Astiella homolleae 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 : 20-23

Astiella homolleae Groeninckx sp. nov.

http://www.ipni.org/urn:lsid:ipni.org:names:77161721-1

Figs 2G , 5 J–K, 10, 11A

Diagnosis

Astiella homolleae sp. nov. resembles A. perrieri sp. nov. in having reduced corolla tubes with the stamens always exserted beyond the corolla throat, but differs in having a perennial, erect habit (vs annual and creeping), stipules with many, long fimbriae (4–8 vs 2–4 fimbriae and 1–4 mm vs 0.8–2.7 mm long), a corolla tube papillate on the inside with trichomes towards the base (vs glabrous), and seeds triangular in outline with a verruculate microsculpturing (vs seeds elliptic in outline with granulate microsculpturing).

Etymology

The species is named in honour of the French botanist Anne-Marie Homolle, who annotated many of the Madagascan Spermacoceae specimens in the herbarium of Paris.

Type

MADAGASCAR: Antsiranana province, Sava region, Antalaha district, Partie occidentale du massif de Marojejy (nord-est) de la vallée de l’Ambatoharanana au bassin supérieur de l’Antsahaberoka, forêt ombrophile sur argile latéritique de gneiss et granite, 1300 m, 9 Nov.–2 Dec. 1959, Humbert & Saboureau 31739 (holo-: P; iso-: BR).

Additional material examined

MADAGASCAR: Antsiranana province, Sava region, Andapa district, Pentes occidentales du massif de Marojejy (nord-est), bassin de la Lokoho, à l’est d’Ambalamanasy II, forêt ombrophile sur latérite de gneiss, 450–800 m, 28 Nov.–6 Dec. 1948, Humbert & Capuron 22130 ( BR, P). Masoala Peninsula, S of Ambanizana, Andranobe, Piste A, primary wet evergreen forest, 200 m, 18 Feb. 1999, Hoffman et al. 61 (K); Masoala Peninsula, trail leading south from Ambanizana along coast 1–2 km S of Ambanizana, 0–20 m, 26 Sep. 1989, Schatz 2746 ( MO, P, TAN). Sambava district, Antsiranana, sous-préfecture d’Andapa, commune rurale de Doany, fokontany de Betsomanga, versant nord-ouest du Marojejy, camp I, 0.5 km à l’ENE du camp I, relevé LG 18, forêt dense humide sempervivente, versant, 860 m, 19 Oct. 2001, Gautier, Ravelonarivo & Andriamparany 3873 (K); Vallée inférieure de l’Androranga, affluent de la Bemarivo (nord-est) aux environs d’Antongodria [Antongondriha], massif du Betsomanga, 1200 m, 17–20 Nov. 1950, Humbert & Capuron 24314 ( P); Vallée inférieure de l’Androranga, affluent de la Bemarivo (nord-est) aux environs d’Antongodria [Antongondriha], massif du Betsomanga, 1300– 1350 m, 17– 20 Nov. 1950, Humbert & Capuron 24369 ( P). Toamasina province, Analanjirofo region, Mananara district, Rivière Anove, bois, côte est, 200 m, Sep. 1912, Perrier de la Bâthie 3743 ( P). Maroantsetra district, Maroantsetra, Antalavia, ca 50 m inland from the sea, lowland evergreen forest, many Guttiferae, amongst litter on forest floor, steep slope, 150 m, 20 Feb. 1988, Cheek & Dominic 1325 (K, MO, TAN); Côte est, environs de la baie d’Antongil, bois, 400 m, Nov. 1912, Perrier de la Bâthie 3750 ( P). Sainte Marie district, Sainte Marie, Dec. 1849, Boivin s.n. ( P). Atsinanana region, Toamasina II district, Betampona près d’Ambodiriana, W de Tamatave, forêt orientale, Dec. 1925, Perrier de la Bâthie 17438 ( P). Fianarontsoa province, Vatovavy-Fitovinany region, Mananjary district, Kianjavato, route du Mananjary, bords de chemins, Jan. 1964, Bosser 18878 ( P, TAN). Bord de la Lokoho, 1000 m, 2 Jan. 1949, Cours 3437 ( BR, P). Locality unknown, s. loc., s.d., Humblot 453 ( P).

Description

Perennial herb, up to 60 cm tall, rooting at the basal nodes; stems quadrangular in cross section, glabrous or rarely with a few scattered trichomes. Stipule base 1–2 mm long, with a few scattered trichomes; fimbriae 4–8, 1– 4 mm long, colleter-tipped. Leaves petiolate; petioles 2–5.5 mm long, glabrous; blades elliptic or ovate, rarely narrowly elliptic or narrowly ovate, 7–32.5(–92) × 4.5–14.5(–30) mm, glabrous, darker green above, very pale green below; base attenuate; apex acuminate or acute, rarely obtuse; margin glabrous; midvein prominent; secondary veins 3–6 on each side of the midvein, prominent or invisible; intersecondaries invisible. Inflorescences terminal, compound dichasia, multi-flowered; peduncle 0–40 mm long, glabrous or rarely scabrate. Pedicels 0.5–5 mm long, glabrous or rarely scabrate. Flowers heterostylous. Calyx green; tube reduced; lobes 4, triangular or narrowly triangular, 0.9–1.2 × 0.3–0.4 mm, glabrous, colleters in between. Corolla white; tube reduced, 0.2–0.6 mm long, glabrous; lobes 4, narrowly elliptic to elliptic, 2–3 × 0.6–1.2 mm, glabrous or with a few trichomes outside, papillate with trichomes towards the base inside. Stamens inserted near the base of the corolla lobes, exserted for 2.5–3 mm beyond the corolla throat in brevistylous flowers, exserted 0.7–1 mm beyond the corolla throat in longistylous flowers. Anthers ellipsoid, 0.4–0.6 mm long in brevistylous flowers, 0.7–0.8 mm long in longistylous flowers; filaments dorsifixed, 2.3–3 mm long in brevistylous flowers, 0.5–0.6 mm long in longistylous flowers. Pollen tricolporate, oblate spheroidal to prolate spheroidal; E 20–16 μm; P 15–22 μm; ectocolpi long; endocolpi long; tectum bireticulate; suprareticulum microreticulate to reticulate; infrareticulum present as granules in the lumina of the suprareticulum. Ovary 2-locular, broadly depressed obovoid, 0.6–0.7 × 0.8–1 mm, glabrous; placenta attached near the middle of the septum, stalked, globose, bearing numerous ovules per locule. Style ca 1.2 mm long and included in brevistylous flowers, 3.5–4.5 mm long and exserted for 2.6–4 mm beyond the corolla throat in longistylous flowers, papillate or hirtellous; stigma bilobed, lobes ca 0.4 mm long in brevistylous flowers, 0.8–1.3 mm long in longistylous flowers, papillate or hirtellous. Capsules broadly depressed obovoid, 1–2 × 1.8–2.5 mm, crowned with the persistent calyx lobes, glabrous, dehiscence loculicidal. Seeds numerous per locule, triangular in outline, ventral groove absent, 0.4–0.5 × 0.2–0.4 mm, black; seed coat surface reticulate, microsculpturing verruculate.

Distribution

NE to E Madagascar: Antsiranana province, Sava region, Andapa, Antalaha, and Sambava districts; Toamasina province,Analanjirofo region, Mananara, Maroantsetra, and Sainte Marie districts; Toamasina province, Atsinanana region, Toamasina II district; Fianarantsoa province, Vatovavy-Fitovinany region, Mananjary district.

Habitat

Humid forest; laterite and granite substrate; at 0–1300 m elevation.

Conservation status

The species is known from 15 collections, of which two without locality. The number of locations is eight. The extent of occurrence is more than 20,000 km 2; the area of occupancy equals 48 km 2. Throughout its distribution range there is a high human pressure on the habitat of this species, even within the protected areas. A continuing decline of 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.