Acalypha diminuta 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 : 416-417

1. Acalypha diminuta Baill.

Histoire physique, naturelle et politique de Madagascar, Atlas , 2, fasc. 27: t. 194 ( Baillon 1891). — Type: pl. 194 in Baillon (1891), holotype.

ICONOGRAPHY. — Baillon (1891: pl. 194); Leandri (1942: 254); Fig. 28A.

ETYMOLOGY. — The specific epithet probably refers to the small size of the male segment of the inflorescences.

DISTRIBUTION AND HABITAT. — Endemic to Madagascar (Diana, Sofia, Boeny, Melaky, Menabe, Atsimo-Andrefana, Androy, and Alaotra-Mangoro [only one collection]). Dry deciduous forest, spiny thickets; sometimes in riparian forest. On Tertiary limestone, sandstone, and unconsolidated sand. Altitudinal range (40-) 50-850 (-1450) m ( Fig. 13 ).

PRELIMINARY CONSERVATION ASSESSMENT. — The EOO of Acalypha diminuta is estimated to be 310 217 km 2 and its AOO 104 km 2, which is less than the 500 km 2 threshold of the B2 subcriterion of the Endangered category. This species grows mainly in the western dry deciduous forests. Most of these forests are highly degraded (40%) and the major threat to the dry deciduous forests is slash-and-burn clearing for grazing and agricultural lands. Grasslands and pastures have replaced the forests in the western slope and the central highlands ( Moat & Smith 2007; Gautier et al. 2018). Ongoing habitat loss will cause continued decline of its EOO and AOO. Acalypha diminuta 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 listing it under the Endangered category.

MATERIAL EXAMINED. — 44 collections. Madagascar. Appert, O.P. 31 (P[P04779831]), 41 (P[P00360914]); Bosser,M.J.13885 (P[P04779814, P04779816]), 13993 (P[P04779821, P04779824]); Capuron, R. 20581- SF (K, P[P05547246]); Cours, G. 1819 (P[P05547244]); d’Alleizette, Ch. s.n. (L[L0241302]); Decary, R. 16089 (K, P[P05547245]), 16122 (P[P05547250]); Gillespie, L. 4034 ( US [US01287336]), 10704 ( MO); Grevé, H. 223 (P[P00360915]); Hladik, A. AH7158 (P[P00780280, P00780618]); Humbert , H. 11237 (B[B100009884], P[P00508516, P00360918]), 11288 (P[P00360919]), 11335 ( BR [BR0000005045020], NY, P[P00508515, P00360917]), 11506 (P[P00360916, P00508517]); Jard. Bot. Tananarive 5749 (P[P00360923]); Keraudren-Aymonin, M. 25933 (P[P00360920]); Leandri, J. 489 (K, P[P05547061]), 491 ( US [US01287337]), 3533 (P[P05547060]), 3569 (B[B100480050], G, NY, P[P05547243]), 3620 (G, P[P05547242]); Lorence, D. 2084 (K, P[P00360921]); Peltier, J.1432 (P[P05547022]); Perrier de la Bâthie, H. 379 (P[P05577069, P05577067]), 9632 (P[P00508520, P00508521, P00360922]), 9816 (P[P00508519, P00360924, P00360925]), 9818 (P[P00360499, P00360500, P00508518]), 9819 (P[P05547062]); Phillipson, P.B.2431 ( MO, P[P00360497]), 2750 (K, MO, P[P00360498]); Pichon, C. CP113 (P[P00780436]); Rakotozafy,A. 319 (P[P05547065]); Ralimanana, H. 239 (G[G00405396], DBEV, K, MO[MO-2965792], P[P05481882], TAN); Richard, M. 173 (K), 547 (K); Service Forestier Madagascar 16576-SF (P[P00360912, P00508522, P00508523]), 27956-SF (P[P00360913]); Seyrig, A. 254 (P[P05547066]), 254B (P[P05547064]), 254 C (P[P05547063]); Wohlhauser, S. SW 310 (G[G00405345], P[P04779528]).

REFERENCES. — Baillon (1895b: 1197); Palacký (1907: 25); Pax & Hoffmann (1924: 21); Leandri (1935: 42); Leandri (1942: 253); Govaerts et al. (2000: 60); Sagun et al. (2006: 124); Montero Muñoz et al. (2018a: 95).

DESCRIPTION

Shrubs, deciduous, to 3 m tall, monoecious. Branches laxly pubescent with simple, short, curved trichomes and simple, erect trichomes, glabrescent when mature; brachyblasts present. Axillary buds subspherical, to 1.2 × 1 mm, perulate, perules 2, imbricate, chartaceous, brownish, glabrous. Stipules to 3 mm long, lanceolate to linear-lanceolate, ciliate with some sparse, simple, short trichomes. Petioles 0.2-0.3 cm long, indumentum similar to that on young branches. Leaf blades 3-5(-5.5) × 1.4- 2 cm, usually elliptic to elliptic-lanceolate, sometimes narrowly elliptic-lanceolate, membranous; base rounded to cordate; apex obtuse and mucronate; margin entire to crenate towards apex, teeth rounded; upper surface subglabrous, with some sparse, simple trichomes on veins; lower surface glabrous, with flattened resinous glands; venation pinnate, secondary veins 5-7 per side. Stipels absent. Inflorescences racemose, androgynous, terminal, to 5 cm long, mostly female with short male segment; peduncle filiform, to 30 mm long, appressed-pubescent. Female segment to 2 cm long; bracts 1-7, not enlarging in fruit, to 1 mm long, lanceolate, sparsely hairy; bracteoles absent. Male segment persistent, to 0.5 cm long; flowers in racemose to subumbelliform cluster; bracts to 0.8 mm long, triangular-lanceolate, sparsely hairy with simple, arachnoid trichomes. Male flowers: pedicel to 0.8 mm long, sparsely hairy; buds to 1 mm diameter,sparsely hairy with simple, arachnoid trichomes. Female flowers 1 per bract, pedicellate; pedicel to 7 mm long, indumentum similar to that on peduncle; sepals 5, to 0.8 mm long, triangular, ciliate with simple trichomes to 0.5 mm long; ovary c. 1 mm diameter, 3-lobed, papillose, surface glabrous but with flattened resinous glands; styles 3, to 2.5 mm long, distinct, glabrous, each divided into c. 10 segments. Allomorphic flowers not seen. Capsules to 4 mm diameter, papillose, glabrous, with papillae more or less capitate, surface glabrous but with flattened resinous glands. Seeds c. 2 mm diameter, globose, minutely foveolate.

NOTES

1) Acalypha diminuta was first illustrated, without description, in Baillon’s Histoire Naturelle des Plantes ( Baillon 1891). The first description of this species, based only on Baillon’s illustration, appears in Engler’s Pflanzenreich ( Pax & Hoffmann, 1924); and 2) this is one of only two species included in Acalypha subgen. Androcephala Pax & K.Hoffm. ; the other is A. gillmanii Radcl. -Sm. of eastern Africa ( Levin et al. 2022).

Figures

FIG. 28. — A, Acalypha diminuta Baill. (photo by L. Gillespie, L. Gillespie 10704); B, C, A. andringitrensis Leandri (photo by P. Phillipson, P. Phillipson 5669); D, E, A. boinensis Leandri (photo by L. Gillespie, L. Gillespie 10813); F, A. decaryana Leandri (photo by P. Lowry II, P. Lowry II 6991); G, H, A. emirnensis Baill. (photo by L. Nusbaumer, P. Ranirison PR994).

FIG. 13. — Distribution map of Acalypha diminuta Baill. in Madagascar.