Bacillariophyceae
# Bacillariophyceae

Bacillariophyceae is a group of pennate diatoms with a raphe (raphids). According to Ruggiero et al., 2015, the diatoms are treated as follows. This treatment largely reflects that used by Algaebase as at 2015, and is also reflected in the current (mid 2020) treatment used in DiatomBase, the World Register of Marine Species (WoRMS) of which DiatomBase is a part, and the Catalogue of Life. This treatment is identical to that of Round et al., 1990, except that all diatoms are treated as a single class, Round et al.'s classes are reduced to subclasses, and the latter's original subclasses are omitted.

It has 3 subclasses, Bacillariophycidae, Coscinodiscophycidae and Fragilariophycidae

## Subclass Bacillariophycidae

Contains the following orders;

* Achnanthales (2k)
* Bacillariales (3k)
* Cymbellales (4k)
* Dictyoneidales (17)
* Eunotiales (2k)
* Lyrellales (38)
* Mastogloiales (825)
* Naviculales (18k)
* Rhopalodiales (527)
* Surirellales (2k)
* Thalassiophysales (1k)

Figures in brackets are approx. how many species per order.

## Subclass Coscinodiscophycidae

Contains the following orders;

* Anaulales (99)
* Arachnoidiscales (83)
* Asterolamprales (252)
* Aulacoseirales (184)
* Biddulphiales (826)
* Chaetocerotales (2k)
* Chrysanthemodiscales - (monotypic) Chrysanthemodisccaceae, Chrysanthemodiscus floriatus A.Mann, 1925
* Corethrales (21)
* Coscinodiscales (2k)
* Cymatosirales (168)
* Ethmodiscales (28)
* Hemiaulales (524)
* Leptocylindrales (13)
* Lithodesmiales (153)
* Melosirales (1k)
* Orthoseirales (53)
* Paraliales (66)
* Rhizosoleniales (487)
* Stictocyclales - Stictocyclaceae, Stictocyclus varicus A.Mann, 1925
* Stictodiscales (200)
* Thalassiosirales (1k)
* Triceratiales (2k)

Figures in brackets are approx. how many species per order.

## Subclass Fragilariophycidae

Contains the following orders;

* Ardissoneales (12)
* Fragilariophycidae
* Climacospheniales (29)
* Cyclophorales (59)
* Fragilariales (3k)
* Licmophorales (323)
* Protoraphidales (13)
* Rhabdonematales (66)
* Rhaphoneidales (325)
* Striatellales (323)
* Tabellariales (222)
* Thalassionematales (67)
* Toxariales (9)

Figures in brackets are approx. how many species per order.

The GBIF also has the following unplaced orders; Centrales, Chaetocerales, Rhaphoneidales,

