Peridiniopsidaceae Gottschling, Kretschmann & Zerdoner, 2017

Peridiniopsidaceae Gottschling, Kretschmann & Zerdoner , fam. nov. —

Type genus: Peridiniopsis Lemmerm. (with its type species, P. borgei Lemmerm. ), Ark. Bot. 2 (1904): 134.

Description: Thecate, phototrophic, free-living primarily freshwater dinophytes. Kofoidian plate formula: ≤4’, ≤2a, ≤7’’, 6c, 5s, 5’’’, 2’’’’, apical pore complex present ( Parvodinium , Peridiniopsis ) or absent ( Palatinus ). Plate surface smooth through granulate, but never with ridges forming areolae, hypotheca variously spinose through smooth. Chloroplast lobes radiating from a central pyrenoid; eyespot and peduncle microtubules present. Dividing or ecdysing cells exiting the theca through the antapical area. n≈40 ( Holt & Pfiester 1982).

The Peridiniopsidaceae , fam. nov., are taxonomically distinct and may include some 15 species occurring in temperate through tropical freshwater habitats around the world (frequently encountered species are Palatinus apiculatus , Parvodinium africanum , P. centenniale , P. deflandrei , P. goslaviense , P. inconspicuum , P. lubieniense , P. umbonatum and Peridiniopsis borgei ). They can be delimited from other peridinialean families based on a combination of traits ( Tab. 1 View TABLE 1 ) including the preferred freshwater versus the otherwise primarily marine environment. They are further distinct from the other genuine freshwater family, Peridiniaceae , because of the presence of not more than two ( versus three) intercalary plates and six ( versus five) cingular plates. Ultrastructural traits such as the presence of peduncle microtubules and chloroplast lobes radiating from a central pyrenoid may provide further evidence for the distinctiveness of the new family. Last but not least, the Peridiniopsidaceae , fam. nov., constitute a monophyletic lineage of the Peridiniales distinct from the Peridiniaceae and other peridinialean lineages in molecular phylogenetics ( Fig. 1 View FIGURE 1 ). Future research will enlighten the systematic positions of Glochidinium , Staszicella , Thompsodinium and many other dinophytes in either of Peridiniaceae , Peridiniopsidaeceae , fam. nov., or other (established or even more new) families in the Peridiniales . Family circumscriptions would have to be adjusted if applicable.