The size range of P. holstii overlaps with P. apiculatum, but these taxa are distinct in several features. The apices are much more narrow in P. apiculatum. Furthermore, the striae of the raphe valve are more radiate. The rapheless valve of P. holstii lacks a cavum, which is present in P. apiculatum.
Diatoms of North America is running a fundraising campaign to keep the servers in operation. We need you to reach our $25,000 fundraising goal.
If you use and appreciate DONA, make your DONAtion today.
For the Gift Designation, type "diatom" in the search box and select "Diatom Lab Research Fund". This is the designated fund for diatoms.org.