ISSN 10630740, Russian Journal of Marine Biology, 2014, Vol. 40, No. 5, pp. 354–363. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © K.I. Shorenko, N.A. Davidovich, M.S. Kulikovskiy, 2014, published in Biologiya Morya.
The morphological features of frustules are still one
of the main criteria for the identification and distin
guishing of diatom taxa. Using a fixed material from
natural populations provides a number of advantages.
Nevertheless, in this case a researcher has to admit
some limitations of the method, including the complex
ity of description of frustule characteristics during the
lifespan of the organism and the impossibility of obtain
ing information on the genetic identity and reproduc
tive compatibility of individuals. Sometimes it becomes
difficult to collect a sufficient amount of material for the
study of the variability of taxon characters and to assess
its meaning, either intra or interspecific. By using
clonal cultures, which are the genetically homogenous
descendants of a single cell, one can solve these and sev
eral other problems. The importance of clone cultures
when applied to systematics, particularly for determi
nation of the boundary of the species and its variability,
deserves special mention. Genetic investigations are
impossible without isolation of clones. Use of clonal
cultures actually has become a standard technique and
a norm in modern diatomology .
The goal of the present study consisted in the assess
ment of the variability and the range of variation of sev
eral morphological characters in the diatom
within a clone compared with variation in the
group of clones obtained from a natural population, as
well as with data on the species diagnosis.
The numerous facts on the existence of cryptic spe
cies and species complexes [29, 39 etc.] necessitate
discussion on the problem of species unity and vari
ability, including samples that were taken from the
same point. In our work, the biological criterion of
crossability/noncrossability is used for confirmation
of species identity of isolated clones . The repro
ductive compatibility of particular clones serves as an
objective basis for the study of variations that do not
extend beyond the species boundaries.
MATERIALS AND METHODS
Takano, 1983, a poorly studied
species that is found in samples from the Atlantic coast
of France, served as the object for this study. The orig
inal description of the species was made by the Japa
nese researcher H. Takano, who indicated the Pacific
intertidal zone in the southern part of Aichi Prefec
ture, Honshu, Japan as the type habitat . Later,
was found in the Japanese Atsumi, Abu
ratsubo, and Tanoura bays [23, 26, 27], as well as in the
Amur Bay of the Sea of Japan, Russia , in the
Coral Sea off the Australia coast , in the Indian
Ocean (Andaman Islands coast) , and in the
Atlantic Ocean (eastern coast of Canada, the Sea of
Marmara, and the Black Sea) [6, 20, 21, 31, 38].
Unfortunately, the abovelisted works are mostly flo
ristic and do not put emphasis on the morphological
variability of the species.
The Variability of the Morphological and Structural Elements
of the Frustule in Genetically Homogeneous and Heterogeneous
Groups of the Diatom
K. I. Shorenko
, N. A. Davidovich
, and M. S. Kulikovskiy
Karadag Nature Reserve, Feodosia, 98188 Russia
Papanin Institute for the Biology of Inland Waters, Russian Academy of Sciences, Borok, 152742 Russia
Received September 19, 2013
—The inter and intraclonal variability of the morphology and ultrastructure of the frustule of
Takano, 1983 was investigated. This study showed a wider intraclonal variability than in the
diagnosis of the species. An emended diagnosis of the species is provided; a twofold reduction in the density
of striae that are visible under a light microscope was found compared to electronmicroscope images.
: variability, clone, frustule morphology and ultrastructure,