Acalypha marginata (Poir.) Spreng.

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 : 460-461

33. Acalypha marginata (Poir.) Spreng.

Systema vegetabilium 3: 879 ( Sprengel 1826). — Tragia marginata Poir., Encyclopédie méthodique. Botanique 7: 725 ( Poiret 1806). — Acalypha integrifolia subsp. marginata (Poir.) Coode, Kew Bulletin 34: 42 ( Coode 1979). — Type: Mauritius. “Les Indes Orientales”, s.d. Anonymous (probably P.Commerson) s.n. (holo-, P-LAM[P00382145]).

Acalypha integrifolia subsp. panduriformis Coode, Kew Bulletin 34: 42 ( Coode 1979). — Type : La Réunion. Cliff between St Philippe and St Joseph near Basse vallée, c. 100 m, 26.II.1975, M. J. E. Coode & T. H. Cadet 4968 (holo-, K[K000431108]; iso-, K[K000431107]).

Acalypha integrifolia subsp. marginata var. saltuum Coode, Kew Bulletin 34: 43 ( Coode 1979). — Type: Mauritius. Macabé, 650 m, 15.II.1975, M. J. E. Coode et al. 4874 (holo-, K[K000431106]; iso-, P[P04779351], MAU[n.v.]).

ICONOGRAPHY. — Fig. 54E.

ETYMOLOGY. — The epithet probably refers to the discolorous margin of the leaf blades.

DISTRIBUTION AND HABITAT. — Endemic to Mascarene Islands ( Mauritius and La Réunion). Lowland evergreen moist forest and secondary forest. Altitudinal range in Mauritius 420-650 m, in La Réunion 100-1200 m ( Fig. 52 ).

PRELIMINARY CONSERVATION ASSESSMENT. — Acalypha marginata is known from Mauritius and La Réunion. Its EOO is estimated to be 8 916 km 2 and its AOO 44 km 2, which is less than the 500 km 2 threshold of the B2 subcriterion of the Endangered category. For the status of forests on Mauritius, see the assessment of A. crateriana comb. nov.; for those on La Réunion, see the assessment of A. filiformis . Ongoing habitat loss will cause continued decline of its EOO and AOO. Acalypha marginata is assessed as Near Threatened (NT) under criterion B. It meets the EOO and 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. — 38 collections. Mauritius. Anonymous 490 (P[P04779328]); Anonymous s.n. (G[G00324533]); Anonymous s.n. (G[G00324534]); Anonymous s.n. (G[G00324537]); Anonymous s.n. (P[P04779363] pr.p.); Ayres, P.B. s.n. (P[P04779841]); Bouton, L. 23 (P[P04779354]), s.n. (G[G00324535]); Commerson, P. s.n. (P[P00382145]), s.n. (P[P04779358]), s.n. (P[P04779360]); Coode, M.J.E. 4370 (K, P[P04779362]), 4778 (K, MO[MO-2452040]), 4867 (K, P[P04779348]), 4868 (K, P[P04779350]), 4869 (K), 4870 (K), 4874 (K[K000431106], P[P04779351]), 4876 (K); Lorence, D. 1954 (K, MO[MO-2452046], P[P04779347]).

La Réunion. Billiet, F. 585 ( BR [BR0000014628085], K, WAG[WAG.1578518]); Boivin, L.H. s.n. (P[P04779331]), s.n. (P[P04779352]); Bosser, M.J. 21043 (P[P04779330]); Brown, Ab. s.n. (P[P04779375]); Cadet, Th. 4925 (K); Commerson, P. s.n. (P[P04779356]), s.n. (P[P04779357] pr.p.), s.n. (P[P04779359]); Coode, M.J.E. 4967 (K), 4968 (K[K000431107, K000431108]), 5006 (K); d’Alleizette, Ch. s.n. (L[L0241920]); Friedmann, F. 847 (P[P04779333]), 919 (K, P[P04779335, P04779353]); Léman, D.S. s.n. (P[P04779332]), s.n. (P[P04779355]); Richard, M. s.n. (P[P04779361]).

REFERENCES. — Bojer (1837: 286); Baillon (1858: 443); Baillon (1861: 267); Baker (1877: 315); Cordemoy (1895: 343); Palacký (1907: 25); Pax & Hoffmann (1924: 106); Coode (1982: 73) as A. integrifolia subsp. panduriformis , A. integrifolia subsp. marginata ; Coode (1982: 74) as A. integrifolia var. saltuum ; Govaerts et al. (2000: 69) as A. integrifolia subsp. marginata ; Seebaluck et al. (2015: 152); Montero Muñoz et al. (2018a: 104).

DESCRIPTION

Shrubs, leaf persistence unknown, to 3 m tall, monoecious. Branches velutinous, glabrescent when mature. Axillary buds naked, hispid. Stipules to 10 mm long, linear-lanceolate,densely pubescent with simple, appressed trichomes, margin papillate. Petioles thick, 0.5-3 cm long, indumentum similar to that on young branches, glabrescent. Leaf blades (4-)6-17-(21) × (2-)2.5-7(-8) cm, usually elliptic to elliptic-lanceolate, sometimes obovate, chartaceous; base rounded to cuneate; apex acute to subacuminate; margin crenate-serrate to serrate, discolorous, teeth rounded to acute, slightly callose-edged; upper and lower surfaces pubescent with simple, short, appressed trichomes, glabrescent; venation pinnate, secondary veins 13-14 per side. Stipels absent. Inflorescences spiciform (male) or glomerulate (female), unisexual, axillary. Male inflorescences to 11cm long; peduncle to 2 mm long, pubescent with simple, short, erect trichomes; flowers glomerate; bracts to 1 mm long, triangular, densely appressed-pubescent. Female inflorescences 0.2-0.4 cm long; sessile;; bracts 3-4, sessile,not enlarging in fruit, to 0.5 mm long, triangular, appressed-pubescent; margin entire; bracteoles absent. Male flowers:pedicel to 0.6 mm long, sparsely hairy;buds to 0.8 mm diameter, sparsely hairy. Female flowers 1 per bract, sessile; sepals 3, to 1.2 mm long, elliptic, appressed-pubescent; ovary c. 1 mm diameter, 3-lobed, papillose-hispid, papillae acute, ending in a simple trichome to 1 mm long, surface pubescent with simple, short trichomes; styles 3, to 2.5 mm long, distinct, rachis thick,sparsely hairy with simple,short,appressed trichomes, each divided into c. 10 segments. Allomorphic flowers not seen. Capsules to 3.5 mm diameter, papillose, papillae to 0.5 mm long, ending in a simple trichome to 1 mm long, surface sparsely hairy with simple, erect trichomes to 0.5 mm long. Seeds c. 3 × 2.2 mm, pyriform, minutely foveolate.

NOTE

Acalypha marginata was treated by Coode (1979) as A. integrifolia subsp. marginata . We consider A. marginata to be a distinct species differentiated mainly by its variegated leaf blades and minute female bracts that are not accrescent in fruit, vs uniformly colored leaf blades and conspicuous female bracts that are accrescent in fruit in A. integrifolia . We include as synonyms A. integrifolia subsp. panduriformis and Acalypha integrifolia subsp. marginata var. saltuum because the morphology of these taxa overlap too much with those of A. marginata to accept them as distinct.

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. 52. — Distribution map of Acalypha marginata (Poir.) Spreng. in the Mascarene Islands.