The Stuart Stidolph Diatom Atlas

Introduction This collection of LM images of marine diatoms, made in the Eighties and Nineties, epitomizes the craftsmanship of the analog era of photomicrography. In the form presented here, it has become a peer-reviewed work, to which reference can be made in publications. The following notes supply the general information required for interpretation of the images. Photomicrographic technique All images were made with the following objectives: 20x/NA/0.70 and dry 40x/NA 0.95 planapochromatic, 90x/NA 1.4 apochromatic or a 60x/N.A. 1.4 planapochromatic oil immersion, combined with a 3.3x or 6.7x NFK photo eyepiece and enlarged to the magnification specified for the image in question. The film used was Kodak 2415 document film, developed in a slightly modified version of Kodak D19. All images are unstacked - instead, images at different focus settings are presented in some cases. The photomicrographs were taken with conventional central brightfield illumination, phase-contrast or interference contrast were not used. Magnifications The legends mention magnifications for the various images. From these data, the optical combination used can be derived as follows: 90 x 6.7 = x2000 40 x 3.3 = x750 60 x 6.7 = x2000 20 x 6.7 = x500 40 x 6.7 = x1000 20 x 3.3 = x250 Scale bars were added to the plates representing 10µm at 1000x and the correspondingly scaled value for the other magnifications. Identifications Wherever possible Stidolph’s identifications were based on the illustrations supplied by the original author. If original data were unavailable, the reference source in closest agreement with the specimens was used. In some cases, the identification was given by the maker of the slide, deposited in the collection mentioned. When Stidolph doubted this, a note was added. Where possible, we have verified this and commented accordingly. The references given by Stidolph are in a separate table, see further. The identifications originally given still followed the “classic” system, where Lyrella species were assigned to the genus “Navicula”, for instance. We have added the current names. The authorship of the species in question was not given in the original text of the atlas and has also been added. Materials The materials are specified in the legends for the plates. Some were samples from which slides were made by Stidolph (deposited in the Stidolph collection, herbarium of the National Institute of Water and Atmospheric Research (NIWA), Wellington, N.Z.), others are slides by other makers, deposited in the collections specified. The materials typically represent marine (sub)tropical habitats, the diatoms illustrated are typically inhabitants of the benthos or epipelic.