Biology Reference
In-Depth Information
(B)
(A)
(C)
Plate 1.2
(A-C) Maxilla and enlarged posterior maxillary teeth of the Natal black snake
(
Macrelaps microlepidotus
).
The natural history of this rare semifossorial species is poorly
known. A non-front-fanged colubroid, it has traditionally been grouped with the unusual front-
fanged genus,
Atractaspis
(see text). There are a number of anecdotal cases of bites by this
species. Unfortunately, there is no documented clinical review of any of these victims. Effects
have allegedly included loss of consciousness and possible cranial nerve involvement, but
further information is required in order to critically evaluate the potential hazard associated
with bites from this uncommon species. As illustrated in the comparison of two specimens
in
Plate 1.2A
, the most posterior maxillary teeth are markedly enlarged and gently recurved.
They contain a shallow groove that extends along almost the entire medial-posterior surface
of the tooth (the position of the groove from an antero-lateral view is indicated by the arrow
in
Plate 1.2B
). The groove is visible (arrows) in
Plate 1.2C
. The uppermost specimen in
Plate
1.2A
is AMNH #5897; the other specimen in
Plate 1.2A
and
Plate 1.2B and C
is AMNH
#18227. See Appendix E for locality data; photos copyright to Scott A. Weinstein.
dentition (e.g., the Natal black snake, or Natal swartslang,
Macrelaps microlepidotus
,
Plate 1.2A-C
), and front-fanged (“proteroglyphous”) canaliculated morphology (e.g.,
the dwarf garter snakes,
Homoroselaps
spp.), with
Atractaspis
spp. exhibiting markedly
enlarged distensible canaliculated fangs (
Plate 1.1B and C
) and notably elongated venom
glands. Deufel and Cundall (2003) noted the similarities between unilateral fang use in
Atractaspis
and unilateral “slashing envenomation by some rear-fanged snakes.” However,
the loss of pterygoid teeth and associated maxillary movement resulted in the inability of
Atractaspis
spp. to perform “pterygoid walk” prey transport.
1
These authors remarked
1
“Pterygoid walk” prey transport refers to the alternating pterygoidal movements employed during active
deglutition of a seized prey item. This generally advances the maxillae, thereby drawing the grasped prey
into the snake's esophagus, and facilitates swallowing.