Angraecum inflatum, a new species in Angraecinae (Orchidaceae) from Madagascar

A new species from Madagascar, Angraecum inflatum Hermans, is described and illustrated for the first time. It is compared with similar species from section Lemurangis. A preliminary conservation assessment is provided.


Introduction
Angraecum Bory (subfamily Epidendroideae: tribe Vandeae: subtribe Angraecinae) (Chase et al. 2015) is a large genus of over 200 species occurring mainly in Africa, Madagascar and adjacent islands of the Indian Ocean but it is notably speciose on Madagascar with 148 species, two subspecies, and four varieties. Just over 10% of these taxa also occur in the Mascarenes and the Comoros (Hermans in Goodman 2021, in press). Following the major work on the Madagascan angraecoid orchids by Schlechter (1915Schlechter ( , 1925 and Perrier de la Bâthie (1938Bâthie ( , 1941, Garay (1973) produced a taxonomic revision of the genus at sectional level. Several investigations of the phylogeny and biogeography of the genus have recently been made (Michenau et al. 2008;Szlachetko et al. 2013;Andriananjamanantsoa et al. 2016;Simo-Droissart et al. 2018) which suggest that Angraecum, as currently accepted, is polyphyletic. However, because these studies have sampled only a limited selection of species, we do not feel confident in accepting those segregates that have been established based on molecular data and lack morphological support.

Materials and Methods
As part of ongoing research and fieldwork on the orchid flora of Madagascar at the Royal Botanic Gardens Kew, the University of Vienna and PBZT Antananarivo, specimens of putative new taxa were compared with descriptions, herbarium material and drawings of all of the type specimens and many other specimens, to ascertain their novelty. This has resulted in the recognition of a new species in section Lemurangis, a section first established by Garay (1973: 501), for a small group of plants of eight species, predominantly endemic to Madagascar. The conservation status of the new species given in this paper is a summary of the full IUCN Red List assessments which will be completed and submitted for review and publication by IUCN once the species name is validly published. The assessment has been compiled based on current knowledge of the taxon, by one of the authors (Landy Rajaovelona), who is an IUCN Red List assessor, using the IUCN Red List Categories and Criteria (2012).

RECOGNITION. Angraecum inflatum fits well in sect.
Lemurangis Garay which is characterised by the long stem, distichous leaves, few-flowered inflorescences shorter than the leaves and short rachis. It is distinct in having short fleshy ovoid leaves, winged stem sheaths with an erose-lacerate apical margin, inflorescences with a very short peduncle, and flowers with a lip with thickened margins, a small longitudinal callus at the base and an ampulliform spur and the capsule maturing as other flowers develop. DISTRIBUTION Angraecum inflatum is endemic to Madagascar, restricted to the Amoron'i Mania region (Fianarantsoa province). The type locality is now being cleared for charcoal and the cultivation of Pelargonium, grown increasingly in the region to produce essential oils. The two collections with the recent observations represent a total of two 'locations' (sensu IUCN 2012) with respect to the main threat, which is shifting agriculture. With the observations and the two collections outside the protected areas, we infer that the destruction of the habitat will induce a strong continuous decline in the area of occupancy (AOO), habitat extent and quality, the number of subpopulations and mature individuals in the next ten years. Angraecum inflatum is therefore assessed as Endangered (EN) under criterion B2ab (i, ii, iii, iv, v). PHENOLOGY. December to February. ETYMOLOGY. The epithet name refers to swollen leaves, lip margin and puffed-up spur. NOTES. Angraecum inflatum is most similar to A. baronii (Finet) Schltr. from Madagascar but in that species the stem is more extensively branched, the leaves are narrowly lanceolate (vs ovate) and the apex attenuate (vs rounded); the peduncle is about twice as long; and the flowers are similar in size but the lip is more acuminate and thin towards the apex and the spur is cylindrical and curved at the apex (vs ampulliform). It is also similar to A. costatum Frapp. in Cordem. from Réunion but in that species the plant is more erect with slightly longer and less succulent leaves; the flowers are a little larger and the spur about twice as long; the lip lacks a basal callus and the spur is slightly swollen towards the apex (vs ampulliform).
The circumscription of section Lemurangis needs further research as part of a revision of all the sections of Angraecum but the key below summarises the differential characteristics of the currently recognised species.
Artificial key to the species of Angraecum sect. Lemurangis