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Sargassum is the most diverse genus in the brown algal order Fucales, which is an ecologically important primary producer in marine ecosystems. The Philippines has about 73 species of Sargassum identified based solely on morphology, representing 18% of its reported global diversity. The genus is known for its morphological plasticity which makes identification of its species challenging. Taxonomy is particularly problematic in the Philippines where molecular data for Sargassum is lacking. We collected 34 samples of Sargassum from Eastern Samar, Philippines, an area known to have significant species diversity. Using newly designed primers to amplify the nuclear ribosomal internal transcribed spacer (ITS) region, we generated gene sequences and reconstructed the phylogeny of Sargassum to infer species diversity of the Eastern Samar samples. Based on morphological assessments of samples, we found S. corderoi, S. polycystum and five other morphotaxa. Molecular assessments, on the other hand, show the presence of only three morphotaxa. Bayesian inference, maximum parsimony and maximum likelihood generated almost identical trees which showed that S. corderoi and Sargassum sp. aff. siliquosum samples are nested in a clade of S. ilicifolium. This is the first time that S. corderoi has been reported in Eastern Samar. Another species, S. polycystum, formed a clade consisting of well-supported subgroups. This study is a step towards updating the taxonomic identification of Sargassum species found in the Philippines using molecular and morphological data. The biomarker used in our study could improve the identification of Sargassum species in a species-rich subtropical-tropical geographical area such as the Philippines, in phylogenetic studies of Sargassum.

Resurrecting extinct species is a fascinating and challenging idea for scientists and the general public. Whereas some theoretical progress has been made for animals, the resurrection of extinct plants (de-extinction sensu lato) is a relatively recently discussed topic. In this context, the term 'de-extinction' is used sensu lato to refer to the resurrection of 'extinct in the wild' species from seeds or tissues preserved in herbaria, as we acknowledge the current impossibility of knowing a priori whether a herbarium seed is alive and can germinate. In plants, this could be achieved by germinating or in vitro tissue-culturing old diaspores such as seeds or spores available in herbarium specimens. This paper reports the first list of plant de-extinction candidates based on the actual availability of seeds in herbarium specimens of globally extinct plants. We reviewed globally extinct seed plants using online resources and additional literature on national red lists, resulting in a list of 361 extinct taxa. We then proposed a method of prioritizing candidates for seed-plant de-extinction from diaspores found in herbarium specimens and complemented this with a phylogenetic approach to identify species that may maximize evolutionarily distinct features. Finally, combining data on seed storage behaviour and longevity, as well as specimen age in the novel 'best de-extinction candidate' score (DEXSCO), we identified 556 herbarium specimens belonging to 161 extinct species with available seeds. We expect that this list of de-extinction candidates and the novel approach to rank them will boost research efforts towards the first-ever plant de-extinction.