Secamone goyderi Klack., 2001

Klackenberg, Jens, 2001, Notes on Secamonoideae (Apocynaceae) in Africa, Adansonia (3) 23 (2), pp. 317-335 : 330-334

3. Secamone goyderi Klack. , sp. nov.

Species haec Secamone brevipes affinis lobis coronae dorsiventraliter aplanatis et praesertim cum S. letouzeana congruens epidermide folii subtus tuberculata et pubiscentibus sed differt ab duabus tubo corollae calyce distincte longiore; praeterea ab illa stigmate breviore et ab hac tubo corollae pubescenti differt.

TYPUS. — Thomas & Wilks 6592, Gabon, Moyen- Ogooué region , between Ndjale town and railway station, 35 m alt., 22 July 1986 (holo-, MO!).

Suffrutescent twiner; branches covered with short appressed, retrorse, reddish hairs. Leaf blade 7-9 × 3.5-4.5 cm, elliptic to broadly elliptic to somewhat obovate, cuneate at the base, shortly acuminate at the apex, somewhat coriaceous; indumentum of short reddish appressed hairs, sparse above but denser and more distinctly visible in contrast to the glaucous lower finely papillate epidermis below; venation pinnate, looped with straight parallel divaricate to almost rightangled veins; midrib when dry impressed above, distinctly raised below; petiole 5-12 mm long, with appressed reddish hairs.

Inflorescences extra-axillary, shorter than the adjacent leaves; cyme rather dense and manyflowered, basically dichasial but with internodes of different lengths and sometimes almost suppressed, pubescent; internodes up to 1 cm long; pedicels 2-4 mm long; bracts triangular, less than 1 mm long. Calyx without surrounding bracts; lobes much shorter than the corolla tube, c. 1.3 × 0.9 mm, triangular, acute at the apex, with dense reddish hairs outside. Corolla obpyriform in bud with rounded apex, fused for c. 2/5 of its length into a tube, contorted with the left lobe-margins overlying, not to slightly twisted to the right, with appressed reddish hairs outside and tube with short hairs inside, yellow to creamy; tube campanulate and furnished with shallow pouches, c. 1.7 mm long; lobes probably recurved, c. 2.7 × 1.3 mm, oblong, truncate at the apex; corolline corona insignificant. Staminal column c. 1.6 mm high. Staminal corona present; lobes dorsiventrally flattened, c. 1.2 mm long, narrowly rectangular and slightly broadened at base of free part, with narrow basal part, straight, longer than the staminal column, attached along at least 1/2 of the stamen. Pollinia c. 0.2 mm long. Style head slightly projecting above the corona lobes; apical portion slightly longer than the basal portion, c. 1.3 mm long, slightly broadened below the apex, entire.

Follicles not seen. — Figs. 5 , 6 (map).

The description of the flower is based on the type only.

DISTRIBUTION AND HABITAT. — Secamone goyderi is distributed in the central part of the tropical African rain forest area in Congo- Brazzaville and Gabon. It is known from low elevation, up to 550 m, in secondary scrub forest. Flowering specimens seen from May to August and November .

NOTES. — Secamone goyderi is sympatric with S. brevipes and S. letouzeana , although it seems to be restricted to elevations below 600 m while S. letouzeana grows higher up. It differs from S. brevipes by its long corolla tube, being much longer than the calyx. On the contrary, the style head being long and projecting about twice as long as the staminal column in S. brevipes , is short and hardly projecting in S. goyderi . Vegetatively the new species differs by having leaves with a pale and tuberculate/papillate lower epidermis covered with reddish hairs. In this character it is similar to S. letouzeana , which, however, has deepy cleft corolla with a completely glabrous tube. In S. goyderi the corolla tube is hairy inside.

This species is named after David GOYDER, Kew, who has analysed African Asclepiadaceae for many years with a special interest in Secamonoideae , but was kind enough to leave a few taxa to me to study.

PARATYPES. — CONGO- BRAZZAVILLE: Farron 4610, 4 km SW Grand-Bois, 1965 ( P) ; de Nere 503, région de Boko, plateau des Cataractes , 1963 ( P) . — GABON: Le Testu 8100, Lastoursville , Poubi, 1930 ( P) ; Le Testu 8860, ibid., Djoconamoye , 1931 ( P) ; Louis, Breteler & de Bruijn 934, massif du Claillu, along road Mimongo to Koulamoutou , between Dibandi and Diyanga, 20- 30 km NE of Mimongo, c. 550 m, 1983 ( P) .

4. Secamone letouzeana (H. Huber) Klack. , comb. nov.

Toxocarpus letouzeanus H. Huber, Bull. Mus. Hist. Nat., B, Adansonia 11: 447 (1989). — Type: de Wilde & de Wilde-Duyfjes 1695, Cameroon, N’Kolbisson, c. 8 km W of Yaoundé , c. 700 m alt., 1964 (holo-, P!; iso-, MO!, YA).

Suffrutescent twiner; branches covered with short appressed, retrorse, reddish hairs. Leaf blade 7-9 × 2-2.7 cm, narrowly ovate to elliptic, cuneate to almost truncate at the base, acuminate at the apex; indumentum of short whitish appressed hairs, sparse and glabrescent above but denser on a glaucous lower finely papillate epidermis below; venation pinnate, looped with straight parallel divaricate to almost right-angled veins; midrib when dry impressed above, distinctly raised below; petiole 4-8 mm long, with dense short appressed hairs.

Inflorescences extra-axillary, shorter than the adjacent leaves; cyme rather lax and manyflowered, basically dichasial but with internodes of different lengths and sometimes almost suppressed, pubescent; internodes up to 1.5 cm long; pedicels 2-3 mm long; bracts triangular, c. 0.5 mm long. Calyx without surrounding bracts; lobes shorter than the corolla tube, 0.6- 0.8 × 0.3-0.7 mm, narrowly oblong to triangu- lar, acute to obtuse at the apex, with dense reddish hairs outside. Corolla cylindric in bud with subacute apex, fused for 1/6-1/4 of its length into a tube, contorted with the left lobe-margins overlying, twisted to the right, with few reddish hairs outside, glabrous inside, white to yellowish to greenish cream, sweet-scented; tube urceolate and furnished with small pouches that slightly protrude between the calyx lobes, 0.6- 1.2 mm long; lobes probably erecto-patent, 3.3- 4.7 × 0.5-0.9 mm, narrowly oblong, rounded to truncate at the apex; corolline corona lacking. Staminal column 0.6-0.8 mm high. Staminal corona present; lobes dorsiventrally flattened, 0.3-0.6 mm long, rather narrow but broader near the base jutting out into the cavities of the corolla tube, straight, shorter to longer than the staminal column, attached at lower part of the stamen. Pollinia 0.05-0.1 mm long. Style head distinctly projecting above the staminal column; apical portion about 1.5 to almost 2 times as long as the basal portion, 0.5- 0.7 mm long, not to only slightly broadened at the apex, entire.

Follicles not seen. — Figs. 2 (map), 7.

DISTRIBUTION AND HABITAT. — Secamone letouzeana is distributed in the central part of the tropical African rain forest area between Cameroon and northern Congo-Kinshasa. It is known from 600-1300 m altitude and grows at road cut and in marshy places. Flowering specimens seen from January, March and July .

NOTES. — This species has strikingly delicate flowers. For diagnostic characters, see Secamone goyderi .

MATERIAL STUDIED. — CAMEROON: Jacques-Félix 2591, Bangangté, 1300 m, 1938 ( P); Breteler 941, Forest along river Sanaga near Goyoum, 20 km West of Deng Deng, 635 m, 1961 ( P); de Wilde & de Wilde- Duyfjes 1695, N’Kolbisson, c. 8 km W of Yaoundé, c. 700 m, 1964 ( P, MO). — CENTRAL AFRICAN REPUBLIC: Tisserant 1399, plateau de l’Oubangui, région de Bambari, 50 km E Bambari, 1924 ( P). — CONGO- KINSHASA: Breyne 919, Maluku, 1970 ( BR, MO, K); Breyne 3065, Maluku, 1976 ( BR); Pauwels 4878, Terr. Maluku, au-delà de la Nsele, 1965 ( BR, MO); Pauwels 5283, Terr. Maluku, rivière Nsele, 1975 ( BR, MO). — GABON: Le Testu s.n., Haut-

Ogooué, 21 mar. 1930 ( MO) ; Ollerton 76, c. 15 km W of Lope on main road, 1997 ( K) ; Reitsma, Wilks & Nzebi 3398, c. 20 km NW of Booué, Mt. de Casque , 1987 ( K) .

Figures

Fig. 5. — Secamone goyderi: A, habit; B, flower in bud; C, flower; D, flower with two corolla lobes removed; E, portion of corolla from within; F, gynostegium; G, gynostegium with one anther removed; H, anther, lateral view; I, pollinaria; J, stigma head; K, magnification of lower leaf surface. (A-K, Thomas & Wilks 6592). — Drawn by P. von KNORRING.

Fig. 6. — Distribution of Secamone goyderi.