Inversodicraea warmingiana (Gilg) Engl.

Tchouto, P. & Burgt, X. van der, 2017, A synoptic revision of Inversodicraea (Podostemaceae), Blumea 62 (2), pp. 125-156 : 138-139

12. Inversodicraea warmingiana (Gilg) Engl.

Inversodicraea warmingiana (Gilg) Engl. (1915) 274; (1926) 462; H. Hess (1953) 365; Obermeyer (1970) 208. — Sphaerothylax warmingiana Gilg (1901) 17; Warm.& Gilg (1903) 240;Baker & C.H. Wright (1909) 128;Engl. (1930) 58. — Ledermanniella warmingiana (Gilg) C. Cusset (1974) 275; (1983) 380. — Type: Baum 904 (B destroyed; BM, C n.v., COI n.v., G n.v., K, L n.v., M n.v., U n.v., Z n.v.), Angola, Huíla /Cuando Cubango, Menempremp, near Wolombo, Cubango River, ‘Im Kubango bei Menempremp 1300 m (Wolombo). Abschüssige Stellen des Kutsi (Cuchi) und Kubango (Cubango) ….’, fl., 11 May 1900, alt. 1300 m.

Etymology. Named for Johannes Eugen(ius) Bülow Warming 1841–1924, a Danish botanist who wrote the first textbook and gave the first lectures on the subject of ecology. Podostemaceae was reputed to be his favourite plant family, which he researched and published upon in Brazil.

Distribution — Angola and possibly just over the border into Namibia.

Habitat & Ecology — Waterfalls; 940–1500 m altitude.

Conservation — Inversodicraea warmingiana was listed on www.iucnredlist.org as Vulnerable A3c after an assessment in 2006 ( Sieben 2010) which states “a planned dam in the Oko- vango River will seriously impact the population in Namibia with an estimated 30–50 % of the population that could be lost”. This assessment was based on the assumption that the species occurs in Namibia which is unproven (see below), and also the mistaken assumption that “the species is only found in two sites”. The first of these two sites is the Ruacana Falls on the border of Angola and Namibia. And there is now indeed a hydro plant on the river there. However, the dam is on the Angolan side, and it looks from Google Earth that the (formerly) suitable territory for the species would also have been on that side. It is expected that both Hess and Exell & Mendonça collections came from the Angolan side. The second site is in S. Angola, cited as being the Kubango River. However, I. warmingiana is the most commonly collected Inversodicraea in Angola. Apart from the Cubango River, it is known also from the Cunene, Cuanza, Cuchi, and Cutata Rivers, occurring in four provinces of Angola. Yet, since we have not mapped this species, nor collected the data on threats, we do not reassess the species here. Given the number of locations and threats from hydroelectric projects in Angola it is likely that it would be rated as Vulnerable under Criterion B if reassessed.

Additional specimens. ANGOLA, Cunene, ‘ Prov . Huila. Schnellen von Lacavala (Rio Cunene) 40 km oberhalb’, 9 June 1952, Hess 52/1966 (BM, ZT n.v.); ibid., Ruàcanà , c. 1000 m, 8 June 1937, Exell & Mendonça 2740 (BM, COI n.v) ; Malanje / Cuanza Sul, Prov . Malange, R. Cuanza, Condo Falls , c. 1000 m, stems fleshy, as thick as a finger, brownish green, fl., 29 Mar. 1937, Exell & Mendonça 137 ( BM, COI) ; R. Cuanza, bridge between Cabuta and Cassoque ,fl., 25 June 1937, Exell & Mendonça 3085 ( BM, COI) ; R. Cuanza, Port Condo, Gossweiler 14147 (B destroyed, BM, COI n.v., K, L n.v., LISC n.v.) ; Huíla / Cuando Cubango, Rio Cubango, Aug. 1937, G. Boss in Herb.Trans.Mus.36671 (BM, PRE n.v.); ibid., In den Fällen bei Vila Ponte [Kuvango], 1380–1450 m, 19 June 1962, Hess 52/2039 (BM, G n.v., UPS n.v., ZT n.v.); Cuando Cubango, Prov . Bié, Falle des Rio Cuchi (Kutsi) im Malova-Gebirge c. 100 km Östlich Vila da Ponte, 1500 m, 25 June 1952, Hess 52/2071 ( BM) ; Huila / Cuando Cubango, Falle des Rio Cutata , 40 km Östlich Vila da Ponte, 1470 m, 20 June 1952, Hess 52/2052 ( BM) .

Further specimens for this taxon are cited in Cusset (1983).

Notes — Unique in Inversodicraea due to the apex of the fruit having six wings, one from each of the non-commissural longitudinal ribs; also it has the highest altitudinal range of all species of the genus. Otherwise, I. warmingiana is closely similar to I. fluitans of Angola, both having oblong-ovate scale-leaves with 5–7-toothed margins, and long flexible floating stems (30–40 cm, but up to 80 cm long in I. fluitans ) that lack scale-leaves except for the short, flowering side-branches. In this architecture they are similar to I. paulsitae and I. annithomae , but unlike these species, the main stems are branched. Inversodicraea fluitans has an androecium that exceeds the ovary, while that of I. warmingiana is minute.

Cusset (1983: 382) reports that specimens from the Cuanza River in Malanje District, Angola, differ in several characters from the remaining specimens of the species. We have not been able to review all the specimens concerned so suspend judge- ment as to whether these represent a separate taxon or not.

Obermeyer (1970) mistakenly attributes this species to Botswana

Inversodicraea warmingiana is recorded from 14 specimens deriving from three river catchments in Angola (the Cubango and its tributaries the Cutato and Cuchi , the Cunene, and the Kwanza ( Cuanza )) and appears to be the most frequently recorded species of the genus in Angola.

Gilg was based in B, but the specimens there were destroyed ( Obermeyer 1970: 208), so a lectotype should be chosen from specimens at another herbarium, ideally a specimen seen by Gilg.