Acalypha filiformis Poir.

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 : 436-437

15. Acalypha filiformis Poir.

Encyclopédie méthodique. Botanique 6 (1): 205 ( Poiret 1804). — Type: Mauritius. “ Île de France ”, s.d., P. Commerson s.n. (lecto-, designated by Montero Muñoz et al. [2018a: 97]: P[P05604464]; isolecto-, MPU[MPU014933], P[P05604471]).

Acalypha filiformis var. arborea Poir., Encyclopédie méthodique. Botanique 6 (1): 205 ( Poiret 1804). — Acalypha reticulata var. arborea (Poir.) Müll.Arg. , Linnaea 34: 32 ( Müller Argoviensis 1865). — Type: La Réunion. “Elle croît a l’île Bourbon”, 1774, P. Commerson s.n. (holo-, P[P05604473]!; iso-, MPU[MPU014949]!).

Tragia reticulata Poir., Encyclopédie méthodique. Botanique 7: 725 ( Poiret 1806). — Acalypha reticulata (Poir.) Müll.Arg. , Prodromus Systematis Naturalis Regni Vegetabilis 15 (2): 851 ( Müller Argoviensis 1866). — Type: La Réunion. “l’Île-de-Bourbon”, s.d., P. Commerson s.n. (holo-, P-LAM[P00382118]; iso-, P[P05604477]).

Acalypha arborea Commers. in Poir., Encyclopédie méthodique. Botanique 6: 205 ( Poiret 1804) nom. nud.

Acalypha lantanaefolia Bojer, Hortus Mauritianus 286 ( Bojer 1837)

nom. nud. ICONOGRAPHY. — Fig. 35C.

ETYMOLOGY. — The epithet probably refers to the thin peduncles and rachis of the inflorescences.

DISTRIBUTION AND HABITAT. — Endemic to Mascarene Islands ( Mauritius and La Réunion). Lowland evergreen moist forest and secondary forest. Altitudinal range in Mauritius 240-500 m and in La Réunion 100-600 m ( Fig. 30 ).

PRELIMINARY CONSERVATION ASSESSMENT. — Acalypha filiformis is known from Mauritius and La Réunion. Its EOO is estimated to be 8 509 km 2 and its AOO 60 km 2, which is less than the 500 km 2 threshold of the B2 subcriterion of the Endangered category. For the situation of Mauritius forests, see the assessment of A. crateriana comb. nov. In La Réunion the situation is somewhat more favorable. This island still has at least 52% of its native forests, but 18% of the remaining native forest is moderately to highly invaded by alien species, causing the habitat quality to decrease ( Strasberg et al. 2005). Ongoing habitat loss and degradation will cause continued decline of its EOO and AOO. Acalypha filiformis is assessed as Near Threatened (NT). 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. — 96 collections. Mauritius. Anonymous s.n. (G[G00324525]); Anonymous s.n. (G[G00324529]); Anonymous s.n. (G[G00324530]); Anonymous s.n. (P[P05604442]); Anonymous s.n. (P[P05604468]); Anonymous s.n. (P[P04779380] pr.p.); Anonymous s.n. (G[G00324520]); Anonymous s.n. (G[G00324530]); Barclay, C. 15464 (K); Blackburn, J. 46 (K); Boivin, L.H. s.n. (P[P04779575]), s.n. (P[P05604457]), s.n. (P[P05604461]); Bouton, L.s.n. (G[G00324523]), s.n. (G[G00324524]), s.n. (G[G00324526]), s.n. (G[G00324527]); Brown, Ab. s.n. (K); Commerson, P. s.n. (P[P04779572]), s.n. (P[P04779577]), s.n. (P[P05604438]), s.n. (P[P05604439]), s.n. (P[P05604464, P05604471], MPU[MPU014933]), s.n. (P[P05604465]), s.n. (P[P05604466]), s.n. (P[P05604467]), s.n. (P[P05604469]), s.n. (P[P05604470]), s.n. (P[P05604472]), s.n. (P[P00799457]); Coode M.J.E. 5062 (P[P05604456]); Friedmann, F. 2618 (P[P05604379]); Grondal s.n. (S[S17-37513]); Guého, J. 17043 (P[P04779573]), 17048 (P[P05604381]); Jussieu, A. s.n. (S[S17-37570]); Koechlin, B. 194 (P[P05604424]); Lorence, D. M70 (C, MO[MO-2966288], WAG[WAG.1578519, WAG.1578520]), DL 1221 (K, P[P05604380]), 1226 ( MO [MO-2966279]), 2261 (K, P[P05604451]), 2262 (K, US[US01287450]); Perrotet, M. s.n. (P[P05604453]), s.n. (P[P05604462]); Richard, M. s.n. (P[P05604455]), s.n. (P[P05604463]); Royal Botanical Gardens 20 (K); Sieber, F.W. 64 (G), 179 ( BR [BR0000021450310], G[G00324532], P[P05604454], W[W320333]), 369 (P[P05604460]).

La Réunion. Anonymous 661 (L[L0240843]); Barclay, C. 1306 (K); Barthe, M. s.n. (P[P04779568]); Boivin, L.H. 1390 (P[P04779574, P05604482, P05604484]), 1391 (P[P04779576, P05604483]); s.n. (P[P05604480]), s.n. (P[P05604481]), s.n. ( UPS [UPS V-716418]); Bory de Saint-Vincent, J.B.G. s.n. (G[G00324528]); Bosser, M.J. 20662 (P[P04779585]), 20940 ( MO [MO-2966277], P[P04779586]); Cadet, Th. 584 (P[P04779587]), 899 (K, P[P04779588]); Commerson, s.n. (P[P00382118]); P.s.n. (P[P04779363]), s.n. (P[P05604465] pr.p.), s.n. (P[P05604473], MPU[MPU014949]), s.n. (P[P05604477]), s.n. (P[P05604478]), s.n. (P[P05604479]), d’Alleizette, Ch. s.n. (L[L0242099]); du Petit-Thouars, L.M.A. s.n. (P[P04779473]), s.n. (P[P05604450]), s.n. (P[P05604458]); Frappier,M. 6 (P[P05604444]), 8 (P[P05604448]), 9 ( GH, P[P05604446]), 10 (P[P05604447]), s.n. (P[P05604443]), s.n. (P[P05604449]); Friedmann, F. 1078 (G, P[P04779584]); Giraudy, H. s.n. (P[P00324567]); Goudot, J. s.n. (P[P04779373]); Jussieu, A. s.n. (P[P04779569]); Léman, D.S. s.n. (P[P04779570]); Monin, M. s.n. (P[P05604475]); Perrotet, M. s.n. (P[P04779567]); Richard, M. 191 (P[P04779583]), 203 (P[P04779571]), 204 (P[P04779580]), 416 (P[P04779582]), 762 (P[P04779578, P04779581]), s.n. (P[P04779579]); Rivals, P. s.n. (P[P04779589]).

Mauritius or La Réunion. Boivin, L.H. s.n. (P[P00324574]), Desvaux, A.N. s.n. (P[P00324572]), s.n. (P[P00324573]); Pervillé, A. 733 (P[P00324571]).

REFERENCES. — Bojer (1837: 286); Baillon (1858: 443) as Tragia reticulata ; Baillon (1861: 266) as A. arborea ; Müller Argoviensis (1866: 851) as A. reticulata ; Baker (1877: 316) as A. reticulata ; Müller Argoviensis (1882: 26) as A. reticulata ; Pax (1890: 61) as A. reticulata ; Pax (1894: 96) as A. reticulata ; Cordemoy (1895: 342) as A. reticulata ; Voeltzkow (1917: 447) as A. arborea ; Pax & Hoffmann (1924: 102) as A. reticulata ; Leandri (1942: 258) as A. reticulata ; Coode (1979: 45) as A. reticulata ; Coode (1982: 69, 76); Govaerts et al. (2000: 62, 99, 105); Seebaluck et al. (2015: 150); Montero Muñoz et al. (2018a: 97).

DESCRIPTION

Shrubs, leaf persistence unknown, to 3 m tall, monoecious. Branches pubescent with simple, appressed, curved, antrorse trichomes, glabrescent when mature. Axillary buds subspherical, to 0.7 × 0.5 mm, perulate, perules 2, valvate, membranous, brownish, sparsely hairy. Stipules to 4 mm long, linear, thick, margin ciliate and with some minute glands. Petioles 0.5-2.5 cm long, indumentum similar to that on young branches. Leaf blades 2.5-7 × (1.8-)2-2.5(-3) cm, elliptic-lanceolate to ovate-lanceolate, chartaceous; base rounded; apex rounded to acute; margin crenate, slightly revolute, teeth rounded; upper and lower surfaces sparsely hairy with some sparse, simple, short trichomes on veins, glabrescent, margin ciliate; venation actinodromous, basal veins 3 or 5, secondary veins 4-5 per side. Stipels absent. Inflorescences spiciform, androgynous, and solitary female bracts, axillary. Androgynous inflorescences to 11 cm long, mostly male with 1 female bract; peduncle to 10 mm long, pubescent with simple, short, more or less appressed trichomes. Female segment: bract 1, sessile, enlarging in fruit to 10 mm diameter, orbicular, subglabrous, with some simple, short trichomes, glabrescent; margin entire; bracteoles absent. Solitary female bracts: peduncle to 20 mm long, laxly pubescent with simple, short, appressed trichomes; bract similar to those of androgynous inflorescences. Male segment persistent, to 9 cm long; flowers glomerate; bracts to 0.5 mm long, triangular, slightly fleshy, pubescent with simple, short trichomes. Male flowers: pedicel to 0.5 mm long, sparsely hairy; buds to 0.5 mm diameter, sparsely hairy. Female flowers 1-2 per bract, sessile; sepals 3, to 1 mm long, triangular-lanceolate, pubescent with simple, short trichomes; ovary c. 1 mm diameter, 3-lobed, papillose-hispid, papillae to 0.8 mm long, ending in hyaline trichome to 0.5 mm long, surface sparsely hairy; styles 3, to 6 mm long, slightly connate at base, sparsely hairy on rachis, each divided into 12-14 segments. Allomorphic flowers not seen. Capsules to 2 mm diameter, papillose-hispid, papillae triangular, ending in hyaline trichome to 0.5 mm long, surface sparsely hairy, glabrescent. Seeds c. 1.7 × 1 mm, pyriform, minutely foveolate.

NOTES

1) Acalypha reticulata has been usually considered to be the accepted name of this species. Leandri (1942) stated that A. filiformis and A. reticulata are conspecific, but he kept A. reticulata as the accepted name. Applying the rule of priority, the accepted name must be A. filiformis , and A. reticulata should be placed in synonymy; 2) A. filiformis is monoecious, but it is striking that the female and androgynous inflorescences always appear on different branches; 3) Boivin mixes two species under collector number Boivin 1391 ( A. filiformis [P04779576, P05604483] and A. integrifolia [P04779414, P04779415, P04779417, P04779329, P04779469]); and 4) the following specimens P00324571, P00324572, P00324573 and P00324574 are labeled as being from Madagascar (without a specific locality), but the labels are not original and A. filiformis is endemic to the Mascarene Islands. The location given for these specimens almost certainly is incorrect.

Figures

FIG. 35. — Mature female bracts: A, Acalypha decaryana Leandri (R. Decary 2985); B, A. emirnensis Baill. (G. McPherson 14590); C, A. filiformis Poir. (P. Commerson s.n.); D, A. fimbriata Schumach. & Thonn. (J. Audru 40466); E, A. gillespieae G.A.Levin & I.Montero (L. Gillespie et al. 10692); F, A. gracilipes Baill. (R. Rabevohitra 2054); G, A. humbertii Leandri (W. Kaudern 222). Illustration by Iris Montero Muñoz. Scale bars: A, C-G, 1 mm; B, 2 mm.

FIG. 30. — Distribution map of Acalypha filiformis Poir. in Mascarene Islands.