>> First of all, var.arenicola and var.occidentalis are said to be
>> allopatric, thus should be considered subspecies according to your
>> classification.
>
>"said to" is the important point. There may be some geographic
>gradation, however. Further study is clearly indicated.
Well until it is said not to be, they should be considered
subsp.and not var. according to your key. Innocent until proven guilty!
>> The seeds are said to be subglobose in D.arenicola,
>
>Where do you have this from? The protologue says:
>"seminibus elliptico-ovoideis reticulatis."
>This is exactly the condition found in D.yutajensis.
I'm basing myself on "The Botany of the Guayana Highland" by
Maguire and Wurdack. There it says subglobose seeds for D.arenicola.
>
>> but in D.yutajensis and D.montana are ellipsoid
>
>No difference to the above.
>
>>, though most often slightly fusiform in the latter.
>
>And papillate (vs. reticulate in _D.arenicola_).
Sorry, but as I understand it, papillae are projections from the
seeds. Reticulated are the seeds of all D.montana, D.villosa,
D.graminifolia, D.chrysolepis, D.communis, D.hirtella, D.colombiana, and
others except D.capillaris and D.intermedia among the Brazilian species.
>> varying from 3-4mm in length in D.a, 4-4.3mm in D.y, and 3-5mm in D.m.
>> The sepals of D.y are c.3-5mm long, 2.5-3mm in D.a.,
>
>"sepalis (...) 4.2 mm longis"
Again, I got the info from the same publication.
>> Here we see that those of D.y, are larger than in both other species.
>
>Yes. _D.arenicola occidentalis_ is generally a larger plant than the
>type.
But *not* larger than D.montana. Only the flower scapes are longer
in var.occidentalis, bearing more flowers, and having different-shaped
sepals, when compared to var.arenicola. D.montana and D.yutajensis seem to
be larger and more robust than D.arenicola var.arenicola + var.
occidentalis in every way, not to mention once again that the petioles are
shorter than the lamina in teh former 2 and vice-versa in the latter 2.
>> Yet D.y.and D.m. have in common leaf shape and size: linear
>> -spathulated, c.1-2cm long.
>
>No difference (variation included) in _D.arenicola_.
Yes there is: leaf width and length, including the relation
between petiole and lamina.
Best Wishes,
Fernando Rivadavia
Tokyo, Japan