BirdingNZ.net

This is from a document about New Zealand ornithology that was written in 1868. It mentions three species of fantail in New Zealand; it treats the pied morph and black morph as two different species and says that a third, Rhipidura tristis, is found in Otago.
The OSNZ 2010 checklist does not address this directly (a limitation of how the pied morph and black morph are of the same taxon). It lists Rhipidura melanura and Rhipidura tristis as both being early terms for the South Island fantail; Rhipidura melanura is from 1843 and Rhipidura tristis is from 1853.
Was Rhipidura tristis ever actually thought to be a fantail species that was limited to Otago, or is this an isolated error?

Yes this is a typical situation when assessing taxonomy.

Each of these names is available - i.e. it was correctly published by the authors (according to the rules available at the time). It was the norm for morphs, such as black fantail, to be named as separate taxa at this time, as this was pre-Darwinian and there was a poor understanding of what these colour morphs were.

So the role of nomenclature is to make a judgement based on the currently available taxonomic information about which names are valid. This is a "moment in time" type of judgement and opinions change over time I am afraid, as knowledge improves and also as trends emerge. In the 1950s there was a trend for lumping, nowadays everybody splits. Remember there is no "truth" as species are a human construct.

In this case, a number of genetic and morphological studies indicate that the best approach is to consider that there is a single species of fantail in NZ that should be called Rhipidura fuliginosa as fuliginosa is the earliest available name. This was described by Sparrman in 1787 from a specimen from the South Island (this is called the type locality and is crucial in understanding what is going on). Thus as there are several subspecies the South Island subspecies is called Rhipidura fuliginosa fuliginosa

Rhipidura tristis was described by Hombron & Jacquinot in 1853 and thus this name post-dates Sparrman by 66 years. It is listed as a synonym in the checklist (which is one of the roles of the checklist). This does not mean the name is irrelevant but simply that it is not currently considered valid. If one day the Otago fantails were shown to be distinct this name would have date priority.

If a split were to be made separating black fantails from pied then another name Rhipidura melanura would have date priority as it is from a publication by Gray in 1843.

None of these judgements is an error per say simply a difference of opinion. If you multiply the number of species in the world by the number of nomenclatural opinions you quickly see why nomenclature and taxonomy is such a big job.

Paul

Thanks, Paul.

Growing up in Blenheim, we had a large number of the Black Morphs in our childhood neighborhood - it was somewhere between ¼ and ½... it felt that way anyway; my sisters said black were hens; pied were males (that's how close the ratios were then). By the time I got to High School, and learned about punnet squares it made more sense about recessive genes and roughly ¼ were black morph. Now when I go and visit, it's lucky if there's 1 in 15-20...

There's a couple of places along the Wairau River Bed where they still make up those large fractions: the changes in frequency, in a location, over time interests me

I've felt it'd be interesting if ebird could allow for reports on morph ratio trends. I suppose we can put that in the notes anyway