Acalypha tremula I.Montero & Cardiel

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 : 478

46. Acalypha tremula I.Montero & Cardiel

Systematic Botany 45 (1): 127 ( Montero Muñoz et al. 2020a). — Type: Madagascar. Sava [Antsiranana], Province de Diego-Suarez, Vohemar , commune rurale de Daraina, forêt d’Ankaramy , 181 m, 13°17.1’S, 49°40.91’E, 26.II.2004, L. Nusbaumer & P. Ranirison 1227 (holo-, G[G00006790], iso-, K, P[P04786267, P05547264], TAN). — Paratypes: Madagascar. Sava region (Antsiranana prov.), Fivondronana , Diego II, commune Mahavanona , Montagne des Français , forêt d’Ampitiliantsambo , à 3 heures de marche à pied, à l’Est d’Andranomanitra , 205 m, 12°23’13”S, 49°23’04”E, 14.I.2005, R. Randrianaivo et al. 1160 ( BR [ BR0000005242887 ], CNARP, MO [MO2965736], P, TAN); Ambilobe, Mahamasina, Réserve Spéciale d’Ankarana, chemin d’Ambohimalaza, sous-bois sur basalte, 110 m, 12°58’1.20”S, 49°6’5.11”E, 08.II.2003, M. Bardot-Vaucoulon 1400 (P[P00455711], K, MO [MO-2966207], TAN); Vohemar, commune rurale de Daraina, forêt de Solaniampilana-Maroadabo, 422 m, 13°06.50’S, 49°33.97’E, 03.II.2006, L. Nusbaumer & P. Ranirison LN 2181 (G[G00074394]).

ICONOGRAPHY. — Montero Muñoz et al. (2020a); Figs 69G ; 73B. ETYMOLOGY . — The epithet refers to the resemblance of the long petiolate leaves of this species to those of the Eurosiberian tree Populus tremula L. ( Salicaceae ).

DISTRIBUTION AND HABITAT. — Endemic to Madagascar (Diana and Sava). Dry deciduous forest. On clay soil on basement rocks. Altitudinal range 110-420 m ( Fig. 68 ).

PRELIMINARY CONSERVATION ASSESSMENT. — The EOO of Acalypha tremula is estimated to be 2 609 km 2 and its AOO 16 km 2. It has been collected from three protected areas: Montagne des Français (see assessment of A. gillespieae ), Ankarana Special Reserve (see assessment of A. ankaranensis ), and Loky-Manambato (see assessment of A. menavody ). The small number of locations, together with continuing habitat loss and degradation in these areas, lead us to assess A. tremula as Endangered: EN B1ab(i,iii) + B2ab(ii,iii). MATERIAL EXAMINED. — 4 collections. Madagascar: Bardot-Vaucoulon, M. 1400 (K, MO[MO-2966207], P[P00455711], TAN); Nusbaumer, L. LN 1227 (G[G00006790], K, P[P05547264, P04786267]), LN 2181 (G[G00074394]); Randrianaivo, R. 1160 (BR[BR0000005242887], CNARP, MO[MO-2965736], TAN).

DESCRIPTION

Shrubs, probably deciduous, to 4 m tall, divaricately branched, monoecious. Branches slightly angular,dark brown, rugose,pubescent with simple, antrorsely curved trichomes, glabrescent when mature. Axillary buds, spherical, to 1 mm diameter, perulate, perules 2, imbricate, chartaceous, scarious, glabrous. Stipules to 3 mm long, triangular-lanceolate, apex acute, midrib prominent, scarious toward margins, glabrous. Petioles slender, (3-) 4-6 cm long, glabrous. Leaf blades (4-)5-7.5 × (3.5-) 4-6.5 cm, broadly ovate to subtriangular, subchartaceous; base rounded to truncate; apex acuminate, acumen 0.5-1 mm long, acute; margin crenate to serrate,teeth rounded to subacute; upper surface subglabrous, with some sparse, simple, erect trichomes; lower surface subglabrous, with some simple trichomes on veins; axils of secondary veins with hair-tuft domatia; margin ciliate in sinuses (except on older leaves); venation actinodromous, basal veins 3, secondary veins 3-5 per side. Stipels absent. Inflorescences spiciform, androgynous and male, axillary, sometimes bearing erinaceous galls. Androgynous inflorescences to 7 cm long, mostly male with 1 female bract; sessile. Female segment: bract 1, sessile, enlarging in fruit to 3 × 4 mm, reniform, glabrous; margin subentire, with minute blackish papillae; bracteoles absent. Male segment persistent, to 6.5 cm long; flowers glomerate; bracts to 0.5 mm long, ovate-lanceolate, sparsely hairy with some simple trichomes at apex. Male inflorescences to 7 cm long, filiform; sessile; rachis thin, glabrous; bracts like those on androgynous inflorescences. Male flowers: pedicel to 0.5 mm long, glabrous; buds to 0.5 mm diameter, glabrous. Female flowers 1 per bract, sessile; sepals 3, to 1 mm long, triangular-lanceolate,ciliate; ovary c. 1.5 mm diameter, 3-lobed, echinate with linear projections to 2 mm, hispidulous and ending in simple trichome(s) or gland, surface hispidulous; styles 3, to 5 mm long, distinct or slightly connate at base, sparsely hairy with simple, short trichomes, each divided into 5-7 slender segments. Allomorphic flowers not seen. Capsules to 3 mm diameter, erinaceous, projections linear,to 3.5mm long, acute, hispidulous,ending in trichome(s) or gland, surface sparsely hispidulous. Seeds c. 1.3 × 1 mm, pyriform, smooth.

Figures

FIG. 69. — A, Acalypha nusbaumeri I.Montero & Cardiel (photo by L. Nusbaumer, L. Nusbaumer LN1169); B, A. pervilleana Baill. (photo by L. Gillespie,L. Gillespie 10649); C, A. perrieri Leandri (photo by L. Gillespie, L. Gillespie 10835); D, A. radula Baker (photo by L. Gillespie, L. Gillespie 10758); E, A. rottleroides Baill. (photo by L. Nusbaumer, L. Nusbaumer 1933); F, A. spachiana Baill. (photo by L. Gillespie, L. Gillespie 10856); G, A. tremula I.Montero & Cardiel (photo by R. Randrianaivo, R. Randrianaivo 1160); H, A. urophylla Boivin ex Baill. (photo by L. Nusbaumer, L. Nusbaumer LN1663).

FIG. 73. — Mature female bracts:A, Acalypha spachiana Baill. (H. Humbert 19791); B, A. tremula I.Montero & Cardiel (R. Randrianaivo et al. 1160); C, A. urophylla Boivin ex Baill. (J. Goudot s.n.); D, A. urophylla (J. M. Hildebrandt 2914); E, F, A. urophylla (S. Malcomber 1746); G, A. vulneraria Baill. (F. Randriatafika 812); H, A. wilkesiana Müll.Arg. (Sagun et al. 2010; Sagun & Risna SR50). Illustration by Iris Montero Muñoz. Scale bars: 1 mm.

FIG. 68. — Distribution map ofAcalypha tremula I.Montero & Cardielin Madagascar.