Saxicolella futa Cheek
Creators: name: Cheek, Martin
name: Molmou, Denise
name: Magassouba, Sekou
name: Ghogue, Jean-Paul
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Malpighiales
Podostemaceae
Saxicolella
Saxicolella futa

description: <b>7.</b> <b>Saxicolella futa</b> <i>Cheek</i> <b>sp. nov.</b> Type: Guinée (Republic of Guinea), Guinée Moyenne, Futa Djalon, Labé, Chutes de Salaa, 877 m alt., fr. 18 Jan. 2018, <i>Cheek</i> 18973 (holotype K [K000592222]; isotype HNG). http://www.ipni.org/urn:lsid:ipni.org:names:77297288-1 <i>Sapicolella futa</i> ined. Couch <i>et al.</i> (2019: 171, 213) <i>Annual herb</i>, (1 –) 1.5 – 2 cm diam., stems including fruits 1.8 – 2.2 mm tall (Fig. 7A &amp; B). <i>Roots</i> radiating, adhering strongly to substrate, dorsiventrally strongly flattened (thallus or ribbon-like), 0.2 – 0.5 (– 0.8) mm wide, internodes 1.5 – 2.2 mm long, repeatedly bifurcating at angles of 80 – 100 (– 120°), drying bright white, resembling <i>Riccia</i> (thalloid liverwort) (Fig. 8). <i>Stems</i> monomorphic, extremely short, in the fork of root bifurcations, bearing a sessile rosette, phyllotaxy spiral, leaves 2 – 3, spathellum single, terminal. <i>Leaves</i> concave, irregularly ovate or elliptic, 0.2 – 0.3 × 0.2 – 0.2 mm, apex acuminate, basal attachment broad, stipules absent, distal leaves larger than proximal. <i>Spathellum</i> pre-dehiscence ellipsoid, 0.3 × 0.25 mm, apiculate, basal part sheathed in leaves; dehiscing irregularly, then broadly funnel-shaped c. 1.2 × 0.8 mm. <i>Pedicel</i> erect, c. 0.6 mm long. <i>Tepals</i> 2, filiform, suberect, 0.2 mm long. <i>Stamen</i> one, filament 1.25 – 1.6 mm, erect, exceeding ovary; anther oblong, 0.18 – 0.2 × 0.18 mm, cells opposite. <i>Gynoecium</i>, gynophore curved, 0.6 × 0.1 mm. <i>Ovary</i> unilocular, ellipsoid in fruit, (0.7 –) 0.8 – 0.85 × 0.3 – 0.5 mm, elliptic in transverse section, c. 0.3 × 0.5 mm (Fig. 7H), with six shallow longitudinal ribs (commissural ribs not developed). Stigmas 2, complanate, oblong, 0.175 – 0.2 × 0.1 mm. <i>Fruit</i> placenta spindle-like (Fig. 7E). <i>Seeds</i> oblong-ellipsoid 0.25 × 0.18 – 0.19 mm (hydrated) (Fig. 7K). <b>RECOGNITION</b>. Differing from other <i>Sapicolella</i> species with sessile spathellae (<i>S. marginalis, S. deniseae</i>) in the shoots not marginal, numerous, closely spaced, but single, at root bifurcations; leaves lacking stipules (not stipulate); root slender (&lt;1 mm wide, repeatedly and regularly bifurcating along its length (not&gt;1 mm wide, not or rarely bifurcating along its length). <b>DISTRIBUTION</b>. Guinée (Republic of Guinea), Guinée Moyenne, Fouta Djalon. <b>SPECIMENS EXAMINED. GUINEA</b>. Fouta Djalon, Pita, above Chutes de Kinkon, 857 m alt. fl. 18 Jan. 2018, <i>Cheek</i> 18979 with Molmou (HNG, K [K000592222]); ibid 18 Jan. 2018, <i>Cheek</i> 18980 with Molmou (HNG, K [K000592223]); Pita, Chutes de Kambadga, 710 m alt. fr. 19 Jan. 2018, Cheek photo record; Labé, Chutes de Salaa, 877 m alt., fr. 18 Jan. 2018, <i>Cheek</i> 18973 (holotype K [K000592222]; isotype HNG). <b>HABITAT</b>. Waterfalls in the former cloud forest zone. The species grows at three sites each with several other Podostemaceae-Podostemoideae species (see case study above) but flowers, fruits and dies in advance of those, growing higher up in the riverbed than all other species of that group. 710 – 877 m alt. <b>CONSERVATION STATUS</b>. Known so far from three locations: 1) Chutes de Salaa near Dalaba (type locality); 2) above the Chutes de Kinkon; 2) Chutes de Kambadga, downstream of Kinkon. The AOO is estimated as 12 km 2 using the IUCN (2012) -preferred 2 km × 2 km grid cells and the extent of occurrence as 81.8 km 2. Here <i>Sapicolella futa</i> is assessed as Endangered, EN B2ab(iii) since there are severe and imminent threats at all three locations. At locations 1) and 2) there are plans to build hydroelectric dams that are very likely to result in local extinction of the species (pers. obs. Cheek 2018). At site 2) the species is threatened by contamination of the water source by silt from run-off and by eutrophication due to contamination as the Kinkon river traverses the major town of Pita: fewer than 50 plants were seen at this location, and occupied a total area of &lt;2 m × 2 m. In the next 10 years this species is expected to be reassessed as Critically Endangered (CR), or even “possibly extinct”. However, it is possible that further surveys may find additional sites for the species, which would be welcome. Seed banking and public awareness actions will be put in place as soon as possible. 1 Note added in proof May 2022: new imagery dated 21 Nov. 2021 shows the site completely submerged, extinction has likely resulted <b>PHENOLOGY</b>. Presumably germinating no earlier than May, with the beginning of the wet season, before which its habitat is dry. Flowering may begin as early as November after the conclusion of the wet season in October. By January fruit has formed and the plants are dead. <b>ETYMOLOGY</b>. Named for the Futa (or Fouta) Djalon highlands of the Republic of Guinea to which the species appears to be unique. <b>NOTES</b>. <i>Sapicolella futa</i> has a shorter growing season, (possibly completing its life cycle in only six months or less) than all other Podostemaceae species present at each of the three locations at which it is known, apart from <i>Tristicha trifaria</i>. Both these two species were dead, dried and in fruit when encountered in Jan. 2018, while all other species of Podostemaceae present at these sites were still alive and only, for the most part, just becoming exposed by falling water and were in the process of beginning their flowering. The fact that, in these three locations, <i>S. futa</i> was found only on rock surfaces 20 – 100 cm above the waterlevel at which most other Podostemaceae (and all other Podostemoideae) occurred suggests that the species may have evolved into a niche to escape competition from those species. The extremely minute and inconspicuous stems, the diminutive ovaries, diminutive leaves, and slender roots in comparison with other species of the genus, may well all be reductions that have enabled it to occupy a niche where the growing season is short, being the last to be submerged, and the first exposed, of all the Podostemoideae niches present within its range. <i>Sapicolella futa</i> is unique in the genus for its very slender (&lt;1 mm wide) ribbon-like roots, for the small size of its flowers, and for the position of the flowering shoots being only at the point of root bifurcations, so that the roots appear to terminate in a shoot before bifurcating. It is also unique in lacking evidence of stipules, but this is possibly concomitant with the reduction of leaf size. At maturity, more than 90 – 95% of the bulk of the plant consists of root, more so than any of the other species of the genus where the shoots are much more numerous and also larger and longer. The flowers and fruits are difficult to discern. Recent surveys in Guinea connected with the Guinea Tropical Important Plant Area programme (TIPAs) have discovered several other new species to science, all of which are threatened. Several of these are, like <i>Sapicolella futa,</i> also rheophytes, restricted to fast flowing water habitats, such as <i>Inversodicraea pepehabai</i> Cheek (Cheek &amp; Haba 2016), <i>I. koukoutamba</i> and <i>I. tassing</i> (Cheek <i>et al.</i> 2019a), <i>Karima scarciesii</i> (Scott Elliot) Cheek (Cheek <i>et al.</i> 2016), <i>Lebbiea grandiflora</i> Cheek (Cheek &amp; Lebbie 2018; Couch <i>et al.</i> 2019), while others are also found on the sandstone rock of the Fouta such as <i>Keetia futa</i> (Cheek <i>et al.</i> 2018a), <i>Calophyllum africanum</i> (Cheek &amp; Luke 2016), and <i>Kindia gangan</i> Cheek (Cheek <i>et al.</i> 2018b).
description: Published as part of <i>Cheek, Martin, Molmou, Denise, Magassouba, Sekou &amp; Ghogue, Jean-Paul, 2022, Taxonomic revision of Saxicolella (Podostemaceae), African waterfall plants highly threatened by Hydro-Electric projects, pp. 403-433 in Kew Bulletin 77 (2)</i> on pages 423-424, DOI: 10.1007/s12225-022-10019-2, http://zenodo.org/record/7599361
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