Planothidium juandenovense sp. nov. (Bacillariophyta) is described from the marine tropical environments of Juan de Nova I. (Mozambique Channel), Rodrigues I. (Mascarene Archipelago) and from Guam (Northern Mariana Is., Pacific). This small an...

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.

Lobban C.S., Schefter M. and Ruck E.C. 2011. Licmophora flucticulata sp. nov. (Licmophoraceae, Bacillariophyceae), an unusual new flabellate species from Guam and Palau. Phycologia 50: 11–22. DOI: 10.2216/09-85.1 A new species of Licmophora, L. flucticulata sp. nov., forms distinctive, rippled, fan-shaped colonies on coral reef seaweeds on Western Pacific islands. It is readily observed underwater with the naked eye but is very weakly silicified, and its frustule does not survive normal acid cleaning. Its identity as a Licmophora species was demonstrated with scanning electron microscopy and small-subunit rDNA sequencing. Licmophora flucticulata has exceptionally long, narrow cells cemented into fascicles that attach to the substratum by short, multistranded mucilage stalks. Its valve and colony morphology are compared to that of L. remulus, L. flabellata and L. aurivillii.

Plastids of Climaconeis (Okedenia) were originally characterized by Mereschkowsky as H-shaped in girdle view with pyrenoids but recent descriptions implicitly or explicitly indicate that the H-shape is seen in valve view. We observed five known taxa–one a variety that we raise to species rank–and two new species: C. silvae, C. riddleae, C. guamensis sp. nov. and C. inflexa (curved species); C. lorenzii (straight species with craticular bars); a straight species without bars that matches Navicula scopulorum var. triundulata = Climaconeis undulata comb. nov.; and a new straight species without bars, C. petersonii sp. nov. In the species with multiple plastids, plastids are plate-like, usually with a pyrenoid in the centre, arranged in pairs along the girdle faces of the cells. In some species with few plastids, including C. riddleae, and possibly C. inflexa, the pyrenoid is also visible in valve view between opposing plastids, such that these species do appear to have plastids that are H-shaped in valve view. We describe the two new species and confirm published SEM observations on other species, including features of the pores that help distinguish C. guamensis from the very similar C. riddleae.