# Synsepalum longiflorum (Sapotaceae), a new species endemic to the Sanaga River basin, Cameroon

Fabrice Nzoyeuem Djonko, Olivier Lachenaud, Murielle Simo-Droissart, Gilles Dauby, Bonaventure Sonké

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Fabrice Nzoyeuem Djonko, Olivier Lachenaud, Murielle Simo-Droissart, Gilles Dauby, Bonaventure Sonké. Synsepalum longiflorum (Sapotaceae), a new species endemic to the Sanaga River basin, Cameroon. Candollea, 2025, 80 (2), pp.229-237. 10.15553/c2025v802a7. hal-05505346

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# Synsepalum longiflorum (Sapotaceae), a new species endemic to the Sanaga River basin, Cameroon

Authors: Djonko, Fabrice Nzoyeuem, Lachenaud, Olivier, Simo-Droissart, Murielle, Dauby, Gilles, and Sonké, Bonaventure

Source: Candollea, 80(2) : 229-237

Published By: The Conservatory and Botanical Garden of the City of Geneva (CJBG)

URL: https://doi.org/10.15553/c2025v802a7

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# Synsepalum longiflorum (Sapotaceae), a new species endemic to the Sanaga River basin, Cameroon

Fabrice Nzoyeuem Djonko, Olivier Lachenaud, Murielle Simo-Droissart, Gilles Dauby & Bonaventure Sonké

## Abstract

NZOYEUEM DJONKO, F., O. LACHENAUD, M. SIMO-DROISSART, G. DAUBY & B. SONKÉ (2025). Synsepalum longiflorum (Sapotaceae), a new species endemic to the Sanaga River basin, Cameroon. *Candollea* 80: 229-237. In English, English and French abstracts. DOI: http://dx.doi.org/10.15553/c2025v802a7

The new species *Synsepalum longiflorum* Nzoyeuem, O. Lachenaud & Sonké, endemic to the Sanaga basin in Cameroon, is described and illustrated. It is easily separated from its congeners by its red and yellow corolla with an exceptionally long tube (20–42 mm vs. ≤ 7 mm in other species). These characteristics are strongly suggestive of bird pollination, so far undocumented in African *Sapotaceae*. The species is preliminary assessed as “Vulnerable” [VU] in accordance with the IUCN Red List Categories and Criteria.

## Résumé

NZOYEUEM DJONKO, F., O. LACHENAUD, M. SIMO-DROISSART, G. DAUBY & B. SONKÉ (2025). Synsepalum longiflorum (Sapotaceae), une nouvelle espèce endémique du bassin de la Sanaga, Cameroun. *Candollea* 80: 229-237. En anglais, résumés anglais et français. DOI: http://dx.doi.org/10.15553/c2025v802a7

La nouvelle espèce *Synsepalum longiflorum* Nzoyeuem, O. Lachenaud & Sonké, endémique du bassin de la Sanaga au Cameroun, est décrite et illustrée. Elle se distingue aisément de ses congénères par sa corolle rouge et jaune à tube exceptionnellement long (20–42 mm vs. ≤ 7 mm chez les autres espèces). Ces caractéristiques suggèrent fortement une pollinisation par les oiseaux, cas inconnu jusqu'à présent chez les *Sapotaceae* africaines. L'espèce est évaluée de manière préliminaire comme “Vulnérable” [VU] conformément aux Catégories et Critères de la Liste Rouge de l'UICN.

## Keywords

SAPOTACEAE – *Synsepalum* – Cameroon – New species – Ornithophily – Taxonomy

Addresses of the authors:

FND: Laboratory of Biological Evolution and Ecology, Free University of Brussels, 50 Av. F. Roosevelt, CP 160/12, B-1050 Brussels, Belgium; Plant Systematics and Ecology Laboratory, Higher Teachers' Training College, University of Yaoundé I, P.O. Box 047, Yaoundé, Cameroon.

E-mail: djonkof@yahoo.com

OL: Meise Botanical Garden, Domein van Bouchout, 1860 Meise, Belgium; Service Général de l'Enseignement supérieur et de la Recherche scientifique - Fédération Wallonie-Bruxelles, 1 rue Lavallée, 1000 Brussels, Belgium; Herbarium et Bibliothèque de Botanique africaine, CP 265, Université Libre de Bruxelles, Boulevard du Triomphe, B-1050 Brussels, Belgium.

MSD, GD: AMAP, Univ. Montpellier, IRD, CNRS, INRAE, CIRAD, Montpellier, France; Plant Systematics and Ecology Laboratory, Higher Teachers' Training College, University of Yaoundé I, P.O. Box 047, Yaoundé, Cameroon.

BS: Plant Systematics and Ecology Laboratory, Higher Teachers' Training College, University of Yaoundé I, P.O. Box 047, Yaoundé, Cameroon; International Joint Laboratory DYCOFAC, IRD-UYI-IRGM, Yaoundé, Cameroon; Missouri Botanical Garden, Africa & Madagascar Department, P.O. Box 299, St. Louis, Missouri 63166-0299, U.S.A.; Herbarium et Bibliothèque de Botanique africaine, CP 265, Université Libre de Bruxelles, Boulevard du Triomphe, B-1050 Brussels, Belgium.

Submitted on Janvier 30, 2025 - Accepted on September 24, 2025 - First published online on November 19, 2025

ISSN: 0373-2967 (print), 2235-3658 (online) - Published by the Conservatoire et Jardin botaniques de Genève

Open access article under Creative Commons Attribution Licence (CC BY 4.0)
**Introduction**

Located on the Atlantic coast of Central Africa, Cameroon has an exceptionally rich flora estimated at 7,500 plant species (ONANA, 2011). This number is likely underestimated since some parts of the country are still poorly known botanically, including much of the Sanaga River basin, the largest river in Cameroon, which drains an area of c. 140,000 km² (VAN DER WAARDE, 2007). This area has a wide variety of habitats, including wooded savannas, riparian forests, and both evergreen and semi-deciduous forests on drained soils (LETOUZEY, 1985).

The biodiversity in the Sanaga basin is increasingly threatened by the construction of hydroelectric dams, of which three are already operational at Edéa, Song Loulou, and Lom Pangar, while a fourth, at Nachtigal, is nearing completion, and a fifth is being planned at Kikot. Botanical inventories carried out in the context of the environmental impact study of the Kikot dam have led to the discovery of several new species (SONKÉ et al., 2024), including a species of *Synsepalum* (A. DC.) Daniell (*Sapotaceae*) that is described here.

*Synsepalum* s.l. includes 37 species of trees and shrubs from tropical Africa (POWO, 2025), most of which occur in the Guineo-Congolian rainforest zone. The genus was previously restricted to a group of species with well-developed petaloid staminodes, fused sepals and no stipules (e.g. AUBRÉVILLE, 1959, 1961, 1964; HEINE, 1963); now it has been expanded to include the former genera *Afrosersalisia* A. Chev., *Pachystela* Pierre ex Radlk., *Pseudopachystela* Aubrév. & Pellegr., *Tulestea* Aubrév. & Pellegr. and *Vincentella* Pierre (PENNINGTON, 1991), which embraces species displaying stipules, free sepals and/or no staminodes. Characters of *Synsepalum* in the broad sense include 5-merous flowers with undivided corolla lobes, no disk, 5-locular ovaries, 1-seeded fruits, seeds with a broad ventral scar and leaves with widely spaced secondary veins; the last character separates *Synsepalum* from the related genus *Englerophytum* K. Krause, which has closely parallel secondary veins. Two recent molecular phylogenetic studies (BORG et al., 2019; POTTER & ULEH, 2025) found *Synsepalum* and *Englerophytum* in a well-supported clade together, but neither genus is monophyletic as currently delimited. It is therefore likely that *Synsepalum* will have to be divided again, but more extensive sampling is required before making any change to the classification; pending this, the enlarged circumscription of the genus adopted by PENNINGTON (1991) remains in use. *Synsepalum* s.l. is in need of a thorough taxonomic revision, and while two new species have been described in recent years (HAWTHORNE, 2014; ROKNI et al., 2019), many more remain to be published.

**Materials and methods**

The description of the new species is based on the study of living material, herbarium and spirit collections, field notes and pictures. Material of the following herbaria were consulted: BR, BRLU, P, WAG and YA. All the specimens cited have been seen. During prospecting surveys, specimens were georeferenced using GPS map 66S. The georeferenced specimen data were imported into QGIS 3.38.0 geographic information software to produce a distribution map. Ecological and geographical data were collected from specimen labels and field observations. Descriptive terminology follows BORG (2013). Phytogeographical considerations follow WHITE (1979, 1993). Preliminary extinction risk assessments were made using the IUCN Red List Categories and Criteria (IUCN 2012, 2024). The geographical parameters of area of occupancy (AOO) estimated using a 2 × 2 km grid, and extent of occurrence (EOO) were calculated using GeoCAT (BACHMAN et al., 2011).

**Taxonomy**

*Synsepalum longiflorum* Nzoyeuem, O. Lachenaud & Sonké, sp. nov. (Fig. 1, 2).

**Holotypus:** CAMEROON. Central Region: Nkolmelen, Ponis Island, 4°14'19"N 11°5'19"E, 1.VIII.2023, fl., *Sonké* 7507 (BR!; iso-: BRLU!, G!, K!, M!, MO!, P!, WAG!, YA!).

*This species differs from all its congeners by its corolla being red at base and yellow at apex, with a tube 20-42 mm long (vs. white, green or yellowish, with a tube ≤ 7 mm long).*

*Shrub* up to 4 m tall and 5 cm DBH; trunk cylindrical from base; bark thin, fibrous, brown, peeling off in longitudinal strips; slash cream, with scarce and slow-draining white latex; branching following Aubréville's model (HALLÉ & OLDEMAN, 1970; HALLÉ et al., 1978) with leaves clustered (2-10 together) towards apex of twigs; twigs cylindrical, 1-3.5 mm thick, with dense golden-brown appressed hairs, older twigs sometimes glabrescent. *Stipules* 3-8 mm long, acicular, persistent for at least as long as leaves. *Leaves* simple, alternate, spirally arranged; petiole 2-7 mm long, with dense golden-brown appressed hairs; leaf blade 2-12.9 × 0.8-5.3 cm, obovate or rarely elliptic, acute to obtuse at base, obtuse to rounded or shallowly emarginate at apex, entirely glabrous or with scattered appressed hairs on underside, dark green above, pale green below, drying olive green to grey-green; midrib prominent on both sides, more strongly so below; secondary veins 7-17 pairs, inserted at a very broad angle to midrib, flat or slightly impressed above, prominent below, forming inconspicuous loops 1-2 mm from margin; intersecondary veins sometimes present, one between every pair of secondary veins; tertiary veins laxly reticulate and rather inconspicuous. *Flowers* cauliflorous, ramiflorous and axillary, solitary or fasciculate
<figure><img src="image_3.png" /><figcaption>**Fig. 1.** – *Synsepalum longiflorum* Nzoyeuem, O. Lachenaud & Sonké. **A.** Plant habit; **B.** Slash with drops of white latex; **C.** Branches arranged according to Aubréville's architectural model; **D.** Apex of twig with dense stipules; **E.** Twig and leaves, seen from below; **F.** Underside of the leaf (showing venation).</figcaption></figure>

[A: Nzoyeuem Djonko et al. 75; B: Nzoyeuem Djonko et al. 151; C: Sonké 7508; D: Nzoyeuem Djonko et al. 265; E: Nzoyeuem Djonko et al. 75; F: Relevé Cameroun 364] [Photos: A,B, D–F: F. Nzoyeuem Djonko; C: B. Sonké]
(2–8 per fascicle), pendulous; pedicel 4–13 mm long, slightly thickened towards apex, with dense golden-brown appressed hairs. *Calyx* with 5 free imbricate ovate sepals, 4–7 × 2–4 mm, rounded at apex, pubescent outside like pedicel (except parts covered in bud), glabrous inside. *Corolla* bright red with yellow apex, glabrous on both sides; tube 20–42 mm long, 4–8 mm in diam. at base and 6–12 mm in diam. at apex, narrowly infundibuliform to almost cylindrical, 5-grooved longitudinally between lobes in its upper part; lobes 2–5 × 4–5 mm, triangular, erect, margins induplicate; stamens 5, glabrous, inserted on corolla tube slightly above mid-height; filaments 11–16 mm long; anthers just exserted from corolla, medifixed, introrse and reflexed, 3–5 × 1–2 mm, oblong to narrowly ovate, with two thecae each opening by a longitudinal slit; staminodes absent; ovary 2–4 mm in diam, ovoid, hirsute, with 5 locules; style 2.5–3.8 cm long, linear, hairy in lower 5–6 mm, otherwise glabrous, shortly exserted, 1–5 mm longer than corolla tube. *Fruits* 2.6–3.5 × 1.5–1.6 cm, ellipsoid to ovoid, acute at apex and topped with persistent style, brown, hirsute, with calyx and corolla remnants persistent at base. *Seed* 1 per fruit, 1.4 × 0.8 × 0.8 cm, asymmetrically ellipsoid, dorsal side shiny brown and more strongly convex than ventral side, the latter entirely covered by a 1.4 × 0.7 cm elliptic scar, occupying almost half of the total surface area of the seed.

*Etymology*. – The epithet refers to the flower length, which is by far the longest recorded in both *Synsepalum* and African *Sapotaceae*.

*Distribution, ecology and phenology*. – *Synsepalum longiflorum* is endemic to the middle Sanaga River basin in Cameroon (Fig. 3). This area is part of the Lower Guinea subcentre of endemism (WHITE, 1979).

The species grows in open and seasonally flooded shrub formations along the Sanaga River, on shallow soils with scattered rocks, alongside species such as *Alsodeiopsis zenkeri* Engl. (*Icacinaceae*) and *Garcinia ovalifolia* Oliv. (*Clusiaceae*). It has also been observed in the undergrowth of riparian forests dominated by the tree *Talbotiella couteronii* Sonké et al. (*Fabaceae*) (SONKÉ et al., 2024). Locally, *Synsepalum longiflorum* is rare; it has been encountered in only four of the 129 riparian vegetation surveys conducted along the Sanaga River, each time as a single individual.

Flowers have been seen in January, April, July and August, and fruits in October. Young leaves appear at the same time as the flowers. Flowering is asynchronous with both buds and open flowers usually observed on the same plant (Fig. 2A). The plants produce many flowers but very few fruits have been observed (1–2 fruits per plant).

*Conservation status*. – *Synsepalum longiflorum* is known from 15 collections representing 15 unique occurrences and two

to four subpopulations. The EOO is calculated as 1,368 km², whereas the AOO is estimated at 36 km²; both fall within the limits for the “Endangered” category under criterion B. All occurrences are found outside protected areas. The four northernmost occurrences of the species are located at Badissa (one occurrence), Ebebda (two occurrences 300 m away from each other) and Melan-Megan (one occurrence). At all these sites the habitat is threatened by small-holder farming since seasonally flooded areas along the Sanaga, while not usually planted with permanent crops, are being increasingly used for cocoa nurseries — as the proximity of the river facilitates watering of the seedlings. These occurrences represent three locations in the sense of IUCN; although the occurrences in Ebebda and Melan-Megan are only 5 km apart, they are separated by four small branches of the Sanaga River, and therefore unlikely to be affected by the same threat event. Two occurrences are located just upstream of the Kikot dam, and at least one of them (but possibly both, depending on the exact plans selected for the dam) will be flooded by the reservoir; they are considered as one location. The occurrence near the Nachtigal falls (one location), and the eight occurrences at Ntol-Lébanga (one location since they are very close to one another), are situated downstream of the Nachtigal dam, whose construction is expected to cause a decline in habitat extent and quality due to lower water levels. For all these reasons we expect a current and future decline in habitat extent and quality, EOO, AOO, number of locations and number of mature individuals of the species. With regard to the most serious threat (hydroelectric dams), the 15 occurrences represent six locations, which is the lower limit for the “Vulnerable” category according to criterion B, and *Synsepalum longiflorum* is therefore preliminary assessed as “Vulnerable” [VU B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v)].

*Notes*. – This species is unmistakable in the flowering stage due to its red and yellow corolla with an exceptionally long tube, which is a unique character among African *Sapotaceae*. Other species of *Synsepalum* have a white, green or yellowish corolla with a much shorter tube, at most reaching 7 mm long. In the absence of flowers, it may be confused with *S. dulcificum* (Schumach. & Thonn.) Daniell or *S. passargei* (Engl.) T.D. Penn., two other riparian forest species occurring in Cameroon and having somewhat similar leaves; indeed, the earliest collection of *S. longiflorum* (Wilde & Wilde-Duyfjes 2791) was originally misidentified as *S. dulcificum*. This latter species is easily separated from *S. longiflorum* even when sterile by the absence of stipules, while *S. passargei*, which does have acicular stipules, differs by the hirsute indumentum of the petioles and young twigs, and the secondary leaf veins almost reaching the margin. Both species are indeed very different from *S. longiflorum* in their floral characters; they have, among other characters, well-developed staminodes and a short corolla tube (almost absent in *S. passargei*).
<figure><img src="image_4.png" /><figcaption>**Fig. 2.** – *Synsepalum longiflorum* Nzoyeuem, O. Lachenaud & Sonké. **A.** Ramiflorous flowers; **B.** Cauliflorous flowers; **C.** Axillary flower, side view (note the longitudinal grooves on the tube); **D.** Axillary flowers, one of them showing part of the inside; **E.** Mature fruit with remnants of corolla.
[A: Sonké 7508; B: Sonké 7495; C: Relevé Cameroun 180; D: Sonké 7495; E: Nzoyeuem Djonko et al. 151] [Photos: **A-B, D**: B. Sonké; **C, E**: F. Nzoyeuem Djonko]</figcaption></figure>
<figure><img src="image_5.png" /><figcaption>Fig. 3. – Distribution of *Synsepalum longiflorum* Nzoyeuem, O. Lachenaud & Sonké.</figcaption></figure>

The closest relatives of *Synsepalum longiflorum* are probably two East African species, *S. muelleri* (Kupicha) T.D. Penn. and *S. subverticillatum* (E.A. Bruce) T.D. Penn. Both species share with *S. longiflorum* ind duplicate corolla lobes and a corolla tube with 5 longitudinal grooves (characters not found in any other species of the genus), flowers without staminodes, acicular persistent stipules, and a somewhat similar leaf venation (although their tertiary veins are more prominent). The corolla of *S. muelleri* is also similar in shape to that of *S. longiflorum* but much shorter. The differences between the three species are summarized in Table 1.

The position of *Synsepalum muelleri* and *S. subverticillatum*, described respectively under *Vincentella* and *Pachystela*, has long been problematic since they do not fit very well in either genus (HEMSLEY, 1968; KUPICHA, 1978, 1983); this was in fact one of the reasons that led PENNINGTON (1991) to sink these genera under *Synsepalum*. However, as noted in the Introduction, *Synsepalum* in its current broad sense is not monophyletic and quite heterogeneous morphologically, and the resurrection of some of the genera currently treated as synonyms is expected in the future. In this case, the new species and its

presumed relatives (*S. muelleri* and *S. subverticillatum*) would probably find a position in *Vincentella*. In the phylogenetic analysis by POTTER & ULEH (2025), where the new species was not included, *S. muelleri* and *S. subverticillatum* are sisters to each other and nested in a clade also including *S. revolutum* (Baker) T.D. Penn., the type species of *Vincentella*. Members of this clade show considerable variation in floral characters (e.g. shape and length of corolla tube, presence or absence of staminodes, anthers apiculate or not) but share acicular stipules, leaves green on both sides with reticulate tertiary veins, free sepals, hirsute ovaries and fruits, and linear styles. In other *Synsepalum* species the ovaries and fruits are either glabrous or, more usually, with appressed hairs, and stipules are mostly absent; when they are present (in species formerly accommodated in *Pachystela*) the leaves have a silvery indumentum below, the tertiary veins are rather obscure and tending to be scalariform, and the style is thicker.
Additional specimens examined. CAMEROON. Central Region: Binoum, Ndonlo Island, 4'10'21"N 11'02'47"E, 25.IV.2022, fl., *Nzoyeuem Djonko et al.* 75 (BRLU, MO, YA); Binoum, Ndonlo Island, 4'12'07"N 11'04'32"E, 16.X.2022, fl. & fr., *Nzoyeuem Djonko et al.* 151 (BR, BRLU, K, MO, P, YA); Nkolmelen, Ponis Island, 4'15'32"N 11'07'04"E, 11.I.2024, fl. & fr., *Nzoyeuem Djonko et al.* 265 (BRLU, K, MO, P, YA); Ebebda, 4'25'31"N 11'16'40"E, 26.I.2024, fl., *Nzoyeuem Djonko et al.* 306 (BRLU, K, MO, P, YA); Ntol-Lebanga, 4'13'49"N 11'07'57"E, 14.I.2024, fl., *Relevé Cameroun 180* (BRLU, K, MO, P, YA); Bad-issa, 4'38'55"N 11'22'24"E, 23.I.2024, fl., *Relevé Cameroun 364* (BRLU, K, MO, P, YA); Melan-Megan, 4'26'12"N 11'19'30"E, 25.I.2024, fr., *Relevé Cameroun 384* (BRLU, K, MO, P, YA); Ebebda, 4'25'40"N 11'16'41"E, 26.I.2024, fl., *Relevé Cameroun 413* (BRLU, MO, P, YA); Nkolmelen, Island of Ponis, 4'14'28"N 11'07'22"E, 31.VII.2023, fl., *Sonké 7495* (BR, BRLU, K, M, MO, P, WAG, YA); ibid., 4'14'26"N 11'07'24"E, 31.VII.2023, fl., *Sonké 7496* (BR, BRLU, K, M, MO, P, YA); ibid., 4'14'24"N 11'07'13"E, 1.VIII.2023, fl., *Sonké 7501* (BR, BRLU, K, M, MO, P, WAG, YA); ibid., 4'14'19"N 11'07'04"E, 1.VIII.2023, fl., *Sonké 7506* (BR, BRLU, K, M, MO, P, WAG, YA); ibid., 4'14'19"N 11'07'05"E, 1.VIII.2023, fl., *Sonké 7508* (BR, BRLU, K, M, MO, P, WAG, YA); Nachtigal, about 20 km of Obala, along Sanaga River, 4'21'00"N 11'38'00"E, 1.VII.1964, fl. buds, *de Wilde & Wilde-Duyfjes 2791* (BR [BR000001723041], WAG [WAG0043626], YA [YA0011961]).

Discussion

The discovery of *Synsepalum longiflorum* brings to 38 the number of known *Synsepalum* species so far. Since several other species from Atlantic Central Africa are awaiting to be described, the actual number probably reaches 45 species. At least 15 species of *Synsepalum* occur in Cameroon, 12 already listed in ONANA (2011) plus *S. longecuneatum* De Wild. and *S. seretii* (De Wild.) T.D. Penn. that have been collected several times during recent inventories, and the species described herein. Among them, *S. batesii* (A. Chev.) Aubrév. & Pellegr., *S. brenanii* (Heine) T.D. Penn. and *S. longiflorum* are endemic to Cameroon (POWO, 2024). The high diversity and endemism of the Cameroonian flora has already been noted by several authors (e.g. ROBBRECHT, 1987; DE BLOCK, 1998; SONKÉ, 1999; LACHENAUD, 2019; COUVREUR et al., 2022).

It is remarkable that such a conspicuous species has so far been overlooked. All the known collections are very recent except for a single specimen collected in 1964. This is probably due to the fact that *Synsepalum longiflorum* has a very restricted distribution in the Sanaga River basin, which riparian forests had not received much attention from botanists. Indeed, recent prospections have led to the discovery of other species apparently restricted to riparian habitats along the Sanaga, such as *Talbotiella couteronii* and other species belonging to *Ledermanniella* Engl. (*Podostemaceae*), *Nectaropetalum* Engl. (*Erythroxylaceae*), *Phragmanthera* Tiegh. (*Loranthaceae*) and *Turraea* L. (*Meliaceae*).

Although no pollinators have yet been observed visiting the flowers of *Synsepalum longiflorum*, their morphology and coloration are strongly suggestive of specialised bird pollination, presumably by sunbirds (*Nectariniidae*). Bird-pollinated flowers often present the following features: (1) red corollas, a colour that is not easily perceived by insects; (2) are frequently pendulous, which makes them easier for birds than insects to access; (3) often have a long tube, which allows long-billed nectarivorous birds to reach the nectar while keeping away most other visitors (CRONK & OJEDA, 2008). Flowers of *S. longiflorum* are remarkably similar in shape and coloration to those of *Pycnandra longiflora* (Benth.) Munzinger & Swenson, another *Sapotaceae* from New Caledonia that is believed to be ornithophilous (MUNZINGER & SWENSON, 2016). They also resemble in the same way those of *Desfontainia spinosa* Ruiz & Pav. (*Columelliaceae*) from Central and South America or *Epacris longiflora* Cav. (*Ericaceae*) from Australia, both of which are well-known examples of bird pollination (e.g. WERTH, 1915). Ornithophily has evolved in many families of flowering plants, but is unusual in *Sapotaceae*, whose species have mostly small white or green flowers that are presumably entomogamous. As far as we know there are no previous records of ornithophily among African or Neotropical

<table><caption>Table 1. - Morphological comparison between *Synsepalum longiflorum* *Nzoyeuem*, O. Lachenaud & Sonké, *S. muelleri* (Kupicha) T.D. Penn. and *S. subverticillatum* (E.A. Bruce) T.D. Penn. Characters diagnostic for one species are in bold.</caption><thead><tr><th></th><th>S. longiflorum</th><th>S. muelleri</th><th>S. subverticillatum</th></tr></thead><tbody><tr><td>Leaf base</td><td>acute to obtuse</td><td>attenuate</td><td>attenuate</td></tr><tr><td>Leaf apex</td><td>obtuse to rounded or emarginate</td><td>acuminate</td><td>acuminate to rounded</td></tr><tr><td>Pedicel length [mm]</td><td>4-13</td><td>not or hardly distinct (to 1 in fruit)</td><td>not or hardly distinct</td></tr><tr><td>Corolla colour</td><td>red with yellow apex</td><td>white</td><td>white</td></tr><tr><td>Corolla tube length [mm]</td><td>20-42</td><td>c. 7</td><td>c. 2</td></tr><tr><td>Corolla lobes</td><td>triangular, much shorter than tube</td><td>triangular, much shorter than tube</td><td>oblong, much longer than tube</td></tr><tr><td>Anthers</td><td>reflexed</td><td>erect</td><td>reflexed</td></tr><tr><td>Style</td><td>shortly exserted</td><td>shortly exserted</td><td>far exceeding corolla tube</td></tr><tr><td>Distribution</td><td>Cameroon</td><td>Malawi, Mozambique</td><td>Kenya</td></tr></tbody></table>
*Sapotaceae*. MOMOSE et al. (1998) reported bird pollination in some Malaysian species of *Palaquium* Blanco and *Madhuca* J.F. Gmel., but these have white flowers of a campanulate or cupular shape, and their pollination syndrome is probably less specialised. It is hoped that monitoring the phenology of *Synsepalum longiflorum* will help identify its pollinator, and understand why the plants bear many flowers and so few fruits; it is not clear whether this is due to the rarity of pollination or pollinator, to frequent damage done to the ovaries by birds' bills, which is a frequent phenomenon in bird-pollinated species (CRONK & OJEDA, 2008), or to the plant lacking enough resources for fruit development.

## Acknowledgements

The expeditions that led to the discovery of this new species were conducted within the framework of the Memorandum of Understanding between the Institut de Recherche pour le Développement (IRD), the Plant Systematics and Ecology Laboratory (Higher Teachers’ Training College, University of Yaoundé I), Biotope, and the Missouri Botanical Garden (MBG) with financial support of EDF-Cameroon (which has since become Kikot Hydro-Power Company). We would like to express our gratitude to Charles Bodel, Antoinette Kiboum (Kikot Hydro-Power Company), Frederick Jacob (EDF France) and to Pierre Couteron (IRD) for their logistical support during field missions. Special thanks are due to Désiré Ntamack and to the additional collectors who assisted us in the field, especially Imma Tcheferi, Thomas Medou and Amstrong Elisé Demanou. We are also grateful to Tariq Stévart and Ehoarn Bidault (MBG) for their logistical organization of the first author’s visit to BRLU. Finally, we thank Laurent Gautier and Joel Calvo for their comments on a first version of the paper.

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