Dioecy in Wendlandiella and palms in general Dioecy occurs in nearly half of the angiosperm families (VAMOSI et al., 2003; RENNER, 2014) and dioecy is found in all palm subfamilies except the monotypic Nypoideae (ASMUSSEN et al., 2006; DRANSFIELD et al., 2008). Based on parsimony and maximum likelihood optimizations, NADOT et al. (2016) hypothesized that dioecy evolved directly from monoecy in Arecoideae and Calamoideae whereas it evolved from hermaphroditism in Coryphoideae. According to CASTAÑO et al. (2014) the fact that all 107 genera of the palm subfamily Arecoideae are monoecious, with the exception of Chamaedorea and Wendlandiella, suggests strongly that the common ancestor of this group was also monoecious. Thus, the two genera could be used as an interesting model to test the different evolutionary pathways proposed by DORKEN & BARRET (2003) for the origin of dioecy in Angiosperms (gynodioecy vs monoecyparadioecy). Our study contributes to a better understanding of the reproductive structures in Chamaedoreeae, which is fundamental for further ontogenetic studies and molecular histological approaches exploring underlying sexual differentiation processes responsible for dioecy in the group.

Published as part of Stauffer, Fred W., Eychenne, Joan, Ortega, Nesly & Balslev, Henrik, 2019, Structural biology and evolution in the monotypic Amazonian palm Wendlandiella (Arecoideae: Chamaedoreeae), pp. 15-30 in Candollea 74 (1) on page 26, DOI: 10.15553/c2019v741a3, http://zenodo.org/record/5724641