Coral-reef diatoms (Bacillariophyta) from Guam: new records and preliminary checklist, with emphasis on epiphytic species from farmer-fish territories

The marine diatom flora of the tropical western Pacific island of Guam is all but unknown. Following several taxonomic/systematic papers, this floristics paper documents 179 new records of diatoms identified from light microscopy and/or scanning electron microscopy. Samples were collected from diverse habitats for several research projects in the authors’ laboratories, but the majority reported here are epiphytic, especially from pomacentrid farmer-fish territories. While many of the species are well known from other regions, some recently named, rarely seen, or poorly-described taxa include Amphora decussata Grunow;Ardissonea fulgens var. fulgens (Greville) Grunow and var. gigantea (Lobarzewsky) De Toni; Campylodiscus humilis Greville; Falcula paracelsianus Voigt; Hyalosira interrupta (Ehrenberg) Navarro; Olifantiella pilosella Riaux-Gobin; andTriceratium pulchellum (Grunow) Grunow. A preliminary checklist incorporating the new records and our previous records totals 237 taxa, which is a step towards the development of the regional flora. Many taxa remain to be identified from the documentation so far and few samples have been analyzed from other habitats such as sediments and mangroves. Only 28–42% of the species in this checklist also occurred in lists from the Society Islands, Mahé, Puerto Rico and The Bahamas—but all regions remain seriously undersampled. We do, however note some apparent differences in common and distinctive species