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

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 S

ri La

nka

N. n

aja S

ri La

nka

N. n

aja N

epal

N. n

aja N

epal

N. n

aja P

akist

an

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)