The aim of this study was to use cytochrome c oxidase 1 (CO1) sequences to recover a phylogeny
for seven morphologically described spirostreptid millipede taxa from southern Africa, and to evaluate
the correspondence between morphological and molecular phylogenies. Genetic p-distance generally
increased with taxonomic divergence: inter-specific mean 15.33 % (14.09 %–17.02 %), inter-generic mean
18.43 % (6.83 %–26.81 %) and inter-order mean 24.16 % (range 18.56 %–30.77 %). Congruent Bayesian,
maximum parsimony and neighbour-joining analyses of 520 nucleotides of the CO1 gene resolved the orders
Spirostreptida, Julida and Callipodida. Members of genera within the Spirostreptidae (Archispirostreptus,
Bicoxidens, Cacuminostreptus, Doratogonus, Orthoporoides, Plagiotaphrus and Spirostreptus) formed a
single clade within which a sample of Thyropygus (family Harpagophoridae) was paraphyletically nested.
Phylogenetic analyses failed to recover support for the genera Doratogonus, Bicoxidens, Archispirostreptus
and Spirostreptus, as representatives of these genera were not monophyletic. Samples morphologically
identified as the same species (Bicoxidens flavicollis) were part of two different clades, one of which was well
supported and otherwise contained members of Doratogonus. This high level of divergence (mean 12.64 %)
between morphologically identified spirostreptid millipede sister species could indicate that changes in
genital morphology occur rather slowly relative to CO1 sequence substitution, and may underestimate
species diversity.
