TAXONOMIC REVISION OF CAUSONIS (VITACEAE) IN NEW GUINEA

The three species of Causonis (Vitaceae) that occur on the island of New Guinea, namely C. australasica , C. maritima and C. trifolia , are here revised. We provide synonymy, descriptions, a distribution map and diagnostic character illustrations.


Introduction
The grape family (Vitaceae) has been the focus of extensive research over the years due to its great economic importance and its phylogenetic and biogeographical patterns (Rabarijaona et al., 2020).The family has been found to contain five clades (Ampelopsis sensu lato, Ampelocissus -Vitis, Parthenocissus-Yua, Cissus, and Cayratia-Cyphostemma-Tetrastigma), and to maintain the monophyly of the genera, several genera have been segregated (Wen et al., 2018).
Habitat and ecology.Forests, hills, from sea level to 1000 m.
Phenology.Flowering and fruiting throughout the year.
Proposed IUCN conservation category.Causonis australasica occurs only in Australia and Papua New Guinea.The EOO and AOO are calculated as 1,095,884 km 2 and 144 km 2 , respectively.The EOO suggests that this species might be Least Concern, whereas the AOO suggests it might be Endangered.However, the species does not fulfil the other parameters required for the species to be assessed as Endangered (e.g.small number of locations, continued decline and extreme fluctuations), and therefore this species is classified as Least Concern (LC).
Distribution in New Guinea.Indonesia (Irian Jaya) and Papua New Guinea (Autonomous Region of Boubainville, Milne Bay) (see Figure 1).
Habitat and ecology.Coastal, alluvial or sandy soil, swamps, forest edge, regrowth; near sea level to 3500 m.
Phenology.Flowering and fruiting throughout the year.
Proposed IUCN conservation category.Causonis maritima is distributed from India and China to North Australia with no apparent threats, and therefore it can be treated as Least Concern (LC).In New Guinea, although we only have four collections, the EOO is calculated to be 676,693 km 2 , and therefore it is also considered to be Least Concern (LC).side moderately to densely hairy with hairs like these on the stem mostly concentrated on veins; veins protruding, 1 main basal vein, 4-8 pairs of secondary veins.Inflorescence a ramified, axillary, mostly dividing dichotomously, corymbose dichasium, 2-12 cm long; peduncle 1.5-8 cm long, hairy as on stem, pedicel 1-3 mm long, hairy with hairs to 0. Distribution.Australia, Bangladesh, Brunei, Cambodia, China, India (including Andaman and Nicobar Islands), Indonesia (Borneo, Java, Lesser Sunda Islands, New Guinea, Sulawesi, Sumatra), Laos, Malaysia, Micronesia, Moluccas, Myanmar, Nepal, Palau, Pakistan, Papua New Guinea, Philippines, Singapore, Solomon Islands, Sri Lanka, Thailand, Vanuatu and Vietnam.
Habitat and ecology.Forests on hillsides or by streams, on rocks; around 70-1300 m altitude.
Phenology.Flowering and fruiting throughout the year.
Proposed IUCN conservation category.Causonis trifolia is a widespread species across Asia with no apparent threats, and therefore it can be treated as Least Concern.In New Guinea, we have been able to confirm the identity of ony one specimen because it was the only one bearing fruits, but it is extremely likely that the species is widespread in the country.As such, the species is classified as Least Concern (LC).

Figure 1 .
Figure 1.Map showing the distribution of Causonis australasica, C. maritima and C. trifolia in New Guinea.