Out of New Guinea? Two new species of Zygogynum (Winteraceae) extend the genus west of Lydekker’s and Wallace’s Lines

The Winteraceae comprise 100 – 130 species in five to nine genera. The genus Zygogynum is currently
thought to have a Papuasian-Pacific distribution and is only known from the western Pacific islands (New
Caledonia, Vanuatu and the Solomon Islands), Australia and New Guinea, including the far western Bird’s Head
Peninsula, but is not yet recorded from islands to the west of the Sahul Plate and the biogeographic boundary of
Lydekker’s Line. Here, two new species of Zygogynum are described from west of both Wallace’s and Lydekker’s
Lines. Zygogynum moluccanum is described from the Moluccan islands of Indonesia, and Z. sundaicum, a new species
and generic record for the Sunda shelf, is described from the northern part of the Malaysian State of Sarawak in
Borneo. In addition to descriptions and illustrations of the new species, the generic delimitation, fossil record and
potential dispersal agents of Zygogynum are discussed.