Aerangis ellisii, an epiphytic orchid endemic to Madagascar, occurs in humid and subhumid forests, and is recorded from 12 Regions, at sites ranging from 22 to 1,700 m in elevation. The species is known from 63 collections made between 1921 (Decary 309) and 2020 (Antananarivo Spirit collection 749T114). Eight of these collections (Cowan s.n., Decary 7461, Homolle 1251, Humbert 6067, Keraudren 1563, Mason 2259, Perrier 5025, and Sieder 793) do not have adequate locality information to be informative to this assessment and were excluded. The remaining 55 collections have adequate locality data, and represent a total of 43 occurrences.

Fifteen occurrences are recorded from 10 protected areas, however, they are threatened by illegal logging. In addition to these legally protected sites, one occurrence was made in the conservation zone surrounding the footprint of a mining project, this occurrence is already targeted for conservation. Fifteen collections representing ten occurrences (Labat 2975; Antilahimena 9804; Rajaonary 12; Ramananjanahary 386, 357, Rabarimanarivo 731, 180; Ludovic 614; Ramandimbisoa 24; Rakotoarivelo 266; Razafindraibe 289; Spirit collection 748T114; Humbert 12212; Perrier 16902, 17294) are located outside the protected area network, and are threatened by forest clearing due to shifting agriculture and forest degradation due to small scale agriculture, along with wood harvesting for subsistence and frequent wildfires. Furthermore, three occurrences are documented from the footprint of a mining project that has undergone and is undergoing intense human pressure from forest clearing and these occurrences should now be considered as extirpated. Moreover, 14 occurrences, each represented by a single collection made in areas outside the protected areas network, and mainly collected over 50 years ago (including Decary 6063, 7500, 13325, 309; Bosser 13812, 15084, 17580, 15599; Perrier 18468, 8093, 12404; Cours 5719; Waterlot 45; and Peltier 1896), from areas that have largely been cleared for shifting agriculture, along with wood harvesting for subsistence, and where wildfires continue to be frequent and habitat degradation continues, should also be considered as either extirpated, or expected to be extirpated in the near future.

The species has a high ornamental value and is collected for horticultural purposes and trade, this posing a further threat to its survival.

Aerangis ellisii is thus known from 55 collections representing 26 existing and 17 extirpated occurrences. The extent of occurrence (EOO) of A. ellisii is calculated as 168,943 km² (far exceeding the limits for Vulnerable status under criterion B1) whereas its area of occupancy (AOO) is estimated at 108 km² (which falls within the limits for endangered status under criterion B2). With regard to the most serious plausible threat, forest clearing due to agriculture practices (tavy) and wildfire, the 26 existing occurrences represent 12 locations (sensu IUCN 2022), thus exceeding the upper threshold for Vulnerable status under criterion B. The loss of the occurrences in the footprint of a mining project and outside of protected areas has induced a continuing decline of the AOO, the number of subpopulations, and mature individuals. Aerangis ellisii would have been assigned a NT status under criterion B. We also suspect a population decline based on the reduction of the AOO, 33%, from 160 km² in 2010 to 108 km² in 2040 based on the loss of 17 occurrences of the species (three in the footprint of a mining project and 14 in unprotected forests) due to forest clearing and forest degradation (due to small scale agriculture, along with wood harvesting for subsistence and wildfires), where the causes of reduction may not have ceased and may not be reversible based on a decline in AOO which leads us to consider the species under a threatened category according to criterion A. Therefore, Aerangis ellisii is assessed under criterion A as VU A4C.

Aerangis ellisiian, epiphytic orchid endemic to Madagascar humid and subhumid forests, is known from 12 Regions: Analamanga, Itasy, and Vakinankaratra in the formerly recognized Province of Antananarivo; Sava and Diana in the formerly recognized Province of Antsiranana; Amoron'i Mania, Ihorombe, Matsiatra Ambony and Vatovavy in the formerly recognized Province of Fianarantsoa; Alaotra-Mangoro and Atsinanana in the formerly recognized Province of Toamasina; and Anosy in the formerly recognized Province of Toliara (Madagascar Catalogue 2022).

The population of Aerangis ellisii is currently thought to be decreasing since its habitat is threatened by forest clearing due to mining activities, and forest degradation by illegal logging, timber harvesting for small-scale subsistence, wildfires, slash-and-burn agricultural practices (tavy), and illegal collecting. The number of mature individuals is not known and cannot be estimated since the species is an epiphyte on the trunks and branches, on rocky basalt, quartz, granite outcrops, and gneiss, in humid and subhumid forests, and mossy shrublands.

Aerangis ellisii is an epiphytic herb on the trunk and branches, on moss and lichen-covering trees in humid and subhumid forests, mossy high-land shrubland, on basalt, quartz, granite, and gneiss rocky outcrops, between 22 and 1,700 m in elevation (Madagascar Catalogue 2022).

Aerangis ellisii is threatened by forest clearing due to mining activities and shifting agriculture, and forest degradation due to small-scale agriculture, along with wood harvesting for subsistence and wildfires. The species is also threatened by illegal collecting and trade.

The species has a high ornamental value and is collected for horticultural purposes and trade.

Aearangis ellisii, an epiphytic orchid endemic to Madagascar, is known from ten protected areas: Analamazaotra National Park, Andringitra National Park, Befotaka-Midongy du Sud National Park, Corridor Ankeniheny-Zahamena Natural Resources Reserve, Corridor Marojejy-Anjanaharibe Sud-Tsaratanana-partie Nord Natural Resources Reserve, Ibity Massif Harmonious Protected Landscape, Manongarivo Special Reserve, Ranomafana National Park, Tsaratanana Strict Nature Reserve, and Tsitongamabarika Natural Resources Reserve. Seeds are banked in Ambatovy and Antananarivo seed banks. The species is currently listed in Appendix I of CITES and ex situ conservation is recommended (micro-propagation and living collections).