Bemangidia L.Gaut.

Boluda, C. G., Randriarisoa, A., Naciri, Y. & Gautier, L., 2023, A Taxonomic Revision of the Madagascar-Endemic Genus Bemangidia (Sapotaceae), with Description of a Second Species, Edinburgh Journal of Botany 80 (1996), pp. 1-17 : 6-7

Bemangidia L.Gaut. , Taxon 62(5): 979 (2013)

– Type species: Bemangidia lowryi L.Gaut. , Taxon 62(5): 979 (2013).

Trees to 25 m tall, sparsely branched, all organs with white latex. Leaves alternate, clustered at apex of the twigs, leaving conspicuous scars when shed. Stipules present, broadly triangular, V-shaped in cross-section, rusty pubescent, early caducous. Leaves with long petioles (1/3 to 2/3 of blade length), elliptical, rusty pubescent when young, glabrescent or totally glabrous when mature; leaf venation brochidodromous with numerous straight parallel lateral veins (secondaries almost indistinguishable from intersecondaries). Flowers fasciculate inserted at twig apices above the previous flush of leaves or axillary among the leaves, pentamerous, large (sepals at least 12 mm long); pedicel rusty pubescent, pendulous. Calyx quincuncial; sepals broadly lanceolate, the two external thicker than the internal ones, with involute margins impressing a median groove on the internal sepals, rusty pubescent on the external surface, beige-pubescent on the internal surface; the three internal sepals pubescent on the external surface and glabrous on the internal surface. Corolla gamopetalous, tube shorter than the lobes, lobes broadly lanceolate, contorted in bud, overlapping to the right. Stamens isomerous, opposite to the corolla lobes; filaments short, glabrous, attached to the top of the corolla tube, attached at 1/3 to 1/4 from the base of the anthers. Staminodes alternipetalous, more or less cordate at base, margin ciliate. Ovary superior, with 5 uniovulate locules, 5-lobed, densely hirsute. Fruit a single-seeded berry. Seed ellipsoid, testa shiny; seed scar ovate basi-ventral.

Distribution. Bemangidia is endemic to Madagascar. It is so far known only from the Bemangidy forest, located approximately 55 km north-northeast of Tolagnaro (Fort Dauphin) within the Tsitongambarika Protected Area. This enigmatic genus has been reported only from a small area of few square kilometres. It may be present in the neighbouring areas, although recent explorations focused on Sapotaceae in Andohahela and Beampingaratra did not yield any collections. The potential distribution of Bemangidia , determined using the Maxent software and information on all available collections (Supplementary file), suggests that suitable habitats are only present in the southeast of the island, from the area where Bemangidia has been reported up to 230 km north. A second small disjunct area with a lower probability appears in the Fenoarivo area 1000 km northwards; this is a quite well-prospected area from which Bemangidia has never been reported.

Habitat and ecology. Bemangidia grows on moist evergreen lowland to lower montane forests of the southeast of the island. Individual plants grow sparsely, forming very low-density populations (the genus is known from only nine collections) on slopes as well as on mountain ridges up to 700 m a.s.l. Bemangidia fruits and seeds are larger than those observed for most other Sapotaceae from Madagascar; however, they overlap in size with the large fruits and seeds of some members of the genera Capurodendron and Mimusops L., and they are smaller than those of Tsebona .

Lemurs and large birds are known to disperse Capurodendron and Mimusops ( Gautier et al., 2022) ; therefore, it can be hypothesised that Bemangidia seeds may be dispersed, at least along the southeastern region, by the same animals. Because neighbouring regions are modelled as adequate habitats for Bemangidia and dispersal does not seem to be limited, the restricted known distribution of the genus could be simply the result of limited botanical exploration, because the two known species appear to be present at low densities. Alternatively, it could be explained by the extinction of populations in other regions due to natural factors, such as species competition, or anthropogenic factors, such as selective logging and massive deforestation.

Notes. As a member of the tribe Tsebonae within the subfamily Sapotoideae , Bemangidia has pentamerous flowers with a quincuncial calyx, lacks dorsal appendages in the corolla lobes, and has a contorted aestivation, villous staminodes, and seeds with plano-convex cotyledons without endosperm (the latter character only observed in B. lowryi ). It has, however, a very distinct brochidodromous venation pattern with very numerous lateral veins (secondaries hardly distinct from intersecondaries), these characters separating it from Capurodendron and Tsebona . It is further distinguished from Tsebona by its isomerous androecium, and from Capurodendron by its external calyx lobes longer than 10 mm and impressing a median groove on the internal ones ( Gautier et al., 2013).

Key to Bemangidia species

1a. Leaves 4.3–14 × 1.4–3.5 cm, apex usually acute, 70–145 pairs of lateral veins forming an angle of 45°–60° with the midrib, not or only slightly raised in herbarium material, not forming a striated surface, external sepals c. 12 mm long ___________ B. frankliniae

1b. Leaves 18–22 × 6–6.5 cm, apex mostly rounded, 175–330 pairs of lateral veins forming an angle of 70°–90° with the midrib, slightly raised in herbarium material to form a striated surface, external sepals c. 20 mm long _______________________ B. lowryi