Biology Reference
In-Depth Information
Figure 4.3
Profiles of three hazard level 1 colubrids.
Depicted in the figure are head and
dentition profiles of the tiger keel-back,
R. tigrinus
(upper left panel), boomslang,
D. typus
(upper right panel), and Kirtland's twig, vine, or bird snake,
T. kirtlandii
(bottom panel). All
three hazard level 1 colubrid species have inflicted well-documented life-threatening and/or
fatal envenomations. All have serous Duvernoy's glands associated with markedly enlarged
noncanaliculated posterior maxillary teeth. Although these are grooved in
D. typus
(deep
grooves that extend over approximately 50-65% of the tooth surface; some of these grooves
may be located on the medial-posterior surface of the teeth, and thus are not visible in this
profile; upper right panel; see also
Plate 4.20
E-K) and
Thelotornis
spp. (deep grooves that
traverse almost the entire tooth surface, bottom panel; see also
Plate 4.56
C, H-K),
R. tigrinus
and
R. subminiatus
have ungrooved teeth (upper left panel; see also Plates 4.45C and 4.46D-
G). All produce potent procoagulant toxins that activate prothrombin, and Factor X, but some
pharmacological studies suggest variability of these activities among different populations
and/or individual snakes. The role of these toxins in the natural history of these taxa remains
unclear and/or unverified, but observations of wild and captive specimens indicate that these
species use their venoms in the capture and/or subjugation of prey. Clinical manifestations
of envenoming by any of these snakes results in consumptive coagulopathy, DIC, bleeding,
anemia, thrombocytopenia, and other serious hemostatic disturbances (see
Plate 4.20
L-O).
Severe cases may result in acute kidney injury (see Sections 4.3 and 4.6, and
Figure 4.4
) and
death. Figure copyright to Kevin M. McAllister.
4.3.4 Proven Guilty Without a Trial: Three Additional Unsupported
Reports of Fatal Outcomes after Bites by
Tachymenis peruviana
,
Oligodon arnensis
, and
Xenodon severus
4.3.4.1
Tachymenis peruviana
: An Undeserved Reputation of Lethal Potential?
Of the six species in the dipsadid genus
Tachymenis
(slender snakes), only
T. peruvi-
ana
(Peruvian slender snake; Plate 4.49A and B) has acquired a reputation for lethal
potential. This species has enlarged, recurved posterior maxillary teeth that contain a
