GregorHagedorn - Tue Nov 09 2004 - Version 1.2 Parent topic: LinneanCore This page is for discussing issues about hybrid names as units of LC.
There are two categories of hybrid name units: Nothotaxa (named hybrids), and Hybrid Formulae. These are not exclusive: Nothotaxa are a subset of Hybrid Formulae. That is, all Nothotaxa can be represented as a Hybrid formula, but not all Hybrid formulae have been formally named as nothotaxa. [Is this correct????]. Nothotaxa do not exist in ICZN (indeed, names established for hybrids are unavailable in zoology).
Nothotaxa
Questions:
Do nothotaxa exist for Bacteria? (I suspect not.)
Do Nothotaxon names follow all other ICBN rules governing the concurrent rank?
Gregor: I do not understand - what is a concurrent rank? ICBN specifies that all ranks for genus and below have a corresponding notho-rank. In H.10.1. further: "Names of nothotaxa at the rank of species or below must conform with the provisions (a) in the body of the Code applicable to the same ranks and (b) in Art. H.3."
Nothotaxon names are usually represented with a prefix "X" or "x" -- is this character part of the "name-unit", or is it treated as some sort of prefix separate from the base name? Does LC need to model this distinction?
Gregor: I always thought to better use a flag (like ABCD?) - but as Rich points out the same problem occurs in the formula. ICBN already defines canonical form: "H.3A.1. The multiplication sign in the name of a nothotaxon should be placed against the initial letter of the name or epithet. However, if the mathematical symbol is not available and the letter "x" is used instead, a single letter space may be left between it and the epithet if this helps to avoid ambiguity. The letter "x" should be in lower case."
Can Nothotaxon names be based on complex hybrids (e.g., [Genus1 aus x bus] x Genus1 cus) or back-crosses (e.g., [Genus1 aus x bus] x Genus1 bus); or are they only based on simple hybrids (e.g., Genus1 aus x bus)?
Gregor: I understand they can be complex.
Hybrid Formulae
Questions:
Should hybrid formulae (without Nothotaxon names assigned to them) be treated as separate LC instances (with their own GUID)?
Gregor: as you say, there is no prinical difference, and in usage they are interchangable. In practice the hybrid formula serves as a name. I therefore think yes. Compare ICBN H.10B.1. "When contemplating the publication of new names for hybrids between named infraspecific taxa, authors should carefully consider whether they are really needed, bearing in mind that formulae, though more cumbersome, are more informative."
Should there be a standardization of lower-case "x" character, or should the standard be a Unicode multiplication sign?
Gregor: I think we should define the canonical form as having the multiplication sign, to be future-compatible rather than backwards. ICBN H.3.1 states: "the hybrid nature of a taxon is indicated by placing the multiplication sign x before the name of"
Is there/should there be standards for formatting of hybrid formulae:
Genus1 aus x bus -- vs. -- Genus1 aus x Genus1 bus
(Genus1 aus x bus) x cus -- vs. -- (Genus1 aus x bus) x Genus1 cus
Nested brackets, vs. hierarchical brackets ((Hybrid1) x Hybrid2) -- vs. -- [(Hybrid1) x Hybrid2]
Other formatting issues?
How to deal with a "Genus" value for an inter-generic hybrid -- i.e., create an LC instance of Genus1 x Genus2 for Genus1 aus x Genus2 xus?
Gregor: I think you need nothogenus anyways. I cannot see the problem - perhaps you can give an example?
When gender of "parent" taxa are not known (most zoological hybrids), should there be a prefered sequence standard (Genus1 aus x bus -- vs. Genus1 bus x aus?
Gregor: ICBN recommends a canonical form: "H.2A.1. It is usually preferable to place the names or epithets in a formula in alphabetical order. The direction of a cross may be indicated by including the sexual symbols (female/male) in the formula, or by placing the female parent first. If a non-alphabetical sequence is used, its basis should be clearly indicated." -- This also answerers Rich's question: if sex is unknown, the formula should be in alphabetical order.
What special considerations for inter-rank hybrids: Genus1 aus x bus var. cus, or Genus1 aus x Genus2?
Other hybrid formulae issues?
-- Main.RichardPyle - 09 Nov 2004
The question of nothoranks is mentioned in TaxonomicRankRareRanks, the current proposal is not to introduce separate ranks, but to deduce nothorank from rank-code plus a hybrid flag. -- Gregor
Gregor: I wonder whether the equation of nothotaxa = named hybrids is correct. I find the phrasing of ICBN H.3.1 rather ambiguous. Elsewhere it clearly calls the formula case also hybrid taxa. So named hybrid taxon = nothotaxon, but a non-name hybrid taxon has just as well a nothorank?