Warneckea masoalae R. D. Stone 2006, sp. nov.

(Fig. 10)

Species insignis habitu truncifloro et nervis lateralibus foliorum invalidis plus minusve intramarginalibus, a congeneribus mihi cognitis bene distincta.

TYPUS. — Madagascar. Antsiranana province, Masoala peninsula, canyon of Ampanavoana river, 15°40’45”S, 50°09’35”E, alt. 75 m, understory of evergreen rain forest on south side of river, 8.XII.2001, Stone et al. 2407 (holo-, CAS; iso-, CAS, G, K, MO, P, TAN, TEF, US; flowers and fruits in spirit collection at CAS).

DESCRIPTION

Evergreen small tree 4 m high; branchlets terete, the youngest subquadrangular; internodes 5-12 cm long. Leaves subcoriaceous, light green on both surfaces (when dry); petiole robust, 6-12 mm long, ± flattened or canaliculate on the adaxial side; blades ovate to lance-ovate, (12-) 16.5-22.5 cm long, (5.5-)8.0- 11.9(-12.8) cm wide, broadly rounded at the base and sometimes subcordate above the petiole, attenuate-rounded in the upper third and abruptly acute or broadly short-acuminate at the apex (acumen up to 1 cm long); mid-nerve canaliculate on the upper surface, very prominent on the lower and wide at the base (up to 2.5 mm), becoming progressively narrower toward the apex; lateral nerves one pair, diverging from the mid-nerve at the base of the blade, much weaker than the mid-nerve but somewhat prominent on both surfaces, ± intramarginal (distance 2-9 mm from margin in the basal half of the blade), confluent with the transverse veins and forming a series of shallow loops for ± the entire length of the blade (sometimes curvilinear near the base); transverse veins like the lateral nerves or slightly thinner, their orientation ± perpendicular to the mid-nerve or somewhat oblique; reticulate tertiary veinlets evident on both surfaces (especially the lower).Cymules agglomerated in compact, ligneous cushions 1-2(-3) cm in diameter at well spaced intervals along the trunk. Flowers sessile or nearly so (pedicels rarely up to 1 mm long), each subtended by three pairs of imbricate, orbicular, cucullate bracts c. 1 mm long. Hypantho-calyx green, obconic, 3 mm long, 4 mm wide, the lobes broadly rounded, c. 1 mm long and 2 mm wide, scarious margined, the two external lobes auriculate and amplective at the base. Petals white, spatulate, 4-4.5 mm long, 1.8-2 mm wide. Anthers ochroleucous, 2 mm long (1.5 mm when dry), the connective conic with the extremity abruptly acute, the dorsal side keeled and lacking a gland; pollen sacs lateral (anterior), well separated from each other; filaments blue, 8 mm long.Style protruding by c. 2-3 mm from the corolla in bud, 9-10 mm long at anthesis; ovary imperfectly bilocular; ovules 8. Fruits subglobose, 12 mm long, 11-12 mm wide, crowned by the erect, persistent calyx; epigynous chamber smooth, marked only by the petal and filament scars. Embryo with a short radicle and lacking a hypocotyl, the outer cotyledon fleshy, globose, filling the entire seminal cavity, the inner cotyledon rudimentary, c. 0.5 mm long.

REMARKS

This new Warneckea, known only from the type collection, is so distinctive that it cannot be closely compared with any other currently recognized species. It is most remarkable for its trunciflorous habit and leaves with lateral nerves rather weak and intramarginal, in the latter respect superficially resembling Memecylon. Yet it is clearly a Warneckea on account of the smooth leaf surfaces with evident reticulum of small veins, the auriculate-amplexate calyx lobes, and the embryo morphology.

Warneckea masoalae might be confused with W. pulviniflora Jacq. -Fél. which has cymules in smaller cushions (up to 1 cm in diameter) at the defoliated nodes of robust branchlets (not down the trunk). The latter species also differs by its shorter petioles, smaller leaf blades, primary lateral nerves strongly curvilinear and suprabasilar (diverging from the mid-nerve c. 1 cm above the base), smaller flowers, longer style, and somewhat larger fruit.