Polysiphonia collabens (C.Agardh) Kütz. Dataset GBIF Backbone Taxonomy Rank SPECIES Classification kingdom Plantae phylum Rhodophyta class Florideophyceae order Ceramiales family Rhodomelaceae genus Melanothamnus species Melanothamnus collabens Name Homonyms Polysiphonia collabens (C.Agardh) Kütz.