New species of benthic marine diatoms (Bacillariophyta) from the Western Pacific islands of Guam and Yap

In the course of preparation of a major checklist for Yap and ongoing investigations into the benthic marine diatom flora of Micronesia, thirteen new araphid and raphid pennate diatom species have been recognized and are described here. Plagiogramma subatomus is even smaller than P. atomus and the pseudoseptum forms a box with only a small opening toward the cell interior. Licmophora romuli is similar in size and spathulate shape to L. remulus, but the majority of the striae in the lamina lack vimines. L. graphis is exceedingly delicate, pencil-shaped, with apical striae 60–70 in 10 µm. Divergita biformis and D. decipiens are straight species with striae biseriate on the margin, uniseriate on the valve face, differing in the shape and prominence of the sternum and the shape of the valve-face areolae. D. macinnisii (from Marshall Islands, but included here for comparison) is curved, again with the decussate areolar pattern on the mantle, but with single extended areolae along each side of the linear sternum. These characters slightly amend the diagnosis of the genus. Thalassionema baculum is a very short member of the genus, linear and isopolar. Climaconeis tarangensis is curved and differs from C. riddleae in stria density and areola shape; C. minaegensis is straight, without a stauros or craticular bars, of intermediate length, 228–247 µm. First SEM observations of Climaconeis lorenzii are presented and an updated key to Climaconeis is appended. Parlibellus paschalis is a tube-dwelling species differing from P. delognei is lacking cuniculi and pores in the central area. P. waabensis is a relatively large species, possibly tube-dwelling, that differs from P. delognei in shape and spacing of central striae and from P. berkeleyi in width and stria density. Pleurosigma simulacrum differs in ultrastructural details from P. intermedium. Lastly, Nitzschia tarangensis is a conopeate species, spathulate in profile with ribs along the edge of the valve depression and bordering the raphe, and with pores in the peri-raphe zone.

A checklist of marine benthic diatoms (Bacillariophyta) from Mexico

This article summarizes nearly three decades of research on marine benthic diatoms from coastal areas in Mexico. The studies analyzed yielded 1162 taxonomic entities that include species, varieties, and forms, plus a considerable number of informal designations; i.e., “aff.” and “cf.”. The taxonomic list resulted from surveying all available published data on the topic, mostly by the authors, from northwest and southeast Mexico, with the objective of providing an up-to-date basis for further research on benthic diatoms from Mexico and related areas. Members of the Class Bacillariophyceae are the best represented with 881 taxa, followed by the Coscinodiscophyceae and Fragilariophyceae with 165 and 116 taxa, respectively. This is the first floristic list of benthic marine diatoms for Mexico, and it shows that many areas of the country’s extensive coastal zone are yet to be surveyed, while simultaneously providing a basis for future ecological and biogeographical studies.