Cosmarium difficile var. messikommeri (Croasdale) Kouwets, 1997 Dataset GBIF Backbone Taxonomy Rank VARIETY Classification kingdom Plantae phylum Charophyta class Conjugatophyceae order Desmidiales genus Cosmarium species Cosmarium difficile Name Synonyms Cosmarium laeve var. messikommeri Croasdale, 1981 Homonyms Cosmarium difficile var. messikommeri (Croasdale) Kouwets, 1997