Acalypha linearifolia Leandri

Muñoz, Iris Montero, Levin, Geoffrey A. & Cardiel, José María, 2023, Monograph of Acalypha L. (Euphorbiaceae) of the Western Indian Ocean Region, with the description of a new species from Mayotte, Adansonia (3) 45 (26), pp. 395-496 : 458

31. Acalypha linearifolia Leandri

Notulae Systematicae. Herbier du Muséum de Paris. Phanérogramie. Paris 10: 275 ( Leandri 1942). — Type: Madagascar. Prov. Toliara, Ambovombe, Kotoala, 21.I.1931, R. Decary 8423 (lecto-, designated by Montero Muñoz et al. [2018a: 103]: P[P00513090]; isolecto-, S[S07-14664],TAN[TAN000510], US [ US 01014148]) . — Former syntype: Madagascar. Prov. Toliara, delta de la Linta, 17-24.VIII.1928, H. Humbert & C. F. Swingle 5385 (P[P00513086, P00513087, P00513088, P00513089], US [ US 00096361]) .

ICONOGRAPHY. — Leandri (1942: 276); Fig. 57C.

ETYMOLOGY. — The specific epithet refers to the linear leaf blades characteristic of this species.

DISTRIBUTION AND HABITAT. — Endemic to Madagascar (Atsimo-Andrefana, Androy, and Atsinanana [one known collection]). Littoral forest and littoral thicket. On unconsolidated sand and Tertiary limestone. Altitudinal range sea level to 10 m ( Fig. 50 ).

PRELIMINARY CONSERVATION ASSESSMENT. — Acalypha linearifolia is known from five collections. Its EOO is estimated to be 84 834 km 2 and its AOO 16 km 2. The large EOO is due to one collection presumably made in Toamasina by G. Cours. The other collections are from southern Madagascar. This species grows mainly in littoral forests (see assessment of A. gracilipes ). There are no collections made in protected areas. In addition, no specimens of this species have been collected for 70 years, so we cannot rule out that this species has become extinct. Due to habitat loss and the absence of recent collections, A. linearifolia is assigned a preliminary conservation status of Endangered: EN B2ab(ii,iii,iv); although it meets the values needed for a threatened category based on the B2 subcriterion, this species could probably be assessed as extinct (EX).

MATERIAL EXAMINED. — 4 collections. Madagascar: Cours, G. 4637 (P[P00324458, P00513085]), 4638 (G, P[P00513084]); Decary, R. 8423 (P[P00513090], S[S07-14664], TAN[TAN000510], US[US01014148]); Humbert , H. 5385 (P[P00513086, P00513087, P00513088, P00513089], US[US00096361]).

REFERENCES. — Govaerts et al. (2000: 72); Montero Muñoz et al. (2018a: 103).

DESCRIPTION

Shrubs, probably evergreen, to 1.5 m tall, monoecious. Branches densely pubescent with stellate trichomes, glabrescent when mature. Axillary buds ovoid, to 1 × 0.7 mm, perulate, perules 2, valvate, membranous, brownish, pubescent with stellate trichomes; Stipules to 1 mm long, lanceolate, pubescent with stellate trichomes, margin with some sessile glands. Petioles to 0.2 cm long, indumentum similar to that on young branches. Leaf blades ericoid, 3.5-4.7 × 0.1-0.2 cm, linear, coriaceous; base acute; apex obtuse to rounded; margin entire, revolute; upper and lower surfaces densely pubescent with stellate trichomes; venation prominent on lower surface, pinnate, secondary veins to 15 per side. Stipels absent. Inflorescences spiciform, male, and solitary female bracts, axillary. Male inflorescences to 1.4 cm long, with glossy exudate; subsessile, peduncle to 2 mm long, pubescent with stellate trichomes; flowers glomerate; bracts orbicular, to 0.5 mm diameter, pubescent with stellate trichomes. Solitary female bracts subsessile, peduncle to 2 mm long, pubescent with stellate trichomes; bract short-petiolate, enlarging in fruit to 4 × 5 mm, suborbicular, densely pubescent with stellate trichomes; margin entire to denticulate, central tooth not prominent; bracteoles absent. Male flowers: pedicel to 0.5 mm long, glabrous; buds to 0.5 mm diameter, pubescent with stellate trichomes. Female flowers 1 per bract, sessile; sepals 3, to 1 mm long, ovate-lanceolate, pubescent with stellate trichomes; ovary c. 1 mm diameter, 3-lobed, papillose, surface pubescent with stellate trichomes; styles not seen. Allomorphic flowers not seen. Capsules to 3 mm diameter, papillose, surface pubescent with stellate trichomes. Seeds c. 2 × 1.8 mm, subglobose, minutely foveolate.

Figures

FIG. 57. — Mature female bracts: A, Acalypha leptomyura Baill. (J.-N. Labat & T. Deroin 2320); B, A. levinii I.Montero & Cardiel (L. Gillespie 10809); C, A. linearifolia Leandri (G. Cours 4638); D, A. magistri I.Montero & Cardiel (D. Ravelonarivo 273); E, A. mayottensis I.Montero & Cardiel (J.-N. Labat, F. Barthelat, C.M. Hladik & A.B. Sifary 3272); F, A. medibracteata Radcl.-Sm. & Govaerts (R. Decary 16103); G, A. menavody (Leandri) I.Montero & Cardiel (M. Bardot-Vaucoulon 1016); H, A. nusbaumeri I.Montero & Cardiel (L. Nusbaumer LN1169). Illustration by Iris Montero Muñoz. Scale bars: A, C, D, F, H, 1 mm; B, E, G, 2 mm.

FIG. 50. — Distribution map of Acalypha linearifolia Leandri in Madagascar.