[Taxacom] Diagnoses for monotypic genera

[Stephen Thorpe]

 Igor,You seem to be mixing up taxonomy with nomenclature. I was talking taxonomy. It might be argued that the diagnosis for a monotypic genus should specify those characters which a species needs to have in order to be included in that genus. That way, if someone finds a new species, then they can tell whether or not it belongs to that genus. So, for example, although the single known species might be green, the colour isn't part of the generic diagnosis because a new species which is brown, but otherwise similar, would also be included in the genus. Some, but not all, characters of the species are important at the generic level and so only these important characters should be part of the generic diagnosis.Cheers, Stephen
    On Tuesday, 13 July 2021, 06:18:22 pm NZST, igor pavlinov <ipvl2008 at mail.ru> wrote:  
 
 The ICZN presumes that (https://www.iczn.org/the-code/the-code-online/): 11.9.3. A species-group name must be published in unambiguous combination with a generic name (either explicit, or implicit by context)11.9.3.4. the generic combination, although it must be unambiguous, can be tentative If generic allocation of a new species is ambiguous, there are two possibilities to make a new species name binomial: a) the name of an already established genus, to which the new species might tentatively belong, is indicated, or b) a new genus is established. Each taxonoimic diagnosis is context-dependent, it provides a possibility of distinguishing a taxon from others presently known, and not from those to be discovered in the future. In particular, - Generic diagnosis must distinguish a new genus from other known genera of the same family. If all genera are two-winged, why to indicate this in the generic diagnosis? - Specific diagnosis must distinguish a new species from other known species of the same genus.  If there are no other species currently known in the latter, there is no need to indicate diagnosis of the newly established one, so the formula «the same as for the new genus» seems to be correct. Cheers, Igor - - -
Igor Ya. Pavlinov, DrS
Zoological Museum of Lomonosov Moscow State University
ul. Bol'shaya Nikitskaya 6
125009 Moscow
Russia
http://zmmu.msu.ru/personal/pavlinov/pavlinov1.htm 
http://zmmu.msu.ru/personal/pavlinov/pavlinov_eng1.htm  
Понедельник, 12 июля 2021, 23:43 +03:00 от Stephen Thorpe via Taxacom <taxacom at mailman.nhm.ku.edu>:
 I suppose it might be argued that one should imagine what characters would be possessed by possible future new species that would result in their inclusion in the presently monotypic genus. So, for a simplified example, the species might have three wings and be green, but the genus would include anything else with three wings, regardless of colour, so the generic diagnosis would not mention colour, only the number of wings.Stephen
    On Monday, 12 July 2021, 08:34:30 am NZST, Mario Schädel via Taxacom <taxacom at mailman.nhm.ku.edu> wrote:
 
 Dear Taxacom readers,

from time to time, reviewers and editors complain about how my
colleagues and I handle diagnoses for species which can not be
identified as belonging to an existing group that is ranked as ‘genus’.
Based on the underlying logic in my opinion it is best to give a
diagnosis for the species and then for the monotypic genus either write
‘as species’ or ‘not applicable because monotypic’ (I would prefer the
latter solution).

Are there publications arguing for this procedure? It would be very
convenient to point reviewers or editors to such a publication instead
of writing long-winding explanations why we think the two alternatives
(below) are a bad idea. To explain myself in a bit more detail: The
alternatives to my preferred ways are:


1. splitting up the diagnosis into a genus and a species part (this gets
suggested the most).

The decision whether a character is genus or species level is obviously
very subjective and arbitrary. Whether such a decision was correct can
only be known when and if a second species gets discovered. While it is
arbitrary and subjective, this may sound trivial; however in practice I
find it to be problematic.


2. giving a diagnosis for the genus (exactly as I would formulate it for
the species) and then for the species writing ‘as for the genus’.

This may sound even more trivial. ‘as for the species’ – ‘as for the
genus’ – Where is the difference? The difference is that in practice
many authors do not critically check what assumptions there are behind
diagnoses. Even more so if they come from well established colleagues.
Subsequently, authors simply include a new species into an existing
genus if the new species matches the description of the genus, instead
of thinking about synapomorphies between the two species.

In my opinion, not providing diagnoses for the genus can be very helpful
in this regard, as it doesn’t lure future authors to a convenient but
potentially wrong solution. In my field – I work with arthropod fossils
– there are numerous examples of genus names that turned into garbage
taxa because of exactly this process. Extinct species are especially
prone for this and with those the process of untangling such messes is
even harder, because there is only incomplete morphological data
available. Yet, I can imagine such things to also be problematic in
fields where there are only few resources available for reconstructing
phylogenies using molecular or combined data.


I would be very happy if someone could point me towards publications
that deal with this problem, which I then can reference to, when needed.


Best wishes,

Mario Schädel


--
he/him
PhD Student
Zoomorphology
Ludwig-Maximilians-Universität München
Munich, Germany
mcranium.github.io

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