Mendoncia combretoides (A. Chev.) Benoist, Notul. Syst.

Magnaghi, Emily B. & Daniel, Thomas F., 2017, Systematics of Mendoncia (Acanthaceae: Thunbergioideae) in the Paleotropics, Proceedings of the California Academy of Sciences 64 (3), pp. 37-94 : 54-56

1. Mendoncia combretoides (A. Chev.) Benoist, Notul. Syst. (Paris) 11:143. 1944.

Thunbergia combretoides A. Chev., Explor. Bot. Afrique Occ. Franç. 1:490. 1920.

TYPE.— IVORY COAST. Bas Sassandra: bassin du Cavally , pays des Tépos , village de Grabo , [ca. 04°55ʹ02.14ʺN, 007°29ʹ35.69ʺW], 4 Aug 1907, Chevalier 19745 (lectotype, designated here: P-00435313 -photo!; isolectotypes: P-00435314 !, P-00435315 -photo!).

Young stems evenly and densely pubescent with yellowish- to golden-brown, mostly branched (sometimes also with some unbranched and antrorse) trichomes 0.2– 1 mm long, trichomes of internodes soon becoming sparse to nearly glabrous. Leaves subcoriaceous to coriaceous, petioles to 25.4 mm long, pubescent with cauline type trichomes, blades ovate to elliptic to obovate-elliptic, 44–133 mm long, 23–86 mm wide, rounded to truncate to subcordate at base, acuminate to acute-apiculate to rounded to slightly emarginate at apex, abaxial surface pubescent with scattered, branched trichomes 0.2– 0.4 mm long, trichomes often restricted to major veins, adaxial surface glabrous to sparsely pubescent with branched trichomes 0.2– 0.4 mm long and unbranched, antrorsely appressed trichomes to 1 mm long, trichomes usually restricted to midvein. Inflorescences borne in leaf axils on young, mostly herbaceous and leafy stems, solitary or opposite at nodes, dichasia 1–4 (–6) per axil, peduncles to 23 mm long, pubescent like young stems. Bracteoles yellowish brown to pale green, mostly persistent in fruit, elliptic to ovate-elliptic, 15–21 mm long, 7–13 mm wide, rounded at base, acute-apiculate at apex, abaxial surfaces densely pubescent with cauline type trichomes (sometimes becoming sparse to nearly absent on older bracteoles), adaxial surface glabrous or mealy-glandular. Calyx mealy-glandular and sometimes with sparse branched trichomes like those of young stems. Corolla white, 17. 5–22 mm long, externally glabrous (or minutely mealy-glandular), tube 17–18 mm long, internally pubescent at base of stamens with glandular trichomes 0.2– 0.5 mm long, limb 6.5 mm in diameter, lower lip ca. 4 mm long. Stamens not seen. Style 16–18 mm long, glabrous to minutely glandular, stigma subcapitate to subequally 2-lobed, lobes 0.1– 0.4 mm long. Drupe ovoid to ± ellipsoid to obovoid, 16–19 mm long, 10–15 mm in diameter, surface glabrous to mealy-glandular.

PHENOLOGY.— Flowering: May–August; fruiting: February, August–November.

DISTRIBUTION AND HABITATS.— Tropical western Africa ( Gabon, Ghana, Guinea, Ivory Coast, Liberia; EOO = 565,420 km 2; Fig. 7 ). Plants occur in lowland and montane, moist to wet, evergreen forests; secondary forests; gallery forests; swamp forests; and grass fields. Elev. 100–850 m. Occurrence of plants is higher in forests where rainfall is between 1500–2500 mm /yr ( Holmgren et al. 2004).

ILLUSTRATION.— Fig. 8 .

Chevalier (1920) listed two of his collections, 19600 and 19745, in the protologue. Chevalier 19745 (P-00435313) is here designated as the lectotype based on the descriptive notes found on the specimen label.

Lock & Hall GC 44752 from Ghana differs from most other collections by the acute to subattenuate bases of the leaf blades. McPherson 15543 from Gabon was identified as M. gilgiana by Vollesen. A duplicate of this collection at K was annotated by Breteler as an undescribed new species, “ M. rabiensis Breteler. ” Using the keys to species herein, this collection conforms very nicely to M. combretoides (e.g., branched trichomes on young stems, petioles, peduncles, and abaxial surface of bracteoles; inflorescences borne at nodes of younger, leafy stems, etc.), but was collected beyond the currently known distributional range of that species. It differs from most collections of M. combretoides only in the relative sparseness of the branched trichomes and the somewhat narrower leaves. However, similarly narrow leaves are known among M. combretoides in western Africa (e.g., Chatelain & Téhé 9366 from Ivory Coast), and M. gilgiana shows similar variation in leaf form. McPherson 15543 is a fruiting collection that lacks flowers; thus, its ultimate identity should be reevaluated when flowers are available. However, based on the preponderance of characters available, it seem reasonable to treat this collection as M. combretoides , and a range extension of ca. 1470 kilometers to the southeast of its nearest known occurrence in Ghana.

ADDITIONAL SPECIMENS EXAMINED.— GABON: Ogooue-Maritime: near Rabi, Shell Oil camp, 01°55ʹS, 009°55ʹE, McPherson 15543 (K, MO) . GUINEA. Lola: Nimba Mountains, Gouan Valley, 07°41.4ʹN, 008°22.9ʹW, Jongkind et al. 8377 ( FHO, MO) . GHANA. Eastern: Atewa Range Extension F.R., [ca. 06°08ʹ07.11ʺN, 000°37ʹ12.27ʺW], Lock & Hall GC 44752 (K) . IVORY COAST. Agnebi: Forêt de Yapo, Aké Assi s.n. ( MO) ; Agboville , Forêt de la Mamo, 05°44ʹN, 004°06ʹW, Chatelain & Téré 712 (G) ; Réserve du Yapo [ca. 05°43ʹ23.60ʺN, 004°05ʹ41.47ʺW], Cremers 556 ( P) ; Agboville, S part of Yapo Forest, ca. 05°51ʹN, 004°08ʹW, de Kruif 688 ( CAS); KM 9 of Yakassé–Mé-Kodiousou road [05°49′N, 03°54′W], Leewenberg 8042 (K, MO) ; Sous-prefecture, Azaguié, Forêt de Yapo , 05°44ʹN, 004°08ʹW, Téré 1955 (G) ; Agboville, Forêt de Yapo, 05°45ʹN, 004°10ʹW, Téré 2528 (G) . Bas Sassandra: bassin du Cavally, pays des Tépos, entre Nékaougnié et Grabo , Chevalier 19600 (K, P-00435310-photo only; P-00435311-photo only; P-00435312) . Lagunes: 9 km W of Bécédi [ca. 05°37ʹ53.49ʺN, 004°39ʹ12.91ʺW], Leeuwenberg 7908 (K, MO) . LIBERIA. Grand Bassa: along the road from Tapita to Tchien , 13 mi NE of Tobli, [ca. 06°01ʹ22.91ʺN, 009°52ʹ57.98ʺW], Jansen 873 (K, MO) . Grand Gedeh: Webo District, Gletown, Baldwin 6764 (K) ; along the road from Tchien to Zwedru Fijnhout exploitation, near Cavalla river , Jansen 2556 (K, MO) . Nimba: Yéképa, Granfield, Mt. Nimba , Adam 24131 ( MO) ; Yéképa, Nimba, Mont Alpha (mine) upper Jiti River , Adam 27577 ( CAS, MO, P) ; Gangra, Adam 30077 ( MO) ; Grassfield [07°29ʹ10.44ʺN, 008°34ʹ12.54ʺW], Adam 31567 ( MO) ; banks of Yiti River , 07°28.74ʹN, 008°34.22ʹW, Jongkind & Bilivogui 9655 (K) . County unknown: without locality, Yallah 122 (K) .

Figures

FIGURE 7. Map of central Africa showing distributions of Mendoncia combretoides and M. lindaviana.

FIGURE 8. Mendoncia combretoides. A. Habit (Chevalier 19600, habit; Jansen 2556, inflorescence). B. Portion of midvein and secondary veins on abaxial surface of leaf (Jansen 2556). C. Enlargement of trichomes on midvein of abaxial surface of leaf (Jansen 2556). D. Apex of style and stigma (Jansen 2556). E. Drupe with persistent bracteoles (Adam 24131). F. Drupe with bracteoles removed (Adam 24131). Drawn by Sarah Adler.