Checklist of diatoms from the Laurentian Great Lakes. II

An updated diatom (Bacillariophyta) checklist for the Great Lakes is provid ed. The present checklist supplants the preliminary checklist published in The Journal for Great Lakes Research in 1978 and effectively represents a 2 0-year update. A series of procedures were used in this update which includ ed: a reexamination of taxa reported in the 1978 list, additions of taxa re ported from the Great Lakes during the past 20 years, and a revision of tax onomy, commensurate with systematic and nomenclatural changes which have oc curred primarily during the past 8 years. 1488 diatom species or subordinat e taxa are considered to be correct reports from the Great Lakes out of the 2188 diatom entities reported in the list. Of the 124 genera reported 105 are considered to be names in current use. The number of diatom species rep orted represents a 16.5% increase and the number of genera reported represe nts a 78% increase over those reported in the 1978 checklist. 13% of the sp ecies reported and 32% of the genera reported are due solely to nomenclatur al changes. Results indicate that Great Lakes diatoms are a biodiverse comp onent of the ecosystem, commensurate with the wide range of habitats found in the system. The present checklist indicates that most of the newly added species are primarily benthic or periphytic in nature and these represent largely understudied habitats. These results suggest that the present check list may only represent approximately 70% or less of the extant diatom flor a of the Great Lakes system.