taxonomy

Historical

The term Taxonomy (‘Taxéonomie’ in French) appears late, in 1813, by the Swiss botanist Augustin Pyrame de Chandelle (1778-1841) and comes from the Greek taxis meaning “placement”, “classification”, “order” and nomos designating “law”, “rule”. In 1819, he considered the spelling erroneous and he preferred then “taxonomy” to which he removed the “e” to shorten the word. Thus, taxonomy refers to a branch of biology, whose purpose is to describe living organisms and to group them into entities called taxons to identify and then name them and finally classify them and recognize them via keys of dichotomous determinations.

The word taxon was created in 1948 by the botanist Herman Johannes Lam and derives from the term taxonomy by truncation. It is a conceptual entity that is supposed to group together all living organisms that share certain well-defined taxonomic or diagnostic features.

Historically, we attribute to the Greek philosopher, Aristotle, the first classification of animals, visible in his zoological work The History of Animals – Historia Animalium. Taxonomy has evolved over time and has experienced multiple revolutions such as the systematic approach (pure science of taxon classification, Carl Von Linné, 1707-1778), binominal name (Augustin de Candoll, 1778-1841), genealogical (Jean-Baptiste de Lamarck, 1744-1829 and Charles Robert Darwin, 1809-1882) up to modern development and genomic progress, a discipline of modern biology studying the functioning of a genome-wide organism, its DNA , who as a result. It becomes obvious, as discoveries, concepts and technological advances that there is an evolution of the taxonomy of species.

The species

The term species is defined as a community of living beings interfecund or interfertile (probable cases most of the time in hybrid individuals). Species are named after the binomial system (Linnaeus), sometimes even trinominal. Thus, the scientific name of a species is the combination of two Latin words or considered as such, usually written in italics.

Classification

It is through these methods that species and subspecies can be visually grouped, by classification, and in tree form, according to taxa and sub-taxa, as shown in the following figure.

Classification hierarchisée selon David & al., 2011
Hierarchical classification according to David & al., 2011

It therefore seems obvious, knowingly the taxonomic difficulties, that the first people to have been able to give taxa were largely mistaken, combining or removing species that were finally grouped or dissociated, partly because of the weak knowledge of the era in the field of genonimia, but also selected criteria. For example, Trimeresurus insularis occurs both in all the small islands of the probe, Kepulauan Nusa Tenggara in Indonesia, but also in a green or yellow color. The greens would have initially been quite confused with Trimeresurus albolabris with whom he also shares his territory. There is also, in the case of Trimeresurus but also other venomous species, the question of venom. For example, T. puniceus has changed taxon following the analysis of the latter, notably the non-use of the phospholypase-A2 hydrolase, which is an integral part of its composition.

At this stage, one can easily understand the taxonomic difficulty that the genus in question represents in this book.

We still have 3 solutions:

I) We can place all the species under the Trimeresurus complex, we speak then Trimeresurus “sensu lato” (Trimeresurus “in the broad sense”)

II) It is also possible to cut and place the species by types: Viridovipera, Paria, Popeia, etc.

III) Use the genera as subgenera of Trimeresurus becoming: Trimeresurus (Paria), Trimeresurus (Viridovipera), Trimeresurus (Trimeresurus), etc. (David & al. 2011)

If science and technology have made it possible to study genomics in depth, thus making it possible to clarify the different clades, the fact remains that the morphological aspect of the individuals makes it possible to describe the different species in a basic manner. Therefore, if the exo-morphology changes, it is natural that the skeleton also changes, as shown in the following figures, influenced by the distinct evolution of the species according to their respective environments (Guo, P., & Zhao, EM ( 2006)).

Conclusion

Originally, all Asian crotalinae were grouped in the family Trimeresurus. This clade then proposed six genera: Trimeresurus, Ovophis, Protobothrops, Tropidolaemus and Triceratolepidophis. (Malhotra, A., & Thorpe, R. S. (2004)). Since then, technological advances, particularly in genomics, have made it possible to specify the genera, separating the families presented above and replacing them with new ones: Craspedocephalus, Himalayophis, Parias, Peltopelor, Popeia, Sinovipera, Trimeresurus and Viridovipera. In 2004, the genus Cryptelytrops was reconsidered, but it never seems to have the unanimous approval of the scientific community (Yann Bartholin, 2017, personal communication, Mark O’Shea, March 2013, Thorpe, RS, Creer, S., Lallias, D., Dawnay, L., Stuart, BL, & Malhotra, A. (2015)). It remains however still used. The green crotalinae, named bamboo rattlesnake, was considered to be a single species, Trimeresurus gramineus (India holotype) (Malhotra, A., & Thorpe, R. S. (2004)). In particular, it was determined that he was in fact not the type species, and that it was actually Trimeresurus viridis (David & Al. 2011). Trimeresurus viridis is a taxon, more used since 1899, and replaced by the current Trimeresurus insularis.

The species are still very close to each other. For example. Sinovipera sichuanensis and Viridovipera stejnegeri are closely related to a genome scale. But Viridovipera stejnegeri is also closely related to Trimeresurus albolabris. The three species also share the same territory, China (Zhu, F., Liu, Q., Zhong, G., Xiao, R., Fang, M., & Guo, P. (2016)).

Another example highlighting the taxonomic difficulty is in the Popeia complex. In 2016, studies revealed that the differences between P. toba and P. barati were not sufficient to differentiate them and should therefore be considered as a single species: P. sabahi. Their study was based on molecular and morphological parameters.

In general, it is common, mainly outside the scientific community, to speak of Trimeresurus “sensu lato”, thus speaking of Trimeresurus spp.

Sources:

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Rollard, C., Chippaux, J. P., & Goyffon, M. (2015). La fonction venimeuse.

Jackson, K. (2007). The evolution of venom-conducting fangs: insights from developmental biology. Toxicon, 49(7), 975-981.
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Thorpe, R. S., Creer, S., Lallias, D., Dawnay, L., Stuart, B. L., & Malhotra, A. (2015). Convergence of multiple markers and analysis methods defines the genetic distinctiveness of cryptic pitvipers. Molecular phylogenetics and evolution, 92, 266-279.

Wostl, E., Sidik, I., Trilaksono, W., Shaney, K. J., Kurniawan, N., & Smith, E. N. (2016). Taxonomic Status of the Sumatran Pitviper Trimeresurus (Popeia) toba David, Petri, Vogel & Doria, 2009 (Squamata: Viperidae) and Other Sunda Shelf Species of the Subgenus Popeia. Journal of Herpetology, 50(4), 633-641.