Sigmatella sigma (Kützing) Frenguelli, 1923 Dataset GBIF Backbone Taxonomy Rank SPECIES Classification kingdom Chromista phylum Ochrophyta class Bacillariophyceae order Bacillariales family Bacillariaceae genus Nitzschia species Nitzschia sigma Name Homonyms Sigmatella sigma (Kützing) Frenguelli, 1923