Taxacom: Neotypification and common usage

[Thomas Pape]

Daniel:

As for your question on standards and possible limits for "common usage", one of the underlying principles upon which the Code is based is that "There is no "case law" in zoological nomenclature. Problems in nomenclature are decided by applying the Code directly, and never by reference to precedent. If the Commission is called on to make a ruling on a particular case, the decision relates to that case alone".

As for the specific issue, the authors behind Set 1 base their decision on the wrong assumption that the syntype specimen is the holotype. This specimen is a syntype (if it was one of the original specimens seen by the author in 1842), but the fact that it is the only specimen recovered does not give it any priority over the other (and potentially lost) specimens in the type series. Any specimen in the type series is eligible for being designated as a lectotype, but considering the syntype to be a holotype does not qualify as a lectotype designation for designations made after 1999. Set 1 therefore does not solve the central issue of a possibly mixed type series.

Set 2 rests on their arguments that what has been called a syntype specimen is actually NOT part of the original set of specimens seen by the author in 1842. If their arguments are accepted, their designation of a neotype is valid (if fulfilling other conditions provided by the Code), and the name proposed by the authors of Set 1 is a junior synonym. [NB: neoparatypes are not recognized by the Code.]

A thorough assessment rests on whether or not the single syntype is actually a syntype, and whether or not this specimen is in a condition that allows for a reliable taxonomic decision.

Regards,
Thomas


-----Original Message-----
From: Taxacom <taxacom-bounces at lists.ku.edu> On Behalf Of Daniel Gustafsson via Taxacom
Sent: 10. december 2022 05:59
To: taxacom at lists.ku.edu
Subject: Taxacom: Neotypification and common usage

Dear colleagues,

I'm looking at a case where a parasite species was described about 180 years ago (1842) from what may be a mixture of species (amount unknown), of which only a single syntype specimen remains. Unfortunately, this syntype specimen appears to not be the same species as has been reported from this host in the intervening 180 years. The original description is largely useless even to get to the genus level, and the original illustration is poor, but shows at least one potentially important character (setae in a certain area) which are absent in the illustration *and* in the remaining specimen, but present in the species that normally parasitizes this host. Two authors in the 1960?1970s redescribed the species poorly, and this redescription is of a different species than the syntype specimen, which they did not examine.

In 2020, two sets of authors discussed this species (one set in reaction to the other), and reached different conclusions:

Set 1 -- the syntype specimen (which they erroneously call the
'holotype') is conspecific with the illustration and not contradicted by the original description. Therefore, the name of this species can follow the specimen, which thus is assumed to be from an unknown host. The species of parasite that is normally found on this host thus needs a new name, which they provide, including a description and illustration and a review of the previous reports. They have visited many of the museums where previously reported specimens are stored, and invariably these are the same as the new species, and not the same as the syntype specimen. 
No further specimens conspecific with the syntype specimen have been found, but the group is very poorly known so this is not a surprise. 
These authors do not redescribe or illustrate the syntype specimen, and appear to have made no efforts trying to compare this specimen with other specimens in the same collection from the same collector 180 years ago. The question of mix-up of specimens is thus open.

Set 2 -- it cannot be established beyond reasonable doubt that the syntype specimen is actually part of the original set of specimens seen by the author in 1842, and much of his collection is lost. The collection has changed hands at least once since 1842, it is unknown who slide-mounted the specimens, and at least two earlier authors contradict each other concerning which specimens were included in the original purchase. It is therefore possible that the rest of the original type series included the species normally found on this host, and that the syntype specimen is either a mix-up, a contamination, or some other form of error. All other reports of parasites in this genus from this host have used the 1842 name, and for the purposes of stability, we should continue to use this name and treat the new name established by Set 1 as a subjective junior synonym. To this end, Set 2 erects a neotype and four neoparatypes, which correspond to the parasite species normally found on this host, as well as the one illustrated and described as a new species by Set 1. Set 2 keeps the door open to applying to the Commission for an official ruling if this neotypification meets well-founded resistance.

In the ~180 years between the original description and the revision, there appear to be about 25?30 publications that use the old name for this species. However, all except two of these are either just inclusions in lists of members of a given genus, with no further information added, or regional faunal lists where identity of the specimens has been assumed based on host associations. Until 2020, there has been no way to identify the original species either from descriptions or illustrations, and as Set 1 also do not describe the syntype specimen, this is still true.

Without going into which set of authors is correct (although I'd value input on this as well), I'm wondering about the process of setting aside type specimens that are suddenly found not to represent the common understanding of the species name. Where, if anywhere, is the limit for "common usage" the stability of which could be threatened if the names are changed? I've seen various case reports and opinions in the Bulletin, where often authors will list a number of publications within a certain framework to show that the name is in use, but is there any official standard for this?

Further, if there is an accepted official standard, is this affected by the circumstances of usage? Apart from faunal lists where identity is assumed based on host associations, there is no information of any kind attached to this name between 1842 and the present. The 2020 authors also do not attach any new information beyond that the syntype is not conspecific with the species normally found on the host.

It would seem to me that this kind of usage would "count" towards any kind of standard for the number of publications a name needs to appear in to be commonly accepted. Is just listing a name without making any effort to establish whether you're applying the name to the correct taxon sufficient to assert that the name is in common, universal usage? 
Seems to me this would be rewarding laziness.

I'd value any input on this.

Cheers,
Daniel


--
Dr. Daniel R. Gustafsson, Research Assistant Professor Institute of Zoology Guangdong Academy of Sciences, Guangzhou, China.

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