Mischogyne gabonensis (Pellegr. ex Le Thomas) Gosline

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation

Predicted extinction risk: threatened. Confidence: low confidence

Gosline, G., Marshall, A.R. & Larridon, I. (2019). Revision and new species of the African genus Mischogyne (Annonaceae). Kew Bulletin 74: 28. https://doi.org/10.1007/s12225-019-9804-7

Type

Gabon, Mayumba, region de Nyanga, 26 Aug. 1914, Le Testu 1768 (hololectotype P, sheet here designated [P00315820]; isotypes BM! [BM000547338], BR × 2* [BR0000008801661, BR0000008802330], LISC* [LISC000379], P × 2* [P00315817, P00315818], WAG × 5* [WAG0175098, WAG0175099, WAG0247284, WAG0247285, WAG0247286]).

Morphology General Habit

Tree 3 – 7 (– 25) m tall, up to 25 cm in diam., branches and twigs glabrous

Morphology Twigs

Twigs light grey to brown, striate

Morphology General Shoots

Shoot buds with light brown hairs 0.05 – 0.1 mm long

Morphology Leaves Petiole

Petioles 5 – 10 mm long, 1.5 – 2 mm in diam., sparse indumentum of hairs 0.1 mm long or glabrous

Morphology Leaves

Leaf lamina obovate, 8 – 16 cm long, 4 – 7 cm wide, length:width ratio 2 – 2.5, apex rounded, abruptly acuminate, acumen linear, 1 – 3 cm long, 0.5 – 1 cm wide at base, 0.2 – 0.4 at mid-length, base cuneate, coriaceous, glabrous on both sides, glossy green above and light green below when fresh, drying matte, olive to brown, lighter below; midrib glabrous above and below; secondary veins 6 – 9, ascendant at 30° – 50° from midrib to 20 – 40% of length of the leaf, anastomosing near margin

Morphology Reproductive morphology Flowers

Flowers with flower buds 0.7 – 1.3 cm long, 0.3 – 0.5 cm in diam. Pedicel 0.5 – 1.2 cm long, 0.3 – 0.9 mm in diam., pubescent, hairs 0.1 – 0.3 mm long, appressed, light brown

Morphology Reproductive morphology Flowers Calyx

Calyx opens by rupturing, usually, into two parts drying dark brown, tomentose outside and inside, often the tips are lost leaving truncate “sepals”, thin, fragile and caducous Sepals united into a thin membranous capsule, ovoid to conical, 0.7 – 1.3 cm long, 0.3 – 0.5 cm wide, length:width ratio 2 – 2.5, base rounded, apex acute or caudate

Morphology Reproductive morphology Flowers Corolla

Petals narrowly elliptic, 1.4 – 1.6 cm long, 0.3 – 0.5 cm wide, length:width ratio 3 – 3.5, base truncate, apex acute, outer surface densely pubescent, hairs 0.1 – 0.3 mm long, appressed, light brown, inner surface tomentose becoming glabrous, white when fresh, inner surface dark brown in herbarium material-Torus truncated conical, 2.2 – 3 mm long, 1.5 tapering to 1 mm diam., upper part densely pubescent

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens mounted spirally on lower 60% of torus but generally fallen in herbarium specimens; carpels at the top, divergent Stamens 50 – 60, 1 – 3 mm long, 0.5 – 0.8 mm wide; yellow when fresh, filament 0.1 – 0.2 mm long, connective with an indumentum of hairs 0.1 mm long between thecae terminating in an extension of 0.1 – 0.2 mm

Morphology Reproductive morphology Flowers Gynoecium Carpels

Carpels 3 – 7, 3 – 5.5 mm long, 1 – 1.5 mm in diam., densely pubescent, hairs 0.05 – 0.2 mm long, velvety, appressed, white; stigma sessile, bilobed, 1 – 1.1 mm long, 0.6 – 0.9 mm wide, glabrous, yellow drying black

Morphology Reproductive morphology Fruits

Fruits nearly sessile with 1 – 3 ovoid monocarps 6 – 6.5 × 2.8 – 3.2 cm, green with white speckles

Morphology Reproductive morphology Seeds

Seeds 6 in yellow pulp, 2 × 1.5 cm with an indumentum of fine white hairs.

Distribution

Cameroon, Bioko (Equatorial Guinea), Gabon.

Ecology

Lowland evergreen rain forest.

Conservation

This taxon is only known from four locations: (1) The Mt Cameroon sites are at the edge of the Mt Cameroon National Park but not within it and subject to community logging. (2) The specimen from the south of Cameroon is not in the Campo-Ma’an National Park, but in an area designated as a production forest. (3) Specimens from Bioko are from within the Reserva Científica de la Caldera de Luba. The forest in the reserve is described as pristine, but a new road is already increasing development pressure in the area (Cronin et al. 2015). (4) The exact location of the Gabonese specimen from Mayumba is unknown and it is not clear that it still exists. A “sustainable” development, including forestry, is planned for the Mayumba area (http://www.sfmafrica.co.za/projects/gabon). There are threats to plants in three of the four known locations. From the known specimens we compute an AOO of 24 km2 and an EOO of 66192 km2. This justifies an IUCN category of Endangered B2ab(ii).

Phenology

Flowering in January, November. Fruiting November.

Note

The specimens from Mt Cameroon occur in one of the wettest environments in Africa with over 4000 mm ppa. Couvreur records the tree as up to 25 m tall, 25 cm diam. (T. L. P. Couvreur 1033), which makes it quite distinct from the smaller and more branched Mischogyne elliotiana. The leaves also have a longer and often linear acumen. This evidence justifies raising this taxon to the species level. Annick Le Thomas (1969) described this taxon as a variety in the Flore du Gabon based on Pellegrin’s nomum nudum Uvariastrum elliotianum (Engl. & Diels) Sprague & Hutch. var. gabonensis. Her diagnosis distinguishes the variety by fewer carpels (4 – 5) with an attenuate apex and sepals and pedicels puberulent. Her full description appears to be based on Mischogyne elliotiana, and the distinctive capsular calyx is not described. Meaning ‘from Gabon’. Similar to Mischogyne elliotiana in its flowers and fruits. Distinct in being a medium-sized tree to 25 m tall rather than a small tree or shrub 3 – 10 m tall; in having 3 – 7 carpels rather than 7 – 12; and in having sepals united in a capsular membranous calyx rather than three free reduplicate-valvate sepals; in the carpel indumentum velvety appressed with hairs 0.05 – 2 mm long, rather than with longer bristly semi-erect hairs 0.8 – 1 mm long.