Taxacom: Collective groups and form(al) genera

[Francisco Welter-Schultes]

Dear Ziv,
If you propose a name for a collective group, that name would 
automatically not have a type species no matter if you designate one or 
not. You could not fix a type species for it, any type species 
designation would be invalid. You could designate one, but only 
ineffectively.

For the collective group see the definition in the Glossary:

"collective group. An assemblage of species, or stages of organisms 
(e.g. eggs or larvae), that cannot be allocated with confidence to 
nominal genera. Names proposed or used for collective groups are treated 
as genus-group names but special provisions apply to them (see Article 
42.2.1)."

If you propose a name for an assemblage of species which you cannot 
allocate with confidence to nominal genera, you propose a name for a 
collective group. Once this condition is met, "assemblage of species 
which you cannot allocate", the rest follows automatically. As said 
above, even if you designate a type species this act will be ineffective 
and invalid. It would not render your name anything else but a name for 
a collective group.

If the form genera you are talking of were proposed for such 
assemblages, which the authors demonstrably could not allocate with 
confidence to nominal genera, they fall under the definition of a 
collective group. Consequently these names do not have type species - 
and any type species designation would be invalid.

It is not possible to state "the form genera have type species, so they 
are not collective groups". The condition of the Glossary definition is 
superior. If they are collective groups because they comply with the 
Glossary definition, they have no type species, and any previously 
published type species designation is to be rejected as invalid.

This is how I understand the Code in this matter.

I hope this helps.

Best wishes
Francisco

Am 25.06.2025 um 04:50 schrieb Ziv Lieberman via Taxacom:
> Hi all,
> I'm thinking about the differences between "form" or "formal genera" and
> "collective groups" and how to best approach these entities when
> establishing new nomenclature.
> In ants, there are many groups of fossil taxa which have been established
> for convenience, without implying that they form a natural group - mostly,
> e.g., impressions of wings or incompletely preserved fossils which can be
> associated based on one or more morphological features. Authors generally
> state that these are "form genera" (or, perhaps confusingly, "formal
> genera", especially in the Russian school of paleontology). However, they
> are nomenclaturally treated as "real" genera, including in that they have
> type species.
> To my understanding, these "form genera" align with the Code's definition
> of collective groups: "An assemblage of species. . .that cannot be
> allocated with confidence to nominal genera. Names proposed or used for
> collective groups are treated as genus-group names but special provisions
> apply to them". These provisions are given in 42.2.1 ("The names
> established expressly for certain assemblages of taxonomic convenience
> known as "collective" groups. . .established at the genus-group level are
> to be treated as genus-group names in the meaning of the Code." 42.3.1
> states "Collective groups have no type species."
> Therefore, I arrive at the conclusion that even though many "form(al)
> genera" are "established expressly for assemblages of taxonomic
> convenience", they are *not* collective groups, since they have type
> species.
> This leads to my direct question: If I want to establish a new collective
> group, should I follow 42.3.1 and not fix the name to a type species? This
> seems like it must be the right answer, but I am hesitant because I have
> never seen an example of such a name in practice.
> Further, if the type species of a form genus is transferred to a type-free
> collective group, are there any additional complications to consider?
> Thank you!
> -Ziv
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