Acalypha isaloensis 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 : 448

23. Acalypha isaloensis I.Montero & Cardiel

Systematic Botany 45 (1): 122 ( Montero Muñoz et al. 2020a). — Type: Madagascar. Ihorombe (Fianarantsoa prov.), Massif de l’Isalo , à l’est de Ranohira, Andohakandrareza , au SE de la Piscine, 810 m, 22°33’S, 45°21’E, 14.II.1990, J.N.Labat 2119 (holo-, P[P00513133]; iso-, ILLS, K).— Paratypes: Madagascar. Ihorombe (Fianarantsoa prov.),Isalo, canyon des Singes, 746 m, 22°29’12.239”S, 45°22’43.381”E, 15.IV.1967, H. Jacquemin H278J (P[P04804757, P04804758]); Isalo, canyon des Rats, pied des falaises le long du ruisseau, 899 m, 22°28’47.759”S, 45°22’39.601”E, III.1960, M.Keraudren-Aymonin 402 (P[P04804755]); Ranohira, Isalo-Gebirge, 900 m, 22°33’20.307”S, 45°25’09.167”E, 22.XII.1959, H.-J.Schlieben 8236 (B, BR[BR0000021450358], G, K) .

ICONOGRAPHY. — Montero Muñoz et al. (2020a); Fig. 46C.

ETYMOLOGY. — The epithet refers to type locality, the Isalo massif ( Madagascar), to which this species appears to be endemic.

DISTRIBUTION AND HABITAT. — Endemic to Madagascar (Ihorombe).Dry deciduous forest.On sandstone. Altitudinal range 746-900 m ( Fig.40 ). PRELIMINARY CONSERVATION ASSESSMENT. — The EOO and AOO of A. isaloensis are estimated to be 8 km 2. This species appears to be a narrow endemic known only from the Isalo massif. All collections are from the Isalo National Park, which has been a category II protected area ( Dudley 2008) since 1962. This protected area is threatened by burning to improve grazing, which is a cultural heritage of the Bara people, as well as logging and the impact of introduced species ( Kull 2004; Swierkosz 2007; Andreone et al. 2013). In recognition of its restricted geographic range (a single known location) and the cited threats, A. isaloensis is assigned a preliminary conservation status of Critically Endangered: CR B2ab(i,iii,iv).

MATERIAL EXAMINED. — 3 collections. Madagascar: Jacquemin, H. H278J (P[P04804757, P04804758]); Keraudren-Aymonin, M. 402 (P[P04804755]); Labat, J.-N. 2119 (K, P[P00513133]).

DESCRIPTION

Shrubs or subshrubs, leaf persistence unknown, to 0.8 m tall, monoecious. Branches puberulent with sparse simple, short, trichomes, glabrescent when mature. Axillary buds ovoid, to 1 × 0.7 mm, perulate, perules 2, valvate, membranous, brownish, densely pubescent with simple, short, appressed trichomes. Stipules to 1.2(-2) mm long on young branches, sometimes reduced to 0.5 mm long on older branches, triangular-lanceolate, apex acute, with appressed trichomes, margin with sessile glands. Petioles (2-) 3-4.5 cm long, indumentum similar to that on young branches. Leaf blades (5-)6-10(-11.5) × 2-3.5(-4) cm, elliptic to oblong-lanceolate, membranous; base rounded to subcuneate; apex subacuminate,acumen to 10mm long,rounded, mucronate; margin sparsely serrulate, teeth minute, obtuse, callose-edged; upper surface laxly pubescent with simple, short trichomes; lower surface indumentum similar to that on upper surface but denser; axils of the secondary veins with pocket-shaped domatia; venation prominent on upper surface, pinnate, secondary veins 5-10 per side. Stipels absent. Inflorescences spiciform, male, and solitary female bracts, axillary. Male inflorescences to 8.5 cm long, filiform; peduncle to 7 mm long, rachis clearly visible,both with indumentum similar to that on young branches; flowers glomerate; bracts to 0.3 mm long, ovate, sparsely hairy with simple, short trichomes, and with some sessile glands at base. Solitary female bracts sessile, enlarging in fruit to 3.5 × 5 mm, subreniform, appressed puberulent, with sparse resinous drops, margin crenate to subentire; sterile bracts sometimes present, solitary, similar to the female bracts but longer, to 1 × 1.2 cm, suborbicular; bracteoles absent. Male flowers subsessile; buds to 0.5 mm diameter, puberulent. Female flowers 1 per bract, sessile; sepals 3, to 0.3 mm long, triangular, puberulent; ovary c. 1 mm diameter, 3-lobed, papillose, papillae acute, ending in hyaline trichome to 0.5 mm long, surface hispidulous; styles to 8 mm long, connate at base, sparsely hairy, each divided into 5-6 slender segments. Allomorphic flowers not seen. Capsules to 3 mm diameter, papillose-hispid, papillae acute, ending in hyaline trichome to 0.8 mm long, surface puberulent. Seeds too young to describe.

Figures

FIG. 46. — Mature female bracts: A, Acalypha indica L. (Sagun et al., 2010, Sagun & Risna SR58); B, A. integrifolia Willd. (P. Commerson 655); C, A. isaloensis I.Montero & Cardiel (J.-N. Labat 2119); D, A. lamiana (Leandri) I.Montero & Cardiel (H. J. Lam & A. Meeuse 6727); E, A. lanceolata Willd. var. glandulosa (Müll.Arg.) Radcl.-Sm. (H. Perrier de la Bâthie 9929); F, A. leandrii I.Montero & Cardiel (J. Leandri 2037); G, A. leonii Baill. (L. Gautier LG4003); H, A. lepidopagensis Leandri (H. Perrier de la Bâthie 9726). Illustration by Iris Montero Muñoz. Scale bars: 1 mm.

FIG. 40. — Distribution map of Acalypha isaloensis I.Montero & Cardiel in Madagascar.