Christmas Bells

Christmas Bells
Christmas Bells - Blandfordia nobilis

Wednesday, September 12, 2012

Mysterious Ant Orchids

I cannot help myself saying this - I have done it before.

These plants are supposedly different species of Ant Orchids - of the Myrmechila genus.

But I have found these plants growing together, half way down Macquarie Pass
and they grow very closely together, yet somehow manage to keep their "differences".
It defies understanding (well, obviously, MY understanding).

Logic would dictate that the ancestors of one strain of these plants plants might well have found their way there.

But to postulate that two separate strains (or "species" if you like) have found their way to this isolated clearing within a rainforest (surrounded by unsuitable habitat for them); and that each species has established itself in this one little "opening" in the forest; yet they remain separate species, just seems so unlikely to me.

So, I fall back on the old Logical Saw of Occams Razor:
  • "It is a principle urging one to select from among competing hypotheses that which makes the fewest assumptions."
Basically, how could such an unlikely event occur?

Or, put more simply, I want to be an Orchid Heretic here, and suggest that these variations which are evident are merely individual variations between particular flowers, and NOT representatives of different species at all.

Shock horror. I may be expelled from the Australasian Native Orchid Society for saying that.

Having said all that, I note that these "species" have been recognised for a very long time. They were raised to species status by Robert FitzGerald Australia's first great Orchid specialist. "His extraordinary skills gave rise to a volume of work completed over seven years called Australian Orchids".
"The standard author abbreviation Fitzg. is used to indicate this individual as the author when citing a botanical name."
Source: http://en.wikipedia.org/wiki/Robert_D._FitzGerald#Australian_Orchids

So if FitzGerald was not troubled by my "doubts", I shall accept his species as valid and good.

Of course, the newer taxonomists have played with his original naming (which were then both classed as "Chiloglottis"). But I am following the "new names", because this name is used to separate the Spring-flowering species of this tribe. They also have their lateral sepals held out to the side of the flower, not recurved under the Labellum (as with the true Chiloglottis group).

This species (M. formicifera) has 
the labellum diamond-shaped
7–10 mm long, 6–7.5 mm wide, 
with a narrow, shiny, black, ant-like callus (gland)
extending from the base to the apex.
Myrmechila formicifera
This species (M. trapeziformis) has 
the labellum 
which is spade-shaped to diamond-shaped,
7–10 mm long, 6–8 mm wide, 
with a short, shiny, black, ant-like callus (gland)
occupying the basal quarter of the upper surface.
In other words, the lower labellum is clean
on the part furthest from the flower stem.

Myrmechila trapeziformis
Myrmechila trapeziformis

4 comments:

Prem Subrahmanyam said...

As I understand it, these are wasp pollinated via pseudocopulation. Could the two "species" exude pseudopheromones that attracted one vs. another species of wasp, and thus keep the two populations segregated? Since this is a more specialized pollination mechanism than just "ooh, pretty flower with nectar for you, Ms. Bee", it is possible to have that level of specialization and segregation.

Flabmeister said...

Denis

I am in full agreement with you. I presume that the current fad for DNA sequencing has confirmed Fitzgerald's determination of separate species.

Where that leads is to suggest that the taxonomists need to come up with a way of briefly describing in simple(ish) language how they have come to their conclusion. I am not necessarily thinking they should aim for the readability level of the Murdoch or Fairfax Press. However, something like the level of communication achieved by David Attenborough, Carl Sagan or James Gliek (Chaos)would be nice. I would have included Malcolm Gladwell in that list but he takes 10 pages to order a hot dog!

Martin

Denis Wilson said...

Thanks Prem.
You are right about the wasps acting as pollinators.
From what I have read, the people who study them have not found separate species of wasps pollinating different species of Orchids, but it is a possibility.
It still does not explain how two different species of plants found their way into an opening within a rainforest, and then happily grow side by side.
Thanks.
Denis

Denis Wilson said...

Martin,
I know there has been some DNA work done on these plants, but I suspect the DNA children are not yet good enough at their work to explain such mysteries.
After all, one lot (Sydney Bot Gdns) do not accept the Jones and Clements work on Greenhoods which are vastly more "distinctive" than these things are.
They should all go back to School, those DNA children.
Denis