Abstract:
The Eastern Arc Mountains (EAM) consist of 13
separate mountain blocks running from southern Kenya
through eastern Tanzania in an arc shape. Organisms occurring
in the forests of these mountains are known for their high
levels of endemism. Some of these organisms have their
closest relatives in distant geographic regions. In this study,
molecular phylogenetic methods, based on partial sequences
of one nuclear (28S) and two mitochondrial (COI and 16S)
genes, are used to determine the relationships of three
Scarabaeinae genera (tribe Canthonini) endemic to the
EAM. Janssensantus and Tanzanolus are found to have a
sister relationship within a lineage of south-eastern African
genera, while Madaphacosoma’s closest ties are with Oriental
and Madagascan taxa Ochicanthon and Epactoides, respectively.
Divergence time estimates suggest a Miocene origin for
the ancestral lineages of the three genera with Janssensantus
and Tanzanolus separating in the Pleistocene. Our results
provide evidence for a Madagascan origin for the EAM
genera.
