The montane butterflies of the eastern Afrotropics - Biogeography and Ecology of the Rain Forests of Eastern Africa - page 157

Tanganyika and the west side of Lake Mobuto.
Of the 30 species resricted to this combined area
12 occur in one area only, mainly in the Kivu area
(9). Thus 18 species are found in two or three
areas, most of which (11) occur in all three areas.
These igures illusrate the srong coherence of
these areas and at the same ime show the import-
ant posiion of the Kivu area to which not only
30% of the endemics of the Westen Border
Range are restricted but where only three
endemics of this combined area are missing. It is
not clear why there are many more endemics in
the Kivu area than in Rwenzori, unless the former
offers better opportuniies for speciaion by geo-
graphic isolaion, being more extensive and with
more mountain tops.
Not surprisingly, there are connecions
between the Westen Border Region and the
Mount Elgon/west Kenya area, four species being
exclusively disributed in both areas. All these
species occur in the Kivu area. Similarly there are
two species that only occur in west Tanzania and
the Westen Border Range. In view of the large
number of species and the high endemicity in the
Westen Border Range, the exclusive connecions
to the northeast and to the southeast must be
regarded the result of range epansion rather than
the combinaions Westen Border Range/west
Tanzania or Westen Border Range/west Kenya
ever having been single areas of speciaion.

exclusively in all three areas, so there is little
reason for combining the three. Also any of the
three possible combinaions of two of the three
areas is not significant. The combinaion cenral
Kenya/west Kenya, for instance, would be
characterised by two out of the 10 endemics
found in the two areas (i.e. eight are confined to
one area only), the combinaion cenral
Kenya/north Tanzania by one out of nine. How
could we (and why should we) select one of these
combinaions?
Summarising, as far as we can speak of patten
here the ollowing patten emerges. In EAT there
are 259 taxa (177 species) resricted to highland
forest. Of these, 255 (157 species) do not occur
outside EAT. The endemics are not uniformly
distributed: 106 (64 species) are found in one of
the iniially recognised areas of endemism with
highest concenraions in the Usambara Moun-
tains (15, 12), Nguru (8, 7), Uluguru (10, 8),
Uzungwa (8, 8) and Kivu area (12, 9). There are
seven potenial areas of endemism without
endemics even at the subspecies level (10, if we
only consider the species level). Although they
can no longer be considered areas of endemism
most of them can be combined with other areas
into larger areas of endemism. There are no
endemic species that occur in more than 1 9 areas,
and only nine occur in more than 10 areas. Thus,
the mountains in EAT as a whole cannot be con-
sidered an area of endemism. Combinaion of
areas into larger areas of endemism (i.e. charac-
terised by endemics occurring in all subareas)
yields two larger areas with high concentraions of
endemics, namely, the Easten Arc mountains
and the Westen Border Range. Other combina-
ions are of minor importance as far as endemism
is concened, and seem to consist mainly of rather
loose sets of individual mountains.

(c) The six remaining combined areas of Table
8.5 have few endemics only and cannot be con-
sidered important cenres of diversificaion. Two
of the combined areas, west Tanzania (consising
of the areas Ufipa, Mpanda and Kigoma), and
Malawi (with Nyika Plateau, Zomba and Mlanje),
have been disinguished only or the sake of con-
venience; they lack characterising species (i.e.
endemics that occur in all subareas). Further
north there is more coherence although also there
the numbers of endemics are low. Ethiopia, with
four endemics and six widespread species, stands
slightly apart since it cannot be combined with any
paricular area. The remaining three combined
areas, west Kenya, central Kenya and north
Tanzania, share 40% of their species, but only
one species, Papilio

Eeal geographic connetions

The connecions with areas outside EAT are dif-
ferent from those found in the grassland
butterflies.

Oiental conneaion
In contrast to the grassland butterflies, the forest ch rapkowskii, occurs