Corresponding author: Thomas L.P. Couvreur (
Academic editor: Pavel Stoev
A distinctive new monotypic genus from Gabon is described in the tropical plant family
Un nouveau genre monotypique du Gabon est décrit dans la famille tropicale des
Couvreur TLP, Niangadouma R, Sonké B, Sauquet H (2015)
The Central African country of Gabon is merely 270 000 km² in size, but is home to an incredible botanical diversity (
A probable new genus of
Herbarium, alcohol and photographic materials were used to produce the descriptions. In order to identify other specimens of this new genus, we looked at all undetermined
A preliminary phylogenetic analysis indicated that the new taxon was nested in tribe
DNA extractions of silicagel-dried leaf samples from two individuals of
Maximum Parsimony (MP) analyses were performed using PAUP* (version 4.10b;
Maximum likelihood analyses were conducted using RAxML version 7.2.7 (
All Genbank numbers used can be found in
Both markers represented 2669 total characters, 187 of which were excluded because of ambiguity in the alignment and 407 (16.5%) were parsimony informative. Both MP and ML phylogenetic analyses led to the same topology, with similar levels of support (Fig.
Genus with
Small trees with distichous, simple pinnately veined leaves with an entire margin and reticulate third-order venation. Species androdioecious (?) (flowers unisexual staminate or bisexual). Inflorescences one to three-flowered, axillary on old branches or at base of trunk, with one to three short sympodial rachilla. Flowers actinomorphic. Perianth of 9 free tepals in 3 alternate, valvate whorls of 3 each, differentiated in outer tepals (sepals) and middle and inner tepals (petals). Petals similar (subequal in length), spreading horizontally or reflexed at anthesis. Stamens 16-19, free, basifixed with a very short filament. Anthers introrse, probably opening by two longitudinal slits, connectives tongue shaped, yellow. Carpel one, densely pubescent, stigma cylindrical coiled, ovules 7–10, uniseriate. Monocarp sessile, cylindrical densely pubescent.
A single species only known to Gabon (Fig.
We dedicate this new genus to Sir David Attenborough, British broadcaster and naturalist, in honor of his lifelong dedication to nature, conservation, evolution and natural history programs. His passion for nature have influenced and inspired a generation of biologists and naturalists, including the first and senior authors of this paper.
Maximum likelihood tree with support values indicated on branches (ML bootstrap above; MP bootstrap below). Flower morphology of the genera in the
Distribution map of
Gabon, Estuaire, Monts de Cristal, near first bridge after Kinguele,
Tree 4–6 m tall, 2 to 4 cm in diameter at breast hight (d.b.h.), bark dark brown with patches of green, old branches black, glabrous, young branches black, sometimes pubescent. Leaves distichous, simple, entire, pinnately veined. Petiole 3–4 mm long, 2–3 mm in diameter, glabrous or sparsely pubescent when young, slightly grooved on top, leaf lamina inserted on top. Lamina 20–26 cm long, 4.5 to 9 cm wide, length:width ratio 2.5 to 4.5, narrowly elliptic to elliptic to narrowly ovate to ovate, apex long acuminate, acumen 2–3 cm long, base obtuse, coriaceous, young sparsely pubescent to glabrous above, glabrous below, old leaves glabrous above and below, mid rib sunken above, sparsely pubescent when young below, glabrous above, glabrous above and below when old, secondary veins 9–12 pairs. Inflorescences axillary, on old branches and cauliflorous towards the base of the trunk. Sympodial rachis up to 6 mm long, but sometimes up to 1.5 cm long, densely covered with short appressed hairs, with 0–10 minute densely packed lower bracts densely pubescent brown. Flowering pedicels 2 to 10 mm long, densely covered with short appressed hairs, red, upper bract inserted at base or up to ½ of pedicel, covered with short appressed hairs, red. Flowers actinomorphic, bisexual or unisexual staminate (androdioecious), with 9 tepals in total, differentiated in one whorl of 3 sepals and 2 whorls of 3 petals, all alternate. Sepals 2–3 mm long, 1.5–2 mm wide, length:width ratio 1.5, ovate, valvate, apex acute, base truncate, densely covered with short appressed hairs outside, glabrous inside, red. Outer petals 4–10 mm long, 2.5 to 5 mm wide, length:width ratio 2 to 2.5, elliptic, apex acute, base truncate, densely pubescent with appressed hairs outside, densely pubescent with short tomentose hairs inside, deep red. Inner petals 4–9 mm long, 2–4 mm wide, length:width ratio=2 to 2.5, elliptic, apex acute, base truncate, densely pubescent with short tomentose hairs outside, densely pubescent with short tomentose hairs inside along margins, glabrous towards center, deep red. Petals spreading horizontally or recurving backwards at anthesis. In staminate and bisexual flowers, stamens 16–19, 3–4 mm long, outer ones shorter than inner ones, filament shorter than 0.2 mm, narrow, connective umbonate (tongue shaped), glabrous, bright yellow. Anthers introrse, probably opening by two longitudinal slits. In bisexual flowers, carpel one, 4–5 mm long, ca. 1 mm wide, densely pubescent with silvery long appressed hairs, ovules uniseriate, 7–10, stigma cylindrical coiled, 2–3 mm long, sparsely pubescent towards the top, white cream. Mature fruits not seen, young fruiting pedicel 6 mm long, densely pubescent with appressed hairs. Young monocarp cylindrical, densely pubescent with silvery appressed hairs. Seeds not seen. (Figs
Flowers collected in April and November, young fruits collected in November.
Endangered [EN B1ac]. Two localities in Gabon are known for this species: Monts de Cristal N.P. and south of the Ivindo N.P. The population found in Kinguele (Monts de Cristal) was close to the road and several (around 10) individuals were seen. We also looked for this species in other parts of the Park (around Tchimbélé) and did not see it again. The herbarium specimen collected from Ivindo indicates “en peuplement” (in population) suggesting that several individuals were seen. However, the coordinates on the herbarium sheet place this collection outside the national park. The Area of occupancy (AOO) is 12,000 km² and the Extent of occurrence (EOO) is 6.2 km², suggesting a very restricted overall distribution. We thus suggest a status of endangered given that only a handful of individuals have been seen and that these populations are quite close to disturbances.
The species name epiteth highlights the striking resemblance with flowers of some species of
The androdioecious nature of
Gabon:
Illustration of
Morphological characters of the six genera found in tribe
Genus |
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Character | |||||||
Species diversity/distribution | 8 / West and Central Africa, 1 species in East Africa | 2 / West and Central Africa | 1 / Tanzania | 1 /Gabon | 1 / Central Africa | ~14 / Central and West Africa | 8 / West and Central Africa, 2 species in East Africa |
Tertiary venation | intermediate | reticulate | intermediate | reticulate | parallel | parallel | parallel |
Inflorescence position | terminal | terminal | axillary | axillary, cauliflorous | axillary | axillary, cauliflorous | axillary, cauliflorous |
Sex distribution | bisexual | androdioecious | bisexual (?) | androdioecious (?) | bisexual | bisexual | androdioecious |
Sepal aestivation | valvate | imbricate | imbricate | valvate | valvate | valvate | valvate |
Petal number | 3 | 6 | 6 | 6 | 6 | 6 | 6 |
Petal disposition | Upright, appressed forming a pollination chamber | Spreading horizontally, no pollination chamber | Outer petals recurved backwards, inner petals erect upwards, no pollination chamber | Recurving backwards to spreading horizontally, no pollination chamber | Pendulous, no pollination chamber | Upright, appressed forming a pollination chamber | Outer petals recurved backwards or erect upwards, inner petals erect upwards, pollination chamber possible |
Petal relative length | outer absent | outer=inner | outer=inner | outer=inner | outer<inner | outer<inner | outer=inner |
Torus (stamen portion) | flat/conical | flat/conical | short cylindrical | short cylindrical | short cylindrical | short cylindrical | short cylindrical |
Torus (carpel portion) | flat/convex | flat/convex | concave | concave | concave | concave | concave |
Apex of connective | discoid/tongue-shaped | discoid/tongue-shaped | discoid | discoid/tongue-shaped | discoid | discoid | discoid |
Nr of carpels | numerous | 13–20 | 4 | 1 | 4 | 3–14 | 2–20 |
Number of ovules per carpel | 1 | 2 | 5–8 | 7 | ~ 18 | 6–10 | 20–30 |
Ovule arrangement | basal | 1-seriate lateral | 1-seriate lateral | 1-seriate lateral | 2-seriate | 2 or 1-seriate lateral | 2-seriate lateral |
Monocarps | stipitate | stipitate | sessile | sessile | sessile | sessile | sessile |
The molecular phylogenetic analyses presented here confirms that
We suggest that the morphological differences outlined above are sufficient to erect a new species for
Table
– Inflorescence position: Within
– Monocarp base: Another synapomorphy for the SMPP clade is the sessile monocarps. In contrast,
Other characters appear to have little taxonomic use but are interesting as they underline the important floral morphological variability within
– Androdioecy in
–
The closest relative to
Though the flower has all the structural characters of a typical
Reflexed petals. Most buzz pollinated flowers show strongly reflexed petals exposing the stamens and the carpels. Reflexed petals are quite common in
Stamens: The stamens of
Anthers. In typical buzz pollinated flowers, the anthers generally have apical pores or short slits that release the pollen grains during vibration. However, non-poricidal anthers have also been linked with buzz pollination in a number of other genera (
Long stigma. The conspicuous stigma sticking out of the stamens in
Isabelle Morlais and the OCEAC lab members are thanked for allowing us to undertake the DNA extractions and PCR amplifications of the material. Adama Faye is thanked for his assistance in the lab. Richard Saunders and one anonymous reviewer are thanked for detailed comments on the MS. We are also grateful to the Centre National de la Recherche Scientifique et Technique (CENAREST) in Gabon and the Agence National des Parques Nationaux (ANPN) for delivering the necessary research permits. Jan Wieringa is thanked for help with both the genus and epithet names. Hans de Vries is kindly thanked for his botanical illustration of