A plastid DNA phylogeny ofDasymaschalon(Annonaceae) and allied genera: Evidence for generic non–monophyly and the parallel evolutionary loss of inner petals

Abstract

Dasymaschalon and the closely related genera Desmos, Friesodielsia and Monanthotaxis together comprise ca. 170 species of trees, shrubs and woody climbers distributed in tropical Africa and tropical Asia. These genera form the desmoid clade, which, because of the presence of diverse flower and fruit syndromes including different types of pollination chambers and moniliform monocarps, offers an opportunity to investigate potentially ecologically significant shifts in flower and fruit characters. Despite its morphological diversity, however, generic delimitation within the desmoid clade is problematic and the intergeneric relationships of the constituent genera are only poorly understood. Bayesian, maximum likelihood and maximum parsimony analyses of plastid DNA sequence data (matK, psbA–trnH, ndhF, rbcL, trnL–F; ca. 5.4 kb; 52 taxa) were used to clarify phylogenetic relationships within the desmoid clade. The evolution and taxonomic utility of selected fruit and flower characters was investigated with likelihood and parsimony ancestral character reconstructions. The results indicate problems in the current delimitations of Dasymaschalon and Friesodielsia. Friesodielsia as currently circumscribed is polyphyletic, with African Friesodielsia species allied to the African genus Monanthotaxis, and only distantly related to Asian representatives. The majority of Dasymaschalon species form a strongly supported clade, but three species are more closely related to Asian species of Friesodielsia. Ancestral character reconstructions indicate that seed number and monocarp shape are of limited value in generic circumscriptions, and that the three–petalled corolla characteristic of Dasymaschalon evolved independently twice within the desmoid clade. Disruptions to homeotic gene expression or strong selective pressure for a partial enclosure of the mature stamens and carpels by the corolla are hypothesised to underlie the parallel evolution of pollination chambers formed by outer petal homologues subsequent to inner petal loss.

Which frugivory‐related traits facilitated historical long‐distance dispersal in the custard apple family (Annonaceae)?

“…We also find strong support that moniliform fruits (long strings of bead‐like fruitlets, found in e.g., extant Dasymaschalon , Desmos and Monanthotaxis , Guo, Hoekstra, et al., ; Wang et al., , Figures a and j), dehiscent fruits (e.g., found in extant Xylopia and Cymbopetalum , Figures j and i), and (relatively) small seeds (Figure c) are traits associated with long‐distance dispersal. Both moniliform and dehiscent fruits have been shown to be particularly attractive to birds (Gautier‐Hion et al., ; Guo, Hoekstra, et al., ; Lomáscolo & Schaefer, ), although Xylopia has been observed to be fed on by both birds and primates (Johnson & Murray, ).…”

Cutting up the climbers: Evidence for extensive polyphyly in Friesodielsia (Annonaceae) necessitates generic realignment across the tribe Uvarieae

“…with two other genera, Desmos and Monanthotaxis. This close relationship is corroborated by several diagnostic characters, including the glaucous abaxial surface of the leaves (Wang & al., 2012), inaperturate pollen with echinate-microbaculate ornamentation (Walker, 1971a; Le Thomas, 1980Thomas, , 1981Bygrave, 2000;Doyle & Le Thomas, 2012), and monocarps (when multi-seeded) with distinct constrictions between neighbouring seeds (Wang & al., 2012). As is generally the case in Annonaceae, however, these characters show homoplasies or reversals and therefore are not found in all species in the Dasymaschalon alliance.…”

“…Taxon and DNA region sampling. -The 42-taxon dataset generated by Wang & al. (2012) was used as the basis for an expanded taxon sampling, including additional species from the Dasymaschalon alliance, with a focus on Friesodielsia and Monanthotaxis, which were inadequately sampled previously (6 out of 49 Friesodielsia species, and 7 out of 66 Monanthotaxis species).…”

“…180 species in the Dasymaschalon alliance). Wang & al. (2012) recently conducted a phylogenetic analysis of the Dasymaschalon alliance based on a more extensive taxon sampling (42 taxa, accounting for ca.…”

A nonet of novel species of Monanthotaxis (Annonaceae) from around Africa

“…Species of Popowia only differed from Monanthotaxis by having the petals in two whorls, however species of Enneastemon have the petals intermediate between Popowia and Monanthotaxis , which is a single whorl at the base of the flower, and in two whorls apically. With the rise of molecular phylogenetic analyses it has appeared that the genus Friesodielsia is polyphyletic, with most of the African species being sister to the genus Monanthotaxis (Chatrou et al 2012; Richardson et al 2004; Wang et al 2012). Further data sampling has also revealed that the monotypic genus Exellia is nested in Monanthotaxis .…”