A study of gross morphological and histological syringeal features of true francolins (Galliformes: Francolinus, Scleroptila, Peliperdix and Dendroperdix spp.) and spurfowls (Pternistis spp.) in a phylogenetic context

Abstract

Modern taxonomies of francolins recognise 41 congeneric species, forming the largest genus of terrestrial gamebirds (Galliformes). Recent molecular, ecological and behavioural studies challenge this view, suggesting that they comprise two unrelated, monophyletic groups. There are ‘true’ francolins (Francolinus, Dendroperdix, Peliperdix and Scleroptila spp.) that are relatively small, ground-roosting birds, and spurfowls (Pternistis spp.) that are large birds that can roost in trees. This study explores gross morphological and histological syringeal anatomy of francolins, spurfowls and sister taxa to test whether differences are concordant with a molecular-based hypothesis. Differences found were the presence of a shield-versus diamond-shaped tympanum among francolins and spurfowls respectively. The first bronchial half rings are mineralised among francolins except in Dendroperdix sephaena, whereas almost no mineral deposition was observed among spurfowls. Histologically, francolins have a small, rounded pessulus (except in D. sephaena, which has a rounded, larger pessulus) contrary to the larger pessulus observed among spurfowls, which is rounded and triangular in Pternistis capensis and P. natalensis. Both gross and histological similarities within, and differences between, francolin and spurfowl syringes support this division. However, D. sephaena shows intermediate features between francolins and spurfowls.