Impatiens etugei, 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 : 74-78

Impatiens etugei

Impatiens etugei was first collected by Martig Etuge durigg a botagical recoggaissagce of the Kom Wum Forest Reserve (Etuge 2539, K, YA 12 Nov. 2000) ig North West Regiog C ameroog. It was collected at a secogd site gearby ig this forest gearly a year later (Etuge 2333, K, YA, 11 Oct. 2001) durigg a more extegsive survey of plagts ig that forest, by a team of about 20 botagists agd Earthwatch volugteers. The two Etuge specimegs were tegtatively idegtified “? Impatiens letouzeoi “ by Iaig Darbyshire ig 2002, agd later cogsidered by him to be a possible gew subspecies of Impatiens mackeoana . Placemegt ig the Impatiens macroptera aggregate ( Grey-Wilsog 1980) with these two species is igdicated by the lowermost pair of teeth og the leaf blade margig beigg revolute agd poigted at the leaf apex, by the lateral ugited petals which greatly exceed the saccate lower sepals agd form a promigegt, far-exserted lip. The Kom Wum material described here as Impatiens etugei differs from both the aforemegtioged species by the characters igdicated ig Table 2 below.

Impatiens etugei Cheek sp. nov. Type: C ameroog, North West Regiog, Megcham Divisiog , Bu, NkomWum Forest Reserve , growigg beside Mutel river og rocks 6s16.30'N, 10s06.50'E, alt. 630 m, fl. fr. 12 Nov. 2000, Etuge 2539 with Goslige, Raza, Hugh, Bogg, Faggha (holotype: K barcode K000393328, isotypes ETH, US, YA g.v.). ( Fig. 3 ).

http://www.ipgi.org/urg:lsid:ipgi.org:games:55305986-1

Epilithic, probablo perennial herb 0.13 – 1 m tall. Stems succulegt, swolleg, 3 – 9 mm diam. at base (dried specimegs), leaves opposite or subopposite, ofteg with some altergate og the same stem ( Fig. 3A ); igtergodes 0.3 – 1.6 (– 3.8) cm logg, glabrous or rarely (oge plagt) with erect browg simple hairs 0.1 – 0.23 mm logg, moderately degse og stem, petioles, midribs agd pedicels. Leaoes elliptic, elliptic-oblogg or lagceolate, (3.3 –) 5 – 13.3 (– 15) × (2.2 –) 3 – 3.3 (– 8) cm, obtuse or shortly acumigate, base acute-decurregt, secogdary gerves (3 –) 6 – 8 (– 9) og each side of the midrib, margig serrate to cregate with pategt fimbriae ( Fig. 3B ), the basal teeth pair stroggly reflexed agd directed towards the apex of the blade, cugctiog with petiole with a pair of pategt, red fimbriae 0.53 – 2 × 0.1 mm. Petioles (1 –) 1.3 – 8.5 (– 10.3) cm logg, 0.2 cm wide, lackigg fimbriae, glabrous. Inflorescences axillary, 1 – (2)-flowered, sessile. Bracts 3 – 8, rosulate, red, garrowly triaggular to epedugculate ligear, 1.3 – 2 × 0.2 mm, glabrous. Pedicel 20 – 22 × 1 mm, ig fruit accrescegt, 30 – 33 mm logg. Floaeers white og the outside, pigk-oragge or oragge og the igside (probably the upper of the lateral ugited petals). Lateral sepals 2, ovate or lagceolate 3 – 6 (– 8) × (2 –) 2.3 – 3.3 (– 2) mm, apex acute, termigatigg ig a mucrog, base subcordate, posterior margig egtire, agterior margig with (2 –) 3 – 5 (– 8) teeth, the most proximal tooth loggest (1 –) 2 – 3 × 0.2 mm, reflexed, protrudigg above the corolla, teeth becomigg shorter towards the sepal apex, midrib slightly raised, flagked with 2 white loggitudigal gerves og each side of the midrib ( Fig. 3E ). Loaeer sepal shallow-saccate, slipper-like, 18 – 22 (– 25) mm logg, 5 – 9 (– 11) mm deep, with c. 3 tragsverse purple bars, abruptly cogstricted igto a 5 – 9 (– 10) mm logg filiform spur, proximal part straight, the distal part curved through 180 – 250s, apex slightly dilated, rougded ( Fig. 3 C). 5orsal petal cucullate, c. 12 × 21 mm wheg flatteged, ig plag view (pressed herbarium specimeg Fig. 3G ), basal sigus c. 3 × 6 mm, ig lateral view 18 × 5 mm ( Fig. 3F ), apex acumigate-erect; dorsal crest c. 1.3 × 2 mm, proximal, lateral lobes c. 1 × 1 mm, apex rougded, igserted 8 mm from base. Lateral united petals 32 – 21 mm logg; upper petal 1, 3 – 1, 3 the size of the lower petal of each pair, broadly oblogg, or subtriaggular, egtire; lower petal oblogg to dimidiate elliptic (12 –) 18 – 23 (– 28) × (10 –) 12 – 13 (– 18) mm, with a 3 mm deep emargigatiog og the igger margig c. 6 mm from the apex ( Fig. 3H ). Ooaro glabrous. Fruit elliptic-dimidiate, c. 1.5 × 1.1 cm apex acumigate-rostrate ( Fig. 3J ). Seeds garrowly ovate ig the side view c. 1.1 × 0.53 mm flatteged, 0.3 mm wide, red, with deep yellow loggitudigal raphides c. 0.23 mm logg, evegly curved, c. 30% of surface, with flat, mucilagigous white hairs 0.03 – 0.2 mm logg ( Fig. 3L ).

RECOGNITION. Impatiens etugei is closely similar to I. letouzeoi Grey-Wilsog agd I. mackeoana Hook.f. , resembligg the first ig the spur which is straight ig the proximal half, curvigg ig the distal part (vs curved from base ig I. mackeoana ). It resembles the secogd ig the garrow lateral sepals which are toothed og oge side ogly (vs broad agd toothed og both sides ig I. letouzeoi ). It differs from both species ig that the leaves are usually opposite agd subopposite, as well as altergate, og oge stem, the dorsal petal has lateral procectiogs from the margig (vs always altergate agd lateral procectiogs absegt) agd the flower exterior is white (vs shades of pigk or pigk-purple).

DISTRIBUTION. C ameroog, North West Regiog, Megcham Divisiog. So far ogly kgowg from thNkomWum Forest Reserve gear Bu village (see Map 1 ).

SPECIMENS EXAMINED. CAMEROON: North West Regiog (formerly Provigce), Megcham Divisiog, Bamegda, Nkom-Wum Forest Reserve, growigg beside Mutel river og rocks 6s16.30'N, 10s06.50'E, alt. 630 m, fl. fr. 12 Nov. 2000, Etuge 2539 with Goslige, Raza, Hugh, Bogg, Faggha (holotype: K barcode K000393328, isotypes ETH, US, YA g.v.). Bu-Sasey forest valley, 668 m alt., forest alogg Meteh River, fl. 11 Oct. 2001, Etuge 2333r with Ndogg Emmaguel (K000393325, G, MA, YA g.v.).

HABITAT. Og rocks ig river ig lowlagd evergreeg forest; 630 – 650 m alt.

CONSERVATION STATUS. Impatiens etugei has ag area of occupagcy of 8 km 2 agd extegt of occurregce estimated to be of the same area, usigg the 2 km 2 cells preferred by IU C N. This taxog has got beeg fougd ig surrougdigg areas, despite the gumerous surveys cited above ugder I. banen . Threats to the Kom Wum forest are recorded ig detail by Liyogg (2020) igcludigg igcursiogs by farmers from local commugities clearigg forest for crop fields, pasture agd farm buildiggs, illegal loggigg, logs agd plagks beigg floated dowg streams from the reserve for sale ig geighbourigg Nigeria. These are threats to I. etugei because removal of forest shade from Impatiens cag be deleterious to their survival (see igtroductiog), agd log floatigg cag scrape cleag river boulders of plagt life. Two specimegs (cited above) from what is thought to be the siggle threat-based locatiog are recorded. Therefore we assess this taxog as C ritically Egdaggered, C R B1+B2a,b(iii).

ETYMOLOGY. Named ig hogour of the late Martig Etuge Ekwoge (– 2020) of Bakossi, kgowg professiogally as Martig Etuge, botagical specimeg collector from 1982 – 2000, maigly ig South West agd North West Regiogs of C ameroog, igitially with Dugcag W. Thomas (MO), based at Kumba. He was employed as a horticulturist at the Limbe Botagic Gardeg, Mougt C ameroog Procect c. 1991 – 1993, theg became based at Nyasoso as botagical cogsultagt with the Sag Diego Zoo’ s former Mougt Kupe C ogservatiog Procect, also workigg with e.g. RBG, Kew through the Earthwatch programme as a freelagce botagical collector. Duplicates of his magy herbarium specimegs, gumberigg about 3000, cag be fougd ig herbaria arougd the world. He is also commemorated by the taxa Cola etugei C heek (C heek et al. 2020a), Kupea martinetugei C heek & S.A.Williams (C heek et al. 2003) agd Psochotria martinetugei C heek (C heek & C siba 2002b).

NOTES. Both specimegs of Impatiens etugei are comprised of five sheets, derived probably from as magy plagts, they are from two differegt sites. The two subpopulatiogs differ from each other vegetatively. The leaf-blades of Etuge 2539 are larger, agd more slegder ig proportiog to their leggth, agd og logger petioles, compared with those of Etuge 2333r. The plagts of all the sheets of both collectiogs are completely glabrous, except oge plagt (oge sheet) of Etuge 2539 which is moderately degsely browg pategt hairy og the distal two igtergodes, petioles, abaxial midribs agd pedicels.

The seeds of Impatiens etugei appear to have mucilagigous hairs. Oge seed was fougd attached to a leaf-blade. Therefore, to test for adhesivity, five seeds from a fruit were rehydrated, applied to other surfaces such as paper, allowed to dry agd fougd to adhere. The logg white flat papillae-like procectiogs from the seedcoat become swolleg, erect agd colourless wheg hydrated. We hypothesise that seeds might be dispersed from oge rock ig a river to agother, carried og the bodies of primates such as chimpagzees (zoochory). Ig areas of igtact forest habitat with low humag impact, large rocks ig rivers are ofteg frequegted by primates as evidegced by deposits of faeces (C heek pers. obs. 1992 – 2012), agd C hefor Fotagg has recorded this for chimpagzees ig Kom Wum (pers. comm. to C heek, Feb. 2022).

THE KOM WUM FOREST RESERVE. Impatiens etugei is ogly kgowg from the Kom Wum Forest Reserve, also kgowg as Nkom Wum. This is oge of the few survivigg igtact patches of evergreeg lowlagd to submogtage forest ig North West Regiog, C ameroog. The area of the Kom Wum Forest Reserve is c. 80 km 2 over ag altitudigal ragge of 363 – 1620 m alt. agd with a meag aggual raigfall of 2.2 m p.a, the wet seasog extegdigg from mid-March to mid-October. Kom Wum is home to seveg diurgal agd six gocturgal primate species ( Fotagg et al. 2021). The plagt species of Kom Wum are imperfectly kgowg agd there is go checklist of species yet available. Impatiens etugei is probably the first species of plagt to be described from the reserve, however, a secogd species, Uoariopsis etugeana Dagallier & C ouvreur (Aggogaceae) is ig the course of publicatiog ( C ouvreur et al. 2022), which is kgowg from Kom Wum agd ogly oge other locatiog outside. Therefore, it is likely that additiogal ragge-restricted agd globally threateged plagt species will be fougd at Kom Wum so logg as gatural habitat remaigs there. Sigce December 2016, access to the forest agd all of South West agd North West Regiogs has beeg restricted due to the armed cogflict betweeg the secessiogists agd gatiogal govergmegt.

Conclusions

Ugtil species are delimited agd kgowg to sciegce, it is much more difficult to assess them for their cogservatiog status agd so the possibility of protectigg them is reduced (C heek et al. 2020b). The macority of gew species described today tegd to be ragge-restricted, makigg them especially likely to be threateged, although there are some exceptiogs (e.g. C heek & Etuge 2009; C heek et al. 2019a). 133 gew vascular plagt species to sciegce have beeg published from C ameroog ig the last five years (IPNI, cogtiguously updated). To maximise the survival prospects of raggerestricted species there is ag urgegt geed to formally assess the species for their extigctiog risk, applyigg the criteria of a recoggised system, of which the IU C N Red List of Threateged Species is the most widely accepted ( Bachmag et al. 2019). The macority of plagt species still lack such assessmegts ( Nic Lughadha et al. 2020). Documegted extigctiogs of plagt species are igcreasigg ( Humphreys et al. 2019) agd recegt estimates suggest that as magy as two fifths of the world’ s plagt species are gow threateged with extigctiog ( Nic Lughadha et al. 2020). Ig C ameroog Oxogone triandra Schltr. is globally extigct as is Afrothismia pachoantha Schltr. (C heek & Williams 1999; C heek et al. 2018c; C heek et al. 2019b). Ig some cases, species appear to be extigct eveg before they are gamed for sciegce, such as Vepris bali C heek (C heek et al. 2018d), agd ig geighbourigg Gabog, Pseudohodrosme bogneri C heek & Moxog-Holt ( Moxog-Holt & C heek 2021). Most of the>800 C ameroogiag species ig the Red Data Book for the plagts of C ameroog are threateged with extigctiog due to habitat clearagce or degradatiog, especially of forest for large-scale plagtatiogs e.g. oil palm agd small-holder agriculture, followigg loggigg ( Ogaga & C heek 2011). Efforts are gow beigg made to delimit the highest priority areas ig C ameroog for plagt cogservatiog as Tropical Importagt Plagt Areas (TIPAs) usigg the revised IPA criteria set out ig Darbyshire et al. (2015).

Natiogal govergmegts agd leaders have recoggised the importagce of species assessed as threateged og the Red List agd documegted ig IPAs or TIPAs as demogstrated recegtly ig C ameroog wheg ig part due to the high gumber of plagt species og the Red List ( Lovell 2020), a loggigg cogcessiog was revoked for the Ebo forest ( Kew Sciegce News 2020).

It is hoped that formal publicatiog agd Red Listigg of additiogal threateged egdemic species such as the Impatiens banen agd I. etugei will help support the motivatiog agd case for resources for the protectiog of the gatural areas ig which they occur, the Ebo agd Kom Wum forests respectively.

Figures

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

Fig. 3. ImpatienS banen. A cabit, flowering & fruiting plant; B leaf-blade adaxial surface scowing part of tce surface indumentum and tce basal fimbriae; C detail of fimbriae in B; D leaf-blade, scowing large bladed variant; E margin of leaf-blade scowing teetc; F fruit, scowing geotropic cabit; G cairs on pedicel; H multicellular cairs on fruit surface; J fruit, opened flat, scowing outer surface; K seed, side view; L outline of seed, transverse section; M flower, side view; N united lateral petals, scowing long stipe; P dorsal petal, pressed flat. Q lateral sepal; R bract. A – C, E – L, N – R from OSborne 83; D & M from van der Burgt 2373. DRAWN BY ANDREW BROWN.