[Taxacom] Annual biogeogeographer's exam Q 7

[John Grehan]

Q. 7. Give examples of Lanyu biogeography that are geographically anomalous.

'Lanyu (=Orchid or Botel Tobago) island lies 70 km south-east of Taiwan and
the biota is known for its diversity, as well as its close affinities with
the Philippines. One hundred and ten plant species on Lanyu occur in the
Philippines, but are not in Taiwan proper, and the genus *Vanoverberghia*
(Zingiberaceae) is known only from Lanyu and northern Luzon (Funakoshi and
Ohashi, 2000). Likewise, the endemic *Gekko kikuchii* of Lanyu Island is
more closely related to Philippine taxa than to other Taiwanese and Ryukyu
Archipelago species (Brown et al., 2009a). *Podocarpus costalis*
(Podocarpaceae) is endemic to islets from Lanyu to Luzon (deLaubenfels,
1988). *Acaypha grandibracteata* (Euphorbiaceae) is on the Batanes and
Babuyan islands north of Luzon, also Lanyu and other small islands off
Taiwan (Sagun et al., 2010). In terms of its ecology, this *Acalypha* is a
small island specialist, but the biogeographic question is: Why does it
occur only on these small islands? Many of these groups on Lanyu and other
parts of this arc are related to groups in the Pacific. For example, in
*Cyrtandra* (Gesneriaceae), a clade distributed along a narrow arc:
southern Ryukyu Islands, Lanyu, Philippines, Sulawesi and Java, is sister
to a widespread central Pacific clade (Fig. 8.5).

A tropical Pacific group of stick insects, Stephanacridini, has the total
range: Lanyu Island, Peninsular Malaysia, all Indonesia, the Philippines,
Micronesia, Melanesia, north eastern Queensland, Fiji, Tonga, Samoa and
east to the Tuamotu Islands (Buckley et al., 2010, distributions from
Hennemann and Conle, 2006b, 2008, 2009). In its morphology the tribe is
closely related to Achriopterini of Madagascar and the Comoros.'