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IDENTIFYING SNAKES
Morphology, keys and DNA diagnostics
MORPHOLOGY: Head shape
http://www.virginiaherpetologicalsociety.com/identification-keys/id-keys-snakes/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
www.venomdoc.com
As are some lizards……
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 Africahttp://people.whitman.edu/~clarkedn/characterglossary.html
Scale row reductions
Ovophis spp.
KEYSHow 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.
1. TRADITIONAL DICHOTOMOUS KEYS
http://www.flmnh.ufl.edu/herpetology/fl-guide/snakekey.htm
2. FLOWCHART
Quinn Snake Identification Chart
3. INTERACTIVE ON-LINE
3. INTERACTIVE ON-LINE http://www.discoverlife.org/20/q?guide=Snakes
3. INTERACTIVE ON-LINE
http://www.herpsofnc.org/herps_of_nc/snakes/SnakeID/search.asp
3. INTERACTIVE ON-LINE
Species File Softwarehttp://orthoptera.speciesfile.org/Common/key/KeyDriver.aspx?KeyBlockID=10002
3. INTERACTIVE ON-LINE
(DEscription Language for TAxonomy)http://delta-intkey.com/lep/index.htm
PROBLEMS TO BE SOLVEDA key is only as good as the data that it is based onMost 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 russeliiPitvipers (many spp)
oxiana
naja
sagittifera
phillipinensis
samarensis
sputatrix
sumatrana
Asian cobras Naja(11 spp. since 2000)
http://pages.bangor.ac.uk/~bss166/Taxa/AsNaja.htm
atrakaouthiasiamensis
mandalayensis
Naja naja
Naja kaouthia
Naja oxiana
Wüster & Thorpe 1992
N. kaouthiaN. kaouthiaN. kaouthiaN. kaouthia
N. kaouthiaN. sagittiferaN. sagittifera
N. kaouthiaN. oxianaN. oxiana
N. naja Sri LankaN. naja Sri Lanka
N. naja NepalN. naja NepalN. naja Pakistan0.01
Cryptic diversity of cobras in India?
Morphology Mitochondrial DNA
•Cryptic species associated with N. kaouthia?•Deep divergences in N. naja
N. n
aja
Sri La
nka
N. n
aja
Sri La
nka
N. n
aja
Nep
al
N. n
aja
Nep
al
N. n
aja
Pakis
tan
Morphology
?
Morphology vs. molecules in Naja najaand the importance of sampling
Morphological cline vs. deep molecular splits: one species or two?
Mohapatra et al. (2011) PLoS Negl Trop Dis 5(4): e1018. doi:10.1371/journal.pntd.0001018
Bungarus nigerCryptelytrops erythrurusOvophis monticolaNaja spp.
Cryptelytrops spp.Naja sagittifera
Echis sochureki/E. carinatus
Peltopleor macrolepisTrimeresurus malabaricusHypnale hypnale
?
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)
