Abstract: Continent-wide disjunctions, where related taxa are distributed across isolated regions within the continent, are rare in grasses and remain poorly understood. The genus Trichoneura occurs in both the New World and the Old World, with no species occurring in both continents, and its distribution displays continental disjunctions. The current distribution of African Trichoneura is said to be a result of the formation of an African arid corridor, yet this remains understudied. Using complete chloroplast genomes and nuclear genes of seven newly sequenced Trichoneura species, we studied their phylogenetic relationships and divergence history, reconstructed their ancestral history, and modeled their ecological niche to understand their evolution and current distribution pattern. Our findings revealed that the plastomes of Trichoneura are generally conserved and range in length between 135 069 and 134 139 bp. Molecular results show that Trichoneura is monophyletic and diverged around 5.78 Ma. The Late Miocene origin of this genus correlates with the formation of the African arid corridor, which explains their fragmented distribution in Africa. Dispersal and vicariance are likely to have played pivotal roles in driving their divergence, leading to subsequent distribution toward Neotropical regions during the Pliocene period. Trichoneura mollis and Trichoneura lindleyana occurring in different regions displayed varying morphology, and we suggest further morphological and phylogenetic analysis to determine their taxonomic delimitation.

Key words: arid corridor, disjunct, divergence, evolution, Trichoneura.