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 : 125-127

11. Rhodocodon monophyllus Knirsch, Mart. -Azorín & Wetschnig sp. nov.

≡ Rhodocodon calcicola var. monophyllus Perrier de la Bâthie (1938: 115) , nom. inval.

Type:— MADAGASCAR. Bois sur les rocailles gneissiques, sur la rivière Besafotra, affluent de droite du Menavava, Boina, bassin de la Betsiboka, Novembre 1899, Perrier 990 (holotype P 02160895!, Fig. 21 ).

Description:—Deciduous bulbous plants, 20 ‒ 55 cm high. Bulb white, 2 ‒ 4 × 1.5 ‒ 3 cm, with bulb scales spreading, distichously arranged; roots white, branched. Leaf solitary, synanthous, the limb lanceolate, spreading, 8 ‒ 17 × 2 ‒ 4.5 cm, firm, glaucous green, smooth, glabrous, the petiole 3 ‒ 12 × 0.3 ‒ 0.5 cm, long sheathing the basal part of the stem above the ground, with distinct red spots. Inflorescence a lax, erect, raceme; peduncle green, 12 ‒ 35 cm long,

smooth; raceme 6 ‒ 18 cm long with 10 ‒ 25 flowers; pedicels 7 ‒ 10 mm long, green, suberect to patent, reflexed at the apex, up to 15 mm in fruit; lowermost bracts triangular, acute, dark green, 1.5 ‒ 2 × 0.3 mm, sometimes inserted on the stem below the insertion of the pedicels, with a spur 0.2 ‒ 0.3 mm long; bracteoles absent; flowers white with a green tinge, nodding. Perigone urceolate, 3.4 ‒ 3.6 × 3.3 ‒ 3.5 mm, tepals connate for most of their length, with the widest part at the proximal third, contracted at the top, with short, erect, lobes ca. 0.3 mm long. Stamens 6; filaments shortly adnate to the perigone tube and arising from its basal portion; free portion of filaments lanceolate, thickened, papillate, ca. 1.5 mm long, incurved and converging over the ovary; anthers yellow, sagittate, acute, ca. 1 mm long, dehiscing for most of their length. Ovary triangular, subglobose with prominent apical shoulders, ca. 1.3 × 2.0 mm, with 2 upright ovules per locule; style 1.6 ‒ 2 mm long; stigma punctiform. Capsule subglobose, 3 ‒ 4 × 4 ‒ 5 mm. Seeds hemiellipsoidal, L-HW: 4 ‒ 2.7 ‒ 2.6 mm, black, glossy, with a light brown distinct raphe. Fig. 22 .

Diagnosis:— Rhodocodon monophyllus resembles R. calcicola in flower morphology and the papillate filaments, but the former clearly differs by distichously arranged bulb scales, solitary lanceolate leaf with a long petiole with red spots that long sheaths the stem above ground and ovary with prominent shoulders.

Habitat:— Rhodocodon monophyllus grows in grassland on calcareous soils at about 60 m of elevation, located among relict deciduous dry forests that are recurrently burnt. The area is characterized by a distinct dry savanna climate from April to October, the driest months being June and July. The tropical wet season begins at the end of October. The peak of precipitation covers January and February. The annual average precipitation is 1486 mm. The annual average temperature is 26.3°C. During the rainy season these areas are flooded, but in the dry season they are completely dehydrated, the soil showing crevices up to 2 meters deep. This species grows with R. calcicola and Avonsera convallarioides ( Perrier 1935: 68) Speta (1998b: 95) few kilometers north of Mahajanga.

Biology:—Flowering and fruiting time: November to January.

Distribution:— Madagascar. Province Mahajanga: regions Boeny, Betsiboka and Melaky.

Comments:—The pedicels are not articulated as described by Perrier de la Bâthie (1938). Perrier de la Bâthie (1938) commented that the distichous arrangement of the bulb scales is probably an adaption to the rocky habitat. However, we collected this species in sandy soil near Mahajanga, showing the same distichous arrangement of bulb scales.

Selected material studied:— MADAGASCAR. Province Mahajanga: region Boeny , February 2011, W. Knirsch, A. Sieder & J. Andriantiana 6296 ( GZU!) ; Ouest ; Bois sur les Labradorites de l’Antanimena ( Boina ), October 1924, Perrier 16783 (P 00516240!) ; Env. d’Antsalova, Ampandra RN 9, Forêt caducifoliée de bas-fond, sol brun sur calcaire dans le Tsingy, J.N. Labat et al. 2206 (P 023809!) .

Figures

FIGURE 21. Holotype of Rhodocodon monophyllus Knirsch, Mart.-Azorín & Wetschnig: Perrier 990 (P 02160895!).

FIGURE 22. Flower morphology of Rhodocodon monophyllus Knirsch, Mart.-Azorín & Wetschnig (corresponding to WW 4677!). Lateral view (left), dissection in lateral view (center) and apical view (right). Scale bar 1 mm.