Curator of Botany Leon Perrie discusses some of the rules governing scientific names, and explains why we can continue using the name Coprosma grandifolia – at least for now.
A fundamental aspect of scientific names for biological species is that they have two principal parts. The first or generic part names the Genus to which a species belongs.
The second or specific part denotes the particular species. Examples include Homo sapiens (humans), Coprosma robusta (karamū), Coprosma repens (taupata), and Coprosma propinqua (mingimingi).
Scientific names are governed by a strict set of rules. For plants, it is the International Code of Nomenclature for algae, fungi, and plants. One of the most important rules for scientific names is that a species can have only one accepted scientific name.
While there might be taxonomic debates about the genus in which to classify a species, the second part of the name is dictated by the principle of priority.
That is, when multiple specific names (i.e. the second part of a scientific name combination) have been applied to a particular species, whichever was first legitimately published is the one to be used.
This idea of priority is unambiguous – whatever name is first is the ‘winner’. But it can be a pain. For instance, trawling through ancient texts or changes in the circumscription of a species may result in a little or never used name being found to have precedence over a well-established name.
Not only does that mean learning a new name, but identification books, garden labels, and other resources become out-of-date. To deal with such disruptive cases, the International Code of Nomenclature for algae, fungi, and plants contains a mechanism – called conservation – to override priority.
Bending the rules
Three leading custodians for the rules for naming recently wrote:
“Successive Nomenclature Sections have made it quite clear that indulging in name changes for purely nomenclatural reasons is now reprehensible unless new conservation/rejection avenues have been explored.” (reference 1)
This statement really struck me. From my interactions with botanical societies and online plant groups, I know that many users of scientific names dislike changes!
My reading of the above statement is that taxonomists should be delving into the nomenclatural tool-box to stabilise scientific names whenever possible. After all, who wants to be reprehensible?!
What of Coprosma grandifolia?
The largest-leaved Coprosma in New Zealand is one of our most commonly-encountered indigenous plants (among the top 1% as judged by iNaturalist observations). Among many te reo Māori names, perhaps kanono and manono are the most commonly used.
In recent times, the especially-apt scientific name Coprosma grandifolia has been applied to this species. That was published by Joseph Hooker in 1852, and was in widespread use by New Zealand botanists during the early part of the 20th century.
The middle of the 20th century saw a mistaken switch to Coprosma australis (which actually applies to a different species), before reversion in 1987 to Coprosma grandifolia. The latter name again became pretty much universally adopted.
However, others (reference 2) recently noted that Joseph Hooker made a technical error (at least as judged by today’s scientific naming rules).
Consequently, his name Coprosma grandifolia was not legitimately published. In that case, the earliest legitimately published name is Coprosma autumnalis, by William Colenso in 1887.
A potential fix
On learning of this, I thought it could be a good case for using the nomenclatural tool-box to conserve the name Coprosma grandifolia as the correct scientific name for this species. This would maintain prevailing usage, and avoid the disruption of a name change for one of New Zealand’s most common native plants.
After all, Joseph Hooker’s error hadn’t been noticed for over 160 years, and William Colenso’s Coprosma autumnalis had never been previously used in modern times.
I have written a paper making the formal case for conserving the name Coprosma grandifolia. It is freely available here: ‘Proposal to conserve the name Coprosma grandifolia (Rubiaceae) with a conserved type’. It contains more details of who did what, and when.
What happens now?
A committee of international experts on the rules of naming plants will vote to accept or reject the proposal within the next few years (with a 60% majority required for a binding decision). I’ll be interested to see on what side of the “reprehensible” line they decide this case falls.
If they accept the proposal, the name Coprosma grandifolia will be locked in for kanono.
If they vote to reject, then Coprosma autumnalis will be the correct scientific name for this species.
In the meantime, you can continue using Coprosma grandifolia, knowing that a decision is pending.
(1) McNeill J, Redhead SA, Wiersema JH. 2015. Guidelines for proposals to conserve or reject names. Taxon 64: 163-166.
(2) Large MF, Mabberley DJ, Wood E. 2020. Coprosma autumnalis (kanono; Rubiaceae) in New Zealand: nomenclature, iconography and phenology. Kew Bulletin 75: 37. DOI 10.1007/S12225-020-9876-4.