Museomics reveal phylogeny of endangered Malagasy grasses

Poaceae is one of the most diverse families in Madagascar, but some lineages have not yet been assessed within a phylogenetic framework. This study focused on the threatened taxa of Chasechloa, historically associated with the South American forest grasses of the genus Echinolaena.

Scanning electron microscopy (SEM) images of the upper floret of Chasechloa madagascariensis (Vorontsova et al. 1822).
Scanning electron microscopy (SEM) images of the upper floret of Chasechloa madagascariensis (Vorontsova et al. 1822). (A–D) Young floret; (A) ventral view; (B) dorsal view; (C) base, ventral view; (D) base, dorsal view. (E–J) Mature floret; (E) ventral view; (F) dorsal view; (G) base, ventral view; (H) base, dorsal view; (I) apex, ventral view; (J) apex, dorsal view. Scale bars = 500 μm (A, B, E, F); 200 μm (C, D, G, H); 100 μm (I, J). AP, appendages; GL, germination lid; L, lemma; P, palea; R, rachilla; ST, stomata.

Silva et al. investigate the evolutionary relationships and origin of Chasechloa using molecular data produced by next-generation sequencing from museum specimens. Chasechloa was found to be only distantly related to Echinolaena. Miocene diversification of Chasechloa is temporally congruent with the origin of other angiosperms in dry forests of North Western Madagascar. Ants may have played a role in shaping the biology of Malagasy grasses as suggested by the presence of oil in the appendages of fertile florets.

Reference

Silva, C., Besnard, G., Piot, A., Razanatsoa, J., Oliveira, R. P., & Vorontsova, M. S. (2016). Museomics resolve the systematics of an endangered grass lineage endemic to north-western Madagascar. Annals of Botany, 119(3), 339–351. https://doi.org/10.1093/aob/mcw208