Bemangidia frankliniae Boluda & L.Gaut., 2023

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 : 7-11

Bemangidia frankliniae Boluda & L.Gaut. , sp. nov.

Differs from the only other known species in the genus, Bemangidia lowryi , by its smaller stipules (1–3.5 mm vs c. 8 mm), its smaller leaf lamina (4.3–14 × 1.4–3.5 cm vs 18–22 × 6–6.5 cm), the apex usually acute (vs mostly rounded), the midrib raised on the adaxial surface (vs nearly flat to depressed), depressed or rarely slightly raised on the abaxial surface (vs strongly raised), its faintly raised to flat lateral veins (vs raised and forming a conspicuous striate surface), the less numerous lateral veins (70–145 vs 175–330) forming an angle of 45°–60° with the midrib (vs 70°–90°), and its smaller sepals (12 mm vs> 20 mm).

– Type: Madagascar, Anosy Region [formerly Toliara Province], Taolagnaro ( Fort Dauphin ), Iaboko , Antsotso Avaratra , Bemangidy Forest , 24°33′42′′S, 047°12′02′′E, 662 m, 11 xii 2007, submature flowers, Razakamalala et al. 3976 (holotype G [barcode G00379482!]; isotypes MO [registration number 3126491!], P [barcode P06242475 !], TAN!).

Figures 2 , 3 .

Small to medium-sized tree up to 13 m tall and 15 cm in diameter, sparsely branched, slash with white latex; ultimate twigs 4–10 mm in diameter, at first rusty pubescent, later glabrescent; growing twigs dark greyish brown drying black; mature twigs with a thin dark grey or greyish brown bark, longitudinally fissured; lenticels sparse to dense, raised, ellipsoid to fusiform, 0.5–1(–2) mm long. Leaves alternate, grouped at the end of the twigs, leaving conspicuous scars when shed; stipules broadly triangular, 1–3.5 × c. 1 mm, V-shaped in cross-section, rusty pubescent, early caducous; petiole 15–60 mm long, 1–2 mm in diameter, longitudinally ridged on herbarium material, smooth when fresh, rusty pubescent when young, later with sparse persisting trichomes; blade elliptical, 43–140 × 14–35 mm, base cuneate, apex acute to acuminate, rarely rounded, chartaceous to coriaceous, covered by a rusty pubescence when young, glabrous or nearly glabrous when mature; midrib depressed, flat or slightly raised on the lower surface, sometimes with scattered trichomes on mature leaves, level to raised on the upper surface; leaf venation brochidodromous with 70–145 straight lateral veins (secondaries poorly distinguishable from intersecondaries), among which c.4–12 per cm are more conspicuous and very slightly raised on herbarium material; the veins diverging from the midrib at an angle of 45°–60°, and reaching an intramarginal vein. Flowers in fascicles of 2–6 inserted at twig apices, above the previous flush of leaves; pedicels rusty pubescent, pendulous, 18–23 × c. 2 mm, thus placing the flowers below the petioles of the uppermost leaves. Calyx quincuncial with 5 sepals united at the base; sepals broadly lanceolate, the two external ones coriaceous, with involute margins, 12 × 7 mm, rusty pubescent externally, pubescent on internal surface except for a triangular centro-basal glabrous region occupying c.1/3 of the surface; the three internal sepals slightly smaller and less coriaceous, rusty pubescent externally, glabrous internally except on the distal portion of the margins. Corolla (developed but not opened) gamopetalous, tube 1.3–2 mm long, with 5 broadly lanceolate lobes 7 × 4 mm, contorted in bud, overlapping to the right. Stamens 5, opposite to the corolla lobes; filaments glabrous, attached to the top of the corolla tube, free part 1.5 mm long, 0.5 mm wide; anthers 5 mm long, filaments attached at 1/3 to 1/4 from their base; thecae glabrous on the external side, hairy on the internal side especially towards the base; connective nearly glabrous on the internal side, hairy on the external side, extending above the thecae in an acute 0.2 mm long appendage. Staminodes 5, alternipetalous, broadly lanceolate, 2 × 1 mm, basis cordate with auricles 0.7 mm long; apex entire, bifid or lacerate, margin irregular to lacerate, ciliate. Ovary superior, with 5 uniovulate locules, 5-lobed, 2.2 × 1.6 mm, densely hirsute; style 6.4–8 mm long, 0.7 mm in diameter, glabrous. Fruit observed only at very early stage of its development, with post-anthesis sepals becoming triangular, larger, 15 × 6–8 mm at the base, pedicel thickened, 3 mm in diameter.

Distribution. Bemangidia frankliniae is endemic to a small region of southeastern Madagascar, located approximately 55 km north-northeast of Taolagnaro (Fort Dauphin) and c. 7 km from the sea, in the Tsitongambarika Protected Area.

Habitat and ecology. The three known specimens were collected on small mountain ridges and summits, in windy moist evergreen forests, between 600 and 700 m a.s.l. Flowers are reported as starting in December and very young fruits in April, indicating that flowering period may range from December to March.

Etymology. The specific epithet honours the Franklinia Foundation, a non-governmental organisation dedicated to the conservation of trees, which founded the project ‘Understanding Malagasy Sapotaceae , a critical step towards conservation of a threatened group of prime importance trees’, in the framework of which this species is described.

Proposed IUCN conservation category. The estimated extent of occurrence (EOO) calculated with all available herbarium specimen data is 8 km 2, and the area of occupancy (AOO) is estimated to be <100 km 2, both qualifications for CR under criterion B. The species exists at a single location with respect to its most plausible threat, which is selective logging. It is known from three herbarium collections, the most recent dating back to 2011. Although the sole region where the species has been found is in a protected area, it is threatened by selective logging, even in the protected area of Tsitongambarika ( Asity Madagascar & Rabarisoa, 2018) and a projected continuing decline in mature individuals is inferred, which justifies the assignment of this species to the category Critically Endangered [CR, B1ab(i,ii,iii, iv,v)+2ab(i,ii,iii,iv,v) ( IUCN, 2012).

Notes. Measurements given for the corolla, stamens, staminodes and ovary are from developed but unopened flowers and can be expected to increase until anthesis.

Additional specimens examined. Paratypes. MADAGASCAR. Anosy Region [formerly Toliara Province]: Taolagnaro (Fort Dauphin), Iaboko , Antsotso Avaratra , Bemangidy Forest , summit of the Ivohibe mountain , 24°33′41′′S, 047°12′01′′E, 670 m, 11 xii 2011, flower buds, Gautier 5790 ( G [barcode G00377561!], MO [registration number MO-3126554 !], P [barcode P00932594 !], TEF!) ; Bemangidy Forest , 24°34′10′′S, 047°12′01′′E, 651 m, 5 iv 2008, very early fruiting stage, Randriatafika et al. 813 ( MO [registration number MO-3126554 !], P [barcode P06242474 !], TEF!) .

Figures

Figure 2. Bemangidia frankliniae Boluda & L.Gaut. A, Flowering branch; B, leaf (adaxial surface); C, leaf (abaxial surface); D, detail of leaf adaxial surface; E, detail of leaf abaxial surface; F, calyx; G, calyx (longitudinal section showing the ovary); H, corolla detached and spread, viewed from outside; I and J, corolla detached and spread, viewed from inside. Drawn from the type specimen, Razakamalala et al. 3976, by G. Loza.

Figure 3. Bemangidia frankliniae Boluda & L.Gaut. A, Detail of the abaxial surface of a dried leaf; B, tree upper branches; C, detail of a flowering branch; D, flower buds. Photographs: A (the type specimen, Razakamalala et al. 3976), Carlos G. Boluda; B–D (Gautier 5790), L. Gautier.