Inversodicraea torrei (C.Cusset) Cheek

Tchouto, P. & Burgt, X. van der, 2017, A synoptic revision of Inversodicraea (Podostemaceae), Blumea 62 (2), pp. 125-156 : 141

18. Inversodicraea torrei (C.Cusset) Cheek

Inversodicraea torrei (C.Cusset) Cheek in Cheek & Haba (2016a) 2. — Ledermanniella torrei C. Cusset (1983) 386, t. 10; (1997) 3. — Type: Torre 5515 (holotype LISC n.v.), Mozambique,summit of Serra Gurué near Mt Namuli, fl., 9 Apr. 1943.

Etymology. Named for Antonia Rocha da Torre (1904–?), collector of the type specimen, noted botanist in Mozambique.

Distribution — Mozambique, known only from Serra Gurué near summit of Mt Namuli.

Habitat & Ecology — No accurate data are available, but rapids above Gurué occur at c. 750 m altitude (observed on Google Earth).

Conservation — This species is a point endemic on the little available evidence. Rapids along a small river, the Licungo, in a steep-sided valley seen above Gurué town (Google Earth imagery dated 26 Nov. 2015, viewed 22 Feb. 2017) are a possible location for this species. An area of occupancy of 1 km 2 can be estimated using the standard IUCN cell size for riverine plants. The river, as habitat for submerged aquatic plants, appears to be at risk from silt from surface run-off, since the east side of the valley had been cleared for agriculture, with bare soil extending to within 20 m of the watercourse. The western side of the valley was a tea plantation monoculture. Intensive tea plantations were established in the colonial period, and have recently been rehabilitated.Anthropic degradation is extensive and increasing at Mt Namuli. Botanical surveys of Mt Namuli in the early twenty-first century failed to refind any Podostemaceae ( Timberlake et al. 2009) . It is to be hoped that this was because the species was overlooked and not that it is extinct. Given the apparent threat to, and single location of I. torrei we assess it here as CR B2 ab(iii), Critically Endangered. The species has not been listed on www.iucnredlist.org.

Additional specimen. MOZAMBIQUE, summit of Serra Gurué near the peak of Mt Namuli, fr., 20 Sept. 1944, Mendonça 2166 (LISC n.v) .

Notes — Distinctive for its thinly scattered (covering <40 % of stem), long slender scale-leaves (length: breadth ratio c. 10: 1) which bear two lateral lobes of the same shape as the main leaflet, and which are held at an angle of c. 45° from it.

Cusset (1997: 3) cites an additional record for this species: ‘ Botswana N: junction of Linyanti and Zambezi Rivers, fl. vii. 1930, E.M. Young s.n. ( BM)’. However, this specimen is discordant from that described in the protologue having, e.g., mainly unlobed scale-leaves and a spathellae with a short rostrum. This specimen may represent an undescribed species, but the spathellae are unopened and flowers invisible. Inversodicraea torrei is known only from a single location, whence last recorded in 1944, about 70 years ago .