Peridiniopsidaceae Gottschling, Kretschmann & Zerdoner, 2017

Gottschling, Marc, Kretschmann, Juliane & Čalasan, Anže Žerdoner, 2017, Description of Peridiniopsidaceae, fam. nov. (Peridiniales, Dinophyceae), Phytotaxa 299 (2), pp. 293-296 : 295

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 ) 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 ). 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.

Figures

FIGURE 1. Peridiniaceae and Peridiniopsidaceae, fam. nov., have distinct systematic positions in the peridinialean molecular tree. Maximum Likelihood (ML) tree (–ln=62.863,31) of 89 Peridiniales operational taxonomic units (OTUs; plus 42 Amphidomataceae as outgroup, not shown) under the GTR+Γ substitution model. For alignment constitution, we defined three regions of the rRNA: SSU, ITS, LSU, and included all Peridiniales, of which sequence information in all three regions were available. Freshwater lineages are shaded in green, and the Peridiniopsidaceae, fam. nov., with its type species, Peridiniopsis borgei, are highlighted. Branch lengths are drawn to scale, with the scale bar indicating the number of nucleotide substitutions per site. The numbers on the branches are statistical support values (above: ML bootstrap values derived from 1.000 non-parametric replicates, values <50 are not shown; below: Bayesian posterior probabilities derived from two independent analyses of four chains with 20.000.000 cycles, sampled every 1.000th cycle, values <.90 are not shown). Asterisks indicate maximal support. Abbreviations: BLA: Blastodiniaceae. E/Pe: clade including Ensiculifera and Pentapharsodinium. HET: Heterocapsaceae. KRY: Kryptoperidiniaceae. PER: Peridiniaceae. T/Pf: clade including Pfiesteria and Thoracosphaera. ZOO: Zooxanthellaceae.