Benthic marine diatom flora of Guam: new records, redescription of Psammodictyon pustulatum n. comb., n. stat., and three new species (Colliculoamphora gabgabensis, Lauderia excentrica, and Rhoiconeis pagoensis) Author Lobban, Christopher S. Division of Natural Sciences, University of Guam, Mangilao, GU 83823, USA e-mail: clobban @ guam. net clobban@guam.net text Micronesica 2015 2015 2 1 49 journal article 299054 10.5281/zenodo.12117576 9ec266f5-1dc7-4272-9fbc-67c7f2b0f5aa 0026-279X 12117576 Mastogloia affirmata (Leuduger-Fortmorel) Cleve Figs 49, 50 Section: Undulatae Ref. illus.: Hustedt 1931 –1959, fig. 962. Samples: GU44AX-1 Dimensions: Length 39 µm; width 22 µm; transapical striae 14 in 10 µm, longitudinal striae 10 in 10 µm except for the wider row adjacent to axial area; partecta 3.3 µm wide, 13 in 10 µm. Diagnostics: Coarsely areolate, those along the raphe notably elongated; apices produced; longitudinal ribs almost straight; partectae very narrowly rectangular. Comments: Distinguished from the very similar M. bahamensis Cleve ( Hustedt 1931 –1957, fig 963, Hein et al. 2008 , pl. 34, fig. 6 and pl. 36, fig. 10), which has irregularly wavy longitudinal ribs, according to Hustedt, and from M. subaffirmata Hustedt (see below) by the much coarser striae. Record based on a single specimen from Guam , but also seen in samples from Yap (unpublished).