Publication Date:
2019-07-17
Description:
Alexandrium ostenfeldii (Paulsen) Balech and
Tangen and A. peruvianum (Balech and B.R.
Mendiola) Balech and Tangen are morphologically
closely related dinoflagellates known to produce
potent neurotoxins. Together with Gonyaulax
dimorpha Biecheler, they constitute the A. ostenfeldii
species complex. Due to the subtle differences in
the morphological characters used to differentiate
these species, unambiguous species identification
has proven problematic. To better understand the
species boundaries within the A. ostenfeldii complex
we compared rDNA data, morphometric characters
and toxin profiles of multiple cultured isolates from
different geographic regions. Phylogenetic analysis
of rDNA sequences from cultures characterized as
A. ostenfeldii or A. peruvianum formed a
monophyletic clade consisting of six distinct groups.
Each group examined contained strains
morphologically identified as either A. ostenfeldii or
A. peruvianum. Though key morphological characters
were generally found to be highly variable and not
consistently distributed, selected plate features and
toxin profiles differed significantly among
phylogenetic clusters. Additional sequence analyses
revealed a lack of compensatory base changes in
ITS2 rRNA structure, low to intermediate ITS/5.8S
uncorrected genetic distances, and evidence of
reticulation. Together these data (criteria currently
used for species delineation in dinoflagellates) imply
that the A. ostenfeldii complex should be regarded a
single genetically structured species until more
material and alternative criteria for species
delimitation are available. Consequently, we propose
that A. peruvianum is a heterotypic synonym of
A. ostenfeldii and this taxon name should be
discontinued.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
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