Astiella delicatula Jovet, 1941

Groeninckx, Inge, Janssens, Steven, Smets, Erik & Verstraete, Brecht, 2017, Description of 11 new Astiella (Spermacoceae, Rubiaceae) species endemic to Madagascar, European Journal of Taxonomy 312, pp. 1-40 : 16-18

Astiella delicatula Jovet

Figs 2E , 4C , 5G–I , 8

Etymology

The specific epithet is based on the Latin adjective ‘delicatus’, meaning ‘delicate’, referring to the slender habit of the species.

Type

MADAGASCAR: Toliara province, Atsimo-Andrefana region, Sakaraha district, Forêt d’Analafanja au nord du Fiherenana, plateau calcaire, Mar. 1934, Humbert 14296 (holo-: P).

Additional material examined

MADAGASCAR: Toliara province, Atsimo-Andrefana region, Sakaraha district, Sous bois forêt tropophile, forêt du Zombitsy, Sakaraha, Mar. 1964, Bosser 19364 ( BR). Menabe region, Morondava district, Kirindi forest, north part, piste de pointe de vue km 7, on road through dry forest, white sand, 19 Jan. 2007, De Block et al. 2173 ( BR, MO, P, TAN). Mahajanga province, Boeny region, Ambato Boeni district, RN d’Ankarafantsika, 21 Mar. 2010, De Block et al. 2369 ( BR, MO, P, TAN).

Description

Annual herb, up to 23 cm tall; stems quadrangular in cross section, only sparsely branching, puberulous, green tinged reddish. Stipule base 0.7–1 mm long, puberulous, slightly tinged red; fimbriae 3–4, 0.5–1.5 mm long, beset with a few trichomes, with colleters in between. Leaves petiolate; petioles 1.5–4 mm long, puberulous; blades ovate at the basal portion of the stem, 9.5–14.5 × 4.5–8.5 mm, narrowly ovate at the distal portion of the stem, 24 –50 × 9–15.2 mm, with a few trichomes particularly on the veins, darker green above, paler green below; base obtuse, attenuate or unequal; apex acuminate; margin scabrate; midvein prominent; secondary veins 3–6 on each side of the midvein, prominent; intersecondaries prominent. Inflorescences terminal or pseudo-axillary, single or compound dichasia, 3- to several-flowered, somewhat resembling a scorpioid cyme; peduncle 6.5–21.5 mm long, sparsely puberulous. Pedicels 0.2–4.5 mm long, glabrous or puberulous. Flowers isostylous. Calyx green; tube reduced; lobes 2, narrowly ovate, 1.1–4 × 0.2–0.3 mm, scabrate. Corolla white; tube cylindrical, 1.6–1.8 × 0.5–0.7 mm, glabrous; lobes 4, ovate, 0.7–1 × 0.4–0.6 mm, glabrous. Stamens inserted in the lower half of the corolla tube and included. Anthers ellipsoid, 0.4–0.5 mm long; filaments dorsifixed, ca 0.2 mm long. Pollen 5- or 6-colporate, suboblate; E 27–28 μm; P 23–28 μm; ectocolpi short; endocolpi short; tectum bireticulate; suprareticulum microreticulate to reticulate, smooth; infrareticulum perforate with granules. Ovary 2-locular, depressed obovoid, 0.3–0.5 × 0.6–0.8 mm, glabrous; placenta attached near the middle of the septum, stalked, globose, bearing 1 ovule per locule. Style 0.4–0.5 mm long, included, glabrous; stigma bilobed, lobes 0.1–0.2 mm long, papillate; nectary disc bipartite. Capsules broadly depressed obovoid, 2–3 × 3.8–5 mm, well-developed beak, crowned with the persistent calyx lobes, glabrous, dehiscence loculicidal. Seeds 1 per locule, ovate in outline, ventral groove present, 1.8–2 × 1.3–1.5 mm, black; seed coat surface reticulate; endosperm ruminate.

Distribution

W Madagascar: Mahajanga province, Boeny region, Ambato Boeni district; Toliara province, Atsimo- Andrefana region, Sakaraha district; Toliara province, Menabe region, Morondava district.

Habitat

Western dry forest; white sand or calcareous substrate; at 950–1000 m elevation.

Conservation status

The species is known from three localities, representing three different locations.The extent of occurrence equals 20,589.658 km 2; the area of occupancy equals 12 km 2. Two collections were made within the boundaries of a protected area. The main threat for the species is the deterioration of its habitat caused by the high human pressure in the area, which has also been observed within the protected areas. A decline in the extent of occurrence, area of occupancy, and area, extent, and/or quality of habitat is projected. The species is therefore considered endangered: EN B2ab(i,ii,iii).

Figures

Fig. 2. Distribution maps. A. Astiella antongilensis Groeninckx sp. nov. B. A. antsalovansis Groeninckx sp. nov. C. A. confusa Groeninckx sp. nov. D. A. deblockiae Groeninckx sp. nov. E. A. delicatula Jovet. F. A. desseinii Groeninckx sp. nov. G. A. homolleae Groeninckx sp. nov. H. A. latifolia Groeninckx sp. nov. I. A. longifimbria Groeninckx sp. nov. J. A. perrieri Groeninckx sp. nov. K. A. pulla Groeninckx sp. nov. L. A. tsaratanensis Groeninckx sp. nov.

Fig. 4. Scanning electron microscopy micrographs of pollen in polar view (PV), the apocolpium (AC), pollen in equatorial view (EV) and the mesocolpium (ME). A. Astiella antsalovansis Groeninckx sp. nov. B. A. deblockiae Groeninckx sp. nov. C. A. delicatula Groeninckx sp. nov. D. A. desseinii Groeninckx sp. nov. Scale bars for A and C: PV, EV = 5 µm, AC = 1 µm, ME = 2 µm; for B and D: PV, EV = 5 µm, AC, ME = 1 µm.

Fig. 5. Scanning electron microscopy micrographs of seeds and a detail of their surface. A–B. Astiella antsalovansisGroeninckx sp. nov.C–D.A. deblockiaeGroeninckx sp. nov.E–F.A. desseiniiGroeninckx sp. nov. G–I. A. delicatula Jovet. J–K. A. homolleae Groeninckx sp. nov. L–M. A. latifolia Groeninckx sp. nov. N–O. A. perrieri Groeninckx sp. nov. P–R. A. tsaratanensis Groeninckx sp. nov. Scale bars for A, C, E, J, L, N = 100 µm; B, I = 50 µm; D = 10 µm; F, K, M, O, R = 20 µm; G, H, P, Q = 200 µm.

Fig. 8. Astiella delicatula Jovet. A. Habit. B. Isostylous flower. C. Open isostylous flower. D. Ovary dissected to show placentation. E. Capsule. Drawn by Marijke Meersman. All from De Block et al. 2173 (BR).