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Aquatic Invasions (2007) Volume 2, Issue 1: 55-58
URL: http://www.aquaticinvasions.ru
© 2006 European Research Network on Aquatic Invasive Species
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Research article
North American freshwater limpet Ferrissia fragilis (Tryon, 1863) (Gastropoda:
Planorbidae) – a cryptic invader in the Northern Black Sea Region
Mikhail O. Son
Odessa Branch Institute of Biology of the Southern Seas, National Academy of Sciences of Ukraine,
Odessa, Ukraine
E-mail: michail.son@gmail.com
Received 24 November 2006; accepted in revised form 5 February 2007
Abstract
In the 2002 North American freshwater limpet Ferrissia fragilis (Tryon, 1863) was recorded for the first
time in the continental waters of Black Sea Region. This is considered to be a continuation of invasion in
the Black Sea Region as this species was previously introduced into Crimean Peninsula reservoirs in the
early 20th century. A juvenile form of F. fragilis found in Central Crimea was previously described as
the freshwater limpet Ancylus lacustris brevis (Puzanov 1925). According to the rules and recom-
mendations (8B and 8.3) of the International Code of Zoological Nomenclature we point that this
information can not be used as nomenclatural act (recommendation of ICZN about providing of first
publication with nomenclature act as printing on paper). Since 2002, F. fragilis has been sampled in the
freshwaters of the Dniestr Delta. It was observed that this invader could sustain the extreme conditions
of an unusually cold winter (2005-2006).
Key words: molluscs, alien species, Black Sea Region, Ferrissia fragilis, invasion, synonymy
Introduction
Studying of the alien freshwater limpets in
Europe presents many fascinating problems to
the investigator, who has to consider their
distribution, invasive history, descent, and
chronology of their spread. Alien freshwater
limpets have been identified variously from
different European and Asian countries under
several names: Pettancylus petterdi (Johnston,
1879), P. australicus (Tate, 1880), Ferrissia
wautieri (Mirolli, 1960), F. clessiniana (Jickelli,
1882) (reviewed in Starobogatov and Prozorova
1990, Walther et al. 2006). During the 20th
century different authors considered this species
as invasive, either from Australia (Starobogatov
and Prozorova 1990) or Central Asia (Falkner
and Proschwitz 1995) or alternatively as a native
European species, which had not been identified
earlier because of small size of this species and
similarity to Acroloxus lacustris (Linnaeus,
1758) (Kinzelbach 1984, Baur and Ringeis
2002). A recent investigation using molecular
taxonomical methods (Walther et al. 2006) has
revealed that these small European Ancylidae are
in fact single Nearctic (North American) species,
Ferrissia fragilis (Tryon 1863). In English-
written literature, findings in Germany of an
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M. Son, Ferr i ss ia f ragi l i s in the Northern B lack Sea Region
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“enigmatic” freshwater limpet as early as 1949
indicate the first European record of F. fragilis
(Walther et al. 2006). However, labeled
specimens of this particular species exist in the
collections of Zoological Institute (St. Peters-
burg): “Gallia, Vermont” (19thcentury) and
“surroundings of St. Petersburg” (1919) (Staro-
bogatov and Prozorova 1990). So, it can be
recognized that these limpets occurred in
European waters earlier than were recorded as
invasive species.
Material and Methods
This paper is based mainly on material collected
by the author in the Dniestr River Basin (South-
Western Ukraine) and also from ornamental
aquaria. This is deposited in the mollusc
collection of the Odessa Branch Institute of
Biology of the Southern Seas (OB IBSS). Some
samples were collected by E. S. Dyatlova
(Odessa National University), and by A. I.
Koshelev (OB IBSS). All newly collected
material was fixed in 70% ethanol. The
specimens in Figures 1 and 2 were photographed
using a stereomicroscope DM-143 with digital
camera.
All aquatic biotopes present in the Dniestr
Delta (river channel, lakes, springs, pools, and
estuary) were investigated annually from 1999 to
2006. Field research was undertaken according
to standard methods (Zhadin 1965).
Expansion of Ferrissia fragilis in Continental
Ukraine and Moldova
In continental Ukraine F. fragilis was recorded
for the first time in summer 2002 (Lake Beloje in
the Dniestr Delta). During 2005-2006 F. fragilis
invaded different parts of the Dniestr Delta
(Ukraine and Moldova) (Figure 3). In 2006 one
mollusc was collected in saline pool on the
southern coast of Tiligul’skij Liman (estuary of
the Tiligul River, SW Ukraine). This second
record may indicate casual spread of F. fragilis
because conditions of this biotope incompatible
with ecological characteristics of freshwater
species. All these specimens were collected in
natural biotopes excepted the Crimean records.
In the Dniestr Delta F. fragilis was found in
flowing waters, mostly on stone substrates and
on reed (Phragmites australis).
Figure 1. Ferrissia fragilis (Tryon 1863) (Photo:
Mikhail O. Son)
Figure 2. Young translucent Ferrissia fragilis from
ornamental aquarium (Photo: Mikhail O. Son)
Figure 3. New records of Ferrissia fragilis. Map of Europe
showing Northern Black Sea Region (inserted); detailed
map indicating (A) Lake Beloje and Dniestr Delta (B)
Tiligul’skij Liman (C) Simpheropol (Crimean Peninsula)
(D) Southern coast of Crimea
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M. Son, Ferr i ss ia f ragi l i s in the Northern B lack Sea Region
57
One ecological aspect of this expansion is
very interesting. Water temperature is very often
an important factor limiting the expansion range
of alien species. It is especially usually for
species which have spread as a result of the of
aquarium trade. These species in Europe (except
more southern regions such as Mediterranean,
Balkans, Southern Ukraine, Crimea and
Caucasus) inhabit mostly artificial warm-water
habitats (reservoirs-coolers, reservoirs of
botanical gardens etc). Despite this, F. fragilis
survived outside its native range during the
abnormal cold winter 2005-2006 when the air
temperature in Southern Ukraine reached minus
ten degrees Celsius. As the invader has been
found mostly in shallow waters (<10 cm) which
are the first to freeze, it means that of this
species could sustain freezing (possible in the
egg capsules’ stage).
Identification of “Mystery” Freshwater
Limpet in Crimea (Ukraine)
The Crimean Peninsula is a region with reduced
freshwater species richness due its geographi-
cally isolated character (Figure 3). Before the
1950s the hydrofauna of Crimea was separated
from that of the main continental waters. Most of
widespread in Europe freshwater molluscs were
absent in Crimean waters. The construction of
the North-Crimean Channel and the subsequent
introduction of freshwater species to Crimean
reservoirs had a destructive effect on the zoogeo-
graphical barriers between the Crimean
Peninsula and continental Ukraine. From the
19th century until recently, macroinvertebrate
investigations in Crimea produced only two
freshwater limpet records. Juvenile limpets were
collected from artificial reservoirs near Simfero-
pol (now capital of the Autonomous Republic of
Crimea, Ukraine) by D. E. Beling in 1919 and
following years by I. I. Puzanov (first published
records, Puzanov 1925). I.I. Puzanov (1925)
discussed differences between this limpet and the
native European A. lacustris. The Crimean
limpets had well-developed concentric sculpture,
smaller size and were different in terms of
proportions of shell and body. Other
characteristics important for identification of
freshwater limpets (sculpture and bend of apex)
could not be determined by I.I. Puzanov in
young translucent individuals, such as those
shown in Figure 2. Probably due to the lack of
taxonomical information on other small-sized
species of freshwater limpets at this time, the
author described these molluscs as a new sub-
species of the above mentioned Acroloxus
(former Ancylus) species – Ancylus lacustris
brevis Puzanov, 1925 (with note that this new
taxa probably must have higher taxonomic range
than subspecies).
For many years it was not known where I.I.
Puzanov’s non-inventoried collections were
situated. When this collection was found,
relevant information became available on the
snail fauna of Crimea before the construction of
the North-Crimean Channel (Son 2005).
Unfortunately, the box containing type material
of Ancylus lacustris brevis had become damaged
over time and the shells were in fact lost.
Using many characteristic attributes, which
separate F. fragilis from A. lacustris (smaller
and flatter shell, more developed concentric
sculpture, small translucent body) we now
consider Ancylus lacustris brevis Puzanov, 1925
as junior synonym of this cryptic invader to
Europe – Ferrissia fragilis (Tryon, 1863).
According to rules and recommendations (8B
and 8.3) of International Code of Zoological
Nomenclature (1999) we point that this
information can not be used as nomenclatural act
(ICZN recommend to provide first publication of
nomenclature act as printing on paper; in this
article we use disclaimer of nomenclature act for
further publication according rules of zoological
nomenclature).
For many years after I.I. Puzanov’s
investigations, no special malacological studies
in Crimean waters took place. The next malaco-
logical studies in Crimean waters, showed the
occurrence of F. fragilis in ponds on the
southern coast of Crimea (Stadnichenko 1987)
and the absence of A. lacustris on the all
Crimean area (Stadnichenko 1979).
Sporadic records of F. fragilis in the Crimea
there this species or have been present since
early XX century or had same separate invasions
and rapid mass invasion in the Dniestr Delta
showed very significant difference. It can be
explained by hydrographical conditions of
Crimean Peninsula and continental part of Black
Sea Coast. On the Crimean Peninsula un-
developed natural freshwater limnic conditions
whereas continental part of Black Sea Coast have
enormous space of river deltas with high
diversity of limnic and slow-flowing biotopes
what correspond to ecological preferences of
F. fragilis.
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M. Son, Ferr i ss ia f ragi l i s in the Northern B lack Sea Region
58
Acknowledgements
We are indebted to E. S. Dyatlova (Odessa
National University, Ukraine) and A. I. Koshelev
(OB IBSS, Ukraine) for helping with collection
of material in the field, and to Dr Frances Lucy
(Institute of Technology Sligo, Ireland) for
valuable comments and English editing. This
work was partly supported by the European
Commission 6th Framework Program Integrated
Project ALARM (contract GOCE-CT-2003-
506675).
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Annex
New records of Ferrissia fragilis (Tryon, 1863) in the Black Sea Region
Location coordinates
Location Latitude, °N Longitude, °E
Record date Species abundance Collector
Turunchuk River (branch of Dniestr
Delta)
46°28' 30°21' 13.08.2005 10-20 individuals M. O. Son
Alexandrovskij Erik 46°24' 30°15' 14.08.2005 10-50 individuals M. O. Son
Alexandrovskij Erik 46°40' 30°25' Summer 2006 10-50 individuals M. O. Son
Lake Beloe 46°27' 30°10' 26.08.2002 1 individuals E. S. Dyatlova
Dniestr River, Site 1 46° 42' 30°17' Summer 2006 10-50 individuals M. O. Son
Dniestr River, Site 2 46°41' 30°14' Summer 2006 10-50 individuals M. O. Son
Dniestr River, Site 3 46°41' 30°13' Summer 2006 10-50 individuals M. O. Son
Brackish pool on the southern coast of
Tiligul’skij Liman
46°38' 31°10' Spring 2006 1 individuals A. I. Koshelev
Lake Beloe 46°27' 30°10' Summer 2006 1 individuals E. S. Dyatlova
