Publication Date:
2023-04-27
Description:
The Prorocentrales are a unique group of dinophytes based on several apomorphic traits, but species delimitation is
challenging within the group. Prorocentrum triestinum was described by Josef Schiller in 1918 as an important bloomforming
species from Trieste (Mediterranean, Adriatic Sea) with a conspicuous asymmetric outline and a small, asymmetrically
located subapical spine. All subsequent records under this name fail to conform to Schiller’s original description.
These inconsistencies have their origin in John Dodge’s 1975 revision of Prorocentrum, which placed Prorocentrum
redfieldii, a more symmetrical, slender species with a long apical spine, into synonymy under P. triestinum. To clarify
this confusion, we collected samples at the type locality of P. triestinum in Trieste and established a strain that is
morphologically consistent with the protologue and suitable for use in epitypification. Morphology and rRNA sequence
data of this strain were compared with four new strains identified as P. redfieldii from the Mediterranean Sea and the North
Atlantic Ocean. Cells of P. triestinum had an asymmetric outline in lateral view and a small, dorso-subapical spine. These
features, which are readily resolved by light microscopy, were distinct from those of the nearly symmetrical and slender cells
of P. redfieldii, which had a long, apically located spine. The species are nevertheless closely related and share an identical
architecture of the periflagellar area with a distinctive, largely reduced accessory pore together with a very small platelet 7.
This apomorphy clearly differentiates both species from other species of Prorocentrum. Both species differ in their primary
rRNA sequences, and ITS and LSU sequence differences will enable them to be distinguished in future meta-barcoding
studies. The present study demonstrates that P. triestinum and P. redfieldii are distinct species and thus contributes to
a reliable biodiversity assessment of Prorocentrum.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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