Abstract:
1. Circellium bacchus is South Africa’s largest ball-rolling dung beetle and a habitat specialist of dense
bush. It is also wingless, a rare phenomenon amongst large dung beetles and, unusual for the group, only
females construct and bury brood balls. She cares for the single brood for 4-5 months, and lives for 3-5
years.
2. The beetles currently occur in two separate populations in South Africa, one in the south-east and one
consisting of at least 8 fragmented sub-populations in the south-west. Here we use both mitochondrial and
nuclear DNA sequences to infer the evolutionary history of this species.
3. The Eastern and Western populations are genetically separated by 14% mitochondrial sequence
divergence, sharing only a single nuclear haplotype. Mitochondrial and nuclear data indicate that C.
bacchus belongs to an ancient (Eocene) relict lineage and that the Eastern and Western populations appear
to have been separated by Pliocene continental uplift and a relictual Pleistocene block of temperate forest.
Subsequent Plio-Pleistocene climatic change caused further fragmentation of the Western Population, now exacerbated by human-induced land transformation.
4. The Eastern and Western populations are identifiable as two distinctly separate entities of possible
species status but with definite need for recognition as evolutionary significant units. The Western subpopulations
are genetically significantly different enough to be defined and recognised as management
units. The Eastern population is largely distributed in the Addo Elephant National Park where its
persistence is currently secure, but the sub-populations of the Western lineage occur as fragments of
various sizes in a matrix of agriculturally transformed landscape.
