Diversification of lindsaeoid ferns and phylogenetic uncertainty of early polypod relationships

We analysed one nuclear gene (18S) and seven plastid markers five protein coding (atpA, atpB, rbcL, rpoC1, rps4) and two non‐coding (trnH‐psbA, trnL‐trnF] for 31 members of Polypodiales and four outgroup taxa. We focused our sampling on the lindsaeoids and associated ferns in order to obtain a better understanding of the diversification of the early polypods. However, the exact phylogenetic position of Saccoloma and Cystodium remained uncertain. Based on relaxed molecular clock analyses, it appears that the crown group lindsaeoids diversified in the Caenozoic, more or less simultaneously with the main radiation of other Polypodiales, even though the original divergence between the lindsaeoid and non‐lindsaeoid polypods occurred before the end of the Jurassic. The current pantropical distribution of lindsaeoids can be explained by either long‐distance dispersal across the oceans or vicariance caused by the retreat of previously widely distributed tropical forests from higher to lower latitudes. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 170 , 489–503.