Biogeography of East African montane forest millipedes - Biogeography and Ecology of the Rain Forests of Eastern Africa - page 103

6 Biogeography of East African
montane forest millipedes

RICHARD L. HOFFMAN

forests are biogeographically related to the fauna
of the Congo and West African rain forests and
thus relictual from previous transconinental
sylvan habitats.

Abstract

Knowledge of the montane diplopod fauna of
East Africa dates back only to the collecions
made by Sjoestedt on Mount Kilimanjaro in
1905-6 and described by Attems in 1909. Little
was added to that beginning unil the onset of
exploraions since about 1964 by personnel from
the universiies of Dar es Salaam and Copen-
hagen. Since the great majority of species dis-
covered in the Tanzanian Easten Arc mountains
are undescribed endemics, it is not possible to
present a comprehensive chorographic analysis.
Only the species of Oxydesmidae have been
worked out (Hoffm an, 1990) for the enire region,
and of the various geographic units only the fauna
of the East Usambaras is at all well known.
Nonetheless it is possible to indicate some
generaliies of interest: (i) with fe w excepions
most of the genera occurring in these mountains
are endemic, so that lines of affinity with other
regions must be sought at the level of ribe or
higher; (ii) in most cases such genera appear to be
the result of local derivaion from formerly wide-
spread ancesral stocks; (iii) the postglacial con-
densation of montane forest to higher mountains
surrounded by seasonally arid savanna or scrub
forest has resulted in profuse local speciaion on
individual ranges or close clusters, involving, so
ar as can be deduced, both symparic and
allopatric isolaing mechanisms. These constella-
ions of local species may thus be classified as
neoendemics in the East African fauna.
In the few groups of Diplopoda so far studied
in any detail, the taxa of the Tanzanian montane

Introduction

Species of the class Diplopoda, and paricularly
those of the polydesmoid family Oxydesmidae,
exhibit an astonishing display of endemism and
local insular speciaion in the Tanzanian moun-
tain ranges considered in this volume. Perhaps no
other group of organisms has responded to the
effects of fragmentaion and isolaion to the extent
revealed by recent studies.
Regrettably, as will become evident, knowledge
of these phenomena has only now reached a
threshold level, and for the most part has
accumulated only during the past two decades.
Owing to the paucity of interested specialists, the
collecion of fresh material has far outpaced the
rate of taxonomic analysis. Present informaion
permits only a tantalising glimpse of an iceberg
ip, a shadowy percepion of what awaits revela-
ion as both field and laboratory studies proceed.
Although the first millipedes endemic to the
montane forests of East Africa were collected as
long ago as the 1890s, the irst real contribuion of
our knowledge of that fauna was made in 1909,
when Graf Carl Attems published the results of
his study of material collected by Y nge Sjoestedt
on Mount Kilimanjaro, totalling 19 species. In the
following decades a few other species were des-
cribed from the East Usambaras, the Ulugurus,
and the Uzungwas, but no real impetus was

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