Heterostemma

Meve, Ulrich, Gâteblé, Gildas & Liede-Schumann, Sigrid, 2018, Two new species from the Ile des Pins (New Caledonia), and a not so new species from Grande Terre (New Caledonia), Phytotaxa 349 (3), pp. 201-213 : 202

Heterostemma

Heterostemma Wight & Arn. ( Wight 1834: 42) belongs to the tribe Ceropegieae Orb. , where it represents the sole genus in the subtribe Heterostemminae ( Meve & Liede, 2004) , which is sister to all other Ceropegieae (Meve et al. 2017) . All recent works treated genera such as Oianthus . ( Bentham 1876: 79, t. 1191), Dittoceras ( Hooker 1883: 17, t. 1422) or Symphysicarpus ( Hasskarl 1857: 101) as synonyms of Heterostemma ( Meve & Liede 2004, Endress et al. 2014, Rodda 2016) making the genus medium-sized with around 35 species. Nevertheless, apart from some regional treatments ( Swarupanandan et al. 1989, Forster 1992, Kambale et al. 2015) a full generic revision was never prepared. Instead, a checklist including typifications was published by Rodda (2016). Plants of Heterostemma are always herbaceous twiners or lianas, typically inhabiting evergreen forests from India to Southeast Asia—only a few species reached Australasia extending as far as Papua New Guinea, New Caledonia, Fiji, Tonga and Samoa. Some species are only locally distributed, others fairly widespread like Heterostemma acuminatum ( Decaisne 1838: 268) , which has been reported from Indonesia (Java), Papua-New Guinea and NO Australia. Forster (1992) regarded material originating from New Caledonia (e.g., Ile des Pins, Upi, Schmid 2065, NOU) as belonging to this species as well ( Forster 1992: 77; in schedis, NOU, P). Meanwhile, a number of new collections were made in New Caledonia by one of the authors (GG). Because gynostegial and coronal structures in Heterostemma are very small and complicated, investigation of fresh and alcohol preserved flowers has now much increased the potential of morphological analyses. In consequence, the specific characters of the New Caledonian populations turned out more clearly, and thus the description of a new endemic species, comprising all NC collections, is proposed here: