Ledermanniella schlechteri (Engl.) C.Cusset (Cusset 1974: 275)

Bidault, Ehoarn, Boupoya, Archange, Ikabanga, Davy U., Nguimbit, Igor, Texier, Nicolas, Rutishauser, Rolf, Mesterhazy, Attila & Stevart, Tariq, 2023, Novitates Gabonenses 93: a fresh look at Podostemaceae in Gabon following recent inventories, with a new combination for Ledermanniella nicolasii, Plant Ecology and Evolution 156 (1), pp. 59-84 : 59

Ledermanniella schlechteri (Engl.) C.Cusset (Cusset 1974: 275)

Figs 4D , 8A, B, C

Dicraeia schlechteri Engl. ( Engler 1909: 381) - Type: same as for Ledermanniella schlechteri .

Inversodicraea schlechteri Engl. ( Engler 1915: 273) - Type: same as for Ledermanniella schlechteri .

Inversodicraea tenuissima Haum. ( Hauman 1944: 180) - Type: D.R. CONGO • Near Kinshasa ["Environs de Léopoldville”]; Aug. 1902; [4°19 ’00” S, 15°19 ’00” E]; 270 m; fl., fr.; Gillet s.n.; holotype: BR [BR0000008975133].

Ledermanniella tenuissima (Haum.) C.Cusset ( Cusset 1974: 275) - Type: same as for Inversodicraea tenuissima .

Type.

D.R. CONGO • Stanley Pool ; Jun. 1899; [4°12 ’00” S, 15°33 ’00” E]; 270 m; fl., fr.; Schlechter 12574; holotype: B; isotypes: BM [BM000910391], BR [BR0000008974969] .

Distribution.

Cameroon, Gabon, Republic of the Congo, Democratic Republic of the Congo. Before 2018, this species was known from 29 collections, including 25 from the area of Brazzaville and Kinshasa, in the Congo and Djoué rivers. Three collections are known from Cameroon, in the Edea and Kribi regions, and in between. In 2018, Nicolas Texier collected this species seven times in Gabon, all of them from the Kongou waterfalls on the Ivindo river. It has not been found elsewhere in Gabon. This species is expected to occur in Equatorial Guinea. One collection is reported from Ivory Coast ( Aké Assi 5259), but was not identified by Cusset, and likely represents another species.

Habitat and ecology.

Falls in rivers from ca 100 to 1800 m wide, 10-460 m in elevation. According to the Gabonese collections, it is very localized when encountered, but forming dense, apparently monospecific mats. At the Kongou falls, it was found in fast-flowing current, but also at the base of falls, on rocks constantly receiving droplets from the falls, located ca 2 m above the water level, and mixed with an undetermined Poaceae species. Flowers and fruits were collected in February in Gabon, and from April to December elsewhere. In the Ivindo river, it has been found in close vicinity with Inversodicraea nicolasii , and Macropodiella hallaei , though apparently not sharing micro-habitats. This species seems restricted to falls, in fast flowing water of the largest rivers (the Congo, Djoué, Ivindo, Kienké, Nyong, and Sanaga rivers), as it was not collected in smaller rapids of those large rivers, nor in smaller rivers. Interestingly, the species was noted as edible on the collection Descoings 5667.

Notes.

As for other species of Ledermanniella , Inversodicraea , and Macropodiella mentioned in this study, L. schlechteri can also produce flowering individuals without developed stems (Texier 2250, 2251, 2349, and 2445), presumably when the species is not in the ideal conditions (slower-flowing waters). More typical forms, with developed stems, were also collected at the same place (Texier 2272, 2274, 2335). In the absence of stems, L. schlechteri can still be recognized by the combination of having pollen as dyads, two stamens (exceptionally 1 or 3), linear leaves that can be divided, the absence of stipules, and, most importantly, the clearly up to 2 mm spathella stalk. When a stem is present, most of the leaves tend to be forked several times and some may bear long, narrowly triangular stipules, the spathella stalk can be up to 11 mm long, and the pedicel up to 7 mm long after anthesis.

Figures

Figure 4. Distribution maps of Podostemaceae in Gabon. A. Inversodicraea annithomae (grey circles), I. boumiensis (red diamonds). B. Inversodicraea nicolasii (red diamonds), I. paulsitae (grey circles), I. tenax (orange triangles). C. Inversodicraea thollonii (red diamonds), Ledermanniella bifurcata (grey circles). D. Ledermanniella aloides (grey circles), L. schlechteri (red diamonds).

Figure 8. Photographs illustrating a selection of species treated in this paper. A, B, C. Ledermanniella schlechteri (A: Texier et al. 2335; B: Texier et al. 2274; C: Texier et al. 2250). D, E. Ledermanniella tenuifolia (D: Boupoya et al. 2417; E: Boupoya et al. 2426). F, G. Macropodiella hallaei (Texier et al. 2249). H, I. Saxicolella nana (Boupoya et al. 1952). Photographs: Nicolas Texier (A-C, F, G), Archange Boupoya (D, E, H, I).