Wetschnig, Knirsch & Martínez-Azorín & Pfosser & Wetschnig, 2015

Knirsch, Walter, Martínez-Azorín, Mario, Pfosser, Martin & Wetschnig, Wolfgang, 2015, The reinstatement and rediagnosis of the madagascan genus Rhodocodon (Asparagaceae, Scilloideae), with validation and remarks on H. Perrier’s taxa, Phytotaxa 195 (2), pp. 101-134 : 118

7. Rhodocodon graciliscapus Knirsch, Mart. -Azorín & Wetschnig sp. nov.

≡ Rhodocodon calcicola var. graciliscapus Perrier de la Bâthie (1938: 116) , nom. inval.

Type:— MADAGASCAR. Environs d’Ampasimentera (Boina), paturages, fl. verdatres, October 1906, Perrier 10946 (holotype P 00573466!, Fig. 14 ).

Description:—Deciduous bulbous plant, 30 ‒ 55 cm high. Bulb subglobose, 1.5 ‒ 2.5 × 2 ‒ 3 cm; roots white, branched. Leaves 3 ‒ 5 per bulb, absent at flowering time, long tapering, linear to oblanceolate, acute, 16 ‒ 23 × 0.4 ‒ 0.9 cm, appearing after anthesis, green, glabrous, smooth, with distinct keel on the abaxial side. Inflorescence an erect, flexuose raceme; peduncle 16–22 cm long, green, glabrous, smooth; raceme 25 ‒ 35 cm long with 35 ‒ 60 flowers; pedicels 10–25 mm long, suberect to spreading; lowermost bracts subpetiolate and adnate to the base of the pedicels, thin, 0.7 ‒ 2 mm long, spurred and membranous, with a needle-like spur of ca. 2 mm long; bracteoles absent; flowers nodding, greenish with a green, thicker cuplike base, and translucent adjacent regions to the suture of the tepals. Perigone urceolate-turbinate, widest at the distal third but slightly contracting at the apex, ca. 4 × 4 mm; tepals connate for most of their length, with acute, green apical lobes, ca. 1.2 mm long, patent or slightly reflexed at the anthesis. Stamens 6; filaments shortly adnate to the perigone tube and arising from its basal portion; free portion of filaments ca. 1.2 mm long, linear, attenuate to the top, glabrous, smooth, incurved and approaching the base of the style; anthers white to yellow, oblong, ca. 1 mm long, sagittate, acute, dehiscing for their whole length. Ovary cylindrical, subglobose to conical, 1.2 × 1 ‒ 2 mm, with 2 ovules per locule, filling the lower half of the cavity; style 1.5 ‒ 1.7 mm long. Capsule subglobose, 3 × 3 ‒ 4 mm. Seeds ellipsoidal, L-H-W: 3.3 ‒ 2 ‒ 2.1 mm, black, slightly glossy, with a black distinct raphe. Fig. 15 .

Diagnosis:— Rhodocodon graciliscapus is similar to R. floribundus , but the former is smaller, having narrower and shorter leaves, inflorescences with peduncle of 1.5 mm in diameter, lacks bracteoles, and shows seeds with a distinct black raphe.

Habitat:— Rhodocodon graciliscapus grows along riverbanks among shrubs in deciduous, dry forests, between 500 ‒ 600 m elevation. The area is characterized by a distinct dry savanna climate from April to October, with the driest months being June and July. The tropical wet season begins at the end of October, with the peak of precipitation in January and February. The annual average precipitation is 1486 mm and the annual average temperature is 26.3°C.

Biology:—Flowering and fruiting time: October to December.

Distribution:— Madagascar. Province Mahajanga: Districts Betsiboka and Boeny, along the river Betsiboka.

Comments:—Our preliminary molecular studies place Rhodocodon graciliscapus in a clade with R. floribundus , that corroborates their similar flower morphology. Perrier de la Bâthie (1938) placed R. graciliscapus as a variety of R. calcicola , although neither flower morphology nor molecular data would support this solution.

Selected material studied:— MADAGASCAR. Province Mahajanga: District Betsiboka, between shrubs along the river in sandy soil, 500 m, February 2011, W. Knirsch, A. Sieder & J. Andriantiana 6309 (GZU!).

Figures

FIGURE 14. Holotype of Rhodocodon graciliscapus Knirsch, Mart.-Azorín & Wetschnig: Perrier 10946 (P 00573466!).

FIGURE 15. Flower morphology of Rhodocodon graciliscapus Knirsch, Mart.-Azorín & Wetschnig (corresponding to WW 4477!). Lateral view (left), dissection in lateral view (center) and apical view (right). Scale bar 1 mm.