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In recent years the taxonomy of Haslea has been in flux. We describe several Haslea taxa from Guam, including four new species, in light of these recent findings. Four delicate, fusiform Haslea species are described from a variety of benthic habitats on coral reefs. These species, H. fusiformis comb. nov. and H. alexanderi, H. apoloniae and H. guahanensis spp. nov. are distinguished by stria density, foramen ('areola') shape, and cell size from each other and from similar taxa. A key to all these taxa is provided. In addition, an arcuate species is described as Haslea arculata sp. nov. The presence of a bilayered wall is shown for all these taxa. We compare the morphology of specimens reported as H. howeana from Guam with Navicula tsukamotoi, recently described from Okinawa, and with 'Navicula cf. howeana' from Puerto Rico. We provide the first account of the complex cingulum of N. tsukamotoi. We conclude that our specimens match N. tsukamotoi and that H. howeana should be returned to Navicula, but we leave open the question of conspecificity. [ABSTRACT FROM AUTHOR]

Iran is a large country with a great diversity of aquatic ecosystems including rivers, springs, shallow seas, lakes, waterfalls, lagoons, and wetlands. Despite the many types of aquatic habitats, there has been a limited study of the diatom flora. The purpose of this study is to present the diatom species and characterize their distribution in the Karaj River, which flows in Iran's Central Alborz region. The Alborz is one of the Irano-Anatolian ecoregions that serve as biodiversity hotspots. The Central Alborz, located in the middle part of this mountainous area, is an outstanding ecological and geological resource. This study uses the diatom flora to determine the biodiversity in one of the major rivers of the Central Alborz. Periphytic diatom samples were collected monthly from six stations along the length of the Karaj River between May 2011 and April 2012. A total of 128 diatom taxa was found from 48 genera expanding our understanding of regional aquatic diversity as 42 species are recorded as new for the diatom flora of Iran. Furthermore, the biogeography of the diatom flora of the Karaj River is considered in relation to the rest of Iran, the Middle East, and Asian and European diatom communities. [ABSTRACT FROM AUTHOR]