An Expanded Plastid Phylogeny of Tectaria (Tectariaceae), with Description of Four New Species from the Solomon Islands

Abstract Recent molecular phylogenetic studies have identified four major clades within the fern genus Tectaria but none of them is supported by any morphological characters. Here we present an expanded phylogeny of Tectaria based on five plastid markers (atpB, ndhF + ndhF-trnN, rbcL, rps16-matK + matK, and trnL-F), with a particular focus on the species from Asia to the Solomon Islands. Our aims are to infer the systematic position of newly included species, providing insights to interspecific relationships of some species groups, and to determine the identity of some specimens with distinct morphology. As a result, three major clades and a total of 14 lineages are identified in Asia to the Solomon Islands. The 19 newly sampled species were well resolved in the phylogenetic tree, of which T. lobbii (representative of rare rheophytes in Tectaria) was confirmed as belonging in the T. angulata–T. vanikoroensis lineage. Four new species from the Solomon Islands, T. acrophoroides, T. glenniana, T. pallescens, and T. vanikoroensis, are recognized and described. Phylogenetic and morphological evidence suggests frequent hybridizations between T. crenata and T. decurrens from Malesia to the Solomon Islands, and between T. devexa and T. simonsii in mainland Asia and adjacent islands, which render the obscure species boundaries within the two groups.