Taxonomy in the IUCN Red List


As the IUCN Red List deals with a large number of taxonomic groups, there is no single taxonomic standard that can be cited. Responsibility for identifying a taxonomic standard, or (in cases where no agreed standard exists) defining one, lies with individual Specialist Groups or, for taxa that are not covered by existing Specialist Groups, standalone Red List Authorities (RLAs). Taxonomic changes (including merges, splits, and nomenclatural changes) or additions (e.g. new species) are arranged through the RLA Coordinator or an especially appointed RLA member (full time or part time). If RLA members are aware of any new species or taxonomic changes within the remit of their Red List Authority that are not in the Red List, please contact the RLA Coordinator.

 

IUCN does not have a taxonomic remit and, while of course individual SSC members with the appropriate expertise can publish taxonomic changes in their capacity as academics, the Red List cannot be used as a venue for publishing formal taxonomic decisions. It is within the remit of RLAs to reject proposed taxonomic changes that members deem to be insufficiently supported or in error, or to decide which of multiple competing taxonomic concepts to apply in specific cases where a decision is required, and these cases must be fully documented with appropriate citations in the relevant accounts’ Taxonomic Notes.

 

The primary goal of IUCN Red List taxonomy is to apply species concepts that are likely to be stable over the lifetime of the assessment and beyond, to ensure that the data and conservation status in an account reflects a genuinely conservation-relevant species. In some cases, this will mean that RLAs prefer to refrain from adopting new taxonomic arrangements until these have been adopted more widely by the relevant specialist community.

 

Newly-described species that do not have any synonymy associated with them (i.e. have not been called by another name in the past) are straightforward additions to the SIS database underlying the Red List; however, those new species that have been associated with another name in the past require additional attention not only to determine the nature of the taxonomic change, but also because those species that have been associated with that biological population in the past need to be reassessed. In other words, assessments are conducted on the taxonomic concept associated with specific biological populations; if one of those populations is considered to be a new species, then the taxonomic concept changes, and a reassessment has to be made on the remainding populations associated with the existing concept.

 

The Taxonomic Note and synonymy sections in SIS are independent of specific published accounts. This means that they can be amended to reflect taxonomic changes that do not demand a reassessment, i.e. cases where a species concept does not change (most commonly, simple nomenclatural changes such as transfer to a new genus). These changes will become visible on the Red List website in the following Red List update, with no need for RLAs to resubmit the associated species accounts.

 

It is important to note that when new taxonomic changes are implemented in SIS, they are always automatically updated on the Red List each time it is launched. It is very important to try to finalize the reassessment of any species already in the Red List which has undergone a recent taxonomic change and requires reassessment, as otherwise any changes to the Taxonomic Note reflecting the updated taxonomic arrangement will be associated with the old published assessment. This will result in the note and the published account being out of sync and they will consequently likely have contradictory information. Similarly, an assessment of a new species whose description affects a published species concept in the Red List should not be published without the corresponding reassessment of existing taxa, to ensure taxonomic consistency between accounts. A species that is no longer regarded as valid but which has a published assessment will remain on the published Red List until such time as the species with which it has been synonymised has a published Red List assessment.

 

Lockdown periods in SIS

 

Prior to Red List version launches, SIS goes in lockdown mode until the launch date. This lockdown period is generally 4-6 weeks before a Red List launch date, and it means that during this time taxonomic changes in SIS should not be made. Thus, any changes to taxonomy need to be done either before or after one of these lockdown periods. During lockdown we should avoid making any further edits to any draft assessments that have been submitted for publication – for any urgent last minute edits please contact the relevant RLA Coordinator, who will liaise with the Red List Unit about these.

 

Reptiles

 

There is no current, widely-accepted global standard or overview of reptile taxonomy overall. IUCN’s Freshwater Turtle and Tortoise Specialist Group publishes its own taxonomic standard as an annual checklist, and other reptile Specialist Groups have adopted or are developing standard taxonomies for boas, pythons and their relatives, anoles, vipers, sea snakes, crocodilians, chameleons and marine turtles. Remaining squamates (and the tuatara) follow the species-level taxonomy being developed by the Snake and Lizard Red List Authority. This is an ongoing process and is a product of literature reviews and collaboration with both expert reptile taxonomists and the developers of TIGR Reptile Database; this latter being the closest work to a reptile taxonomic standard currently available.

A note on snake higher taxonomy: Reptile higher taxonomy is a subject of some contention among herpetologists. One area of inconsistency in recent literature is the nomenclature applied to several major snake groups. At present the Red List adopts the widely-used division of the Colubridae sensu lato into a number of full families (i.e. Natricidae, Dipsadidae, Calamariidae etc.), principally because these represent validly separable evolutionary lineages (clades), often with shared ecological characteristics, and subfamilial divisions are not supported by the SIS database. Many herpetologists however prefer to retain these groups as subfamilies within Colubridae at least until their relationships are better-resolved. Clades within Lamprophiidae (Atractaspinae and Pseudoxyrhopinae) recently treated in the literature as lamprophiid subfamilies are treated as full families in the Red List on a similar basis. This arrangement has resulted in one recognized family name in the Red List (Pseudoxyrhopiidae) which is implied by recent phylogenies but has no explicit literature basis. Snake higher taxonomy is currently under review by the Snake and Lizard Red List Authority to resolve this and other issues.

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