achnanthidium achnanthidium achnanthidium is a genus of diatoms belonging to the family achnanthidiaceae. achnanthidium achnanthidium scientific classification domain: eukaryota clade: diaphoretickes clade: sar clade: stramenopiles phylum: gyrista subphylum: ochrophytina class: bacillariophyceae order: achnanthales family: achnanthidiaceae genus: achnanthidiumkützing, 1844 extant species see text the genus was described in 1844 by friedrich traugott kützing. the genus has cosmopolitan distribution. species: (see a more complete list) achnanthidium affine (grunow) czarnecki, 1994 achnanthidium agardhii (kützing) mereschkowsky achnanthidium alpestre (r. lowe & j.p. kociolek) r. lowe & j.p. kociolek achnanthidium minutissimum (kützing) czarnecki