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First Records for Discus rotundatus and a Feral Population of
Oxychilus draparnaudi (Gastropoda) from Washington, DC
Brent W. Steury1,* and Ian W. Steury1
Abstract - The European land snails Discus rotundatus and Oxychilus draparnaudi were found in
Washington, DC at Oxon Cove in March 2010. These constitute the first records of feral populations
of these non-native species in the District of Columbia.
The native range of the land snail Discus rotundatus (Müller) (Rotund Disc) extends
throughout western and central Europe (Kerney and Cameron 1979) to northern Africa
(Algeria) (Pilsbry 1948); however, this common and evidentially adaptable snail has
expanded its range to include European countries as far north as Finland (Kerney and
Cameron 1979), as far east as Turkey (Örstan 2003), and on the Balearic Island of Mallorca
(Altaba 1996). An adventive species in North America, it has been collected in
Canada in British Columbia, Newfoundland, Nova Scotia, and Ontario and in the United
States in California, Massachusetts, Maine, New Jersey, New York, Pennsylvania, and
Washington (Dundee 1974, Hanna 1966, NatureServe 2009, Pearce 2008). Örstan (2003)
reported that all previous collections of D. rotundatus outside its native range were from
gardens, greenhouses, or (manicured) parks and surmised that this species is being transported
in soil or with plant nursery stock.
On 27 March 2010, we made the first collection of D. rotundatus (Fig. 1) from
the District of Columbia—records based on reviews of Dundee (1974) and Grimm
(1971)—under two rotting logs 20 m apart on a capped landfill along the northern
bank of Oxon Cove, approximately 110 m west of the Maryland state line (38o48'37"N
77o01'00"W). The site is covered by young woodland dominated by Acer negundo
L. (Box-elder) and an understory of the non-native shrub Lonicera maackii (Rupr.)
Herder. (Amur Honeysuckle). The herb layer contains low, wet pockets of the nonnative
grass Phragmites australis (Cav.) Trin. (Common Reed), and the non-native herb
Alliaria petiolata (M. Bieb.) Cavara & Grande (Garlic Mustard) is common on higher
ground. The landfill contains abundant concrete debris, perhaps giving the soils a more
basic pH than would otherwise be expected in this area. The fill material for the landfill
is reportedly all from the District of Columbia area (Stephen Syphax, National Park
Service, National Capital Parks–East, Washington, D.C., Pers. Comm.). This collection
represents the southernmost occurrence of D. rotundatus in the eastern United States.
We counted 3 empty shells and 51 live animals of D. rotundatus and deposited 5 shells
in the Museum Resource Center (MRC) in Landover, MD (B.W. Steury and I.W. Steury,
100327.1). The largest shell measured 6.1 mm at the widest diameter.
The most common, widespread snail on the site was Oxychilus draparnaudi (Beck)
(Dark-bodied Glass-snail), (Fig. 2), a species native to Western Europe and the Mediterranean
(Kerney and Cameron 1979), with feral populations reported from 13 states in the
US (Frest and Rhodes 1982). This is the first record of a feral population within the District
of Columbia, based on records in Frest and Rhodes (1982); however, Soelner (1902)
reported finding this species in a greenhouse in the District of Columbia. This snail was
also commonly found on the Maryland side of the landfill (38o48'46"N 77o00'29"W),
representing the first record for Prince Georges County, and the southernmost occurrence
18316 Woodacre Street, Alexandria, VA 22308. *Corresponding author - Brent_Steury@NPS.
Notes of the Southeastern Nat u ral ist, Issue 10/1, 2011
194 Southeastern Naturalist Vol. 10, No. 1
in Maryland according to Grimm (1971). We found 30 empty shells of this snail and observed
five live animals with dark-blue coloration. Fresh shells were dark amber colored
with a rapidly widening last whorl and well-defined growth-lines, and measured up to
12.7 mm at the widest diameter. The shell size, shape, and sculpture, and the color of
the animal and shell fit well with descriptions for O. draparnaudi given in Burch (1962),
Frest and Rhodes (1982), Kerney and Cameron (1979), and Pilsbry (1948), as compared
with the closely allied O. cellarius (Müller) (Cellar Glass-snail), which rarely exceeds
Figure 1. Discus rotundatus (MRC 100327.1) from Oxon Cove, District of Columbia,, collected 27
March 2010. Scale bar is in mm.
Figure 2. Oxychilus draparnaudi (MRC 100327.2) from Oxon Cove, District of Columbia, collected
27 March 2010. Scale bar is in mm.
2011 Southeastern Naturalist Notes 195
9 mm and typically is a paler animal with a lighter colored shell, narrower last whorl, and
scarcely visible growth-lines. Six shells from the District of Columbia and six additional
shells from Maryland were deposited at MRC (100327.2 and 100327.3, respectively).
Other snails found on the landfill include the first Prince Georges County, MD record
for Cochlicopa lubrica (Müller) (Glossy Pillar), according to the records of Grimm
(1971) and Hubricht (1985). The C. lubrica specimen is deposited at MRC (100327.4).
One empty shell of C. lubrica was found under a board with a mouse nest which also
contained shells of O. draparnaudi, Mesodon thyroidus (Say) (White-lip Globe Snail),
and Ventridens ligera (Say) (Globose Dome). A total of 11 empty shells of V. ligera and
13 shells of M. thyroidus were found over the landfill site.
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