What is a subgenus?
- Thread starter Hybridfish7
- Start date
The term seems to come into play when certain species in a genus is in flux with scientists.
For a while any cichlid that even slightly resembled a convict was considered Archocentrus. (Now only centrarchus is considered the the sole member of the genus)
As time went along and details from DNA testing allowed for more specificity, sub genera started splitting distinct groups in Archocentrus.
Cryptoheros, and Amatitlania, were then considered sub-genera. but now
"Most" scientists now accept the sub-genera as separate true genera.
The Herichthys genus is still in flux, where some accept the carpintus clade as true genera, but those of the labridens group as either a slightly different subgenus, or as a separate genus Nosferatu.
Compare Herichthys carpintus
with subgenus Nosferatu labridens
and bartoni. By looks alone, would you combine Herichthys carpintus with bartoni as the same genus?
I wouldn't (but I don't count)
or
Amatitlania sajica
with Cryptoheros cutteri (I might, but again I don't count)
For a while any cichlid that even slightly resembled a convict was considered Archocentrus. (Now only centrarchus is considered the the sole member of the genus)
As time went along and details from DNA testing allowed for more specificity, sub genera started splitting distinct groups in Archocentrus.
Cryptoheros, and Amatitlania, were then considered sub-genera. but now
"Most" scientists now accept the sub-genera as separate true genera.
The Herichthys genus is still in flux, where some accept the carpintus clade as true genera, but those of the labridens group as either a slightly different subgenus, or as a separate genus Nosferatu.
Compare Herichthys carpintus
with subgenus Nosferatu labridens
and bartoni. By looks alone, would you combine Herichthys carpintus with bartoni as the same genus?
I wouldn't (but I don't count)
or
Amatitlania sajica
with Cryptoheros cutteri (I might, but again I don't count)
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There are sometimes other divisions, like "sections," before you get to the species level. I think you'll find it makes more sense in botany, entomology, or in genera with many members (dozens, hundreds or more) and/or distribution over a very large and diverse geographic area (more than one continent or hemisphere, for example) or having adaptations to very distinctive habitats (for example, cave dwelling members of a genus) or when multiple members of a genus have some distinct feature in common. I've seen biologists themselves debate this and an ichthyologist's use the term likely varies from a botanist.
Or-- as I've also seen it defined: 'when a genus becomes too much too handle.'
Or-- as I've also seen it defined: 'when a genus becomes too much too handle.'
The short answer (in my opinion) is that subgenus names are relevant in nomenclature and taxonomy, but should best be avoided in the aquarium fish hobby, or hobbies for other "pet"organisms. Again, in my opinion, using subgenus names when selling fish amounts to little else than snobbery. However, I do believe that in most cases, their use in the hobby has to do more with inocent lack of knowledge about zoological nomenclature, rather than anything else.
The longer answer has nothing to do with my opinion, and has to come from the ICZN (International Code of Zoological Nomenclature), henceforth referred as the Code: a few relevant excerpts below (NOT in order of appearance in the Code. My own comments in italics):
xxxxx
Article 42. The genus group
42.1. Definition
The genus group, which is next below the family group and next above the species group in the hierarchy of classification, encompasses all nominal taxa at the ranks of genus and subgenus (see also Articles 10.3 and 10.4).
42.2. Provisions applicable to all genus-group nominal taxa and their names
Genus-group nominal taxa and their names are subject to the same provisions whatever their rank, except when these apply explicitly at one rank alone.
6.1. Names of subgenera
The scientific name of a subgenus, when used with a binomen or trinomen, must be interpolated in parentheses between the generic name and the specific name; it is not counted as one of the words in the binomen or trinomen. It must begin with an upper-case letter. [So, a subgenus name can be used for specific purposes but it is NOT part of the binomen (genus, species) for a given taxon]
4.2. Use of names of subgenera
The scientific name of a subgenus must not be used as the first name in a binomen or trinomen unless it is being used at the rank of genus [Art. 6.1].
xxxxx
In practical terms, it can be said that a subgenus is indeed a subgroup within a genus, containing species that have some character(s) in common among them, but not with other subgenera within the genus. However, they must conform to the diagnostic feature(s) of the genus, or they don't belong in it. They can be thought of as clades, but of course, a genus, or a family, or others can also be considered as clades and subclades. Species complexes (basically a group of species whose relationships are as yet not fully understood) may contain various subspecies, various species, and in some cases, sufficiently different taxa as to warrant genus group level changes.
Also, all subgenera in a genus belong to that genus. Equivalent to all subspecies by definition belong in the nominal species, or else, they have to be considered at the species level.
Finally, all these nomenclatural constructs are hypotheses about the relationships between organisms, the realm of taxonomy. Nomenclature just rules their naming. As new knowledge accrues, the current interpretation of relationships may change, and depending on the situation, appropriate nomenclatural changes may follow, also following specific rules. Modern methods, including molecular techniques and integrative methodologies (multiple lines of evidence such as biogeography, paleontology, anatomy, behavioral traits, and others) have and will continue to elicit changes to the names in use and thew inferred relations we may have learned years ago, and which we thought were the 'truth'.
The longer answer has nothing to do with my opinion, and has to come from the ICZN (International Code of Zoological Nomenclature), henceforth referred as the Code: a few relevant excerpts below (NOT in order of appearance in the Code. My own comments in italics):
xxxxx
Article 42. The genus group
42.1. Definition
The genus group, which is next below the family group and next above the species group in the hierarchy of classification, encompasses all nominal taxa at the ranks of genus and subgenus (see also Articles 10.3 and 10.4).
42.2. Provisions applicable to all genus-group nominal taxa and their names
Genus-group nominal taxa and their names are subject to the same provisions whatever their rank, except when these apply explicitly at one rank alone.
6.1. Names of subgenera
The scientific name of a subgenus, when used with a binomen or trinomen, must be interpolated in parentheses between the generic name and the specific name; it is not counted as one of the words in the binomen or trinomen. It must begin with an upper-case letter. [So, a subgenus name can be used for specific purposes but it is NOT part of the binomen (genus, species) for a given taxon]
4.2. Use of names of subgenera
The scientific name of a subgenus must not be used as the first name in a binomen or trinomen unless it is being used at the rank of genus [Art. 6.1].
xxxxx
In practical terms, it can be said that a subgenus is indeed a subgroup within a genus, containing species that have some character(s) in common among them, but not with other subgenera within the genus. However, they must conform to the diagnostic feature(s) of the genus, or they don't belong in it. They can be thought of as clades, but of course, a genus, or a family, or others can also be considered as clades and subclades. Species complexes (basically a group of species whose relationships are as yet not fully understood) may contain various subspecies, various species, and in some cases, sufficiently different taxa as to warrant genus group level changes.
Also, all subgenera in a genus belong to that genus. Equivalent to all subspecies by definition belong in the nominal species, or else, they have to be considered at the species level.
Finally, all these nomenclatural constructs are hypotheses about the relationships between organisms, the realm of taxonomy. Nomenclature just rules their naming. As new knowledge accrues, the current interpretation of relationships may change, and depending on the situation, appropriate nomenclatural changes may follow, also following specific rules. Modern methods, including molecular techniques and integrative methodologies (multiple lines of evidence such as biogeography, paleontology, anatomy, behavioral traits, and others) have and will continue to elicit changes to the names in use and thew inferred relations we may have learned years ago, and which we thought were the 'truth'.
