Acalypha leptomyura Baill.

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 : 456

29. Acalypha leptomyura Baill.

Histoire physique, naturelle et politique de Madagascar Atlas , 2, Fasc. 27: t. 191 ( Baillon 1891). — Type: Madagascar. Baillon 1891: pl. 191, holotype.

ICONOGRAPHY. — Baillon (1891: t. 191); Figs 54C, D ; 57A.

ETYMOLOGY. — The epithet is taken from the Greek ‘leptos’, fine or delicate, ‘ myos ’, mouse, and ‘oura’, tail. It possibly refers to the thin rachis of the inflorescences.

DISTRIBUTION AND HABITAT. — Endemic to Madagascar (Diana, Sofia, Betsiboka, Alaotra-Mangoro, Analamanga, Bongolava, Melaky, Menabe, Atsimo-Andrefana, Androy, Anosy, Atsimo-Atsinanana, and Ihorombe). Lowland evergreen moist forest, dry deciduous forest, and sclerophyllous woodland. On sandstone, unconsolidated sand, and Mesozoic limestone. Altitudinal range (15-) 100-1000 (-1400) m ( Fig. 48 ).

PRELIMINARY CONSERVATION ASSESSMENT. — The EOO of Acalypha leptomyura is estimated to be 385 705 km 2 and its AOO 120 km 2, which is less than the 500 km 2 threshold of the B2 subcriterion of the Endangered category. This species grows in a variety of forests: dry deciduous forests, (see assessment of A. diminuta ), lowland evergreen moist forests (see assessment of A. emirnensis ), and sclerophyllous woodlands, which mostly have been converted to secondary grasslands by human activities such as fires for agriculture or cattle grazing ( Kull 2003; Gautier et al. 2018). This species has been collected in some protected areas, but it is also known from several unprotected forests subject to various threats. Ongoing habitat loss will cause continued decline of its EOO and AOO. Acalypha leptomyura is assessed as Near Threatened (NT) under criterion B. It meets the AOO values needed for a threatened category, but the number of locations is too high to meet the conditions required for a listing under the Endangered category.

MATERIAL EXAMINED. — 42 collections. Madagascar. Andriamihajarivo,T. 1108 ( MO [MO-3025023], P[P01104326], TAN); Baron, R. 4576 (P[P04779799]), 4685 (P[P05547007, P05547009]); Bosser,M.J. 9078 (P[P04779786]), 9089 (P[P04779785]), 10256 (P[P00324462]); Capuron, R. 2020 (P[P05547053, P05547054]); d’Alleizette, Ch. s.n. (L[L0241867]); Decary, R. 1128 (P[P05547011]), 7312 (C, P[P00513075]), 7535 (G, P[P05604421], S), 15818 (P[P05510105, P00324523]), 15823 (P[P05547221]), 17043 (P[P05547217]), 18845 (P[P05547220]); Dequaire, J. 27125 (P[P05547219]); Grevé, H. 109 (K, P[P00513081, P00513082, P00513083]); Humbert , H. 3533 (G, K, P[P00513076, P00513077, P00513078]), 4089 (P[P00513079, P00513080]), 7089 (P[P05547223]), 13829 (P[P00513074]), 18819 (P[P00513067, P00513068]), 19671 (K, P[P05547222]); Labat, J.-N. 2320 (P[P023912], WAG[WAG.1578522]); Leandri, J. 150 (P[P05547050]), 154 (P[P05547051]); 167 (P[P00324570]), 600 (P[P00513065, P00513066]), 930 (P[P05547052]), 2121 (G, P[P05547225]); Morat, P. 4714 (P[P05547008, P05547010]), 4736 (P[P05546999, P05547000, P05547001, P05547002, P05547003]); Nicoll, M.F. 162 (K, MO, P[P00513064]); Perrier de la Bâthie, H. 9812 (P[P00513069, P00513070, P00513071, P00513072]); Rakotonao 11308 (P[P05547005]); Randrianarivony, T. 749 (P[P01084145]); Randrianasolo, A. 6866 (P[P05547006]); Rasamison 12296 (P[P05547049]), 12314 (P[P05547218]); Service Forestier Madagascar 54 (G, P[P00513073]), 166-SF (P[P00513163]); Waterlot, M. 624 (P[P05547004]).

REFERENCES. — Baillon (1892: 1004); Koehne (1892: 131); Palacký (1907: 25); Pax & Hoffmann (1924: 112); Leandri (1942: 271); Govaerts et al. (2000: 72); Montero Muñoz et al. (2018a: 103).

DESCRIPTION

Shrubs, deciduous, to 1.5 m tall, divaricately branched, monoecious. Branches pubescent with simple, curved, antrorse trichomes, glabrescent when mature. Axillary buds spherical, to 0.5 mm diameter, perulate, perules 2, imbricate, chartaceous, brownish, ciliate. Stipules to 1.5 mm long, linear-lanceolate, glabrous except margin with some sessile glands and apex with some hyaline trichomes to 1 mm long. Petioles filiform, 0.3-0.7(-1.5) cm long, indumentum similar to that on young branches, base also with hyaline trichomes to 1 mm long. Leaf blades (1.5-)2.5-3.5(-4.5) × 1-2(-2.5) cm, ovate-lanceolate to subtriangular, membranous; base obtuse to truncate; apex subacuminate, acumen to 8 mm long, rounded to subacute; margin crenate to serrate, teeth rounded to subacute, sometimes with gland at apex; upper surface laxly pubescent with sparse, simple, long, erect trichomes, and with simple, short, curved trichomes on veins; lower surface indumentum similar to that on upper surface but denser; venation actinodromous, basal veins 3, secondary veins 4-5 per side. Stipels slightly fleshy, linear-lanceolate, to 0.5 mm long, glabrous. Inflorescences spiciform, androgynous, and solitary female bracts, axillary. Androgynous inflorescences to 4 cm long, mostly male with 1 female bract; sessile; rachis filiform, pubescent. Female segment: bract 1, sessile, enlarging in fruit to 5 mm diameter, suborbicular, subglabrous, with some sparse, simple, erect trichomes; margin entire to crenate, teeth 5-7, rounded, central tooth sometimes prominent; sterile female bracts sometimes present, similar to regular female bracts, to 1 mm diameter; bracteoles absent. Male segment persistent, to 3.5 cm long; flowers glomerate; bracts to 0.3 mm long, triangular-lanceolate, sparsely hairy with sparse trichomes, margin with some sessile glands. Solitary female bracts sessile, similar to those of androgynous inflorescence. Male flowers: pedicel to 0.3 mm long, sparsely hairy; buds to 0.5 mm diameter, subglabrous, papillose. Female flowers 1 per bract, sessile; sepals 3, to 0.5 mm long, triangular, ciliate; ovary c. 0.6 mm diameter, 3-lobed, papillose-hispid, papillae minute, rounded, ending in simple trichome to 1 mm long, surface pubescent with simple, short trichomes; styles 3, to 3 mm long, distinct, subglabrous, with some long, hyaline trichomes, each divided into c. 10 segments. Allomorphic flowers not seen. Capsules to 2 mm diameter, papillose-hispid, papillae rounded, ending in hyaline trichome to 1 mm long., surface pubescent with simple, short trichomes. Seeds c. 1.5 × 1.2 mm, pyriform, minutely foveolate.

Figures

FIG. 54. — A, B, Acalypha integrifolia Willd. (photo by J. M. Sarrailh); C, D, A. leptomyura Baill. (photo by T. Randrianarivony, T. Randrianarivony 749); E, A. marginata (Poir.) Spreng. (photo by F. Duban); F, A. mayottensis I.Montero & Cardiel (photo by J.-N. Labat, J.-N. Labat 3268); G, H, A. medibracteata Radcl.-Sm. & Govaerts (photo by L. Gillespie, L. Gillespie 10828).

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. 48. — Distribution map of Acalypha leptomyura Baill. in Madagascar.