Afrothismia fungiformis Sainge & Kenfack

Sainge, M.N., Kenfack, D. & Chuyong, G.B. 2013. Two new species of Afrothismia (Thismiaceae) from southern Cameroon. Kew Bulletin 68: 591. https://doi.org/10.1007/s12225-013-9478-5

Type

Type: Cameroon, Southwest Region, Mt Kupe, above Mbulle village, about 10 km from Tombel, 4°47'31""N, 9°40'40""E, 966 m, 7 May 2011, Sainge M. 2639 (holotype YA!, isotypes K!, MO!).

Morphology General Habit

Myco-heterotrophic herb, 2 – 17 cm long; achlorophyllous, stem pale brown, up to 1 mm diam., above ground stem 0.8 – 3 cm, below ground stem 1 – 15 cm, with cluster of inflated bulbils brownish, mostly at the base, 1.4 – 6 mm long, 0.5 – 1.2 mm diam., very few bulbils or none at the axil of leaf on the upper part of stem, with short or no root at its proximal end

Morphology General Scales

Succulent, lanceolate-ovate, alternate scale-like leaves on stem, 2.5 – 6.7 × 0.7 – 4.2 mm (width measured from the base), with an internode range of 4 – 22 mm and 1 – 7 leaves per stem

Vegetative Multiplication Bulbils

Growing in soil to a depth of 15 – 20 cm, each cluster with variable number of bulbils, bulbil cluster and rhizome cream to brownish, bulbil ovate-ovoid, 1 – 1.7 mm diam. bearing an apical rootlet up to 5 mm long, 0.6 mm in diam.

Morphology Reproductive morphology Flowers

Flower on an erect stem, 1 – 2 (3) per stem, zygomorphic, epigynous; papillate, straight; 7 – 17.2 mm long, 5.5 – 6.6 mm diam. (width measured at the widest point in the centre), with a constriction at the neck region which sets the beginning of the tepals from the ventral side, and a few mm above from the dorsal side, lower perigone tube red to brownish 10 – 11 × 5.8 – 6.6 mm, upper perigone tube red 5.6 – 6.8 × 3.4 – 8.4 mm, perigone tube (perianth) caducous leaving the pistil, with single flower in bract axil, bract 6.2 – 13 × 4.6 – 8 mm (width measured from the base), ovate, acuminate, reddish brown, adaxially deeply concave, basal part ribbed and thickened

Morphology Reproductive morphology Flowers Tepal

Tepals 6; free at the top, fused at the base with the perianth tube with no external back tepals, tepals in pairs of ventral, middle and dorsal: 10.1 – 20.5 × 1.2 – 2.2 mm, 10.1 – 15.1 × 2.2 – 3 mm, and 11.5 – 20 × 1.2 – 3 mm respectively, red, dorsiventrally flattened, triangular at base, and acuminate At the throat, within the 6 tepals is a white fungus-like crown/corona, pubescent, papillate, with traces of 2 red stripes running towards the mouth, basiscopic mouth more or less circular, 2 – 4 mm diam., red

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 6, inserted at the base of the perigone tube (perianth); proximal part of the filament adnate to the perianth tube for about 3 mm, free part of filaments distally incurved, 1.8 mm

Morphology Reproductive morphology Flowers Androecium Stamens Anthers

Anthers basifixed, pendant, 1 mm, firmly adnate to the stigma with a connective appendage

Morphology Reproductive morphology Flowers Androecium Stamens Anthers Connective

Connective appendage depressed, ovate, up to 0.8 mm, densely papillose, thecae dehiscing longitudinally, facing towards the perianth tube-wall, ovary unilocular with basal placentation, 2 – 5.5 × 2 – 8.1 mm, ovule numerous, ovoid-ovate, Style short and thickened, 1.3 × 0.5 mm

Morphology Reproductive morphology Flowers Gynoecium Stigma

Stigma hemispherical, 1.0 – 2.5 mm, papillose, consisting of three fused stigmatic lobes

Morphology Reproductive morphology Fruits

Fruit a pyxidium 4.5 × 2.7 mm; with a distended column-like structure which we call a placenta column, narrowly flattened at the top 11.4 × 1.6 mm, lifting the placenta above the receptacle, exposing the numerous seeds, seeds narrowly lanceolate 0.5 × 0.2 mm.

Distribution

Southwestern Cameroon.

Ecology

Evergreen, submontane forest, growing in soil to a depth of 10 – 20 cm and within rotten leaf litter at an altitude of 966 m. The dominant plant species at this site are Carapa angustifolia Harms, Strychno scongolana Gilg, Garcinia conrauana Engl., Strombosiopsis tetrandra Engl., Tabernaemontana crassa Benth., Garcinia mannii Oliv., Uvariopsis sp., Pycnanthus angolensis (Welw.) Warb. and Cola verticillata (Thonn.) Stapf ex A. Chev. Other species of Thismiaceae and myco-heterotrophic plants that cohabit with this species are Afrothismia saingei Franke, A. gesnerioides Maas, A. winkleri (Engl.) Schltr., Sciaphilia ledermannii Engl., Gymnosiphon longistylus Hutch., Burmannia hexaptera Schltr. and B. congesta Jonker.  The soil of this locality had a pH range of 4.78 – 4.91, 56.13 ppm of Fe, 7.77% of organic carbon, 10.35 of C/N, and 1.03 cMol/kg of Mg. The climate here is also equatorial with two seasons, a dry season from Nov. – March and a rainy season from Mid-March – Nov., annual rainfall 4891 mm (Suchel1972). The topography of this site starts from a gentle slope at an altitude of 756 m to a series of hills with huge valleys.

Conservation

Afrothismia fungiformis is currently known only from two collections from the type locality. Following IUCN (2001) redlist categories and criteria, we assess the conservation status of this species as being Critically Endangered (CR under criteria D). Only seven individuals were found within a 1-ha plot established near Mbulle village, and we estimate the area of occupancy to be far less than 10 km2. The forest here is poorly protected and is progressively degraded through illegal logging and agricultural encroachment. Given the difficulties of collecting myco-heterotrophic plants, the likelihood of collecting additional specimens in the near future to better understand the distribution and the habitat of this species is minute.

Phenology

Flowering and fruiting from May to July.

Note

The species is named after the fungus-like rim structure at the top of the perianth tube. A myco-heterotropic plant close to Afrothismiabaerae Cheek with the straight perianth tube, but differing by the basiscopic mouth and the tepal sinuses lacking appendages.

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: confident