Skink identification help

[Ethan241]

I found this skink which I’m pretty sure is a type of rainbow skink though I have absolutely no idea how to identify it and was wondering if I could get any help in that. The location was at Carnarvon Gorge in Queensland.

 

[Herpetology]

correct that this is a rainbow skink - to me it looks like an Open-Litter Rainbow skink - Carlia Pectoralis, based on the prominent orange markings on the sides and patterning from back to tail

https://biocache.ala.org.au/explore/your-area#-24.9097|148.0413|12|ALL_SPECIES

 

[Bluetongue1]

Beat me to it.
Carlia species can be pain to ID but I am confident this is a male Open-litter rainbow-skink (Carlia pectoralis) just starting to come into breeding colouration.
This is a photo of a female of the species, which has a pale mid-lateral stripe bordered by a darker zone that breaks up into flecking. However you can see it has the same dorsal and tail patterning.

 

[eipper]

It's much more likely to be Carlia rubigo at that location

 

[Bluetongue1]

Like I said, trying to ID these guys can be a real pain. C. pectoralis and rubigo are particularly similar species morphologically, except for a couple of specific. What made me choose pectoralis as the more likely was there did not appear to be any colour developing above the upper flank i.e. none visible dorso-laterally or dorsally. The other feature was the heavy-black edging to the scales along the jaw line and back to the neck and on what little is visible of the upper throat. I accept that it is arguable that what can be seen is not extensive enough to go on, but the intensity of what was visible sold me. In retrospect it would have been more appropriate to phrase my response with a “feel fairly confident” of the species. It is definitely one of the two. Only a ventral shot of the upper body would resolve it without doubt.

 

[GBWhite]

I found this skink which I’m pretty sure is a type of rainbow skink though I have absolutely no idea how to identify it and was wondering if I could get any help in that. The location was at Carnarvon Gorge in Queensland.

HI Ethan,

In all honesty it could be either as it's almost impossible to distinguish species of Carlia without having the lizard in hand.

For future reference here's the diagnostic characteristic for C rubigo taken from the Reptile Database.

Carlia rubigo HOSKIN & COUPER, 2012​

Diagnosis. A moderate sized Carlia (max SVL 44 mm) that can be distinguished from all its congeners by a combined suite of characters. Interparietal scale free. Dorsal scales tricarinate and hexagonally-shaped. Palpebral disc large. Ear aperture round to vertically elliptic with one or two rounded lobules on the anterior margin and sometimes with smaller, rounded lobules on other margins (Fig. 8B). Supraciliaries usually five. Prefrontals usually narrowly separated or in point contact (Fig. 9B). Upper preocular minute or a narrow, vertical sliver (Fig. 10D). Breeding male with pale blue throat and broad orange or coppery flush on flanks; black speckling present on neck and jawline but no heavy black edging to scales on throat (Figs 1C, 2B, 4B, 5B). Adult female with a white mid-lateral stripe that usually breaks up posteriorly into white flecks (Figs 1D, 6B). Both sexes have a pale greyish tinge on the ventral surface.

Cheers,

George.

 

[Bluetongue1]

Ethan, it is not always necessarily to have carlia specimens in hand identify them. This is a good example. It can very much depend upon the photography and locality information available.

What I do not understand here is the rationale behind posting the diagnostic features of only one species, instead of both? Surely it requires both descriptions to draw comparisons, in order to be able to make any worthwhile use of that information. So, following is the missing description,

Carlia pectoralis HOSKIN & COUPER, 2012
Diagnosis. A moderate sized Carlia (max SVL 47 mm) that can be distinguished from all congeners by a combined suite of characters. Interparietal scale free. Dorsal scales tricarinate and hexagonally-shaped. Palpebral disc large. Ear aperture usually round (may be vertically elongate) with a rounded lobule on the anterior margin and usually with sharp to bluntly pointed lobules on other margins (Fig. 8C). Supraciliaries usually five. Prefrontals usually narrowly separated or in point contact (Fig. 9C). Upper preocular minute or a narrow, vertical sliver (Fig. 10E). Breeding male with distinct orange upper lateral stripe and usually also an orange lower lateral stripe, with orange extending onto the chest; blue throat; throat, neck and chin scales strongly edged in black (Figs 1E, 2C, 4C, 5C). Female with white mid-lateral stripe that usually becomes ragged and indistinct or breaks up to flecks posteriorly along the flank (Fig. 1F, 6C). Both sexes have a pale greyish tinge on the ventral surface.
Excerpts from previous post, from which you can read how they differ.

"Carlia rubigo HOSKIN & COUPER, 2012
Diagnosis…
……Breeding male with pale blue throat and broad orange or coppery flush on flanks; black speckling present on neck and jawline but no heavy black edging to scales on throat (Figs 1C, 2B, 4B, 5B). ..."

Cheers,
George."

Following are photos and their captions from the paper submitted to Zootaxa and then published by them. As 4 species were described and only two are of interest here, I have omitted the other two…

HOSKIN & COUPER
Zootaxa 3546 © 2012 Magnolia Press

Comparison of males in full breeding condition: (B) C. rubigo sp. nov., Magnetic Island; (C) C. pectoralis, Woodgate National Park;
Photos: Conrad Hoskin (B), Steve Wilson (C).


FIGURE 4. Comparison of typical lateral pattern of males: (B) C. rubigo sp. nov., QMJ90885, Magnetic Island; (C) C. pectoralis, QMJ63390, Wongi State Forest.
Photos: Jeff Wright


FIGURE 5. Comparison of typical ventral pattern of males: (B) C. rubigo sp. nov., QMJ90885, Magnetic Island; (C) C. pectoralis, QMJ63390, Wongi State Forest.
Photos: Jeff Wright.



I now leave it up to you Ethan…

 

[GBWhite]

Like I said, trying to ID these guys can be a real pain. C. pectoralis and rubigo are particularly similar species morphologically, except for a couple of specific. What made me choose pectoralis as the more likely was there did not appear to be any colour developing above the upper flank i.e. none visible dorso-laterally or dorsally. The other feature was the heavy-black edging to the scales along the jaw line and back to the neck and on what little is visible of the upper throat. I accept that it is arguable that what can be seen is not extensive enough to go on, but the intensity of what was visible sold me. In retrospect it would have been more appropriate to phrase my response with a “feel fairly confident” of the species. It is definitely one of the two. Only a ventral shot of the upper body would resolve it without doubt.

What I do not understand here is the rationale behind posting the diagnostic features of only one species, instead of both? Surely it requires both descriptions to draw comparisons, in order to be able to make any worthwhile use of that information.



Following are photos and their captions from the paper submitted to Zootaxa and then published by them. As 4 species were described and only two are of interest here, I have omitted the other two…

Hi Mike,

As per the referenced descriptions there are obviously other morphological characteristics unique to each species outside colouration that should be considered before coming to a positive identification and as such my previous post was intended to inform the op that they need to be aware that it is not as simple as one may think to confirm an id simply from posting a a pic on a forum.

The rationale is called - Process of elimination.

As per your posts, "It's definitely one of the two" & "only two are of interest here". So obviously if it's not one it's going to be the other. Not hard to work out for anyone with common sense.

Cheers,

George.