Pachytriton brevipes?

[FrogEyes]

In response to Janusz, who asked in another thread about identifying Pachytriton...

There's no absolute method, because the species overlap in many features. There are bound to be exceptional animals which are one species, but which look identical in all respects to another. However, there are obvious trends. Since Wu Yunke et al only spoke of morphological trends in their paper, I downloaded their appendix S3, which contains the raw measurements. Rather than run a proper statistical analysis, I just obtained averages on what I consider key measurements, from each of the distinct groups they analyzed. I have color-coded the features to allow easy comparison here:

Species; Total Length; SVL; Head Length; Head Width; HL % of SVL; HW % of SVL; Forelimb % of SVL; Hindlimb % of SVL
Pachytriton granulosus; 143.1; 76.2; 17.4; 12.1; 22.9; 16.0; 21.6; 23.3
Pachytriton cf. brevipes (Mt. Daiyun); 149.9; 80.6; 19.2; 14.7; 23.9; 18.3; 20.6, 22.1
Pachytriton brevipes (Mt. Wuyi); 165.9; 90.4; 20.7; 16.7; 22.9; 18.5; 19.3; 21.1
Pachytriton labiatus; 168.7; 92.5; 22.8; 17.9; 24.7; 19.3; 19.7; 21.3
Pachytriton archospotus (Mt. Qiyun); 172.6; 90.5; 24.3; 19.9; 26.9; 22.0; 23.5; 26.6

P.granulosus is listed by them as P.labiatus [northeast], and includes all pet trade samples and one sample from near the type locality. The Mt Daiyun population is listed by them as P.brevipes, though their analysis shows it to be clearly distinct genetically from both P.brevipes and P.granulosus. P.archospotus was not measured, presumably because it wasn't necessary for the purpose. Though I lack data from this study, I have pulled data for P.archospotus from the species description - it should resemble the other robust species, as P.granulosus is the only exceptional one.

Things of note:
P.cf.brevipes is intermediate in almost all respects. It has only one known color form - beige with black spots. The combined fore and hind limbs are about 42% of SVL.
P.brevipes is large and robust, and has two known color forms - beige with black spots, with or without red lateral markings. The combined fore and hind limbs are about 40% of SVL.
P.labiatus is large and robust, and has two known color forms - brown, with or without red lateral markings. The combined fore and hind limbs are about 41% of SVL.
P.granulosus is small and gracile, and has all color forms [except beige withOUT red lateral markings]. Total length is about 25mm less than P.brevipes or P.labiatus. SVL is about 15mm less, head length is 5mm and nearly 2% of SVL less than P.labiatus, head width is 6mm and over 3% of SVL less than P.labiatus. The combined fore and hind limbs are about 45% of SVL.
P.archospotus is large and robust, with only one known color form - beige with black spots and without lateral red markings. It has the longest and widest head, both raw and % of SVL (~27% HL & HW). The combined fore and hind limbs are about 50% of SVL.

Looking over the raw data, to see past what the averages hide - very few P.granulosus are as large as P.labiatus, and very few P.labiatus are as small as P.granulosus. There is very little overlap in adult size. An animal over 90mm SVL, all other factors aside, is likely P.labiatus. P.granulosus is much smaller, with a much narrower head and body [shoulder width - not included above] (raw and % of SVL), and longer limbs (% of SVL).

Keep in mind though, that these figures are based on very few localities and small numbers of animals. If 5% of P.granulosus are 100mm SVL, or 8% of P.labiatus are only 72mm SVL, this study would have had a good chance of missing them. The trends were noted species-wide, even though the actual measured samples were localized.

There are distinct differences between P.archospotus and P.brevipes/P.cf.brevipes as well: Head length is greater in P.archospotus (27% vs 24/23%), TL is greater (172.6mm vs 165.9/149.9mm), Head width is greater (22% vs 18.5/18.3%), and combined limb length is greater (50% vs 40/43%). If you know a dentist, perhaps you could just x-ray and check for straight epibranchials

 

[Yahilles]

Although i think that the measure data is just useless for a common keeper (i'd call it too scientific), thanks for the "simple info". About P. archospotus, all the pictures of them show that they should be very easy to distinguish from P. brevipes - they're much larger, with those huge heads, and during breeding season males don't develop swollen cloacas.
One more question - what can you tell us about the phenotypes A and B, are they also P. granulosus in your opinion?

 

[froggy]

I think that is isn't out of the question for a keeper to photograph the animal next to a scale and then work out the measurements, or at least the larger ones. Lots of image software now does calibrated measurements (using a scale object in the picture), which would make it even easier (there is probably a free program somewhere out there, but not sure).

 

[Greatwtehunter]

Jaymes, my P. brevipes have a completely different skin texture than P. labiatus. It is rough, not smooth like P. labiatus.

Here are mine.

And just for giggles, here is P. archospotus.

 

[FrogEyes]

Although i think that the measure data is just useless for a common keeper (i'd call it too scientific), thanks for the "simple info". About P. archospotus, all the pictures of them show that they should be very easy to distinguish from P. brevipes - they're much larger, with those huge heads, and during breeding season males don't develop swollen cloacas.
One more question - what can you tell us about the phenotypes A and B, are they also P. granulosus in your opinion?

As Chris said, measurement isn't so hard - just put the animals on a neutral background with a ruler in view, and take a digital photo. In a graphics program, a line drawn following the skeleton can be compared to the ruler in the photo to get the desired measurement. Such photos are a matter of routine for me, to record unique or important animals.

As for the other phenotypes, I hadn't really looked into them. There are few photos available, and those which are aren't always helpful. In addition, those phenotypes were based almost exclusively on an almost-useless feature - coloration. That said, I've gone back and looked at the available photos...
Pachytriton A - P.granulosus
Pachytriton B - possibly P.labiatus. More than one species has likely been labeled as "B".
Pachytriton C - Paramesotriton ermizhaoi
Pachytriton D (mine) - Paramesotriton sp., genotyping pending.
Pachytriton D (more recently mentioned online) - probably P.archospotus

 

[SludgeMunkey]

Now you all have me worried! As I slowly collect up various adult Pachytriton sp. I too am quickly discovering what a mess the current taxonomy is. The more I read, the more I wonder if the possibility of so many distinct, but poorly identified animals has contributed to the infamous problematic captive breeding experienced by so many of us.

Thank you all for the fine reading.