Colea unifoliolata Callmander & Phillipson 2012, sp. nov.

(Figs 3; 4A)

Haec species a congeneris foliis unifoliolatis, lamina foliari crasse coriacea discolori adaxialiter atroviridi (in sicco atrogrisea) abaxialiter clare purpurea (in sicco atropurpurea) atque corolla saturate magentea fauce alba luteo-maculata distinguitur.

TYPUS. — Madagascar. Prov. Toamasina, Summit of quartzite massif of Ankirindro, c. 25 air-km NW of Maroantsetra via the Antainambalana and then Vohimaro rivers, 15°18’08”S, 49°33’04”E, 671 m, fl., 1.II.1999, Schatz et al. 3915 (holo-, MO!; iso-, P [P00568744]!, TAN!).

PARATYPUS. — Madagascar. Prov. Toamasina, reg. Analanjirofo, Ankirindro, Ankiriandro Mountain, 15°17’37”S, 49°33’10”E, 640 m, imm. fr., 10.I.2003, Antilahimena, Pascal & Ramaroson 1680 (MO, P, TAN).

DESCRIPTION

Treelet 2-3 m tall, usually unbranched. Leaves unifoliolate, (13-)19-21 (including petiole) × 6-7 cm; petiole 2.5-3.5 cm long, c. 2 mm diameter, glabrous, canaliculate,thickened and slightly angled at the apex, verticillate on the branches, 2-4 leaves per verticil; leaf blade elliptic, (10-)16-18 × 6-7 cm, thick succulent, coriaceous, discolorous, dark green above (dark grey when dry), bright purple below, base shortly attenuate; margins entire; apex rounded, rarely acuminate; midrib and secondary veins visible on both surfaces, prominent below, glabrous. Inflorescence a highly contracted raceme, up to 3 cm, cauliflorous on nodules, axes glabrous, bracts setaceous, with a very short glandular indument c. 1.5 × 0.1 mm, with scattered short glandular trichomes. Calyx with 5 veins, 5- toothed, light green (black when dry), c. 5 × 3 mm, glabrous. Corolla funnel-shape, deep magenta, the throat white with yellow splotches, and obscurely 2-lipped, with 5 sub-equal spreading lobes, c.1-1.5 × 0.4-0.5 cm, finely puberulent with a whitish glandular indument outside; tube gradually narrowed to c. 2 mm diameter within the calyx; lobes rounded c. 4-6 × 4 mm. Stamens 4, c. 14 mm in length; anthers c. 2 mm, 2-locular. Style 15-18 mm long.Fruit an indehiscent follicle, pendant, immature fruit c. 3 × 1.5 cm, dark green (black when dried), ripped, c. 0.7-0.8 mm in diameter.

DISTRIBUTION AND ECOLOGY

Colea unifoliolata sp. nov. is only known from lowland evergreen tropical forest in the Makira region on the summit of Ankirindro Mountain, northwest of Maroantsetra (Fig. 1).

REMARKS

Colea unifoliolata sp. nov. is unique within the genus in having unifoliolate leaves. It is characterized by its leaf blade that is thick, coriaceous, discolorous, dark green above (dark grey when dry), bright purple below; its highly contracted inflorescence, the flowers with deep magenta corolla lobes and a white throat with yellow blotches. The new species is the ninth species of the genus Colea known to occur in the Antongil Bay region along with: C. asperrima H. Perrier, C. hirsuta Aug. DC., C. membranacea Aug. DC., C. nana H. Perrier, C. ramiflora Zjhra, C. rosea Zjhra, C. sytsmae Zjhra and C. tetragona DC. However, none of the other species bear unifoliolate discolorous leaves, nor do they possess similarly coloured flowers.

CONSERVATION STATUS

With only two collections, an AOO of 9 km 2 and one subpopulation, none of which situated within the protected area network, C. unifoliolata sp. nov. is assigned a preliminary status of Critically Endangered [CR B2ab(iii)] (IUCN 2001).