HOW COMMON ARE
FOSSORIAL SNAKES?
R .M . Douglas
The w ord "fossorial'' is derived fro m the la tin w o rd FOSSOR, w h ic h means digger. Therefore a fo sso ria l snake is a snake w h ic h is adapted for d ig gin g and lives a large part, or all of its life u nderground.
Fossorial snakes are u su a lly identified by the shape of the head or stru c tu re of the snout. This may vary fro m a w edge-shaped head, w h e n viewed fro m the side to a rounded sn o u t w ith large heavy protective scales. Because fo sso ria l snakes spend m uch tim e u nderground th e ire y e s are not as large as those of other snakes, but u su a lly very sm all to a lm o st undetectable in some species. The ta il is also u su a lly s h o rta n d is b lu n t at the end.
The e xa m p le o f the Q u ill-s n o u te d snake X e ro c a la m u s b. b ico lor, w a s given in N ational M u se um News No 30. The firs t specim en w a s collected in 1 9 3 9 and the second, some 46 years later in 1985. Both specim ens w ere fro m B loem fontein. O ther Free State se m i-fo sso ria l snakes w h ic h are in fre q u e n tly fo u n d include the Cape coral snake, A spide/aps /. lu b ric u s , the G arter snake, Elapsoidea s u n d e v a lli m edia, and the S triped d w a rf garter snake, H om oroselaps dorsalis.
Elsewhere m ost fo s s o ria l snakes are also u ncom m on. Up u n til 1 9 7 0 o n ly seven specim ens of the Purple gloss snake, A m b ly o p id s a s conco/or, w ere collected in S outh A fric a w h ile fro m 1 9 7 0 to 1982 a fu rth e r seven specim ens w ere collected.
A re these snakes rare only because o f th eir fossorial habits?
If we look at the o th e r side of the coin, we fin d th a t other fo s s o ria l snakes such as the B lind snake, Typhlops lalandei, and the W o rm snake, L e p totyp h lop s s. s c u tifro n s , are fa irly com m on w ith in the O range Free State. They are also more fo sso ria l in h abit th a n the p re viou sly m entioned species. Perhaps th is is because they are encountered more fre q u e n tly in gardens and term ite m ounds w here they are more likely to be found.
The Side stabbing snake, f.Atractaspis b ib ro n n ii) sh o w in g p o in te d sn o u t fo r burrow ing.
But h o w com m o n are fossorial snakes? In the O range Free State the venom ous S tile tto or S ide-stabbing snake, A tra c ta s p is b ib ro n i, w as firs t collected at B othaville in 1 973. It w as o nly in 1986 th a t a n o th e r specim en surfaced w h ic h w a s a c tu a lly collected in 1977 at B loem fontein. Thus o nly these tw o specim ens have been collected in the O range Free State.
The C oral snake, (Aspidelaps i lu b ric u s ! has an enlarged ro s tra l sh ie ld fo r burro w in g .
The B lin d snake. (Typhtops b ib ro n ii) s h o w in g ru d im e n ta ry eye and po in te d sn o u t fo r burro w in g .
The Q u ill sno u te d snake, (Xenocalam us b. bicolor) sh o w in g wedge shaped head and ro s tra l scale.
A va ila b le evidence w o u ld therefore suggest th a t some fo s s o ria l snakes are rarer th a n others, but w h e th e r they are indeed rare, or perhaps ju s t being overlooked because of th e ir h a b its and the h a b ita t in w h ic h they occur, is u n k n o w n . These then are some of the m any q u e stio n s about fo s s o ria l snakes w h ic h re m a in to be answ ered.
B I8 L IO G R A P H Y
DE W A A L S W P 1 9 7 8 The S q u a m a ta (ReptMia) o f the O ra ng e Free S tate S o u th A fr ic a M e m n a s M u s B lo e m /o n te m 2 1 -1 6 0
D O U G L A S R M 1 9 8 2 A n e w size re co rd a n d n o te s o n fee d ing in c a p tiv ity o f A m b ly o d ip s a s c o n c o lo r (A S m ith ) J H e rp ,4ss A fr ic a 2 8 1 4 -1 6 H A A C K E. W D 1 98 2 F u rth e r note s on re p ro d u c tio n a nd d is trib u tio n o n the N a ta l
P u rp le g lo ss sn ake A m b ly o d ip s a s c o n c o lo r (A S m ith ) J H e rp ,4ss. A fric a .
2 8 2 4 2 5
E R R A T U M :
Nas. M u s . N e w s 3 0 . page 1 9 Read van D ijk fo r van O isk.
DIJK . D E va n 1 9 6 6 S y s te m a tic a n d fie ld keys to the fa m ilie s , genera a nd species o f S o u th e rn A fr ic a n A n u ra n ta d p ole s A n n N a ta l M u s . 1 8 : 231 2 8 6
SEEKOEIE IN SANLAM PLAZA!
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