Acalypha bardotiana I.Montero & Cardiel, 2023

Montero-Munoz, Iris, Levin, Geoffrey A., Vaquero Lorenzo, Concepcion, Gonzalez, Laura & Cardiel, Jose M., 2023, Novelties in the genus Acalypha (Euphorbiaceae, Acalyphoideae): two new species from northern Madagascar, Plant Ecology and Evolution 156 (3), pp. 365-373 : 365

Acalypha bardotiana I.Montero & Cardiel sp. nov.

Figs 1 , 2

Type.

MADAGASCAR - Diana region [Antsiranana prov.] • Montagne des Francais , descent of the canyon starting from the ruins of the military camp; 12°19 ’46” S, 49°20 ’23” E; 260 m; 6 Apr. 2007; Bardot-Vaucoulon M., Véné G. & Razafindrabelahasy G. 1645; holotype: P [P00643172]; isotypes: K, MO [MO-2966289, accession n° 6120147], TAN (not seen) .

Diagnosis.

Acalypha bardotiana is morphologically close to A. lanceolata Willd. var. glandulosa ( Müll.Arg.) Radcl.-Sm. but differs mainly by having a suffruticose habit and unisexual inflorescences (vs herbaceous habit and androgynous inflorescences), conspicuous stipules up to 8 mm long (vs inconspicuous stipules up to 2 mm long), petioles up to 8 mm long and leaf blades up to 9 cm long (vs petioles up to 4.6 mm long and leaf blades up to 6.5 cm long), and papillose-hispid capsules (vs smooth capsules).

Description.

Suffruticose herbs, 0.5-0.6 m tall, monoecious. Branches pubescent with short, antrorsely curved, simple trichomes and long, erect trichomes to 1 mm long, glabrescent when mature. Axillary buds inconspicuous. Stipules conspicuous, up to 8 mm long and 3.5 mm wide at base, ovate-lanceolate to triangular-lanceolate, acuminate, sparsely hairy with long, simple trichomes to 1 mm long and minute glandular trichomes at margin. Petioles thin, 6-8 cm long, indumentum similar to that on young branches. Leaf blades 6-9 × 4-6 cm, broadly ovate to elliptic-lanceolate, membranous; base obtuse to subcordate; apex acute to acuminate; margins serrate, teeth rounded, sometimes mucronate; upper surface with sparse, erect, simple trichomes up to 1 mm long; lower surface subglabrous, with appressed simple trichomes on veins; venation actinodromous, basal veins 3(-5), secondary veins 4-5 per side. Stipels absent. Inflorescences spiciform, unisexual, male axillary, female terminal on lateral branches. Male inflorescences up to 3 cm long, flowers glomerate; bracts minute to 0.5 mm long, linear-lanceolate, sparsely hairy. Female inflorescences moderately densely flowered, up to 8 cm long; peduncle up to 1 cm long, indumentum similar to that on young branches; bracts to 30, sessile, enlarging in fruit to 2.5 × 5 mm, sparsely hairy with erect, hyaline, simple trichomes up to 1 mm long and glandular trichomes up to 1 mm long; margin deeply dentate, teeth 10-12, triangular, acute, up to 1.5 mm long, central tooth not prominent; bracteoles absent. Male flowers with pedicel up to 0.5 mm long, glabrous; buds up to 0.5 mm diameter, glabrous. Female flowers 1 per bract, sessile; sepals 3, up to 0.5 mm long, distinct, ovate-lanceolate, ciliate, with minute simple trichomes up to 0.2 mm long; ovary ca 1 mm diameter, 3-lobed, papillose-hispid, each papilla ending in a long, hyaline trichome up to 1 mm long; styles 3, up to 5 mm long, slightly connate, each divided into 5-6 slender segments, with some hyaline erect trichomes up to 1 mm long. Allomorphic flowers not seen. Capsules up to 2.5 mm diameter, papillose-hispid, each papillae ending in a simple, erect trichome up to 1 mm long, surface sparsely hairy with minute, simple trichomes up to 0.2 mm long. Seeds ca 1.7 × 1 mm, pyriform, minutely foveolate.

Etymology.

The epithet honours Mrs Martine Bardot-Vaucoulon, a French botanist who has conducted extensive botanical research in Madagascar. She is also one of the collectors of the type specimens of this species and kindly provided us with some field images included in this paper.

Distribution and habitat.

Acalypha bardotiana is known only from the north side of Montagne des Français, at 260 m elevation. Montagne des Français is a limestone massif covered with dry deciduous forest, in the Diana region in the extreme north of Madagascar. Acalypha bardotiana grows on reduced clay soil on outcropping blocks of Eocene limestone, in an area of sparse vegetation on sunny rocks in the canyon (Fig. 4 ).

Preliminary IUCN conservation assessment.

Acalypha bardotiana is only known from a single collection and location in the protected area of Montagne des Français. In this location, there were around ten individuals of this species (Martine Bardot-Vaucoulon pers. comm.). The extent of occurrence (EOO) could not be calculated. Its area of occupancy (AOO) is estimated to be 4 km2. Montagne des Français has been relatively well collected (Porter P. Lowry II pers. comm.), so the absence of previous collections suggests this species is not common. Acalypha bardotiana is found in only one location, and its habitat is continuing to decline due to woodcutting, primarily for charcoal, and to the slash-and-burn agriculture ( Goodman et al. 2018; Wilding et al. 2021). Acalypha bardotiana is assessed provisionally as Critically Endangered: CR B2ab(ii,iii,iv).

Figures

Figure 1. Acalypha bardotiana. A. Habit. B. Detail of lower leaf surface. C. Detail of node, stipules, and petiole base. D. Mature female bract. E. Ovary and styles. F. Calyx of the female flower. G. Capsule. H. Seed. Based on M. Bardot-Vaucoulon. G. Vene & G. Razafindrabelahasy 1209 (P and K). Illustration by Laura Gonzalez Hernandez.

Figure 2. Acalypha bardotiana in situ. A. Female inflorescence, leaves, and stipules. B. Habit. Photos by Mrs Martine Bardot-Vaucoulon, used with permission.

Figure 4. Distribution map of Acalypha bardotiana and A. inaequibracteata. Map created with QGIS (2023).