Perhaps it's better to say 'conveniently recognizable' genus.
In large part the problem is that increasingly 'invisible characters' such as molecular data are being used to generate phylogenies from which we then attempt to create taxonomic frameworks. The transition from phylogeny to taxonomy involves delimitating outputs (crown clades) into tangible taxa and it often forces us to observe and describe and explain minute (but for that no the less critical) subtleties of morphological expressions.
Our inability to deal with such levels of finely defined (and oftentimes intuitively contradictory) information springs in large part from the fact that backbone of "traditional systematics" are groups of 'species' clustered into 'genera' (with genera nested into still 'higher' units such as tribes, subfamilies, &c.) and that in the main these units represent conceptual circularities that in many instances have almost arbitrarily been accorded a particular rank. It is vital to remember that taxa, especially those above the ‘rank’ of 'genus' were originally delimitated by recourse to easily observable (and readily explicable) morphological expressions ("characters"), and that furthermore are often accepted by a large part of the botanical community, and by implication most 'end users', on what amounts to hearsay. Mostly these units have never, at least until recently, been 'tested' using non-partisan tools.
For example, Homalomena is 'traditionally' recognized by a spathe fully persistent through to fruiting, pistillate flowers each with an associated staminode, parallel pinnate veins, and aromatic tissues. These are 'easy' characters and produces a 'genus' that includes species in the Neotropics, and especially the everwet/perhumid parts of Indomalaya, Australasia, and W Oceania. This leads to everyone ‘knowing’ what = Homalomena.. The problem is that molecular data contradicts the accepted ‘genus’ Homalomena and points convincingly to there being distinct Neotropical and ‘Asian’ lineages that are sufficiently different and perhaps more importantly temporally separated, to raise questions about whether, when converting the phylogeny into a taxonomy we shouldn’t perhaps split ‘traditional’ Homalomena into two ‘genera’, since this is more informative (to end users) than keeping it all in one genus. Of course the crucial point is that from the phylogenetic (evolutionary) standpoint the names of the ‘genera’ (and indeed their rank) are of no great importance. What is important is that the evidence points to the Asian ‘Homalomena’ and the Neotropical ‘Homalomena’ sharing a common ancestor more than 45 million years ago. The question is therefore is a ‘genus’ ca 45 million years old ‘better’ than one 2 million years old (as appears to be the situation with many Mediterranean aroid genera.
From: firstname.lastname@example.org [mailto:email@example.com] On Behalf Of Alistair Hay
Sent: Monday, 7 February, 2011 7:17 AM
To: Discussion of aroids
Subject: Re: [Aroid-l] New aroid in western Australia? Typhonium on thescaffold !!
I am longing to see if you are going to publish an unrecognisable genus :))))
On 06/02/2011, at 3:10 AM, "Wilbert Hetterscheid" wrote:
> oooh, I am deeply ashamed. This is indeed true. I was writing in the spur of
> the moment I guess. Indeed, Peter and I did not recombine L. mirabile to T.
> mirabile but you youirself, the Inventor of Lazarum. Must feel good to have
> this name reinstated gain, I guess.
> Thus far it seems quite difficult indeed to separate Lazarum from Typhonium
> s.str. Distinguishing Sauromatum s.l. from Typhonium s.str. works [sort of]
> (see Flora of China and the Cusimano et al. paper).
>> -----Oorspronkelijk bericht-----
>> Van: firstname.lastname@example.org
>> [mailto:email@example.com] Namens Alistair Hay
>> Verzonden: donderdag 3 februari 2011 3:24
>> Aan: Discussion of aroids
>> Onderwerp: Re: [Aroid-l] New aroid in western Australia?
>> Typhonium on thescaffold !!
>> Thanks Wilbert :) but one tiny point of correction. It is
>> Typhonium mirabile (A. Hay) A. Hay... If you made the same
>> combination in 2000, yours is an isonym....
>> You are very polite about the Japanese paper. I am astonished
>> it was published in systematic botany at all.
>> What will be intriguing will be to see how these molecular
>> clades are going to be dstinguished morphologically.
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