Finally something I actually know something about.....

I estimate that there are about 150 valid species/subspecies in the PI.
Many of the names used as subspecies are just variations a la Liguus and
they intergrade nonsensibly when present in large series.  The number of
species endemic to a single island is related to island size as one would
expect.....generally.  Anomalies probably indicate a lack of collecting
activity rather than a depauperate fauna....Mindanao is a good example.
There are probably quite a few undescribed species tucked away in isolated
mountain ranges that no one has explored.

The group is ancient.  Much of the PI has been above sea level since at
least the Jurassic when the PI drifted eastward as the South China Sea was
created.  Conjecture is that ancestry should be sought after in
China.....Some researchers keep them as a subfamily of the Bradybaenidae,
while others treat them as a separate family.  I have no opinion.  The
group is really a Philippine endemic.  Early records from Borneo have not
been substantiated and are probably mislocalized specimens from Palawan
Province.  They enter Sulawesi only through the Talaud (spelling?) Islands
that stretch from eastern Mindanao to the northern peninsula of the main
island.

There are basically 6 "provinces" for helicostylids....1)Palawan Province,
2) Mindoro, 3) northern Luzon, actually on a different tectonic plate than
the rest of Luzon, 4) southern Luzon, 5) the Visayans (central islands,
Panay, Negros, etc.), and 6) Mindanao, including Samar and Leyte.  Cebu has
(or had) a bunch of endemics and in some ways could be considered a
province of its own, almost equal to Mindoro.  Other animals and plants
follow the same design.

If you drop the sea level many islands connect to form the provinces
mentioned above.  And you can see that these provinces remained separate
through time (except the Luzon provinces, of course....that scenario is
more complex).  This also reduces the distances required for successful
rafting.  I'm not a big advocate of rafting, but perhaps that's the best
explanation right now.

Contact me personally about Helicostyla references   [log in to unmask]

Kurt

At 01:42 AM 5/12/00 +0000, you wrote:
>Just wondering if anyone might be willing to lend me a book/article or
>two on PI landsnails for a short spell, especially on Helicostyla?
>
>Question: in the Philippines, are many species endemic to one island, or
>are most found on several islands?  How would they get from Island to
>Island - on floating logs?
>
>Cold and Wet in Nova Scotia,
>Ross.
>