Abstract
The family Ceratocoryaceae includes the genera Ceratocorys, Protoceratium, and Schuettiella, whose phylogenetic relationships are poorly known. Here, the new non‐yessotoxin‐producing species of the genus Ceratocorys, Ceratocorys mariaovidiorum sp. nov., previously reported as the toxic Protoceratium reticulatum, is described from examinations by light and scanning electron microscopy, molecular phylogeny, and toxin analyses. The species description is made from culture samples of strains CCMP1740 and CCMP404 from USA waters. Ceratocorys mariaovidiorum is globular and has thick and strongly reticulated plates with one pore within each reticule, just like P. reticulatum, but the key difference between the two species is the presence of five precingular plates in C. mariaovidiorum instead of six as in P. reticulatum. The thecal plate formula is Po, 4′, 0a, 5″, 6c, ~7s, 5‴, 0p, 2′′′′. The apical pore plate is oval with a λ‐shaped pore. The first apical plate is narrow with a ventral pore on the right anterior side; it contacts the apical pore plate and its contact with the anterior sulcal plate is slight or absent. The fourth precingular plate of other Gonyaulacales is absent. Ceratocorys mariaovidiorum may have small spines on the second antapical plate. A phylogenetic study based on internal transcribed spacer/5.8SrDNA supports the morphological classification of C. mariaovidiorum as a new species of Ceratocorys and in a different clade from P. reticulatum.
Highlights
The family Ceratocoryaceae includes the genera Ceratocorys, Protoceratium, and Schuettiella, whose phylogenetic relationships are poorly known
The results presented show that strains CCMP404 and CCMP1720, previously listed as Protoceratium reticulatum (Paz et al 2007, Howard et al 2009, Akselman et al 2015, National Center for Marine Algae and Microbiota (NCMA) 2017), correspond to a new species of the genus Ceratocorys, C. mariaovidiorum
The great morphological resemblance between C. mariaovidiorum and P. reticulatum would account for the previous misidentification, because in ventral view, even in scanning electron microscopy (SEM), they are hardly distinguishable, if at all
Summary
The family Ceratocoryaceae includes the genera Ceratocorys, Protoceratium, and Schuettiella, whose phylogenetic relationships are poorly known. Ceratocorys is a genus of marine dinoflagellates belonging to the order Gonyaulacales and to the family Ceratocoryaceae (Lindemann 1928), which includes the genera Protoceratium and Schuettiella (Gomez 2012). They all have a striking ornamentation and a distinctive general morphology They have a well-sculpted theca, a flat epitheca commonly much shorter than the hypotheca, broad cingular lists or crests, and short or large hypothecal spines (four projecting from the edges of the antapical plate and two single dorsal and ventral spines; Fensome et al 1993, Zirbel et al 2000). The tabulation of thecal plates of Ceratocorys does not completely coincide with that of other gonyaulacoids In the epitheca, it was described as having three apical plates, an intercalary plate (1a), and five precingular plates. The fourth precingular plate in Ceratocorys represents the fourth and fifth precingular plates of other Gonyaulacales, which means that they have fused or that one is missing (Fensome et al 1993)
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