Mendoncia cowanii (S. Moore) Benoist var. coursii 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 : 62-63

2b. Mendoncia cowanii (S. Moore) Benoist var. coursii Benoist, Notul. Syst. (Paris) 11:141. 1944.

TYPE.— MADAGASCAR. Toamasina: Ambatondrazaka, Sahalampy Onibé, [ca. 17°45ʹS, 048°51ʹE], Nov 1938, Cours 1053 (holotype: P-00091099!; isotype: K-000393673!) .

Young stems densely pubescent with yellowish to yellowish brown, interwoven, flexuose, unbranched, eglandular trichomes 0.2– 2 mm long (velutinous), surface of stem not visible. Leaves subcoriaceous, petioles to 15 mm long, velutinous, blades ovate to elliptic to oblong-elliptic, 38– 92.4 long, 18–47. 3 mm wide, subcordate to rounded to acute at base, acute-apiculate to rounded to retuse at apex, abaxial surface pubescent like young stems but blade surface at least partially visible, adaxial surface pubescent with antrorse, eglandular trichomes 0.1– 1 mm, trichomes on each surface usually denser on major veins. Inflorescences borne in leaf axils on young, mostly herbaceous and leafy stems, solitary or opposite at nodes, dichasia 1–2 per axil, peduncles to 50 mm long, velutinous. Bracteoles with color obscured by pubescence, persistent at least to immature stages of fruiting, ovate-elliptic to subcircular, 16.3–23. 5 mm long, 10.2–21. 4 mm wide, rounded to acute-apiculate at apex, rounded to truncate at base, abaxial surface velutinous, adaxial surface mealy-glandular. Calyx densely pubescent with mostly distally pointing, straight, eglandular trichomes to 3 mm long. Corolla purplish to pink, 30.5–38. 7 mm long, externally glabrous, internally mealy-glandular, tube 28–33 mm long, limb 9–11. 3 mm in diameter, upper lip 1.8– 3.6 mm long with lobes rounded to emarginate, 1.8– 3.2 mm long and 4– 4.5 mm wide, lower lip 3–7. 4 mm long with lobes rounded to emarginate 2.2–3. 3 mm long and 3.4– 3.5 mm wide. Stamens not seen. Style 27–29 mm long, glabrous, stigma subcapitate to subequally 2-lobed, lobes 0.1– 0.3 mm long. Drupe (immature) ± ovoid, ca. 13 mm long, ca. 9 mm in diameter, densely pubescent with golden-brown, appressed eglandular trichomes 0.4– 3 mm long.

PHENOLOGY.— Flowering May–September; fruiting October.

DISTRIBUTION AND HABITATS.— East-central Madagascar (Toamasina; EOO = 1,512 km 2; Fig. 9 ). Plants occur in lowland to montane, primary, moist to wet, evergreen forests. Elev. 500–1040 m.

LOCAL NAME.— “Vahiboloina” (Andrianijafy et al. 186).

A full description of this variety is provided above because it is possible that these plants represent a species distinct from M. cowanii . It differs from the nominate variety primarily by the young stems, petioles, abaxial surface of leaf blades ( Fig. 3A ), peduncles, and bracteoles being densely pubescent with yellowish, interwoven, flexuose, unbranched, eglandular trichomes such that the underlying surfaces are not visible (or only partially so on the abaxial leaf blades). The variety occurs in a limited region of Toamasina Province in east-central Madagascar. Domatia are not evident on the abaxial surfaces of leaves, or, if present, they are likely obscured by the dense trichomes that are ubiquitous on that surface. Also in this variety, the overall length of the upper lip of the corolla and the length and width of lobes of the lower lip are shorter and narrower than in M. cowanii var. cowanii , but this may be attributed to lack of flowering material for comparison. Measurements of other characters and flowering times overlap between the two varieties. Additional fertile collections of plants conforming to this taxon should clarify its status as a variety of M. cowanii (as treated here), a more densely pubescent form of that species, or a distinct species.

ADDITIONAL SPECIMENS EXAMINED.— MADAGASCAR. Toamasina: Vavantenina, Commun de Miarinarivo , FKT Anamborano, Savaharina, PN Zahamena, à côté de la rivière Ihofika, limite de PN, 17°41ʹ08ʺS, 048°59ʹ43ʺE, Rakotonandrasana 485 ( MO) ; Réserve Naturelle Integrale Zahamena , forest of Amboditamenaka, 17°44ʹS, 049°00ʹE, Malcomber 2584 ( MO) ; Parc Natl. de Zahamena, Rivière de Sahemora , 17°38ʹ27ʺS, 048°52ʹ32ʺE, Andrianjafy 186 ( MO) ; PK 33 , road Moramanga–Anosibe Anala , 19°10ʹ56ʺS, 48°13ʹ31ʺE, de Block et al. 922 ( BR, K) .

Figures

FIGURE 9. Maps of Madagascar showing distributions of Mendoncia cowanii var. cowanii, M. cowanii var. coursii, and M. vinciflora.

FIGURE 3. Morphological features of Mendoncia spp. A. Abaxial leaf surface of M. cowanii var. coursii (Rakotonandrasana 485). B. Abaxial leaf surface of M. lindaviana (Vermoesen 191). C. Dichasium of M. cowanii var. coursii (Rakotonandrasana 485) with one bracteole removed showing single flower with densely pubescent calyx. D. Oblong drupe of M. lindaviana (Louis et al. 275). E. Cross-section through dried drupe of M. vinciflora (Lewis et al. 1353) showing bony seed with embryo. F. Node of older shoot of M. lindaviana (Breteler et al. 8106) with dichasia borne on branched and woody short-shoots.