Inversodicraea pygmaea G.Taylor

Tchouto, P. & Burgt, X. van der, 2017, A synoptic revision of Inversodicraea (Podostemaceae), Blumea 62 (2), pp. 125-156 : 136-137

8. Inversodicraea pygmaea G.Taylor

Inversodicraea pygmaea G. Taylor (1953) 72, f. 10; (1954) 127. — Ledermanniella taylorii C. Cusset (1983) 376, f. 5 — Ledermanniella pygmaea (G.Taylor) C.Cusset , non L. pygmaea (Pellegr.) C. Cusset (1974) 274. — Inversodicraea ledermannii auct. non. Engl., sensu A.Chev. p.p. ( Chevalier 1938: 297). — Type: H. des Abbayes 353/1951 (holotype BM), Guinea-Conakry, ‘cercle de Kindia, Grandes-Chûtes, Rochers plats au bord de la rivière au niveau des basses-eaux, parmi les Dicreanthus parmelioides , 4-12-1951 ’.

Etymology. Named for the diminutive stature of the species (‘the pygmy

Inversodicraea ’).

Distribution — Guinea-Conakry. Habitat & Ecology — On flat rocks at the edge of the river at low water, among ‘ Dicraeanthus parmelioides A.Chev. ’ (= Stonesia ) rapids; 230 m altitude.

Conservation — Known only from the Grandes-Chûtes of Kindia, which falls give their name to a Forêt-Classé, in the centre of which is a large and expanding bauxite mine operated by Russal (Cheek 2016 pers. obs.). The falls themselves have had their seasonal flow modified by a series of hydroelectric dams upstream, the Baneah and Donkeah dams. These de- velopments are likely to have negatively impacted the Podostemaceae at the falls. However, I. pygmaea may have become extinct after the first hydroelectric project on the river, which was constructed at Grandes-Chûtes, in 1962–1963 by Hidrotehnika of the former Yugoslavia.

Here I. pygmaea is assessed as Critically Endangered, CR B2 ab(iii), given the single location and threats stated above. The area of occupancy is 1 km 2. Inversodicraea pygmaea is not listed on www.iucnredlist.org.

Additional specimen. GUINEA-CONAKRY, cercle de Kindia, Grand-Chûtes, chemin de fer, km 107, fl., 19 Dec. 1908, Chevalier 20232 (P00179378 image).

Notes — Although the trifid leaves are unremarkable, the species is distinctive for its very short (3(–5) mm tall) erect, stout, stems which are thickly and densely clad in uniformly shaped scale-leaves, from the 0.2 mm wide ribbon-like root to the terminal spathellae. The spathellae often ruptures into 3 or 4 equal triangular lobes but this varies, with sometimes one large and one small lobe, for example.

The fruits lack commissural ribs, resembling I. adamesii in this, but the species differs in gross morphology, stamen number, and other features. The non-commissural ribs project so far that they are narrowly wing-like.