Acalypha nusbaumeri I.Montero & Cardiel, 2020

Montero-Munoz, Iris, Levin, Geoffrey A. & Cardiel, Jose M., 2020, Four new species of Acalypha L. (Euphorbiaceae, Acalyphoideae) from the West Indian Ocean Region, PhytoKeys 140, pp. 57-73 : 57

4. Acalypha nusbaumeri I.Montero & Cardiel sp. nov.

Diagnosis.

Acalypha nusbaumeri I.Montero & Cardiel is morphologically similar to A. perrierii Leandri, but differs from it mainly by having leaf blades with subacuminate apices (vs. leaf blades with caudate apices), inflorescences to 1.7 cm long (vs. inflorescences to 3 cm long), and mature female bracts 2 × 2.5 mm, translucent, with crenate margins and two basal bracteoles (vs. bracts 7 × 12 mm, opaque, with entire margins and no bracteoles).

Type.

Madagascar. Reg. Sava [Prov. Antsiranana]: sous-préfecture de Vohemar. Commune rurale de Daraina, forêt de Bekaraoka, partie nord, 13°06'S, 49°42'E, 177 m, 13 Feb 2004, L. Nusbaumer & P. Ranirison LN1169. (holotype: G [G00028080!]; isotypes: K!, MO!, P [P05547228!, P01152829!]). Fig. 6 .

Description.

Shrubs to 0.8 m high, probably deciduous, monoecious. Young branches very slender, divaricate, blackish, pubescent with simple, antrorsely curved trichomes; older branches glabrous. Axillary buds spherical, c. 1 mm diameter, perules 2, imbricate, membranous, external perule dentate, sparsely hairy. Stipules caducous, c. 2 mm, triangular-lanceolate, with a prominent central rib, sparsely hairy with simple, short, erect trichomes. Petioles slender, 2-3.5 (-4.5) cm long, with indumentum similar to that found on young branches. Leaf blades 5-8.5 × 2.5-5 cm, ovate-lanceolate to elliptic-lanceolate, thin-membranous; base obtuse to rounded; margins crenate-serrate; teeth rounded; apex subacuminate, acumen c. 0.5 mm long, rounded and mucronate at apex; upper surface subglabrous, with simple, short, antrorsly curved trichomes on veins; lower surface with indumentum similar to that found on upper surface, axils of the secondary veins with pocket-shaped, sparsely hairy domatia; venation actinodromous, with 3 or 5 veins at the base, secondary veins 3-4 per side. Stipels absent. Inflorescences inconspicuous, androgynous, axillary, c. 1.7 cm long, spiciform, mostly male with 1 female bract near the base; peduncle thick, c. 0.5 cm long, with indumentum similar to that found on the young branches; male segment c. 7 cm long. Female bracts sessile, translucent, enlarging in fruit to 2 × 2.5 mm, orbicular-reniform, subglabrous, with short, simple trichomes on teeth and veins, margins crenate. Bracteoles linear-lanceolate, c. 0.5 mm long, sparsely hairy, with short, simple trichomes, and some sessile glands on the margins. Male flowers inconspicuous, pedicel c. 0.5 mm long, sparsely hairy; buds c. 0.8 mm diameter, glabrous, papillose. Female flowers solitary, sessile; sepals 3, free at base, c. 1 mm long, lanceolate, ciliate with short, simple trichomes; ovary 3-locular, c. 1 mm diameter, densely hispid; styles 3, c. 3.5 mm long, free at the base, each divided into 8-10 slender segments, rachis sparsely hairy. Capsules (immature) to 2 mm diam., echinate, with projections c. 1 mm long, pubescent with simple, short erect trichomes c. 0.5 mm long. Seeds too young to describe.

Distribution and habitat.

Acalypha nusbaumeri is only known from Bekaraoka forest, in the Loky-Manambato protected area, in Sava Region, northern Madagascar (Fig. 2 ). This area has a seasonally dry climate ( Schatz 2000; Goodman et al. 2018). Regarding its vegetation, Loky-Manambato is a special area because it is between the Eastern Humid and Western Dry phytogeographic domains and so has many types of vegetation ( Nusbaumer et al. 2010). Bekaraoka forest has dry deciduous forest on basement rocks ( Moat and Smith 2007, Goodman et al. 2018), which seems to be the characteristic habitat of A. nusbaumeri .

Etymology.

The proposed epithet honors Louis Nusbaumer, researcher and curator of Conservatoire et Jardin botaniques de la Ville de Genève, Switzerland. He works on the systematics, phylogeny, biogeography, and conservation of Malagasy plants. Nusbaumer is also the collector, with Patrick Ranirison, of the type specimen of this species.

Conservation status.

Acalypha nusbaumeri is only known from one collection. The extent of occurrence (EOO) could not be calculated. Its area of occupancy (AOO) is estimated to be 8 km2. Loky-Manambato is a category V ( Goodman et al. 2018) protected area since 2005. The forest in this region has been degraded and continues to be threatened by slash and burn agriculture, fires to clear land for grazing, illegal cutting of precious woods, and in some areas, as Bekaraoka, gold extraction ( Vargas et al. 2002, Rakotondravony 2009, Goodman et al. 2018). Acalypha nusbaumeri is assigned a preliminary IUCN conservation status of Critically Endangered: CR B2ab(ii,iii).

Figures

Figure 2. Map of Madagascar and the Mayotte island showing the distributions of Acalypha gillespieae (square), A. leandrii (rhombus), A. mayottensis (triangle) and A. nusbaumeri (circle).

Figure 6. Acalypha nusbaumeri A flowering branch B detail of lower leaf surface showing the pocket-shaped domatia C detail of node, stipules, and petiole base D detail of node with axillary bud E mature female bract with bracteoles F ovary and styles G calyx of the female flower H capsule. Based on L. Nusbaumer & P. Ranirison LN 1169. Illustration by Iris Montero Munoz.