Morphology, keys and DNA diagnostics 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 Magenetic resonance imaging, lizard is Varanus exanthematicus 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 The dorsal scales cover the snake's back. These are the scales you can see when the snake is 'sitting' on the ground. You count these scales at the widest part of the snake's body. This is the mid-body region, about halfway down the snake's length. The diagram shows you how to count these scales. In this particular example, our snake has 17 rows of dorsal scales at mid-body. This is often just abbreviated as '17 midbodies'. 1. Number of dorsal scales at mid-body

MORPHOLOGY: SCALE STRUCTURE SMOOTH KEELED The dorsal scales cover the snake's back. These are the scales you can see when the snake is 'sitting' on the ground. You count these scales at the widest part of the snake's body. This is the mid-body region, about halfway down the snake's length. The diagram shows you how to count these scales. In this particular example, our snake has 17 rows of dorsal scales at mid-body. This is often just abbreviated as '17 midbodies'. http://www.flmnh.ufl.edu/herpetology/fl-guide/snakekey.htm

MORPHOLOGY: Scale counts Ventral scales These are the 'belly scales' of the snake. They run from the neck down to the bum. Pythons have ventral scales that are about half the width of the body. Both colubrid and elapid snakes have ventral scales that are about the same width as the body. Anal scale This is the scale just in front of the cloaca (the snake's 'bum'). The anal scale may be single or divided. Subcaudal scales These are the scales underneath the snake's tail. Scales are either single or divided, but snakes may have a combination of both single and divided subcaudal scales. 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 1. Traditional dichotomous 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 3. Interactive On-line 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)

Asian cobras Naja (11 spp. since 2000) oxiana mandalayensis atra http://pages.bangor.ac.uk/~bss166/Taxa/AsNaja.htm Asian cobras Naja (11 spp. since 2000) oxiana mandalayensis atra naja kaouthia phillipinensis siamensis This puzzling situation was at least partly resolved by the realization that there are in fact multiple full spp of naja present in Asia an that in many parts, including india, moe than one spp may be present, with different venom effects. samarensis sagittifera sumatrana sputatrix

Cryptic diversity of cobras in India? Morphology Mitochondrial DNA Naja naja Naja kaouthia Naja oxiana Wüster & Thorpe 1992 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 But there are sill unanwwered questions which need more sampling to resolve: eg in India. N. naja Nepal N. naja Nepal N. naja Pakistan 0.01 Cryptic species associated with N. kaouthia? Deep divergences in N. naja

? Morphology vs. molecules in Naja naja and the importance of sampling Morphological cline vs. deep molecular splits: one species or two? Morphology ? N. naja Nepal N. naja Nepal N. naja Pakistan N. naja Sri Lanka N. naja Sri Lanka

? Bungarus niger Cryptelytrops erythrurus Ovophis monticola Naja spp. Echis sochureki/ E. carinatus ? Orissa placed with north-east simply because of record of monocellate cobra from this state. But clearly will be very diff to ne/hilly regions. Eastern region actually extends quite far west along the himalayan region: recent account of a greater black krait bite from Uttarakhand. Pitvipers are also present in this region, but from different lineages to those present in S India: Of these, erythrurus found to be the commonest cause of sakebite in the Chittagong Hills in Bangladesh, with quite severe effects, Ovophis monticola common in Nepal, with severe local sequelae though low fatality rate. MP and Chattisgarh? Unaware of any work on species in this region. 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)