Astiella pulla Groeninckx, 2017

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 : 33-34

Astiella pulla Groeninckx sp. nov.

http://www.ipni.org/urn:lsid:ipni.org:names:77161727-1

Figs 2K , 15

Diagnosis

Astiella pulla sp. nov. resembles A. antsalovansis sp. nov. in having black seeds with a reticulate seed coat surface consisting of 5- to 6-angular testa cells and in having a ring of trichomes inside the corolla tube, but differs in having more robust inflorescence axes (vs slender), 4 to 5 ovules per locule (vs 3), a longer style that is always exserted in brevistylous flowers (vs a shorter style that is included), and fruits 1.5–3.4 × 2.6–4 mm (vs 1–2 × 1.5–3 mm).

Etymology

The specific epithet is the feminine form of the Latin adjective ‘ pullus ’ that means ‘dark-coloured’ and refers to the black seeds.

Type

MADAGASCAR: Mahajanga province, Boeny region, Mahajanga I district:ca 20km before Mahajanga, Marohogo, RN 4, just next to road, 47 m, 19 Mar. 2010, Groeninckx, De Block & Rakotonasolo 271 (holo-: BR; iso-: BR, G, K, MO, P, TAN, WAG).

Additional material examined

MADAGASCAR: Mahajanga province, Boeny region, Mahajanga I district, sur le calc rocin à Marohogo près Majunga, s.d., Perrier de la Bâthie 17633 ( P).

Description

Annual herb, erect, up to 20 cm tall; stems quadrangular in cross section, glabrous or sometimes scabrate on the ribs. Stipule base 0.2–1 mm long, beset with a few short trichomes; fimbriae 4–9, 0.2–0.8 mm long, sometimes inconspicuous, colleter-tipped. Leaves sessile; blades ovate, elliptic, narrowly ovate or narrowly elliptic, 8–32 × 3–8.5 mm, glabrous, darker green above, paler green below; base attenuate; apex acute; margin revolute when dry, scabrate; midvein prominent below, glabrous or scabrate; secondary veins invisible or 3–4 on each side of the midvein; intersecondaries invisible. Inflorescences terminal or pseudo-axillary, very lax compound and reduced dichasia, 3- to several-flowered; bracts at main branchings leaf-like; peduncle absent; inflorescence branches up to 6 cm long, glabrous or scabrate. Pedicels absent or 0.5–1.5 mm long, glabrous or scabrate. Flowers heterostylous. Calyx green; tube reduced; lobes 4, ovate with acuminate tip, 1–1.7 × 0.7–1 mm, glabrous, margin ciliolate. Corolla white; tube cylindrical 2.2–2.8 × 1–1.5 mm in brevistylous flowers, 1.5–2.2 × 0.8–1.2 mm in longistylous flowers, glabrous outside, with a ring of trichomes in the lower half inside; lobes 4, ovate, 0.6–1.4 × 0.5–1.3 mm, glabrous inside except for trichomes towards the margin. Stamens inserted near the base of the corolla lobes and exserted for 0.6–0.9 mm beyond the corolla throat in brevistylous flowers, inserted in the middle of the corolla tube and included in longistylous flowers. Anthers ellipsoid, 0.5–0.7 mm long; filaments dorsifixed, 0.4–0.5 mm long. Pollen 7-aperturate. Ovary 2-locular, depressed obovoid, 0.5–1 × 0.7–1.3 mm, glabrous to sparsely pubescent; placenta attached near the middle of the septum, stalked, subglobose, bearing 4 to 5 ovules per locule. Style 2.3–3 mm long and exserted for 0.2–0.3 mm beyond the corolla throat in brevistylous flowers, 2.5–2.8 mm long and exserted for 0.6–0.7 mm beyond the corolla throat in longistylous flowers, glabrous; stigma bilobed, lobes 0.5–0.8 mm long, hirtellous. Capsules broadly depressed obovoid, 1.5–3.4 × 2.6–4 mm, crowned with the persistent calyx lobes, glabrous or with a few scabrate trichomes, dehiscence loculicidal. Seeds 1, 3 or 4 per locule, elliptic in outline, ventral groove absent, 0.8–1 × 0.6–0.8 × 0.4–0.5 mm, hilum in the middle, black; seed coat surface reticulate, 5- to 6-angular testa cells, microsculpturing favulariate.

Distribution

NW Madagascar: Mahajanga province, Boeny region, Mahajanga I district.

Habitat

Western (degraded) dry forest; dark clay on calcareous underground; at 47 m elevation.

Conservation status

Known from only one locality. Given its apparent rarity and following the recommendation of Callmander et al. (2005) to avoid the Data Deficient category, we consider the species as vulnerable (VU D2) based on its restricted area of occupancy (D2) and the high human pressure present in the entire area resulting in a general decline of suitable habitats (dry forest) for the species.

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. 15. Astiella pulla Groeninckx sp. nov. A. Habit. B. Brevistylous flower. C. Open brevistylous flower. D. Open longistylous flower. E. Ovary dissected to show placentation; all ovules removed from the right locule to show the placenta. F. Capsule. Drawn by Marijke Meersman. A, E–F from Perrier de la Bâthie 17633 (P); B–D from Groeninckx, De Block & Rakotonasolo 271 (BR).