ISSN 1022-7954, Russian Journal of Genetics, 2017, Vol. 53, No. 2, pp. 252–258. © Pleiades Publishing, Inc., 2017.
Original Russian Text © T.Yu. Mayor, Yu.A. Galimova, N.G. Sheveleva, L.V. Sukhanova, S.V. Kirilchik, 2017, published in Genetika, 2017, Vol. 53, No. 2, pp. 233–239.
Molecular Phylogenetic Analysis of Diacyclops and Acanthocyclops
(Copepoda: Cyclopoida) from Lake Baikal Based on COI Gene
T. Yu. Mayor
*, Yu. A. Galimova
, N. G. Sheveleva
, L. V. Sukhanova
, and S. V. Kirilchik
Limnological Institute, Siberian Branch, Russian Academy of Sciences, Irkutsk, 664033 Russia
Institute of Molecular and Cellular Biology, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Received October 26, 2015; in final form, July 5, 2016
Abstract⎯Lake Baikal is inhabited by a relatively large number of cyclopid species, many of which are
endemics. Two genera, Diacyclops Kiefer, 1927 and Acanthocyclops Kiefer, 1927, are the most specious in the
lake. Taxonomic discrimination of the majority of representatives of these genera is difficult owing to their
high morphological similarities and poor standard description. In this study, a molecular phylogenetic anal-
ysis of Lake Baikal members of the Diacyclops/Acanthocyclops group is performed on the basis of mitochon-
drial cytochrome c oxidase subunit I (COI) gene. It is shown that a fragment of COI 1000 bp long is sufficient
for intragenus discrimination of the cyclopids of Lake Baikal. The issues of Diacyclops/Acanthocyclops taxon-
omy are reflected in the obtained molecular data. Two distinct phylogenetic groups of Diacyclops genus with
uncertain taxonomic status are revealed.
Keywords: mitochondrial DNA, molecular phylogeny, Crustacea, polyphyly
Cyclopids of Lake Baikal are highly endemic and
speciose group of organisms. According to recent data,
there are 46 species and subspecies belonging to 11
genera , 64% of which are endemics. Members of
genus Diacyclops Kiefer, 1927 compose one-third of
this list and are all endemic, with the exceptions of
D. bisetosus Rehbeerg, 1880 and D. bicuspidatus Claus,
1857. The last of the described species of this genus
from Lake Baikal is D. zhimulevi Sheveleva, Timosh-
kin, 2010. This species, along with D. eulitoralis Alek-
seev, Arov, 1986, concerns to the smallest cyclopids
described in Lake Baikal. On average, a sexually
mature female measures 0.32 mm without furcal setae.
N.G. Sheveleva and colleagues note that a whole group
of yet undescribed small psammophilous cyclopids with
a body length not exceeding 0.5 mm inhabits the littoral
of Southern Baikal, and D. zhimulevi is merely the first
described member of this group .
Describing 16 new species and subspecies of the
Baikal cyclopids, Mazepova placed them in the genus
Acanthocyclops Kiefer, 1927, noting transitional fea-
tures between two genera (Acanthocyclops/Diacyclops)
. In modern-day systematics , the genus name
used for most of such species is Diacyclops. Morpho-
logical similarity of Diacyclops/Acanthocyclops,
ambiguous separation between them, and lack of stan-
dard descriptions of said species result in taxa being
moved from one genus to another . Complexity of
the Acanthocyclops/Diacyclops group is also due to its
relatively old age and species richness. There are more
than 100 species in genus Diacyclops, making it the
most numerous and diverse genus of all Cyclopoida
[6, 7]. A number of researchers propose that both gen-
era are para- or polyphyletic [7, 8].
As noted by Sheveleva, most studies of Baikal
cyclopids are devoted to description of new species,
and only a few are devoted to their ecology .
Recently, studies on Baikal cyclopids using molecular
methods appeared. Some of them are devoted to esti-
mation of the sizes of genomes and the issue of chro-
matin diminution in Cyclopoida, and others are
devoted to phylogenetic studies [9–11]. At the same
time, however, Acanthocyclops/Diacyclops, the largest
group of cyclopids in Baikal, remains poorly studied.
The present study continues the molecular phylo-
genetic analysis of cyclopids of Lake Baikal, the first
results of which were published earlier . We
increased the size of the analyzed fragment of mito-
chondrial cytochrome c oxidase subunit I gene (COI)
and expanded the number of studied species.
MATERIALS AND METHODS
Samples were collected in Lake Baikal from depths
of up to 40 m within the area of the settlements of Bol-
shiye Koty (51°54′25′′ N 105°04′14′′ E) and List-
vyanka (51°51′11 ′′ N 104°52′55′′ E) in 2009–2011.