Ledermanniella tenuifolia (G.Taylor) 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 tenuifolia (G.Taylor) C.Cusset (Cusset 1974: 275)

Figs 7A , 8D, E

Inversodicraea tenuifolia G.Taylor ( Taylor 1953: 72, plate 11)

Type.

NIGERIA • Ogoja Province : on the Boje-Aboabam path crossing the Afi river; 13 Dec. 1950; [6°12 ’00” N, 8°56 ’35” E]; 100 m; fl.; Keay FHI28241 ; holotype: K, spirit [21952.000]; isotype: BM [BM000910401] .

Distribution.

Sierra Leone, Nigeria, Cameroon, Gabon. The type collection (Keay FHI28241) is the only known collection from Nigeria (Afi river, Ogoja Province). Cusset later identified the two Gabon collections Le Testu 7273bis and Le Testu 7413 from the Ogooué river near Lastoursville (see Notes), as belonging to this species. Two collections from Cameroon are cited on GBIF (Thomas 546 and 2655, this latter under a wrong number) but the identifier is unknown. Since 2017, four collections were made in Gabon that most probably belong to this species. However, they were made in the Okano river, and no recent collections of this species are known from the Ogooué, despite the recent inventories in the surroundings of Lastoursville.

Habitat and ecology.

Falls in rivers from ca 35 to 500 m wide, 50-220 m in elevation. It appears to be very rare, and its ecology and micro-habitats are not yet well understood. Flowers and fruits were collected in June and August in Gabon, and from October to December elsewhere. In the Okano river, it has been found in close vicinity of Inversodicraea tenax , Saxicolella nana , and Tristicha trifaria , though it is unclear whether they share similar micro-habitats.

Notes.

The taxonomic concept associated with this species remains unclear. Examination of the two older collections Le Testu 7413 and Le Testu 7273bis revealed that they lack the typical phyllotaxy of L. tenuifolia , as having leaves distichously arranged, whereas Cusset described them as whorled. Moreover, some leaves of the two Le Testu collections were forked, which is inconsistent with Taylor (1953) and Cusset (1974). In that sense they come close to dwarf members of L. bifurcata . However, we have not been able to examine the type collection of L. tenuifolia for confirmation. For now, and until more material is available, we choose to follow Cusset’s conception and determinations of this species, that include the Gabonese collections Le Testu 7413 and Le Testu 7273bis. We believe this name best accommodates for the recent collections made in the Okano river, even though those show longer leaves than described by Cusset (up to 7 mm long in Boupoya 2424), and lack the typical widening at base. Leaves are nonetheless arranged in a whorl, which is coherent with the original description of L. tenuifolia .

Figures

Figure 7. Distribution maps of Podostemaceae in Gabon. A. Ledermanniella pusilla (red diamonds), L. tenuifolia (grey circle). B. Ledermanniella pygmaea (grey circles), Macropodiella heteromorpha (red diamonds). C. Macropodiella hallaei (grey circles), Saxicolella nana (red diamonds). D. Tristicha trifaria (grey circles).

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).