|Ophiogomphus susbehcha in Maryland
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The population of Ophiogomphus susbehcha has resumed its low-level numbers along the Potomac River after
the high emergence numbers of 2012-2013 In 2014 two casts skins and 2 adults were found (April 27 & April 28).
In 2015 two adults were found (April 29 & May 4), In 2016 only 2 cast skins were located (April 17) and in 2017
and 2018 no cast skins or adults were recorded. The search for this species each year has been significant.
Both myself and several other people have helped locate this hard to find species.
Steve Roble sent an email out on 15-September- 2018 of significant importance pertaining to this species. He
writes, "Earlier this week I found (and identified for the first time) 2 pinned female specimens of Ophiogomphus
susbehcha in our state natural history museum's collection that were collected in Richmond in 1947 (presumably
by undergraduate students from the University of Richmond). These records thus predate by 60 years its modern
documentation in the James River and were collected about 40 years before the species was "discovered" on the
St. Croix River in Wisconsin. I believe only a Susquehanna River, Pennsylvania specimen (previously identified as
O. edmundo) is older (by 30 years). Both specimens were in the orphaned University of Richmond collection, now
housed in the Virginia Museum of Natural History in Martinsville. The bodies are intact but the wings damaged.
Regrettably, I overlooked both specimens during a 2007 visit to the museum (Allen Bryan first photographed an
undetermined Ophiogomphus [= susbehcha] on the James River in Richmond in April 2006, but the ID wasn't
determined until the following year when I collected some exuviae), quickly passing them off as part of a group of
Phanogomphus lividus, but immediately recognized them this time".
It has been a banner year for Ophiogomphus susbehcha. Between April 24th and May 12th, 31 cast skins were
found and 15 adults were identified (7 kept and 8 netted and released). The range of the population is now known
from 16 km of the Potomac River in Frederick County, Maryland.
Steve Roble, Oliver Flint and I met at the Smithsonian to compare specimens of the Chesapeake Snaketail from
the Potomac River (Maryland) and James River (Virginia) along with the Ophiogomphus susbehcha type
specimens in the museum. No distinctive consistent morphological characters could be found between them
except for the larger size of the type specimens. It is our thought that the Chesapeake Snaketails are
Ophiogomphus susbehcha. Whether the Chesapeake Snaketail warrants a new subspecies level will be decided
after the DNA of the Potomac River (Maryland) and James River (Virginia) specimens are compared with that of
the Saint Croix River (Wisconsin) specimens.
Fifteen additional cast skins of the Chesapeake Snaketail were found on the Potomac River near Point of Rocks in
2012 (April 8, 12 & 15) plus one mature male on April 25. This brings the total of this unnamed species recorded
from the Potomac River to nineteen (17 cast skins & 2 adult males).
Two cast skins of what is now referred to as the Chesapeake Snaketail were found on the Potomac River near
Point of Rocks on April 31, 2010. These were likely old skins at least a couple of days old if not more. This brings
the total of this unnamed species recorded from the Potomac River to three (2 cast skins & 1 adult male).
It is no longer appropriate to call this dragonfly the Potomac Snaketail. Over the last couple of years this species
has been found on the James River in Virginia. Cast skins, males and females have been collected. In addition, a
historical record, from the Susquehanna River in Pennsylvania, that was initially mis-identified, also appears to be
No additional specimens have been found on the Potomac River or in Maryland.
The taxonomic status of this species which is clearly related (if not a subspecies of) Ophiogomphus susbehcha
has yet to be worked out.
Original Posting (2006)
The Potomac Snaketail (Ophiogomphus sp.) is currently known only from a single male collected on 20-April-
2002, at 11:10 AM, near the north edge of the C&O Canal NHP line and the railroad property near Point of Rocks,
Frederick County, Maryland. There are no additional specimens (or visual sightings) of this dragonfly despite
extensive attempts during the 2003-2004 field seasons. It was photographed in the field to record actual colors
and later taken to the Smithsonian Institute to have it photographed using a montage imaging camera. The male
was still soft (not mature) when captured thus indicating that it had recently emerged from the Potomac River. It
was allowed to harden for a day before preserving.
The following is a brief description of the Potomac Snaketail. The specimen measured: Length = 46mm, Abdomen
= 32 mm, HW = 26 mm. The left hind wing has an anal loop of 2 cells with a short appendage (vein) while the right
HW does not have a distinct anal loop. The labrum and anticlypeus are white around the edges and muffled gray
internally. The postclypeus is greenish except for upper lateral-yellow edges, which bleed over onto the otherwise
greenish frons. Occiput is bright yellow with a long black row of hairs along the dorsal ridge. The thorax has the
dorsal carina prominent -- highest near middle with a black tipped ante-ala-crest on an otherwise reddish brown
dorsal carina. The mid-dorsal stripe is reddish-brown and prominent; widest anteriorly. The humeral and
antehumeral strips are barely separated but never touch. The antehumeral strip is not complete at the dorsal
end. The humeral strip is complete. A prominent interpleural stripe extends dorsally to, and slightly curves around
the spiracle. The metapleural stripe is prominent and complete. The thoracic stripes are reddish-brown. The
tarsus are black. The tibia are black with no yellow ridge on any tibia. Femora about 50/50 black (apically and
dorsal) and yellowish brown (mostly apically and ventrally). The auricle is yellow. The dorsums of A3-8 have
diminishing basal yellow triangles with a short dorsal yellow line continuing for a short distance. The yellow spot on
the dorsum of A9 is square shape. A10 is all yellow. A3-8 are black on the dorsal-lateral 2/3 of each segment as
seen from a lateral view. The abdominal appendages are dull, light yellowish/brown, and match the description of
Ophiogomphus susbehcha in Vogt and Smith, (1993). The epiproct is much longer than the cerci. The epiproct
has a conspicuous dorsobasal protuberance which is not present in other species belonging to the “mainensis”
group of eastern North American ophiogomphids. This dragonfly keys to Ophiogomphus susbehcha (St. Croix
Snaketail) in existing keys.
The Potomac Snaketail was compared to the holotype male and three paratype males of O. susbehcha in the
National Collection at the Smithsonian. The visual differences in size between the Potomac Snaketail and the
holotype male and the three paratype males of O. susbehcha was significant, much more so than the 50 to 52mm
lengths of the O. susbehcha species and the 46mm length of the Potomac Snaketail would suggest. Clearly the
Potomac specimen is much smaller and less massive than the St. Croix Snaketail’s holotype and paratypes. In
general however, the Potomac Snaketail was structurally closer to the four specimens of O. susbehcha in the
National Collection than any other species of Ophiogomphus.
The only differences in body markings were very slight and could easily be explained because the Potomac
Snaketail specimen was still young when captured when compared to the completely mature O. susbehcha
specimens. Specifically, the Potomac Snaketail when compared to the O. susbehcha had slightly lighter colored
eyes; upper 2/3 of the femurs were lighter in color; and the dorsum of A10 more yellow towards the anterior base.
But again, the overall color/markings on the abdomen and thorax were similar.
The secondary genitalia were indistinguishable from O. susbehcha. Also the superior appendages were very
close. The large dorsal protuberance just anterior to the lateral projections on the epiproct, which sets O.
susbehcha apart from other Ophiogomphus species, was similar. The lateral projections of the epiproct were
distinctly more pronounced on the Potomac specimen than on the O. susbehcha types while the sharply up-turned
ends of the epiproct were identical. The Potomac specimen did differ from the types in that between the upturned
end and the lateral projections of the epiproct an additional bump (small protuberance) was present. This could
be seen on the type specimens but it was not as large or as distinct as on the Potomac Snaketail. This
protuberance was reminiscent of what is seen on some O. mainensis. The cerci were identical in shape and
length to O. susbehcha except that the distribution of the small black pimples were more irregular (not so much in
a line) on the Potomac Snaketail.
All of the species of Ophiogomphus in the National collection were carefully compared to the Potomac Snaketail to
make sure that nothing was missed. Special effort was spent comparing the various species cerci and epiproct
with that of the Potomac Snaketail. Ophiogomphus susbehcha was the only species that came close to matching
the Potomac Snaketail in this respect. Particular attention to specimens of O. mainensis and the two subspecies
of O. incurvatus were undertaken. The possibility that the Potomac Snaketail was one of these two species in
which the cerci were deformed (not fully extended) had been brought to my attention. However, the O. mainensis
and O. incurvatus specimens never showed the large epiproct dorsal protuberance anterior to the lateral
projections that was so obvious on the Potomac specimen and the O. susbehcha types. In addition, there was no
indication of deformity with the abdominal appendages on the Potomac Snaketail specimen.
Because the Potomac specimen is distinctly smaller in size, with a much earlier emergence date, a long distance
from St. Crox river drainage, and has differences in the abdominal appendages from O. susbehcha my conclusion
is that this is most likely a sister species or at least a distinct new subspecies of O. susbehcha.
|Live -- top of abdomen tip
|Montage image -- Side of
|Montage image -- top of
Montage image -- hamules
Base of Hindwing