IDENTIFYING SNAKES
Morphology, keys and DNA
diagnostics
MORPHOLOGY: Head shape
http://www.virginiaherpetologicalsociety.com/identification-keys/id-keyssnakes/virginia_snake_identification.htm
MORPHOLOGY: Head shape
COLUBRID-ELAPID TYPE
VIPERID TYPE
VENOMOUS or NON-VENOMOUS?
Front-fanged or non-front fanged: all snakes are
potentially venomous
As are some lizards……
www.venomdoc.com
MORPHOLOGY: Body Pattern
UNIFORM
SPECKLED
STRIPED
SPOTTED
BLOTCHED
DIAMONDS
BANDED
RINGED
http://www.flmnh.ufl.edu/herpetology/fl-guide/snakekey.htm
MORPHOLOGY: Head Pattern
MORPHOLOGY: Scale counts
1. Number of dorsal scales at mid-body
MORPHOLOGY: SCALE STRUCTURE
SMOOTH
KEELED
http://www.flmnh.ufl.edu/herpetology/fl-guide/snakekey.htm
MORPHOLOGY: Scale counts
2. Number of ventral, anal and subcaudal scales
MORPHOLOGY: Head scales
Snakes of Western and Central Africa
http://people.whitman.edu/~clarkedn/characterglossary.html
Scale row reductions
Ovophis spp.
KEYS
How to Use this Key:
Start with the first question. Decide whether 1a or 1b best describes the
characteristics of the snake you are trying to identify. (There are links to
examples of these traits if you need help.)
If the snake is striped, click on 6; if it is not striped, click on 2. Your choice will
lead you to the next appropriate pair of questions.
Work through the questions, each time choosing the characteristic that best
matches your snake from the two choices. This will lead you to the final
choice which identifies the snake.
http://www.flmnh.ufl.edu/herpetology/fl-guide/snakekey.htm
1. TRADITIONAL DICHOTOMOUS KEYS
Quinn Snake Identification Chart
2. FLOWCHART
3. INTERACTIVE ON-LINE
3. INTERACTIVE ON-LINE
3. INTERACTIVE ON-LINE
http://www.discoverlife.org/20/q?guide=Snakes
http://www.herpsofnc.org/herps_of_nc/snakes/SnakeID/search.asp
3. INTERACTIVE ON-LINE
Species File Software
http://orthoptera.speciesfile.org/Common/key/KeyDriver.aspx?KeyBlockID=10002
3. INTERACTIVE ON-LINE
(DEscription Language for TAxonomy)
http://delta-intkey.com/lep/index.htm
3. INTERACTIVE ON-LINE
PROBLEMS TO BE SOLVED
A key is only as good as the data that it is based on
Most venomous snakes have not yet been sampled within India well
Outstanding issues needing further work in many spp.
Naja spp (N. naja and N. kaouthia)
Echis spp (E. carinatus and E. sochureki)
Daboia russelii
Pitvipers (many spp)
http://pages.bangor.ac.uk/~bss166/Taxa/AsNaja.htm
Asian
cobras
Naja
(11 spp.
since
2000)
oxiana
mandalayensis
atra
naja
phillipinensis
siamensis
samarensis
sagittifera
sumatrana
sputatrix
Cryptic diversity of cobras in India?
Mitochondrial DNA
Morphology
0.01
N. kaouthia
N. kaouthia
N. kaouthia
N. kaouthia
N. kaouthia
N. sagittifera
N. sagittifera
N. kaouthia
N. oxiana
N. oxiana
N. naja Sri Lanka
N. naja Sri Lanka
N. naja Nepal
N. naja Nepal
N. naja Pakistan
Naja naja
Naja kaouthia
Naja oxiana
Wüster & Thorpe 1992
•Cryptic species associated with N. kaouthia?
•Deep divergences in N. naja
Morphology vs. molecules in Naja naja
and the importance of sampling
Morphology
Morphological cline vs.
deep molecular splits:
one species or two?
?
Bungarus niger
Cryptelytrops erythrurus
Ovophis monticola
Naja spp.
Echis sochureki/
E. carinatus
?
Peltopleor macrolepis
Trimeresurus malabaricus
Hypnale hypnale
Cryptelytrops spp.
Naja sagittifera
Mohapatra et al. (2011) PLoS Negl Trop Dis 5(4): e1018. doi:10.1371/journal.pntd.0001018
DNA IDENTIFICATION: THE WAY FORWARD?
Pook and McEwing (2005) Toxicon 46: 711-715
- mtDNA PCR amplified from dried venom samples
- 100-200 mg dried venom used
Kuch (unpublished): bite site swabs successfully used to
identify biting species in Bangladesh
Relies on presence of species sequences in “barcoding”
databases against which query sequence is matched
More useful for research than diagnostics
DNA IDENTIFICATION: THE WAY FORWARD?
With enough information, specific diagnostic tests can be designed
to identify important species by length differences in amplified
product alone (time c. 30 mins, cost c. $10-20)
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