Phylogeny of African long-fingered frogs (Arthroleptidae: Cardioglossa) reveals recent allopatric divergences in coloration

The African anuran genus Cardioglossa contains 19 described species, most
of which are distinguished from one another by striking patterns and
colors. We present a well- resolved phylogeny based on analyses of
mitochondrial and nuclear loci for 18 species of Cardioglossa. This
provides the basis for species-delimitation analyses and interpreting
historical biogeography in the genus. Whereas much of the diversification
within the genus occurred among Central African lineages during the
Miocene following the origin of Cardioglossa in the latest Oligocene or
earliest Miocene, most species-pairs in the genus diverged more recently
during the Plio-Pleistocene. The two most geographically peripheral
species— C. cyaneospila in the Albertine Rift Mountains and C.
occidentalis in the Upper Guinean Forests of West Africa—both diverged
from other lineages during the mid-late Miocene. Because our analyses do
not support C. manengouba and C. oreas as distinct species, we recognize
these geographically separate and phenotypically distinct populations as
subspecies of C. oreas that diverged subsequent to the origin of Mount
Manengouba during the past 1.5 million years. In contrast, we find that C.
leucomystax likely represents two species found in the Lower Guinean and
Congolian forests, respectively. We find recent divergences between
several allopatric lineages (either species or populations) that differ in
coloration and pattern, including in C. nigromaculata which varies in
color across its range in Central Africa and Bioko Island. These recent
divergences among allopatric lineages with distinctive coloration and
pattern raise new questions about the significance of these traits in this
genus for which little is known of its natural history and biology.