Astiella tsaratanensis 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 : 34-37

Astiella tsaratanensis Groeninckx sp. nov.

http://www.ipni.org/urn:lsid:ipni.org:names:77161729-1

Figs 2L , 5 P–R, 11D, 16

Diagnosis

Astiella tsaratanensis sp. nov. resembles A. delicatula Jovet in having a reduced number of ovules per locule, pluricolporate pollen, and seeds with a ventral groove, but differs in having 3 ovules per locule (vs 1), and 4 calyx lobes (vs 2).

Etymology

The species epithet refers to the Madagascan town Tsaratanana.

Type

MADAGASCAR: Antsiranana province, Diana region, Antsiranana I district, Montagne d’Ambre NP, circuit Gite d’Etape-Cascade Antakarana-Voie des Milles Arbres-Gite d’Etape, 20 Jan. 2002, De Block, Rakotonasolo & Randriamboavonjy 1319 (holo-: BR; iso-: BR, CAS, G, K, MO, P, TAN, WAG).

Additional material examined

MADAGASCAR: Antananarivo province, Analamanga region, Ankazobe district, Ambatoharanana près d’Antsevabe, 1000 m, 6 Mar. 1951, Cours 4079 ( P). Vakinankaratra region, Ambatolampy district, Province du Vakinankaratra, district d’Ambatolampy, à 3–4 km en aval de Tsinjoarivo, dans la vallée de l’Onive, bords d’un ruisseau dans la forêt, 1550 m, 30 Nov. 1912, Viguier & Humbert 1846 ( P). Antsiranana province, Diana region, Ambanja district, Montagne Tsaratanana, sousbois, 1000 m, Dec. 1912, Perrier de la Bâthie 3730 ( P). Antsiranana I district, Centre nord, Montagne d’Ambre, bords du bois, basalte, 1000 m, Nov. 1909, Perrier de la Bâthie 9403 ( P); Southwest of Antsiranana, Joffreville, Parc National de Montagne d’Ambre, 990–1100 m, 16 –20 Nov. 1992, Malcomber et al. 1749 (K, P, TAN); Environs de Diego-Suarez, forêt d’Ambre, forêt ombrophile sur argile latéritique de basalte, 1000 m, 23 Dec.–18 Jan. 1960, Humbert 32085 ( BR, P). Fianarantsoa province, Atsimo-Atsinanana region, Farafangana district, RN 3, Manaka Est, [Atondrazaka], bas-fond, 5 Nov. 1952, Botoalina 4475-RN ( P). Mahajanga province, Sofia region, Bealanana district, Montagnes au nord de Mangindrano (haute Maevarano),jusqu’aux sommets d’Ambohimirahavavy (partage des eaux Mahavavy-Androranga:centrenord), forêt ombrophile sur latérite de gneiss, clairières marécageuses aux origines de la Bemafo affluent de l’Androranga, 1900 m, 19 Jan.–12 Feb. 1951, Humbert & Capuron 24975 ( BR, P); Montagnes au nord de Mangindrano (haute Maevarano), jusqu’aux sommets d’Ambohimirahavavy (partage des eaux Mahavavy-Androranga: centre-nord), clairières en forêt ombrophile sur latérite de gneiss, aux bords de la Bemafo, affluent de l’Androranga, 1800 m, 19 Jan.–12 Feb. 1951, Humbert & Capuron 25077 ( P). Toamasina province, Alaotra-Mangoro region, Ambatondrazaka district, Ambatondrazaka, endroits très humides, station 0–114, 800 m, Nov. 1938, Cours s.n. ( BR, P); Ouest, massif de l’Andringitra prês d’Ambodipaiso, près d’Antsoabe, Manaka Est, ca 1200 m, 12 Jan. 1945, Cours 2316 ( BR, MO, P). Locality unknown, s. loc., s.d., Baron 6312 ( P); s. loc., s.d., Homolle s.n. ( P).

Description

Herb, scrambling or prostrate, up to 30 cm tall,with fine rooting system, rooting at the nodes; stems round in cross section, only sparsely branching, glabrous to sparsely pubescent, pale green to reddish green, tinged red near the nodes. Stipule base 1.3–1.5 mm long, sparsely to densely beset with trichomes (ca 0.6 mm long); fimbriae 1–6, variable in length up to 2.5 mm long, colleter-tipped. Leaves petiolate; petioles 1.5–17 mm long, glabrous; blades ovate or elliptic, rarely broadly elliptic, 5.5–39 × 3.5–20.3 mm, sparsely to moderately covered with appressed trichomes 0.1–1.5 mm long, mostly concentrated on midvein and secondary veins, darker green above, paler green below; base attenuate; apex acute; margin scabrate or ciliate; midvein prominent below; secondary veins 3–5 on each side of the midvein, prominent particularly below; intersecondaries invisible. Inflorescences pseudo-axillary, 1- or fewflowered dichasia; peduncle 11–27 mm long, glabrous. Pedicels 1–7.7 mm long, glabrous, green tinged reddish. Flowers heterostylous. Calyx green; tube reduced; lobes 4, narrowly triangular to linear, 1–2 × 0.2–0.5 mm, glabrous or sparsely beset with trichomes, margin usually scabrate rarely beset with long trichomes, colleters in between. Corolla white or pale blue; tube funnel-shaped, 4.8–9.5 mm long, 0.5–1 mm wide at the base, 2–4.2 mm wide at the throat, glabrous outside, sparsely to moderately beset with trichomes inside; lobes 4, ovate, 3.4–5 × 1.1–2.5 mm, glabrous outside, moderately beset with trichomes inside. Stamens inserted in the corolla throat and exserted for ca 1 mm beyond the corolla throat or included in brevistylous flowers, inserted in the lower half of the corolla tube and included in longistylous flowers. Anthers ellipsoid, 0.8–1 mm long; filaments dorsifixed, 0.3–0.8 mm long. Pollen 7- to 8-colporate, suboblate; E 34–37 μm; P 26–29.5 μm; ectocolpi short; endocolpi short; tectum bireticulate; suprareticulum microreticulate to reticulate, smooth; infrareticulum perforate to microreticulate with granules. Ovary 2-locular, broadly obovoid to broadly depressed obovoid, 0.4–1 × 0.6–0.9 mm, glabrous; placenta attached near the middle of the septum, stalked, globose, bearing 3 ovules per locule. Style 3.6–4 mm long and included in brevistylous flowers, 9–11 mm long and exserted for 1.2–2 mm beyond the corolla throat or included in longistylous flowers, glabrous; stigma bilobed, lobes 0.6–1.2 mm long in longistylous flowers, 0.5–0.9 mm in brevistylous flowers, papillate, pale blue. Capsules broadly depressed obovoid, 2.5–4.6 × 3.2–5 mm, crowned with the persistent calyx lobes, glabrous, green, dehiscence loculicidal. Seeds 1 per locule, elliptic in outline, ventral groove present, 1.9–2.3 × 1.4–1.5 mm, black; seed coat surface alveolate, microsculpturing rugulose.

Distribution

NW to E Madagascar: Antananarivo province, Analamanga region, Ankazobe district; Antananarivo province, Vakinankaratra region, Ambatolampy district; Antsiranana, province, Diana region, Ambanja, and Antsiranana I districts; Fianarantsoa province, Atsimo-Atsinanana region, Farafangana district; Mahajanga province, Sofia region, Bealanana district; Toamasina province, Alaotra-Mangoro region, Ambatondrazaka district.

Habitat

Humid forest; along forest stream, forest border; basalt-laterite; at 800–1900 m elevation.

Conservation status

The species is known from 14 collections, of which two without locality. The number of locations is nine. The extent of occurrence is more than 20,000 km 2; the area of occupancy equals 40 km 2. The main threat for the species is the deterioration of its habitat caused by the high human pressure throughout its distribution range, 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 classified as vulnerable: VU 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. 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.