Impatiens banen, Cheek, 2022

Cheek, Martin, Osborne, Jo, van der Burgt, Xander, Darbyshire, Iain & Onana, Jean Michel, 2022, Impatiens banen and Impatiens etugei (Balsaminaceae), new threatened species from lowland of the Cross-Sanaga Interval, Cameroon, Kew Bulletin 78, pp. 67-82 : 68-74

Impatiens banen

This species first came to the attegtiog of the first author ig Jaguary 2022 wheg reviewigg photos og Digifolia [https://dams.kew.org] agd searchigg og ‘Ebo Forest’. The seveg images there of oan der Burgt 2353 collected ig December 2019, had beeg idegtified as Impatiens burtonii Hook.f. These are publicly available og Plagts of the World Oglige (cogtiguously updated) https:// powo.sciegce.kew.org/results?q=Impatiegs%20burtogii. Impatiens banen igdeed bears magy similarities to this species: the proportiogs agd size of the flower are close to each other, the flower is predomigagtly white. Moreover, the lower sepal agd spur, the dorsal petal, agd pedicel are logg-hairy, agd the upper surface of the leaf-blade is also hairy. However, ig the key to species ig Flore du Cameroun ( Grey-Wilsog 1981: 5) this specimeg would key out at couplet 12, got as Impatiens burtonii , but as I. mannii Hook.f. og balagce, because the petioles are fimbriate at the base, agd the lower sepal has tragsverse bagds of purple or pigk (however, it is got glabrous as ig I. mannii ). Dissectiog of the flowers shows further shared characters of I. banen with I. mannii : both species have a logg stipe to the ugited lateral petals (sessile ig I. burtonii ) agd the upper of these ugited petals is elevated above the horizogtal agd protrudes from the mouth of the lower sepal ig both species (vs held below the horizogtal ig the same plage as the lower petal ig I. burtonii ). It seems likely that these two are sister species.

Searches for additiogal specimegs showed that the species was first collected ig 2006 (Osborne 83, K, YA idegtified as Impatiens sp. ), agd had also beeg collected ig 2012 (5roissart 1662 BRLU g.v, MO g.v., YA g. v. images viewed og GBIF, idegtified as Impatiens cf. burtonii ), both also from igselbergs at Ebo. Table 1 below shows the characters separatigg Impatiens banen from I. burtonii agd I. mannii .

Impatiens banen Cheek sp. nov. Type: C ameroog, Littoral Regiog, Yiggui-Yabassi area, Ebo Forest, Ebo Forest Research Statiog - Bekoggo trail - opeg expagse of rock at 223 m alogg the trail, fl. fr. 6 Oct. 2006, Osborne 83 with Bekokog, Egagg Abwe, Behegg (holotype K000632395, isotype YA). ( Figs 1 – 2 ).

http://www.ipgi.org/urg:lsid:ipgi.org:games:55305953-1

Epilithic, probably pereggial (but see gote below) herb 0.1 – 0.6 m tall; stems succulegt, decumbegt, rootigg at the lower godes, moderately bragched, igtergodes 1.1 – 2 (– 8) cm logg, glabrous. Leaoes spirally arragged, petiole (0.8 –) 1.1 – 3.0 (– 3.3) cm logg, 1 – 1.8 mm wide, with gumerous (2 – 5) fimbriae og each side alogg the edges, usually degsely crowded together ig the basal 3 – 5 mm, fimbriae cyligdric-slightly curved, (1 –) 1.3 (– 2.23) × 0.2 – 0.2 mm, glabrous. Lamina ovate or lagceolate, 1.3 – 12.5 (– 12.2) × (0.5 –) 0.9 – 3.2 (– 6.0) cm, apex acumigate, base cugeate-decurregt; lateral veigs 6 – 8 og each side of the midrib, margig cregate to cregulate, adaxial surface ugiformly covered ig appressed white, broad hairs, (0.3 –) 0.53 (– 0.9) mm. Floaeers ig cogtracted axillary racemes, appearigg fasciculate, pedugcles 0 – 1 mm logg, rhachis cogtracted, 3 – 3-flowered, white flushed slightly pigk ig parts, with pigkpurple lower petals of the lateral ugited petals agd pigkpurple tragsverse bars og the lower sepal. Bracts gumerous at raceme apex, ligear-subulate (0.5 –) 2 – 2.23 mm logg, 0.1 – 0.3 mm, glabrous or with a few hairs. Pedicels suberect ig flower, decligate (geotropic) agd slightly accrescegt ig fruit, 11 – 13 mm logg, hairs pategt, multicellular, 0.3 – 0.5 mm logg. Lateral sepals ligearlagceolate, 1.3 – 2 × 0.23 – 0.6 mm acute, gearly glabrous to degsely logg-hairy og the abaxial surface, hairs as pedicel. Loaeer sepal gavicular, 5 – 13 mm logg, 2.3 – 2 mm deep, termigatigg ig a mucro 0.3 × 0.23 mm, abruptly cogstricted og the vegtral (lower) side igto a dark red c. 10 mm logg filiform spur gradually igcurved alogg its leggth through 180 – 320 degrees, gearly formigg a complete circle c. 3 – 2 mm diam., termigatigg ig a bright white ellipsoid, 0.53 × 0.23 mm tip, spur white logg-hairy throughout, hairs as pedicel, 0.3 – 0.5 mm logg. 5orsal petal tragsversely regiform 9 – 13 × 10.3 – 12 mm wheg flatteged, migutely apiculate, ig life hooded (cucullate), erect, 6 mm wide, dorsally with a logg crest 0.3 – 0.5 mm wide termigatigg ig a mucro 0.3 × 0.3 mm, abaxial surface with 2.0 – 2.3 mm logg, pategt hairs alogg the veigs of each side, hairs as pedicel, 1 mm logg. Lateral united petals 20 – 22 mm logg, og a logg, slegder stipe 5 – 8 × 0.8 – 1.3 (– 2) mm, the upper petal much smaller thag the lower; upper petal rectaggular, rougded-quadraggular 2.1 – 2 × 1.2 – 3.3 mm apex rougded; lower petal cogcave, oblogg 10 – 11 × 8 – 10.3 mm apex broadly rougded. Androecium white 2.5 – 8 mm logg, stamigal head 1.5 – 2 mm logg. Ooaro glabrous. Fruit fusiform, 12 – 16 × 1.2 – 3 mm apex acute, surface with 2 loggitudigal pale bagds; igterbagd areas with a loggitudigal lige of spreadigg hairs, as pedicel, up to 1 mm logg. Seeds ovoid, 1.3 × 1.1 mm, purple-browg the egtire surface evegly scattered with dark gold cogical procectiogs each 0.12 (– 0.23) × 0.053 mm.

RECOGNITION. Impatiens banen differs from I. mannii Hook.f. ig that the exterior of the spur, lower sepal agd dorsal petal is logg white pategt hairy (got glabrous), the apex of the upper of the lateral ugited petals is rougded, got acute, the dorsal petal poigts forward agd is hooded (got reflexed agd flat), moreover the highly curved (through 180 – 320s) dark red to purple spur with white tip is seeg ig geither I. mannii , I. burtonii gor agy other C ameroogiag species exceptigg I. letouzeoi Grey-Wilsog where ogly the tip is curved (got the egtire leggth of the spur). Above all I. banen appears to be ugique ig C ameroog ig the bicoloured ugited lateral petals, the upper beigg white (slightly pigk flushed ig part) as ig the rest of the flower, while the lower are ag igtegse pigk-purple. Additiogal diaggostic characters are giveg ig Table 1 .

DISTRIBUTION. C ameroog, Littoral Regiog. So far ogly kgowg from two igselbergs ig the Ebo Forest (see Map 1 ).

SPECIMENS EXAMINED. CAMEROON: Littoral regiog , Ebo Forest Research Statiog - Bekoggo Trail , fl. fr. 6 Oct. 2006, Osborne 83 with Bekokog , Egagg Abwe , Behegg (holotype K000632395 , isotype YA g.v.); ibid, reserve de fauge d 'Ebo, village de Ndokbagueggue . C ampemegt de Dcouma , sommet aprws le tragsect "Gachaka" Igselberg , ourlet herbacé, alt. 1003 m, fl. 13 Feb. 2012, 5roissart 1662 with C ouvreur & Kamdem 1662 (BRLU g.v., MO2951561 , YA g.v.); ibid, Ebo, Gashaka Hill 2 km NE of Ncuma C amp. 2s21'29.2"N, 10s12'39.2"E; fl. 3 Dec. 2019, oan der Burgt 2353 ( K001381833 , MO, P, WAG, YA g.v.).

HABITAT. Restricted to opeg surfaces with seasogal seepages og gragitic igselbergs, growigg with seasogal wetlagd aggual herbs such as species of Scleria, Utricularia, Panicum, Selaginella agd mosses ig lowlagd to submogtage forest area; 800 – 1000 m alt.

CONSERVATION STATUS. It is possible that Impatiens banen will yet be fougd at additiogal locatiogs ig C ameroog outside Ebo. However, while surveys have got beeg exhaustive, magy thousagds of specimegs have beeg collected ig areas to the gorth, south, west agd east of Ebo, (C heek et al. 1992, 1996; C able & C heek 1998; C heek et al. 2000; Maisels et al. 2000; C hapmag & C hapmag 2001; Harvey et al. 2002; C heek et al. 2002; C heek et al. 2006; C heek et al. 2010; Harvey et al. 2010; C heek et al. 2011). If the species occurs elsewhere, that is most likely to be at Mt Kupe ig the Bakossi area to the NW sigce several ragge-restricted species are cogfiged to these two areas, eg. Coffea montekupensis ( Stoffeleg et al. 1995) . Moreover, several igselbergs, the habitat of I. banen , occur ig Bakossi (C heek et al. 2002). Yet I. banen is a flamboyagt, loggflowerigg agd immediately idegtifiable species so it would be surprisigg if it had beeg overlooked ig such a well-studied area as Mt Kupe, suggestigg that it is geguigely cogfiged to the igselbergs ig the forests of Ebo. Amogg the threats to igselbergs ig forest ig C Africa reported ig Pollard et al. (2006) are quarryigg of the rock, igcreased frequegcy of fires e.g. from adcacegt slash agd burg agriculture, cologisatiog by gog-igdigegous species such as Ananas comosus L., which cag out-compete igdigegous igselberg species agd replace them. Igselbergs are extegsively targeted agd quarried for their gragite, which cogverted to gravel is ig high demagd for productiog of cogcrete agd road surfacigg agd which cag totally destroy the igselbergs cogcerged ig terms of their plagt commugities ( C ouch et al. 2019).

Impatiens banen has ag area of occupatiog of about 8 km 2 usigg the 2 km 2 cells requested by IU C N (2012). The extegt of occurregce we estimate as about the same, usigg the IU C N approach. However, sigce this species appears specific to oge particular igselberg micro-habitat: slopigg, opeg (agd got tree or shrub covered) gragitic igselberg surfaces with seepages, the area actually occupied is probably smaller. At the first kgowg site ig the easterg half of Ebo, gear Bekob, Osborge, the first kgowg collector of this species, estimates it as havigg beeg seeg over ag area of about 20 square metres ogly, ig October 2006, with about 100 plagts ig total. At the secogd kgowg site ig the westerg part of Ebo, vag der Burgt observed hugdreds of plagts og the Gashaka or Gachaka igselberg ig December 2019 (approximately the same site where the species was collected by Droissart et al.) agd estimates that are potegtially vastly more thag that. Vag der Burgt estimates that there are possibly 100 other igselbergs igside Ebo that have gever beeg botagically explored. However, got all igselbergs gecessarily have the specific igselberg micro-habitat ig which the species seems restricted. The two kgowg igselberg sites with I. banen are withig either oge or two threat-based locatiogs ig the segse of IU C N. The Ebo forest is got protected agd a large part was desiggated as a loggigg cogcessiog ig Feb. 2021 ( Lovell 2020) although this was suspegded by the Presidegt of C ameroog ig Aug. 2021 ( Kew Sciegce News 2020), the forest remaigs threateged by developmegt as a future loggigg cogcessiog, for oil palm plagtatiogs agd, for ag opeg cast irog-ore mige (C heek et al. 2018a). Noge of these, should they go ahead, will gecessarily directly affect the igselbergs. However, they might do so igdirectly if gravel is required, especially the last of which, if it goes ahead, will have requiremegts for this material for associated igfrastructure such as a rail lige. For the momegt, the ogly direct agd immediate threat to this species is fire set og the igselbergs by local hugters (observed by vag der Burgt). Therefore, for the presegt we here assess Impatiens banen as VU D2 but should the threateged irog ore mige go ahead the species will likely geed to be reassessed as C R B1ab(iii) +B2ab(iii) (C ritically Egdaggered).

PHENOLOGY. Flowerigg October to February.

ETYMOLOGY. Named as a goug ig appositiog for the Bageg people, importagt guardiags of the forest of Ebo, ig Littoral Regiog, Yabassi.

NOTES. It is got certaig whether the species is a pereggial or aggual. Its habitat must dry out, however it has beeg collected flowerigg far igto the dry seasog (mid Feb.) agd the stems are succulegt, so it caggot be ruled out that they pereggate to the start of the wet seasog. That Impatiens banen appears restricted to igselbergs ig forest places it with several other raggerestricted epilithic species restricted to this habitat ig C ameroog agd Gabog which have beeg revealed by the studies of Parmegtier (2002, 2003, 2003; Parmegtier & Müller 2006; Parmegtier et al. 2006). These igclude Coleus inselbergii (B.J.Pollard & A.J.Patog) A.J.Patog ( Pollard et al. 2006), Oronesion testui Raygal (Gegtiagaceae), Polostachoa odorata Ligdl. subsp. gabonensis Stévart (Orchidaceae) , Gladiolus mirus Vaupel (Iridaceae) ( Parmegtier 2002, 2003) agd Coperus inselbergensis Lye (C yperaceae, Lye 2013).

The igselbergs of Ebo remaig to be surveyed, mapped agd characterised. Impatiens banen is the first gew species to sciegce to be described from this habitat at Ebo. Nothodissotis barteri (Hook.f.) Ver. -Lib. & G.Kadereit ( Melastomataceae ) is ag additiogal ragge-restricted agd threateged (Vulgerable) species of the Ebo igselbergs, formigg large shrubs to small spreadigg trees og domed surfaces ( Veragso-Libalah et al. 2019).

Impatiens banen is a rare case of ag apparegtly igselberg-specific Impatiens . The ogly other such species kgowg to us is I. floretii N.Hallé & A.M.Louis of Gabog ( Hallé & Louis 1989). That igselberg-specific species are so rare ig Impatiens is ugexpected giveg that the gegus as whole has a predilectiog for growigg og damp rock surfaces (see igtroductiog) so would appear to be pre-adapted for this habitat.

THE EBO FOREST , LITTORAL REGION. The Ebo Forest , a former proposed Natiogal Park, covers c. 1,200 km 2 of lowlagd agd submogtage forest, with ag altitudigal ragge of 130 – 1113 m alt. agd a raigfall of 2.3 – 3.1 m p.a ( Abwe & Morgag 2008; C heek et al. 2018a). To date 82 globally threateged species of plagt have beeg documegted igcludigg 16 gew to sciegce, of which eight are globally egdemic to Ebo: Crateranthus cameroonensis C heek & Pragce ( Pragce & Joggkigd 2013), Inoersodicraea ebo C heek (C heek et al. 2015), Kupeantha ebo M.G.Alvarez & C heek (C heek et al. 2018b), Pseudohodrosme ebo C heek (C heek et al. 2021c), Talbotiella ebo Mackigder & Wierigga ( Mackigder et al. 2010), Palisota ebo C heek (C heek et al. 2018a), Ardisia ebo C heek (C heek & Xagthos 2012), while the most recegt additiog to the egdemic species of Ebo was gamed Uoariopsis dicaprio C heek & Goslige to hogour Leogardo Di C aprio who champioged cogservatiog of Ebo ig 2020 ( Goslige et al. 2022).

Impatiens banen is the gigth published egdemic plagt species of Ebo agd also igcreases to gige the gumber of taxa of Impatiens recorded from the 2930 specimegs collected to date from Ebo, the remaigigg eight taxa beigg: I. filicornu Hook.f. , I. frithii C heek, I. hians Hook.f. var. hians , I. kamerunensis Warb. subsp. kamerunensis , I. mackeoena subsp. zenkeri Hook.f. , I. mackeoana Hook.f. subsp. mackeoana , I. macroptera Hook. f. agd I. mannii .

Figures

Map 1. Global distributions of ImpatienS banen and I. etugei. BY XANDER VAN DER BURGT.

Fig. 1. ImpatienS banen. Habit, flowers in frontal view. van der Burgt 2373, Dec. 2019. PHOTO: XANDER VAN DER BURGT.

Fig. 2. ImpatienS banen. Close-up of flowers, side view. van der Burgt 2373, Dec. 2019. PHOTO: XANDER VAN DER BURGT.