actinoptychus actinoptychus actinoptychus is a genus of diatoms belonging to the family heliopeltaceae. actinoptychus fossil of actinoptychus splendens scientific classification domain: eukaryota clade: diaphoretickes clade: sar clade: stramenopiles phylum: gyrista subphylum: ochrophytina class: bacillariophyceae order: coscinodiscales family: heliopeltaceae genus: actinoptychusehrenberg, 1843 extant species actinoptychus octodenarius actinoptychus senarius the genus was described in 1843 by christian gottfried ehrenberg. species: actinoptychus octodenarius ehrenberg actinoptychus senarius (ehrenberg) ehrenberg, 1843