For more taxonomic information see Miller and Morris (2004) and Thulin (2020).

Boswellia nana is a very rare endemic of Socotra Island (Yemen), limited to steep limestone cliffs at an altitude of about 200–700 m asl in the northeastern part of the island. This "dwarf" species (although larger trees are also known) has a very restricted geographical range with an extent of occurrence (EOO) of 40 km², and an area of occupancy (AOO) of 40 km². A total of 354 adult trees have been inventoried during recent detailed field surveys, carried out in 2020–2023 by local Socotri and external specialists (Mendel University, La Sapienza, Ghent University; Franklinia-funded Boswellia project; Maděra et al. 2022, Maděra et al. 2024), yet the total global population in the wild can be currently estimated at c. 1,000 trees. Boswellia nana can be found in seven sites in the northeastern cliffs of Socotra Island, which can be considered as one location. The distribution is patchy with here and there a few trees on a single rock or boulder, with sometimes larger stands on cliffs. There are two distinct subpopulations, and both are too small to be viable. The Hamadero-Homhil area contains the typical B. nana (dwarf form), and to the east, different stands with different morphology can be found at Eriseyl (full trees). This species has a relatively narrow altitudinal range and is highly dependent on horizontal precipitation at the northeastern seaside cliffs of Socotra Island, therefore a single event (e.g., a change in climatic conditions resulting in drought affecting these cliffs) can affect the entire global population.

Population trends for this species are unknown, because until the most recent surveys (2020–2023) only two locations were known (Miller and Morris 2004). Future continuous decline is expected for this rare endemic, even though its cliff-growing ecology keeps it relatively safe from browsing by goats. However, recent surveys reveal no young trees, and overgrazing occurs in 37.7% of the area where this species occurs. Extreme weather events and climate change effects can affect the species through landslides, flash floods and droughts, although until now there is no direct evidence for such effects (as it is a very cryptic species). Boswellia nana has recently is also being illegally exported and sold in international markets by succulent collectors. Conservation efforts started in 2020 for B. nana, resulting in increased awareness, local seed germination and reforestation (in Halah-Hamadero area) and are ongoing.

The restricted area of distribution and low abundance of the trees (some of which are strongly affected by goat browsing) indicate a strong extinction risk for B. nana. All trees are found in a single location, and continuing decline is projected due to climate change and overgrazing. Therefore, B. nana is listed as Critically Endangered.

Boswellia nana is endemic to Socotra Island, distributed along steep limestone cliffs in the northeastern part of the island. It has a restricted geographic range with an extent of occurrence of 40 km², and an area of occupancy of 40 km². As all of these trees occur in a small portion of the northern cliffs of eastern Socotra, they are all considered as one location.

According to the most recent (intensive) surveys in 2020–2023 (Franklinia Project Team), there are seven sites where B. nana can be found in Socotra, from the Hamadero highland to the most eastern part of the island (mainly growing on sea-facing cliffs). The most numerous stand is near Erher where 118 specimens have been counted using UAVs (drone) imagery (Maděra et al. 2024). Due to the inaccessible terrain and the ecology of the species, the number of individuals of this species (354 individuals are currently known) is an underestimation, and the total number is estimated at c. 1,000 individuals.

Boswellia nana-like trees in the most eastern stands near the tip of Eriseyl have robust growth forms (up to 3 m) with large leaves, the other (Homhil-Hamadero) stands contain the typical smaller shrubs with smaller leaves. These two different subpopulations are under investigation to understand the intraspecific diversity of the species, and potential cryptic diversity.

The population trend is not known, because until 2004 only two locations were recorded for this species (Miller and Morris 2004). It could be stable because this species grows on cliff faces, habitats that are relatively inaccessible (for goats).

In places where populations of B. nana are in proximity with other Boswellia species, hybrids are possible (e.g., with B. socotrana subsp. socotrana (Miller and Morris 2004) and with B. elongata).

Boswellia nana is a very rare Socotran endemic growing exclusively on limestone cliffs in dry, semi-deciduous woodland. It is restricted to the northeast of the island where it occurs at altitudes between 226 and 710 m. It is usually a small dwarf shrub, however in the most eastern subpopulation larger shrubs occur (up to 3 m in height) and with larger leaves (under study). Boswellia nana can be easily distinguished by its simple and glabrous leaves with irregularly crenate margins (Miller et al. 2004, Thulin 2020). Flowers bloom in short racemes with usually a few red (also pink or creamy-coloured) petals in March and April. The fruits ripen in May; recent seed germination experiments in situ showed that up to 40% of the Boswellia nana seeds recorded were empty and germination rates reached almost 50% (Hamdiah et al. 2022). Notes on morphology, ecology and distribution in Miller (1992, 1997), Thulin and Al-Gifri (1998), Miller et al. (2004), Attorre et al. (2011), Lvončík et al. (2013) and Thulin (2020), now revised after detailed surveys in situ (Madĕra et al. 2024)

The endemic Boswellia species of Socotra undergo general challenges to the archipelago’s terrestrial biodiversity as discussed in Van Damme and Banfield (2011), Attorre and Van Damme (2020), Madĕra and Van Damme (2022). The challenges specifically to the endemic Boswellia in Socotra are reviewed in Maděra et al. (2024). The specific threats to B. nana have been assessed in detail in situ in 2020–2023 (Franklinia Project team; Maděra et al. 2022, Maděra et al. 2024). This dwarf species is threatened by overgrazing (the estimated proportion of the total population affected is 37.7% of which 16.5% high, 16.0% middle and 5.2% low intensity). However, assessments are mainly done in relatively accessible areas while this tree grows mainly on steep cliffs where goats (and researchers) cannot reach.

Climate change effects (heavy rains, landslides, flash floods long periods of drought) will likely affect the population in a negative way in the future, but there is no direct evidence for this yet. Droughts may affect the species, which strongly depends on horizontal precipitation, only appearing at altitudes and areas in the east with daily fog exposure. The species has also been illegally exported and sold in international markets by succulent collectors.

This species is not used by local people; it is illegally traded in international markets (through succulent collectors).

Specific conservation efforts for this endangered species (and other Boswellia in the Socotra Archipelago) started in 2020, including the establishment of local nurseries, awareness, local seed germination and reforestation. One nursery concentrating on B. nana seedlings production has been established in Rosh in 2021 and a reforestation area near Hoq in 2023 within the Boswellia project supported by the Franklinia Foundation (implemented by local teams in coordination with a consortium of Mendel, Sapienza and Ghent Universities and in cooperation with the local authority EPA). A species action plan and monitoring of the existing B. nana subpopulations and their threats are important. Potential pressure from illegal export by succulent collectors and climate change impacts are to be kept into consideration for future conservation efforts.