Acalypha chibomboa Baill., 1436

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 : 427

10. Acalypha chibomboa Baill.

Adansonia, recueil d’observations botaniques 1: 269 ( Baillon 1861). — Type: Comoros, Anjouan, 1850, L.H. Boivin s.n. (holo-, P[P00196274]) .

Acalypha codonocalyx Baill. , Adansonia, recueil d’observations botaniques 1: 271 ( Baillon 1861). — Type: Comoros. Mohéli, “Île Mohilla”, s.d., M. Richard 286 (lecto-, designated by Montero Muñoz et al. [2018a: 94]: P[P00196282]; isolecto-, P[P00196283]).

Acalypha comorensis Pax, Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie. Leipzig 19(1): 95 ( Pax 1894). — Type: Comoros. Anjouan, “Johanna”, VIVIII.1875, J. M. Hildebrandt 1662 (holo-, B or WRSL, presumably destroyed; lecto-, designated by Montero Muñoz et al. [2018a: 94]: BREM[BREM0001792]; isolecto-, K[K000186524, K000186525], L[L0241274], P[P00196280], W[W0004243]). — Former syntype: Comoros. Grande Comore, 1886, C.W. Schmidt 192 [n.v.].

ICONOGRAPHY. — Baillon (1891: pl. 192); Fig. 24G.

ETYMOLOGY. — The epithet refers to the vernacular name of this plant, known as “chibomboa /choubomboa” in Comoros, according Baillon (1861).

DISTRIBUTION AND HABITAT. — Madagascar (Diana) and Comoros Archipelago (Grande Comoro, Anjouan, Moheli, and Mayotte). In Madagascar: dry deciduous forest on basalt; altitudinal range 120-1020 m. In Comoros Archipelago: in valley forest on clay soil: altitudinal range 200-700 m ( Fig. 23 ).

PRELIMINARY CONSERVATION ASSESSMENT. — Acalypha chibomboa is known from Madagascar and Comoros. In the Comoros, its EOO is estimated to be 8131km 2 and its AOO 44 km 2, which is less than the 500 km 2 threshold of the B2 subcriterion of the Endangered category. The Comoros archipelago has lost at least 80% of its native vegetation, and is now dominated by cash-crops and subsistence cultivation. Deforestation rate has decreased but is still ongoing, making Comoros the archipelago with the highest annual net loss of forest in WIOR. In addition, alien species have a detrimental effect on the native flora ( Safford 2001; Chakravarty et al. 2012; Baret et al. 2013). Ongoing habitat loss will cause continued decline of its EOO and AOO. In the Comoros, A. chibomboa is assessed as Near Threatened (NT) under criterion B, because it meets the values needed for a threatened category for the AOO, but the number of locations is too high to meet the conditions required for a listing under Endangered category.

In Madagascar, its EOO is estimated to be 253.391 km 2 and its AOO 20 km 2. This species is only known from six locations in dry deciduous forests in the north of the island (see assessment of A. diminuta ). This species has been collected in some protected areas, as Ankarana Special Reserve (see assessment of A. ankaranensis ), and in the Montagne d’Ambre National Park, where the forests are affected mainly by slash-and-burn agriculture. Currently, Montagne d’Ambre is under additional threat because qat ( Catha edulis , Celastraceae ) cultivation is increasing ( Goodman et al. 2018). Due to ongoing habitat loss that will cause continued decline of its EOO and AOO, A. chibomboa is assessed as Endangered (EN) EN: B1ab(i,iii,iv) + B2ab(ii,iii,iv) in Madagascar.

In the whole region, Acalypha chibomboa can be assessed as Near Threatened (NT). 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. — 23 collections. Comoros Archipelago. Attoumane, M.15 ( MO [MO-2965775]); Barthelat,F.1436 (P[P00631096]); Boivin, L.H. s.n. (P[P00196274]); Bosser, M.J. 18011 (P[P00196228, P00196229]); Coulon, P. 205 (P[P00184949]); d’Alleizette, Ch. s.n. (L[L0241232]); Hildebrandt, J.M. 1662 ( BREM [BREM_0001792], K[K000186524, K000186525], L[L0241274], P[P00196280], W[W0004243]); Humblot, L. 206 (K), 1206 (P[P00196275, P00196276, P00196277]); 1377 (P[P00196278, P00196279]); Jacquemin, H. 837 (P[P00324456]), 837-J (P[P00538326]); Rakotozafy, A. 1152 (P[P00196236]); Richard, M. 225 (P[P00196281]), 286 (P[P00196282, P00196283]); Service Forestier Madagascar 16651-SF (P[P00334973, P00184984]); Waterlot, M. 964 (P[P00196284]). Madagascar. Andrianantoanina, O. 960 (P[P04779784]); Bardot-Vaucoulon, M. 1227 (K, MO[MO-3025011], P[P00455522], TAN); Cours, G. 5485 (P[P00324546, P05510111]); Dorr, L.J. 3622 ( BR [BR0000021450280], C, L[L0449357], MO, P[P00508514, P01295515], WAG[WAG0133270]); Malcomber, S. 1239 ( CAS, K, MO[MO-2965805]); Razanajatovo,M.G. MHR027 (G[G00170087], K, P[P05516023]).

REFERENCES. — Baillon (1891: pl. 192 as A. codonocalyx ); Palacký (1907: 24); Voeltzkow (1917: 447); Pax & Hoffmann (1924: 165); Leandri (1942: 280); Govaerts et al. (2000: 55); Montero Muñoz et al. (2018a: 94).

DESCRIPTION

Small trees, evergreen, to 5 m tall, monoecious. Branches striate, pubescent with simple, short, curved, antrorse trichomes, glabrescent when mature. Axillary buds ovoid, to 1.5 × 1 mm, perulate, perules 2, valvate, membranous, brownish, sparsely hairy with simple, short trichomes. Stipules to 3 mm long, linear-lanceolate, ciliate with simple, erect trichomes to 0.5 mm long. Petioles very slender, 2.5-9 cm long, indumentum similar to that on young branches but less dense, glabrescent. Leaf blades (8-)9-14(-15.5) × 3.5-6 cm, elliptic-lanceolate, membranous; base rounded to subcuneate; apex acuminate, acumen to 25 mm long, acute; margin serrate, teeth acute; upper surface puberulent with sparse, simple, short trichomes, and with simple, short, appressed trichomes on veins, glabrescent; lower surface subglabrous, with sparse simple, short trichomes and flattened resinous glands; venation actinodromous, basal veins 3 or 5, secondary veins 6-9 per side. Stipels absent. Inflorescences spiciform, usually unisexual, sometimes androgynous, axillary. Androgynous inflorescences laxly flowered, to 11 cm long, about equally male and female; peduncle filiform, to 40 mm long, indumentum similar to that on petioles. Female segment to 5.5 cm long; bracts 2-6, sessile, enlarging in fruit to 5 mm diameter, orbicular, sparsely hairy with simple, short, arachnoid trichomes at base, with flattened resinous glands, and ciliate with simple, short trichomes; margin denticulate, teeth 17-19, triangular, ending in sessile gland, central tooth not prominent; bracteoles absent. Male segment deciduous, 6 cm long; bracts to 1 mm long, ovate, pubescent with simple, short, arachnoid trichomes; flowers glomerate. Male inflorescences laxly flowered, to 12 cm long; peduncle to 30 mm long, it and rachis with indumentum similar to that on petioles. Female inflorescences laxly flowered, to 5 cm long; peduncle filiform, to 20 mm long, it and rachis with indumentum similar to that on petioles; bracts 2-5, they and bracteoles like those on androgynous inflorescences. Male flowers: pedicel to 0.5 mm long, sparsely hairy; buds to 1 mm diameter, glabrous. Female flowers 1 per bract, sessile; sepals 3-4, to 1.3 mm long, triangular, subglabrous, ciliate with simple, minute trichomes; ovary c. 1 mm diameter, 3-lobed, smooth. surface pubescent with simple, short, arachnoid trichomes and flattened resinous glands; styles 3, to 4 mm long, slightly connate at base, sparsely hairy on rachis, each divided into c. 6 segments. Allomorphic flowers not seen. Capsules to 4 mm diameter, smooth, surface pubescent with simple, arachnoid trichomes and flattened resinous glands. Seeds c. 3 × 2.3 mm, pyriform, minutely foveolate.

Figures

FIG. 24. — Mature female bracts:A, Acalypha andringitrensis Leandri (H. Perrier de la Bâthie 13640); B, A. ankaranensis I.Montero & Cardiel (A. J. M. Leeuwenberg 14374); C, A. bailloniana Müll.Arg. (G. Viscardi 439); D, A. boinensis Leandri (R. Ramananjanahary 115); E, A. burmanii I.Montero & Cardiel (P. Commerson s.n.); F, A. cardielii I.Montero & G.A.Levin (J. Leandri 115); G, A. chibomboa Baill. (F. Barthelat 1436); H, A. claoxyloides Hutch. (F. Friedmann 5633). Illustration by Iris Montero Muñoz. Scale bars: A, 2 mm; B-H, 1 mm.

FIG. 23. — Distribution map of Acalypha chibomboa Baill. in Comoros Archipelago and Northern Madagascar.