Desmid image database Introduction This database represents the public face of RBGE's desmid database, designed by R.J. Pankhurst as an implementation of Advanced Revelation, and further developed by Martin Pullan. The so-called 'Pandora' databases (of which there are several at RBGE and elsewhere) are very sophisticated in the relational way they handle data but, because they are DOS-based, are not very easy or attractive for the uninitiated to use. For this and several other reasons, it was decided that the best way to make the data available to a wider audience was to create a series of flat-field data dumps from the Pandora database; these could then be interrogated using a web browser. The search-engines required for this have been created by Martin Pullan, using the home-grown data-extraction software HTMLexport. From here on we will refer only to the web-based database, but remember that it is several steps removed from the Pandora database that has provided its data. Structure of the database The database is very similar in structure to that produced by Martin Pullan and Micha Bayer (who no longer works at RBGE) for the ADIAC project, although there are some differences: ADIAC was concerned primarily with photographs of microalgae (diatoms, as it happened), whereas DIADIST, at least in these early stages, is more concerned with published drawings of microalgae (primarily desmids at this stage). The desmid database is built on a taxonomic framework consisting of all the names in West & West's British Desmidiaceae, updated to more modern nomenclature and supplemented from Brook & Williamson (1991), with a few extra changes or additions from John et al. (2002). Onto this framework are the images that you can find here. We have started with the drawings from West & West's British Desmidiaceae, either as whole browsable plates or individually scanned drawings. Ultimately we will also incorporate photographs of desmids, and hope soon to develop the techniques to allow dynamic focusing of images as has been done in ordinary web pages (as distinct from pages resulting from search-engine queries) in our Algae World website (follow links to 'Research' and 'Types').

Current status However, first things first: the scanning of West & West's British Desmidiaceae is not yet complete, and individual figures have been scanned from ca. 120 out of the 167 plates that make up the five volumes (all the plates have been scanned for the browsable pages). The following plates and genera have NOT been scanned for the searchable database: plates 1–10: all the Saccodermae (genera Gonatozygon, Genicularia, Spirotaenia, Mesotaenium, Cylindrocystis and Netrium) plus Penium and Roya plates 27–31: genera Docidium and Pleurotaenium plates 120–167: most of Staurastrum, two species of Euastrum, one species each of Arthrodesmus, Closterium and Micrasterias, and all of Cosmocladium, Oocardium, Sphaerozosma, Onychonema, Spondylosium, Hyalotheca, Desmidium and Gymnozyga. At present the database contains 2728 images and 778 taxa (although several taxa are not accompanied by pictures and therefore will not be found by a search). Technical stuff about the pictures The individual figures from West & West were scanned at 300 dpi using an Epson GT-10000+ flat-bed scanner as either 8-bit grey or 24-bit colour; each was scaled so that the longest dimension was ca. 1600 pixels – in most cases more than adequate to capture the available detail. The files were saved in TIFF format for the Pandora database and in most cases with surrounding irrelevant information (i.e. bits of neighbouring figures) removed using Adobe Photoshop's (version 6.0) cloning tool. For the web database, the contrast was enhanced slightly, and all images were compressed in GIF format for the thumbnails (see the sample results page) and JPEG format for the enlarged pictures. Unlike the browsable whole plates (which are all to the same scale), the individual pictures are scaled individually. Scale information is given as the equivalent width and height of the whole image as shown, in whatever units are given (usually microns). For example, if the 'image height equivalent' is given as 100 microns, and the specimen occupies 75% of the height of the picture, the specimen is 75 microns in that dimension. References Brook, A.J. & Williamson, D.B. 1991. A checklist of desmids of the British Isles. Freshwater Biological Association Occasional Publication No. 28. 40 pp. John, D.M., Whitton, B.A. & Brook, A.J. (eds) 2002. The freshwater algal flora of the British Isles. An identification guide to freshwater and terrestrial algae. Cambridge University Press, Cambridge. 702 pp. + cd of images. Back to database search form