Biology Reference
In-Depth Information
envenomation in South East Asia. A second South East Asian case was published by
Seow et al. from Singapore in 2000.
Rhabdophis tigrinus
(tiger keel-back or yamakagashi) has three subspecies (
tigri-
nus
,
formosanus
, and
lateralis
), while two subspecies (
subminiatus
and
helleri
) of
R. subminiatus
(red-necked keel-back) are currently recognized. The dietary preferences
of
Rhabdophis
spp., summarized in
Table 4.2
, are similar to many other natricids. Careful
review of documented envenomations inflicted by these two species suggests that they
are among the most dangerous members of the former artificial colubrid assemblage.
This threat results from the marked toxicity of their venoms to humans, and their occa-
sional entry into the pet trade due to mistaken identity [they may be confused with sev-
eral species of other keel-backs or, as they are popularly known, Asian garter snakes,
Amphiesma
spp. (e.g.,
A. stolata
;
Plate 4.84A-E
)]. Although this circumstance has
occurred occasionally with
Dispholidus
and
Thelotornis
spp., mistaken identity involv-
ing these species is now uncommon. The potential misidentification of
R. tigrinus
or
R.
subminiatus
with
Amphiesma
spp. (compare Plates 4.45A and B and 4.46A and B with
Plate 4.84A-E
) has resulted in a periodically renewed concern among medical profes-
sionals and amateur collectors. A life-threatening case of
R. subminiatus
envenom-
ing in 1981 resulted in the banning of private ownership of this species in Los Angeles
(
New York Times
, September 13, 1981).
9
Conversely, in 1990, the New York City Health
Department issued a citywide alarm due to concerns that
Rhabdophis
spp. had entered
the retail pet trade. The alarm was issued after a self-taught amateur collector informed
the health department that the snakes being sold as “garter snakes” were actually a spe-
cies of
Rhabdophis
spp. Until correctly identified as
Amphiesma
spp., the initial misin-
terpretation resulted in the removal of several dozen
Amphiesma
spp. from the stock of
a large New York pet store chain (
New York Times
, October 17, 1990). Some hobbyist
periodicals highlighted the potential confusion (Walls, 1991) as collectors expressed con-
cerns regarding the perceived danger of a potentially fatal misidentification.
4.3.2.1 Overview of the Duvernoy's Gland and Associated Dentition of
R. subminiatus
and
R. tigrinus
Rhabdophis subminiatus
and
R. tigrinus
possess enlarged, ungrooved posterior
maxillary teeth (Plates 4.45C and 4.46E-G, respectively). These teeth have a sharp
posterior edge and are notably recurved (Plate 4.46E-G). They are separated from
the anterior teeth by a prominent diastema and, in
R. tigrinus
, are 2.25 times longer
than the teeth immediately anterior to them (Mittleman and Goris, 1974; see Plate
4.46E and F). Although there are a number of documented “dry bites” from these
species suggesting that protracted bites are more likely to result in serious enven-
oming (Viravan et al., 1992;
Table 4.1
), some cases have only involved brief biting/
contact with the snake. In one life-threatening case, the
R. tigrinus
specimen was
55 cm long and had enlarged posterior maxillary teeth measuring 2.3 mm from tip
9
See Appendix D for a critical opinionated essay regarding legal issues relevant to private ownership of
dangerously venomous colubroid snakes.
