Pablo Franco León

Division Dinophyta

Pablo Franco León

Dinoflagellates are usually combined in one class, Dinophyceae, with a variable number of orders and many families that have fluctuating constituents as new research using electron microscopy and molecular techniques expands our understanding. Morphological terminology of dinoflagellate cells is complex and, to a great extent, specific to dinoflagellates.

Use your mouse to rollover the terms in purple for their definitions. If this feature is not supported by your browser, please refer to the accompanying glossary for terminology. For terms not defined here, consult one or more of the following texts: Dodge (1982); Hoppenrath et al. (2009); Steidinger & Tangen (1997); Throndsen et al. (2007). All photos and drawings by Paul Hargraves, unless otherwise indicated.

Species reported from the IRL system in this list are compiled from various publications and personal observations (PE Hargraves), and fall into the following five orders as currently (2011) envisioned:

ORDER PROROCENTRALES

Cell wall with two large cellulose plates and several smaller plates in the apical flagellar area, lacking a cingulum and sulcus.

Figure 1A. General morphology of dinoflagellates from the order Prorocentrales. Figure 1B. Scanning electron microscope (SEM) image of Prorocentrum micans from the order Prorocentrales.

ORDER DINOPHYSIALES

Cells are laterally flattened with a premedian cingulum, a sulcus often with lateral extensions or lists, and a total of 18 or 19 cellulose plates.

Figure 2A. General morphology of dinoflagellates from the order Dinophysiales. Figure 2B. Scanning electron microscope (SEM) image of Phalacroma sp. from the order Dinophysiales

ORDER GONYAULACALES

Cells with cingulum and sulcus, and with a series of cellulose plates organized into the following regular pattern that define the genera morphologically: apical pore complex, which typically lacks a canal plate; apical; anterior intercalary; precingular; cingular; sulcal; postcingular; posterior intercalary; antapical plates. Distinguished from the Peridiniales mostly by the arrangement and number of the thecal plates. Tabulation follows or is derived from one or both of the following patterns:

a. The first apical plate is somewhat asymmetrical, its left lateral triple junction being more anterior than the right lateral triple junction and giving a very asymmetrical pore complex; or

b. There are 2-4 fundital plates, including the posterior intercalary and first antapical plates or their homologues.

ORDER PERIDINIALES

Cells with cingulum and sulcus, and with a series of cellulose plates organized into the following regular pattern that defines the genera: apical pore complex with a canal plate; apical;

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