SPECIES DEMARKATION

[Zhang Dianxiang]

Dear all,
I am revising the old world species of Burmannia. I found some characters
are very stable and geographically correlated, yet ignored by most
students of this genus. The most recent revisor, F.P. Jonker(1938) dumped
so many names to Burmannia coelestis, yet I found there are four well
defined entities: 1. the typical B. coelestis, which is distributed from
Nepal to Southern China, Celebes to Australia and New Guinea, covering the
whole of Malesia and the continental tropical Asia. It is characterized by
having double margined perianth lobes (which means the edges of perianth
lobes are forked). 2. B. chinensis Gandog., distributed from Northern
Thailand and N. Laos to West China, South China(further north than B.
coelestis). An entity characterized by having only the outer perianth
lobes shallowly double-margined at base or half length up, while the
inner perianth lobes are single margined. 3. B. filamentosa (As I call
it), distributed in Eastern Guangdong, which is characterized by the
stamens having well developed filaments which otherwise are missing in
most species in Burmannia. The perianth lobes are similar to B. chinensis.
4. An entity in India (I found a specimen with Hamiltons hand-writing of
B. bifurca, a name only been published as a synonym of B. coelestis by
Hooker), which is characterized by having both outer and inner perianth
lobes single margined. I have dissected almost all specimens I checked, so
you can trust my observation.
Do you think I should call them different species, subspecies, or just
follow other people to dump them into a single species?
I found similar situation in Africa. Most recent flora-authors dumped all
except one names of the species with green leaves to Burmannia
madagascariensis, which becomes widespread from Madagascar to the whole
part of warmer Africa. But I found the Southerner and Eastern entities are
characterized by single-margined perianth lobes, while the western
entities have double margined perianth lobes.

Dianxiang Zhang
Department of Ecology & Biodiversity
The University of Hong Kong
Pokfulam Road, Hong Kong
Tel: (852)29645769
Fax: (852)25176082
Another address: South China Institute of Botany, Academia Sinica,
Guangzhou 510650, China.
Tel: (86)20-87705626-277
Fax: (86)20-87701031