Systematics ofDiplazium laffanianum(Athyriaceae), a Fern Species Endemic to Bermuda

Abstract

Diplazium laffanianum was last collected from its natural habitat in Bermuda in 1905. Now the species is considered extinct in the wild as it exists only in greenhouses, tissue cultures, and as a few young reintroduced sporophytes. For the last 13 years, a collaborative team of researchers from the Government of Bermuda and the Lab for Rare & Endangered Plants at Omaha's Henry Doorly Zoo in Nebraska, USA has been working to bring this species back from the brink of extinction. In this project, we developed propagation methods for D. laffanianum, and we studied molecular and morphological characters to determine the phylogenetic placement of D. laffanianum. We sequenced plastid DNA from D. laffanianum using high-throughput sequencing, downloaded six plastid markers (atpA, atpB, matK, rbcL, rps rps4-trnS, and trnL intron trnL-F) from GenBank for 21 Diplazium and outgroup taxa, and inferred a phylogeny. We examined 185 collections of five Diplazium species closely related to D. laffanianum, and we scored 15 morphological characters to test whether D. laffanianum is a distinct species. The phylogeny placed D. laffanianum in the D. cristatum group, suggesting a Neotropical ancestor, and two morphological characters distinguished D. laffanianum from close relatives. Our results provide evidence for the phylogenetic placement of D. laffanianum, and we are actively propagating and reintroducing individuals to the wild, aiding conservation of the species.