No abstract

Amblovenatum immersum (Blume) Mazumdar (Thelypteridaceae) is newly recorded in Vietnam. It is similar to A. terminans (Panigrahi) J. P. Roux in its woody rhizome and cristate spores but differs in terms of its plant size, lobed pinnae, lobed segments, veinlets, sori and indusia. It was previously found to exist in China, India, Indonesia, Malaysia, Myanmar, Philippines, Sri Lanka, and Thailand as well as in east Africa, tropical America, northern Australia and Micronesia. The present study provides a detailed description, photos, and line drawing of the species. Furthermore, a comparison of the diagnostic characters with the closely related species in Vietnam A. terminans is provided.

Antrophyum is one of the largest genera of vittarioid ferns (Pteridaceae) and is most diverse in tropical Asia and the Pacific Islands, but also occurs in temperate Asia, Australia, tropical Africa and the Malagasy region. The only monographic study of Antrophyum was published more than a century ago and a modern assessment of its diversity is lacking. Here, we reconstructed a comprehensively sampled and robustly supported phylogeny for the genus based on four chloroplast markers using Bayesian inference, maximum likelihood and maximum parsimony analyses. We then explored the evolution of the genus from the perspectives of morphology, systematics and historical biogeography. We investigated nine critical morphological characters using a morphometric approach and reconstructed their evolution on the phylogeny. We describe four new species and provide new insight into species delimitation. We currently recognize 34 species for the genus and provide a key to identify them. The results of biogeographical analysis suggest that the distribution of extant species is largely shaped by both ancient and recent dispersal events.