Report on two rare Myostenostomum species (Platyhelminthes: Catenulida) from the Volga River Basin

2017·3.1 MB·

by  R. P. Tokinova

ZOOSYSTEMATICA ROSSICA, 26(2): 199–204 25 DECEMBER 2017
Report on two rare Myostenostomum species (Platyhelminthes:
Catenulida) from the Volga River Basin
Сообщение о двух редких видах Myostenostomum (Platyhelminthes:
Catenulida) из Волжского бассейна
R.P. TOKINOVA* & S.V. BERDNIK
Р.П. ТОКИНОВА, С.В. БЕРДНИК
R.P. Tokinova, Research Institute for Problems of Ecology and Mineral Wealth Use of Tatarstan Academy of Sciences,
28, Daurskaia str., Kazan 420087, Russia. E-mail: [email protected]
S.V. Berdnik, Research Institute for Problems of Ecology and Mineral Wealth Use of Tatarstan Academy of Sciences,
28, Daurskaia str., Kazan 420087, Russia. E-mail: [email protected]
Two rare catenulid species, Myostenostomum vanderlandi Rogozin, 1992 and M. bulbocauda-
tum Luther, 1960, were found in reservoirs of the Volga-Kama Biosphere Reserve (Middle
Volga Basin, Russia) during a survey of microturbellaria in 2013. Both the species were record-
ed for the first time in the fauna of the Volga Basin, while M. vanderlandi, previously known
only from water bodies of South America, was first found in the Holarctic. The morphological
characters and geographical distribution of the species are discussed.
При проведении исследований в 2013 году, в составе микротурбеллярий водоемов
Волжско-Камского природного биосферного заповедника (бассейн Средней Волги, Рос-
сия) обнаружены две редкие катенулиды Myostenostomum vanderlandi Rogozin, 1992 и
M. bulbocaudatum Luther, 1960. Оба вида впервые отмечены в фауне Волжского бассейна,
при этом M. vanderlandi, ранее известный лишь из водоемов Южной Америки, впервые
указывается для Голарктики. Обсуждаются особенности морфологии и географического
распространения обнаруженных видов.
Key words: Republic of Tatarstan, Volga-Kama Biosphere Reserve, Lake Shatunikha, micro-
turbellarians, Myostenostomum bulbocaudatum, Myostenostomum vanderlandi, new records
Ключевые слова: Татарстан, Волжско-Камский заповедник, озеро Шатуниха, микротур-
беллярии, Myostenostomum bulbocaudatum, Myostenostomum vanderlandi, новые находки
INTRODUCTION nostomum for three species, Myostenosto-
mum tauricum (Nasonov, 1923), M. bulbo-
Catenulida is a group of freshwater
caudatum Luther, 1960, and M. fasciatum
(with few exceptions) microturbellar-
(Vejdovsky, 1880). The main character of
ians (Platyhelminthes) which reproduce
these species distinguishing them from Ste-
mainly by transverse fission of the body
nostomum is the presence of a muscular gut
(paratomy) and form chains of two or more
that is the thickening around the proximal
zooids. Stenostomum Schmidt, 1848 is the
part of the intestine formed by multilayered
largest of the catenulid genera, including
muscle fibers (Luther, 1960). Based on this
more than fifty known species (Noreña et
character, eight species are currently placed
al., 2005, Damborenea et al., 2011). In 1960,
into the genus Myostenostomum, and among
A. Luther described a new genus Myoste-
them five are known from Europe: M. bul-
bocaudatum, M. fasciatum, M. ilmenicum
* Corresponding author. Rogozin, 1992, M. lutheri Rogozin, 1992,
© 2017 Zoological Institute, Russian Academy of Scienсes
200 R.P. TOKINOVA & S.V. BERDNIK. REPORT ON TWO RARE MYOSTENOSTOMUM SPECIES
and M. lutetianum (de Beauchamp, 1948). a cattle watering place. The opposite shores
Two species, M. vanderlandi Rogozin, 1992 are covered with trees and bushes; vegeta-
and M. marcusi Rogozin, 1992, are known tion of the coastal strip is represented here
from South America and one, M. gigerium by reedmace (Typha sp.).
(Kepner et Carter, 1931) is recorded for Microturbellarians were collected man-
North America (Luther, 1960; Rogozin, ually by washing from aquatic plants grow-
1992, 2012; Artois et al., 2013). ing near the lake shores. Worms were trans-
Two representatives of the genus, M. il- ported to the laboratory, where they were
menicum and M. bulbocaudatum, are known studied under the microscope LOMO MIC-
in the fresh waters of Russia in the southern MED–5. Worms were photographed using
Urals (Rogozin, 1992, 2012). Members of the ToupTek UCMOS05100KPA C-mount
this genus can also be found in the Crimean camera. Species identification was carried
Peninsula from which N.V. Nasonov (1924) out on alive specimens using the taxonomic
described M. tauricum. However, it is diffi- diagnoses of A. Luther (Luther, 1960) and
cult to judge to which species the Crimean A.G. Rogozin (Rogozin, 1992).
specimens belong since the name M. tauri-
cum, according to Rogozin (1992), should RESULTS
be considered as a nomen dubium.
Class CATENULIDA
In 2013, two species belonging to the
genus Myostenostomum, M. vanderlandi Family STENOSTOMIDAE
and M. bulbocaudatum, were found during Genus Myostenostomum Luther, 1960
a survey of microturbellaria in reservoirs of
the Volga-Kama State Natural Biosphere Myostenostomum vanderlandi
Reserve (the Middle Volga Basin, Russia). Rogozin, 1992
In this paper, we present the data on find- (Fig. 1A–D)
ings of these species and discuss their mor-
Material examined. Russia: Republic of Ta-
phological characters and the geographical
tarstan, Volga-Kama Reserve, Middle Volga
distribution.
Basin, Lake Shatunikha, on coastal vegetation,
12.IX.2013, S.V. Berdnik, R.P. Tokinova leg., one
MATERIAL AND METHODS specimen studied alive (11 photos, 2 videos).
Remarks. The first representatives of
Specimens of the genus Myostenosto- this species were found by the Dutch zo-
mum were found on Sept. 12, 2013 in Lake ologist Jacob van der Land in the vicinity
Shatunikha (N55°55´44´´, E48°46´29´´), of Paramaribo (Suriname, South America)
located in the vicinity of Belo-Bezvodnoye during research on freshwater meiobenthos
Setllm., in the guard zone of the Raifa (Land, 1970). In his paper, the author fig-
cluster of the Volga-Kama State Natural ured the habitus of Myostenostomum sp. but
Biosphere Reserve. The lake is a drainless refrained from giving a name to a poorly
basin of suffosive origin with a small area examined species. The name for the new
(1.2 ha) and a maximum depth of three m. species and its description was given after a
The lake water belongs to the hydrocarbon- quarter of a century by another researcher.
ate class of the calcium group of waters; the A.G. Rogozin, studying the microturbellari-
total hardness is characterised as soft. The ans in the southern Urals, conducted a brief
active reaction of the medium is close to revision of the genus Myostenostomum and
neutral. The quality of water corresponds described the worm depicted in the figure
to the category of “slightly polluted waters” of van der Land as a new species, M. vander-
(Unkovskaya et al., 2002). The lake shores landi (Rogozin, 1992).
in the western and north-western parts are Description. The studied specimen with-
flat and open, used as lands for grazing and out the genital system and consisting of two
© 2017 Zoological Institute, Russian Academy of Scienсes, Zoosystematica Rossica 26(2): 199–204
R.P. TOKINOVA & S.V. BERDNIK. REPORT ON TWO RARE MYOSTENOSTOMUM SPECIES 201
Fig. 1. Myostenostomum vanderlandi Rogozin, 1992. A, habitus of alive specimen; B, anterior end of
body (arrangement of brain lobes is shown on the right); C, posterior end of body; D, muscular gut
region. For abbreviations see text. Scale bars: 200 μm (A), 50 μm (B, C, D).
zooids. By the main structural features, it is (Fig. 1A, 1C). Ciliated pits (cp) 35 μm in
similar to van der Land’s figure of Myoste- width. Muscular gut [or ‘Muskeldarm’ by
nostomum sp. in thin and vermiformly elon- Luther (1960)] (Fig. 1D) well developed,
gated body with caudal appendage. Body 45 μm long in anterior zooid and not yet
colouration light brown, except for colour- formed in posterior zooid.
less muscular gut. Body length reaching Pharynx (ph) well separated from ante-
1.3 mm in motion, while tail length 65 μm rior part of intestine (i) [‘Darm’ by Luther
© 2017 Zoological Institute, Russian Academy of Scienсes, Zoosystematica Rossica 26(2): 199–204
202 R.P. TOKINOVA & S.V. BERDNIK. REPORT ON TWO RARE MYOSTENOSTOMUM SPECIES
(1960)], 60 μm in length. Protonephridium Myostenostomum bulbocaudatum
(pr) terminating in nephridiopore on tail Luther, 1960
base. According to Rogozin (1992), the (Fig. 2A–E)
brain structure is the most reliable feature
Material examined. Russia: Republic of Ta-
for the recognition of the Myostenostomum
tarstan, Volga-Kama Reserve, Middle Volga
species. Brain in studied specimen generally
Basin, Lake Shatunikha, on coastal vegetation,
corresponding to structure of M. vanderlan-
12.IX.2013, S.V. Berdnik, R.P. Tokinova leg., two
di brain (Fig. 1B). Divided anterior lobes specimens studied alive (25 photos, 4 videos).
(ab) of trapezoidal shape; seven metameric Description. Both the examined speci-
ganglia (mg) in lateral chains adjoining to mens without the genital system and consist
them anteriorly. Posterior lobes shaped like of two zooids. Length of worms in motion
unpaired triangular ganglia (pb) with apex reaching 1.5 mm (specimen 1) and 2.0 mm
directed anteriad and adjoining to anterior (specimen 2). Colour light brown, except-
lobes. Small elongated additional ganglia ing colourless muscular gut (Fig. 2A, 2B).
(ag) adjoining to lateral angles of posterior Body of cylindrical shape, somewhat nar-
ganglia. Refractile bodies absent. rowed and rounded at anterior end. Poste-
Distribution. Republic of Suriname riorly body ends with dorsal caudal append-
(Land, 1970), Russia [Republic of Tatar- age of 65 (specimen 1) to 200 (specimen
stan, Volga-Kama Biosphere Reserve (new 2) μm long. Tail narrowing distally, with
record)]. base conically widened (Fig. 2C, 2D). In
Fig. 2. Myostenostomum bulbocaudatum Luther, 1960. A, habitus of alive specimen 1; B, divided alive
specimen 2; C, D, posterior end of body with ventral protuberance [indicated by arrow] (C) and
dorsal caudal appendage (D); E, scheme of brain structure. For abbreviations see text. Scale bars: 200
μm (A, B), 50 μm (C, D), 100 μm (E).
© 2017 Zoological Institute, Russian Academy of Scienсes, Zoosystematica Rossica 26(2): 199–204
R.P. TOKINOVA & S.V. BERDNIK. REPORT ON TWO RARE MYOSTENOSTOMUM SPECIES 203
specimen 2, ventral surface of body inferior- This can be concluded, for example, from
ly base of tail with small protuberance indi- the following characters. Our specimen has
cating second small tail. Muscular gut most seven pairs of metameric ganglia instead of
powerfully developed in anterior zooids, its five to six pairs of ganglia in the figure of
length reaching 140 μm (specimen 1) and van der Land; the anterior paired lobes have
250 μm (specimen 2), whereas it looking a trapezoidal shape instead of an elongated
like narrow ring in posterior zooids. Cili- oval-triangular shape. Unfortunately, it is
ated pits large, 80 μm (specimen 1) and 110 difficult to judge whether the revealed dif-
μm (specimen 2) in length, lying dorsolater- ferences fit the range of intraspecific vari-
ally on anterior end of body. Mouth opening ability of M. vanderlandi brain structures
rounded, with folded margins. Pharynx well because the only one specimen is available.
developed, cone-shaped. Short anterior part As for another species, all the listed mor-
of intestine better developed in specimen 2. phological features clearly indicate that the
Anterior brain lobes (ab) dentate and ad- studied worms belong to M. bulbocaudatum
jacent to ciliated pits (cp). Posterior lobes described by Luther (1960) from Southern
and transverse cerebral commissure fused, Finland. We consider it is possible to com-
forming arcuate ganglion (pb) with vertex ment the recent new record of M. bulbocau-
directed anteriad and adjacent to anterior datum for Ukraine by Kanana (2016). Ap-
lobes (Fig. 2E). Refractile bodies absent. parently, the species identification in this
Anomopods from the family Chydoridae paper is dubious by reason of the presence
(Crustacea: Branchiopoda: Cladocera) was in the brain of the Ukrainian specimens of
found in the intestine of worms. two anterior chains with ten metameric
Distribution. Southern Finland (Luther, ganglia which are actually absent in M. bul-
1960); Russia [Chelyabinsk Prov., Lake bocaudatum. This feature in the structure of
Baraus (Rogozin, 2012); Republic of Ta- the brain, as well as the presence of the cau-
tarstan, Volga-Kama Biosphere Reserve, dal appendage, brings these specimens clos-
Lake Shatunikha (new record)]. er to M. vanderlandi. However, the available
data are not sufficient to identify it exactly
DISCUSSION
with any known representative of Myoste-
The catenulids species M. vanderlandi nostomum. Therefore, obtaining sufficient
and M. bulbocaudatum found in the Volga- amount of material for comparison and
Kama Reserve (Lake Shatunikha) were searching for the most informative criteria
recorded for the first time in the fauna of for the reliable recognition of Myostenosto-
the Volga River Basin. M. vanderlandi, pre- mum species are important tasks. Molecular
viously recorded only once from Suriname techniques can prove to be extremely prom-
(the Atlantic coast of South America), was ising tools to overcome taxonomic problems
first found in the Holarctic. Any species in the recognition of Myostenostomum.
common for two or more zoographical re-
gions were previously unknown among the ACKNOWLEDGMENTS
Myostenostomum. The remoteness of the
We would like to thank A.G. Rogozin for his
newly identified species population from
support with the identification of species.
the former natural habitat of M. vander-
landi can be explained by the poverty and
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© 2017 Zoological Institute, Russian Academy of Scienсes, Zoosystematica Rossica 26(2): 199–204
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Editorial responsibility: D.A. Gapon
© 2017 Zoological Institute, Russian Academy of Scienсes, Zoosystematica Rossica 26(2): 199–204