also occur in Australia (Manobia, Podontia). A few species of these genera
penetrate the Palearctic (at the southern end of the Far East).
The next group consists of cosmopolitan genera: Altica, Aphthona, Chaetocnema, Epitrix,
Longitarsus, Neocrepidodera, Phyllotreta, Psylliodes. Most flea beetle species in the
Palearctic belong to these genera. However, future revision of generic criteria in Alticinae may
result in splitting of these larger taxa. Epithrix is predominantly Neotropical, while other
genera in this group are well diversified in the Palearctic.
The next group consists of cosmopolitan genera: Altica, Aphthona, Chaetocnema, Epitrix,
Longitarsus, Neocrepidodera, Phyllotreta, Psylliodes. Most flea beetle species in the
Palearctic belong to these genera. However, future revision of generic criteria in Alticinae may
result in splitting of these larger taxa. Epithrix is predominantly Neotropical, while other
genera in this group are well diversified in the Palearctic.
Some genera are nearly cosmopolitan in distribution. This category is
composed of an artificial assortment of different genera, and it
is possible that more precise distributional data will cause some
of them to be shifted to other groups. Dibolia, Argopistes,
Blepharida and Mantura are distributed everywhere except
Australia. Sphaeroderma and Philopona are distributed everywhere
except the New World. Crepidodera is known from all the regions
except the Afrotropical.
Several genera range throughout Eurasia and Africa, with the greatest
diversity of species in the tropics of both continents (Phygasia,
Luperomorpha, Hespera, Podagrica, Hermaeophaga, Hemipyxis,
Hyphasis).
Hippuriphila has a typical holarctic distribution, but is known mostly
from the temperate parts of both continents.
The distribution of Derocrepis is rather unusual for Palearctic genera. In addition
to the Palearctic it is also known from Africa and
North America. However, the African and American members of this
genus need to be verified.
Table 1 also shows that the majority of flea beetle
species are
contained in just a few larger genera (Altica, Aphthona,
Chaetocnema, Longitarsus, Phyllotreta, Psylliodes). Some genera
are monotypic (Lythraria, Novofoudrasia, Ochrosis). Most genera
contain from 1 to 15 named species. The majority of genera
containing only a few species are known from the Far East and have
their center of greatest diversity in the Oriental region.
The Palearctic fauna is notably impoverished compared with that of the
Oriental or Neotropical regions, possibly due to late tertiary
aridization and quaternary glaciation. The major centers of
species diversity are situated to the south of the Palearctic.
Theoretically it is possible to recognize five different centers
of speciation: Western (Mediterranean sensu stricto), Caucasian,
Middle Eastern, Middle Asian and East Asian (Lopatin 1989).
The fauna of Eastern Asia is especially rich due to immigration from
Southern Asia. The other centers are enriched through local
speciation, resulting in an increased number of local endemics.
The ranges of most Palearctic flea beetle species do not exceed
the borders of that region. However, some species are found in
the northern Oriental region, in Africa and especially in North
America (some of them might be the result of introductions). A
comparatively small number of species have a transpalearctic
range. The majority of species are contained within the borders of
the Palearctic subdivisions (Euro-Siberian, Iranian-Turanian
(sensu Emel'anov 1974), and East Asian). In summary, it would
appear that the present-day diversity of the Palearctic flea
beetle fauna can be explained through immigration from Asia,
Middle East and Africa, combined with local speciation under the
influence of tertiary aridization and quaternary glaciation.
