Tylototriton (Yaotriton) revisions

Sorry, this probably isn't what you were hoping for...

A revision has been published, which evaluates many populations of subgenus Yaotriton, from across their known range in Laos, Vietnam, and China. This is the first study to incorporate all taxa including type localities [save one named this year], and the first to cover a large number of localities. Three mitochondrial genes were the focus of study. Tylototriton dabienicus is not included by name (more on that later).
The authors recover three primary branches which correspond to subgenus Tylototriton, T.vietnamensis, and to the remainder of subgenus Yaotriton. Within the last, they identify three main branches and a number of smaller ones. The main branches include a previously unidentified form from Hunan China, plus the remainder. The remainder includes T.notialis, T.hainanensis, T.wenxianensis, T.asperrimus, and a number of other populations which have until now been identified as T.asperrimus, T.cf.vietnamensis, or T.sp.

A number of conclusions are possible. One could recognize as few as two species: a highly variable T.asperrimus and a distinctive T.vietnamensis only recorded from the type locality; or up to 12 species. . The present authors transfer some populations to T.wenxianensis and synonymize T.hainanensis, T.notialis, and most uncertain populations with T.asperrimus. This is essentially consistant with Stuart et al 2010, who suggested the possibility of only three species, but their data and that of others used T.”asperrimus” from non-type localities, leading to a partially incorrect assessment of relationships. Among the traits used by Stuart et al to identify T.notialis was the unique presence of bright coloration on the lateral warts and rear margins of the parotids. Newer information [Sparreboom and Wu, Salamanders of China Lifedesk] shows that type locality T.asperrimus may have colored warts, and T.wenxianensis may have colored parotids. Color is thus more variable than thought in this lineage, and the revision has the effect of placing all the distinctly 'warty' forms in a single species [except T.vietnamensis], and the not-so-warty forms in another. Specimens from Henan (T.dabienicus) and Anhui (which I treat as T.dabienicus) were not included, but are very isolated compared to all other populations, with Hunan being the closest. The authors noted that the Hunan population could not be distinguished from T.asperrimus (T.dabienicus is almost identical to T.wenxianensis). While similar to T.asperrimus in appearance, the Hunan animals are genetically closer to T.wenxianensis, and further study is required to determine their status. The authors also comment that diversity and evolutionary history are difficult to determine because of homoplasy and conservative morphology [common issues in salamanders], and “Inclusion of additional genes, especially nuclear genes, may prove to be essential. MtDNA data alone cannot assess introgression and gene flow” [p. 583].

The authors caution against studies which lack specimens from type localities, and further caution against the limitations of relying on mtDNA exclusively. Given the low genetic divergences and largely similar morphologies, their conclusions are reasonable, even limited as they are by the type of data used. Whether nDNA, morphology, and ecological niche modeling will bear them out remains to be seen. Species are identified by their distinctiveness from one another, but can't be eliminated simply because they do NOT differ in one trait or another.

Further revisions should be expected, and it seems likely to me that already-named species will be revalidated and unnamed forms will be described as new species, at least in part.

I am preparing two revisions of my localities map, to accomodate both the authors' conclusions, and a multi-species alternative.

The paper can be obtained free here:
http://www.google.ca/url?sa=t&rct=j...lPWsDg&usg=AFQjCNEh_OrZ8YLaWcPEAwYRfRLIMhjfIA

Yuan Zhi-Yong, Jiang Ke, Lü Shun-Qing, Yang Jun-Xiao, Nguyen Quang Truong, Nguyen Thien Tao, Jin Jie-qiong, & Che Jing, 2011. A phylogeny of the Tylototriton asperrimus group (Caudata: Salamandridae) based on a mitochondrial study: suggestions for a taxonomic revision. Zoological Research 32(6):577

FrogEyes said:

Sorry, this probably isn't what you were hoping for...

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Think again
Thank you very much for taking the time to offer this information, it´s greatly apreciated. I´m looking forward to newer studies including non mitochondrial DNA. It´s nevertheless smashing that asian caudates are receiving more attention!

When you've updated your locality maps would you be able to make them available to us? It would be interesting to see both versions.

The problem from a hobbyist's perspective is that the asperrimus "complex" animals all look so similar morphologically and are often sold without locality information resulting in a pollution of variable images on the internet. Black, brown, warty etc - they're all there claiming to be the same thing. If the science boffins can't figure it out we don't stand a chance. When this study is concluded it would be great to see bonafide images of each species from each location, assuming a multiple species model is adopted.

Is someone working on the verrucosus/kweichow/shanjing mess too?

All tylos, but without updates, corrections, and revisions of Yaotriton. Includes a photographic record of verrucosus in Bhutan which I dug up [apparently no formal records from Bhutan, ever]:


Yaotriton only, maximum diversity (13 species/lineages). Lineages are paired by size [large=named species; small=similar sibling taxon, usually “cf”], color [light blue sibling to dark blue, etc], and shape [triangle versus circle versus square, square sibling to circle]. White triangles are unassigned to a lineage. “cf vietnamensis” are populations currently refered to as such, but which are not related to T.vietnamensis:


Reduced to seven species by combining sibling populations of “cf” [small symbol] with nominotypic populations [large symbol, changed to small], and T.dabienicus with T.wenxianensis:


Reduced to six species by combining T.notialis with sibling T.asperrimus:


Reduced to five species by adding T.cf.vietnamensis to the above:


Reduced to four species by merging T.hainanensis with the above:


These merges are made according to the phylogenies provided in the paper above [except dabienicus], which are notably exclusively maternal lineages which may not represent species boundaries. This mapping could be seen as a crude form of ecological niche modeling - does it make sense to have species with distributions like ***? The four and five species phylogenies create a more clear geographic picture. Some options haven't been used, such as variations on the T.wenxianensis complex, all of which make geographic sense.

The 13 and seven species options don't work very well. They involve multiple, closely-related, but overlapping species, which biogeographically is unlikely. However, the fact remains that those multiple overlapping lineages exist regardless. Do those lineages result from separate species ranges expanding and contracting across different environments? Do they result from incomplete lineage sorting, in which formerly related maternal populations are now part of separate species? Do they result from hybridization? Using only mtDNA data, the only reliable taxonomy combines T.cf.vietnamensis and T.notialis [and their siblings] with T.asperrimus [and its immediate sibling]. Other sources of data, however, could paint a very different picture and thus make many-species schemes the only viable choice. I notice that the six and seven species schemes are interesting because they show overall divergence north-south, combined with subsequent coastal-inland divergence in most lines, and further north-south divergence. That suggests to me a greater number of species with differing environmental niches.

From a hobbyist perspective, I have two comments: first, maintain breeding groups of precise geographic origin [ha!]; second, if you don't know locality, you should be able to ID fairly easily, as only T.wenxianensis, T.vietnamensis, and T.asperrimus are morphologically distinct [and possibly dabienicus]. All other forms should key out to T.asperrimus. The unnamed form from southern Hunan is problematic, since it looks like T.asperrimus, though it's not likely in captivity anyway.

Black, brown, warty etc - they're all there claiming to be the same thing. If the science boffins can't figure it out we don't stand a chance.

Click to expand...

Yep. In point of fact, this paper concludes that they ARE the same thing. For instance, photos of animals from Dayaoshan [type locality of T.asperrimus] are brownish with rusty colored warts. Obviously, characterizing T.asperrimus as completely black is a HUGE mistake.

Is someone working on the verrucosus/kweichow/shanjing mess too?

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I don't know, but I suspect that Somphouthone Phimmachak is. She started in Laos with Laotriton for her MSc, continued with the discovery of T.notialis, and is now pursuing a PhD in Thailand, working on Thai/Laos tylos.

While there are revisions needed, I think the mess is mainly an illusion of the hobby, compounded by some strange conclusions on the part of the science. The biggest issue is the continued treatment of non-Chinese populations as T.verrucosus, just because they're non-Chinese, even though that treatment makes no sense geographically OR morphologically. Apart from that, there is at least one morphologically distinct and disjunct population, and the T.cf.kweichowensis whose natural origin is unreported. The former is almost certainly a new species, the latter could be a geographical variant or a full species. A conclusion could be reached from captive specimens, but a resolution really calls for knowing the origin. The first map above includes my corrections to the ranges of this complex, where geographical origins are known and animals identifiable [to subgenus].

The discovery of new populations ever further from the previously-known ranges suggests to me a great deal of possibility of new species and populations of both Yaotriton and Echinotriton in eastern China. To be where they are now, at one time, they MUST have occured more or less throughout eastern China.