Raphia zamiana Mogue, Sonke & Couvreur, 2018

Kamga, Suzanne Mogue, Niangadouma, Raoul, Stauffer, Fred W., Bonaventure Sonke, & Couvreur, Thomas L. P., 2018, Two new species of Raphia (Palmae / Arecaceae) from Cameroon and Gabon, PhytoKeys 111, pp. 17-30 : 19-24

Raphia zamiana Mogue, Sonke & Couvreur sp. nov. Figures 4 , 5

Type.

Cameroon: South Region: Vallée du Ntem, Nseng avion forest, Fondation agricole Samuel Menye, 1.5 km from Ma’an in the direction of the Ntem river, 2.34805N, 10.63054E, 513 m a.s.l., 25 February 2018, Mogue K. S. 44 (holotype: WAG; isotypes: K, YA).

Diagnosis.

Raphia zamiana is morphologically most similar to R. monbuttorum in their clustering habitat and straight fibres covering the trunk. Raphia zamiana differs from R. monbuttorum by the size of its stout and stiff rachillae with apical second order rachillae measuring 1 cm in diameter versus less than 1 cm in R. monbuttorum . The inflorescences of R. zamiana are pendulous even from the early stage of development as opposed to the semi obtuse erect position in R. monbuttorum .

Description.

Stem 3-8 m tall, 30-40 cm in diameter, clustering; dead leaf sheaths persistent, trunk hidden in dead leaves and fibres; fibres formed through disintegration of the leaf sheath, ca. 1 cm in diameter, straight with pointed tips, brown to black. Leaves 10-12, 12-21 m long in total, horizontal and then arched downwards towards apex; sheath 90-150 cm long, channelled, smooth, margin fibrous, orange-yellow, spotted with black, white and or grey dots; petiole 4-11 m long, 5-35 cm in diameter towards the base, channelled basally and elliptic apically, smooth, green, spotted with dark and grey; rachis 7-13 m long, 10-11 cm in diameter, elliptic basally and keeled towards the apex, smooth abaxially, spiny adaxially (spines on keel), light green to green; pinnae 147-268 per side, irregularly arranged in 4 planes, arching downwards towards the apex, pinnae adaxial surface green, abaxial surface waxy green; extreme basal pinnae 0.80-1.26 m long, 7-30 mm wide, filiform, middle pinnae 1.50-1.90 m long, 5-9 cm wide, linear, apical pinnae 20-72 cm long, 1.5-3.6 cm wide, linear, midrib prominent adaxially, spines along pinnae midrib and margins, brown to black. Leaves subtending inflorescence reduced (1.20-1.40 m long).

Inflorescences 3 or 4, pendulous, 1.55-2.80 m long in total, 17-44 cm (mature) in diameter at base (including rachillae); young inflorescences light green to purple green, older ones light brown to grey-brown. prophyll 18-20 cm long, 13.7 cm diameter, tubular, bearing 2 keels merging to form a pointed beak; peduncle 26-30 cm long, 10-13.5 cm diameter, dorsi-ventrally compressed, smooth; penduncular bracts several, tubular, with triangular apices, smooth, dark brown abaxially; rachis 1.25-2.60 m long, bearing numerous bracts rarely empty, 50-70 first order rachillae, raphiate shape, dorsi-ventrally compressed, alternating in 2 rows on each side of the rachis, smooth; prophyllar bract found at the base of first order rachillae, tubular, bearing 2 keels at the sides, smooth; basal first order rachillae 0.54-1.05 m long, 4.5-7 cm in diameter excluding rachillae, ca. 14 cm in diameter including rachillae, bud flattened; prophyllar bract bearing 2 keels on both sides, subsequent bracts bearing flowers, rarely empty; second order rachillae 48-65, basal second order rachillae 23-35 cm long, 2-2.5 cm in diameter; middle second order rachillae 15-27 cm long, 2 cm in diameter; apical second order rachillae 9.5-15 cm long, 1.5-1.6 cm in diameter, dorsi-ventrally compressed, alternating in 2 rows on each side of first order rachillae, bud flattened, smooth; middle first order rachillae 39-45 cm long, 3-4 cm in diameter excluding rachillae, 12 cm in diameter including second order rachillae, bud flattened; prophyllar bract at the base bearing 2 keels on both sides, subsequent bracts bearing flowers rarely empty; second order rachillae 32-50, basal second order rachillae 16 cm long, 1.5 cm in diameter, middle second order rachillae 13 cm long, 1.2 cm in diameter; apical second order rachillae ca. 10 cm long, ca. 1 cm in diameter, dorsi-ventrally compressed, alternating in 2 rows on each side of first order rachillae, bud flattened, smooth; apical first order rachillae 25-27 cm long, ca. 2.5 cm in diameter excluding rachillae, 12 cm in diameter including second order rachillae, bud flattened; prophyllar bract at the base bearing 2 keels on both sides; second order rachillae 12-30, basal second order rachillae ca. 10 cm long, ca. 1 cm in diameter; middle second order rachillae ca. 8 cm long, 1 cm in diameter; apical second order rachillae ca. 6 cm long, ca. 1 cm in diameter, dorsi-ventrally compressed, alternating in 2 rows on each side of first order rachillae, bud flattened, smooth; second order rachillae sometimes three times the usual size (more than 25 cm long, 2.5cm wide at the apex). Inflorescence bud ca. 5 cm long, ca. 1.2 cm wide, buds of basal and medial first order rachillae sometimes elongated. Flowers solitary, exerted, inserted in two rows on each side of second order rachillae, staminate flowers distal, pistillate flowers basal. Staminate flower 13-18.5 mm long, 7.5-11.5 mm wide, stalk ca. 1 mm long; subtending bracteole 4.5-13.5 mm long, 7-11.5 mm wide, tubular, bicarinate, margins entire, smooth, with a conspicuous wide apical slit on one side, displaying conspicuous longitudinal veins on the outer side, bracteole completely covering the calyx; calyx 5-11.5 mm long, 5-7 mm wide, fused>2/3 of its length, tubular, bearing 2 or 3 shallow lobes, margins entire to slightly rough, smooth; conspicuous longitudinal veins on outer side; corolla 3, 8.5 –15(– 20) mm long, 4-6 mm wide, basally connate for 1/3 of their length, oblong, apex slightly blunt to acuminate, margins entire, smooth, stiff, displaying a conspicuous longitudinal venation on the inner side; stamens 11-18, filaments 1 –4(– 6) mm long, 1-1.7 mm wide, free, basally adnate to the petals for 1-2 mm, cream white to pale pink; anthers 4-8.8 mm long, 1-1.5 mm wide, sagittate-elongate, medifixed, pale yellow; pistillode absent. Pistillate flowers 15-25 mm long, 10-13 mm wide; outer subtending bracteole 12-19 mm long, 10-13 mm wide, tubular, bicarinate, margins entire, with one wide apical slit, smooth; inner subtending bracteole 5-9 mm long, tubular, margins entire, one side longer, smooth, sometimes tearing; calyx 8.5-16 mm long, fused>2/3 of its length, tubular, 3 shallow lobes or the latter rarely absent, margins entire, smooth, with longitudinal veins conspicuous on both sides; corolla 5-8 mm long, fused, 3 lobes with margins serrated, lobes sometimes slightly acuminate, margins entire, smooth, conspicuous longitudinal veins; staminodial ring with 17-19 fused staminodes, 2-5 mm long, adnate to petals for 1-4 mm; anthers sagittate, 0.5-1 mm long; gynoecium 11-18 mm long, 5-6 mm wide, ovary 9-12 mm, 5-6 mm wide, ovate to oblong, completely covered with scales, developing at ¾ height of the gynoecium, larger scales at mid portion to base; style absent or very short; stigma ca. 1 mm long, papillae not observed but hair-like prolongations present on stigma. Fruits 4-8.7 cm long, 3.5-4.7 cm wide, beak 0.5-0.9 cm long; oblong, scales arranged in 11 or 12 rows, length of scale 16-20 mm, width of scale 15-20 mm, diamond shaped, apex texture rough, shallowly furrowed, green, beak pointed, inflated in the middle; mesocarp yellow when young, orange yellow when mature; seed 1, oblong, with ruminations.

Ecology.

Raphia zamiana is an Atlantic central African rain forest species, endemic to lower Guinea. It appears to have a wide ecological amplitude, growing in rain forest swamps on periodically inundated soils, in coastal forests on inundated sandy soils or in open vegetation like savannahs associated with inundated soils (e.g. Lope National Park, Gabon, Figs 3 , 5C ). It is generally abundant forming large dense almost mono-dominant stands. It has been recorded growing sympatrically with R. hookeri and S. mannii .

Distribution.

Lower Guinea subcentre of endemism ( White 1979). Raphia zamiana occurs in southern Cameroon (Central and South regions) and western Gabon. It is probably also common in Equatorial Guinea although no collections have been made yet. Altitude: 0-700 m (Fig. 3 ).

Preliminary conservation status.

Least Concern. The extent of occurrence of Raphia zamiana is estimated to be 128,243,063 km2 (far exceeding the 20,000 km2 upper limit for Vulnerable status under criterion B1) and the area of occupancy is estimated to be 36,000 km2 (far exceeding the 2,000 km2 upper limit for Vulnerable status under criterion B2). Moreover, this species is known from 9 locations, the upper limit for sub criterion a- of criterion B2 for the Vulnerable status. However, Raphia zamiana is a widespread and common species in its area of occurrence. It is very common along road sides and is abundant growing in dense colonies. To date, it has not been collected within a protected area, but populations were seen in Campo National Park (Cameroon). Incredibly, its first collection dates to 2012. Botanists might have confused it with the well-known and widespread species Raphia hookeri (although both species are very different in their morphology). Given that collecting Raphias is a hard task because of their massive stature ( Dransfield 1986), it was simply omitted. Populations are affected by road building and the drying of swamps for bridges, but these only impact a small number of individuals. Raphia zamiana is therefore assigned a preliminary status of LC, joining most continental African palm species ( Cosiaux et al. 2018).

Etymology.

The name of this species is derived from its vernacular name in Beti (south Cameroon, north Gabon): Zam.

Uses.

This palm is massive thus providing large amounts of thatching material. Its petiole and rachis commonly referred to as ‘bamboo’ are used for house construction, beds, chairs, baskets and mats. These are generally sold along the roads in south Cameroon. In Gabon, its fruits are sold in markets. These are boiled and said to cure hypertension and diabetes. Finally, this species is also used for wine tapping and as a source of grubs.

Vernacular names.

Zam (Beti).

Notes.

Raphia zamiana belongs to the raphiate section ( Otedoh 1982). It closely resembles R. monbuttorum Drude and R. laurentii De Wild. in the morphology of their trunks being clustered and covered with straight fibres. However, it is very distinct by having a pendulous inflorescence bearing stout, stiff and straight rachillae. The inflorescences of R. monbuttorum and R. laurentii usually hang at an obtuse angle especially during the young stages of development, becoming pendulous only when brought down by the weight of fruits. Young, recently developing inflorescences are grey-blue turning green later on.

Raphia zamiana is a very conspicuous palm in southern Cameroon and eastern Gabon, being common along roads and in swamps. In addition, we report several important uses, being one of the most useful Raphias (Mogue, personal observation). However, up to now, it remained uncollected, stressing once again that new species well known to local people have yet to be scientifically discovered and described. A similar situation was recorded for the Vietnamese endemic palm Licuala centralis ( Henderson et al. 2008). This palm was well known and used to make local hats, but was only scientifically described in 2008.

Additional specimen examined.

Cameroon. Central Region. near Ebolbom village, 3 km east of Ngoumou, 2 km northwest of Otélé, 3.599720N, 11.287700E, 700 m a.s.l., 2 May 2013, Couvreur T.L.P. 427 (WAG, YA). South Region: Mvila, Biyeyem, 2.514020N, 11.081930E, 573 m a.s.l., 19 Sep 2015, Mogue K.S. 15, (WAG, YA); Mvila, Biyeyem, 2.514020N, 11.081930E, 573 m a.s.l., 19 Sep 2015, Mogue K.S. 16 (WAG, YA); mountain chain Ngovoyang, 1.5 km in forest from Bikiliki village situated between Bipindi and Lolodorf, 3.181570N, 10.536960E, 460 m a.s.l., 17 Feb 2012, Couvreur, T.L.P.392 (WAG, YA); About 20 km N from Kribi, 3 km N of Longji, N7 road towards Edea, 3.146810N, 9.959510E, 0 m a.s.l., 27 Feb 2018, Mogue K.S. 45 (WAG, YA).

Gabon. Woleu-Ntem: Oyem, 2-3 km from main road in the direction of Konosoville, 01.59849N, 011.62298E, 651 m a.s.l., 12 Nov 2015, Mogue K.S. 17 (LBV, WAG, YA); Ogooué-Ivindo: 180 km on main road from Lastoursville to Lopé, 0.147300S, 11.726011E, 280 m a.s.l., 9 Jun 2016, Couvreur T.L.P. 1122 (LBV,WAG, YA). Ogooué-Maritime: Lagune de Fernan Vaz. Koundakoua, 1.4487220S, 9.2066110E, 3 m a.s.l., 20 Nov 2016, Bidault E. 2722 (BR, BRLU, LBV, MO, P, WAG). Ngounié: Mouila, 19 km from national road, 2.254280S, 11.142840E, 133 m a.s.l., 20 Nov 2015, Mogue K.S. 24 (LBV, WAG, YA).

Figures

Figure 3. Distribution of Raphia gabonica and R. zamiana.

Figure 4. Raphia zamiana, illustrations. A Habit in savannah B Habitat in forest, trunk not visible C Detail of the trunk, with inflorescences and straight fibres D Inflorescence E Partial inflorescence, young F Detail of rachillae G Detail of basal part of 2 nd order rachillae, showing small rachillae bracts encircling young flowers H Detail of partial inflorescence (x 5) I Female flower x 5 J Female inner bract x 5 K Female calyx x 5 L Female corolla x 5 M Detail of staminodial ring and staminodes N Male flower x 5 O Male calyx x 5 P Male corolla x 5 Q male stamens x 6 R Detail of stamen of male flower x 12 S Infructescence T Fruit, longitudinal section. Drawings based on: A Couvreur 1122 B-D, S, T Mogue; 17 E-R Mogue 44. Drawings by Hans de Vries.

Figure 5. Raphia zamiana. A Habitat along the road, with Raoul Niangadouma for scale (Oyem, Gabon) B Close-up of pendulous and " raphiate " type partial inflorescence (coastal forests near Kribi, Cameroon) C Habitat in the savannahs of Lope National Park, Gabon D Habitat in swamp (Ma'an, Cameroon). Photos: Thomas L. P. Couvreur.