Wednesday, 1 October 2008

Three-lined Skink

.....Bassiana duperreyi GRAY, 1838
(Syn: Acritoscincus duperreyi — Wells & Wellington 1984)

Yesterday I came across this Three-lined Skink up the hill in the backyard. Snout to vent, it measured 65mm (they can reach 80mm) and the total length was 165mm. These lizards are found mainly in the north and east of the state where they prefer dry forest or coastal heath. They will shelter among grass tussocks, leaf litter or under rocks. They feed on insects, spiders and other invertebrates. Eggs are laid communally in a small cavity under a rock or log.

Do not read on if you are prone to headaches :-)

For the sake of accuracy, I will now explain a potential problem with my identification. Of course, with only 17 lizard species in Tasmania you'd think it would be easy to identify a skink. Well apparently not. My gut feeling was that this was the Three-lined Skink and I still believe this to be the case. However using a dichotomous key I ran into a problem. Have a look at the suture between the rostral and frontonasal scales. This suture separates the two nasal scales. The suture appears to me to be relatively narrow compared to the width of the frontal scale. In fact I measured it on the computer at only 50% the width of the frontal scale. This would point to Niveoscincus sp. For the Genus Bassiana the suture should be relatively broad. So, there are several possibilities:
  1. The key may have a bug in it.
  2. I may be interpreting the key incorrectly.
  3. My skink may vary from the norm.

On the other hand, the Tasmanian National Parks site clearly states, that "the frontoparietal scales are fused into a single shield on the Three-lined skink, distinguishing it from other striped skinks found in northern and eastern Tasmania". So, that on it's own says I have a Three-lined Skink. The orange colouration on the throat also matches this species as does the general appearance and position of the stripes.

I have drawn a diagram which I have included below to show some of the major head scales.

So if you are still reading this then no doubt you have a serious interest in lizards. Perhaps you are even in a position to clarify things for me. If so, then any help would be greatly appreciated.




(Click Photos or Diagrams to Enlarge)
Three-lined Skink - Bassiana duperreyi - Somethings watching me


Three-lined Skink - Bassiana duperreyi - colouration under throat


Three-lined Skink - Bassiana duperreyi - Dorsal view



Three-lined Skink - Bassiana duperreyi - Lateral view


Three-lined Skink - Bassiana duperreyi - Head Scales


Names of some of the head scales

References:
  • Hutchinson, Swain, Driessen, 2001 - Snakes and Lizards of Tasmania - DPIW & University of Tasmania
  • Parks and Wildlife, Tasmania, 2008 - Head Shields of the Three-Lined Skink , Website
  • Wilson & Knowles, 1988 - Australian Reptiles - Cornstalk Publishing


10 comments:

  1. Didn't get headache. Got the shield. But I'm missing a line?

    ReplyDelete
  2. Hi Mosura
    How on earth did you persuade that skink to be so co-operative?
    I saw another species a few days ago, on a rock, but it was very nervous.
    Great photos.
    Your Tassie Parks and Wildlife Service Website has remarkable detail on your reptiles. Obviously someone there is a specialist.
    Denis

    ReplyDelete
  3. Hi Mosura! Fantastic posts from the past week. I hope to have the time to catch up soon.
    Thanks for the time spent and the great photos!

    ReplyDelete
  4. Thanks Tony - The "line" is where the two scales meet. (Between the rostral and frontonasal scales).

    Thanks Denis - The other lizards I've posted here were photographed by stalking. I cheated with this one. I actually found it half drowned in a puddle so I brought it in and put it in an empty fish tank for the night to let it warm up and have a feed etc. Seems fine now. In the mean time I got a few shots.

    ReplyDelete
  5. Thanks Tilcheff - Thanks for your comments. Glad you're enjoying the photos.

    ReplyDelete
  6. Hey Mosura

    I can't comment on the accuracy of your identification but the shots are great - the third one would make an excellent picture to hang in any house....very arty.

    Best wishes, Adrian

    ReplyDelete
  7. I think you've been complimented enough Mosura, I'll just say what a beaut little lizard. ;-)

    ReplyDelete
  8. Thanks Adrian - for the compliment. Glad you like the pics.

    Thanks Duncan - Yes it was a great little lizard. I love the blaze of colour on their necks.

    ReplyDelete
  9. Key characters like 'relatively narrow' or 'often darker than' or ... well ... all those qualitative characters are about as useful as [insert suitably colourful simile].

    ReplyDelete
  10. Thanks Snail - Yes that's the conclusion I was coming too :-)

    ReplyDelete