Four new species of Acalypha L. (Euphorbiaceae, Acalyphoideae) from the West Indian Ocean Region

Abstract Four new species of Acalypha (Euphorbiaceae, Acalyphoideae) from the Western Indian Ocean Region, based on morphological and molecular evidence, are described, illustrated, and mapped. Acalyphagillespieae sp. nov., A.leandrii sp. nov. and A.nusbaumeri sp. nov. are endemic to Madagascar, and A.mayottensis sp. nov. is known only from Mbouzi islet (Mayotte), in the Comoros Archipelago. We also describe for the first time in Acalypha the presence of membranous or chartaceous perules covering the axillary buds. Preliminary conservation assessments of the new species are also provided.


Introduction
This paper follows the revisionary work on Acalypha L. for the West Indian Ocean Region (Madagascar, the Comoros Archipelago, the Mascarene island, Scattered islands and Seychelles Archipelago) that was begun by Montero Muñoz et al. (2018a, b, in press).
Acalypha, with around 500 species, is the third largest genus in the family Euphorbiaceae, after Euphorbia L. (Riina et al. 2013) and Croton L. (Berry et al. 2005). It includes mainly small trees and shrubs of tropical and subtropical distribution, and some herbs that extend to temperate regions. About 65 species are found in continental Africa (Cardiel and Montero Muñoz 2018), and 39 species were previously known from West Indian Ocean Region (WIOR), most of them endemic there (Montero Muñoz et al. 2018a, b, 2020. A description of the main characteristics of the Acalypha species in WIOR, as well as the previous revisionary works in this region, can be found in Montero Muñoz et al. (2018a, b).
Acalypha is included in the subfamily Acalyphoideae, the most diverse in the Euphorbiaceae (Hayden and Hayden 2000). Although this subfamily is considered to be paraphyletic, the core group of included taxa (Acalyphoideae sensu stricto) is clearly monophyletic. Molecular analyses also support the monophyly of Acalypha (Tokuoka 2007, Wurdack andDavis 2009). Preliminary results of Acalypha molecular phylogeny (Levin et al. 2005, Sagun et al. 2010 suggest that the genus first evolved in Africa, where it is morphologically most diverse. Currently, we are working on the molecular phylogeny of Acalypha species from the WIOR (Montero Muñoz et al. in press) in the context of the phylogeny of the whole genus (Levin et al. in prep.). The preliminary results of this work also confirm the species here described as new. In all four newly described species, the axillary buds are covered by a pair of membranous or chartaceous perules; which are especially conspicuous in deciduous specimens. We have seen perules in other species of Acalypha from the WIOR region, usually associated with seasonally dry habitats. This is the first published report of the presence of perules in Acalypha.

Materials and methods
The taxonomic status of the new species is based on morphological evidence, supported by geographical and ecological data. The descriptions and illustrations provided are based on field images and herbarium specimens located in CAN, G, HKM, ILLS, K, MAO, MO, P and TAN (abbreviations following Thiers 2020). Specimens seen by the authors are indicated with an exclamation mark (!). Herbarium barcodes are included when they are known. Specimens have been studied using a binocular microscope. Information about habit, plant size, and habitat are based on field notes on the specimen labels. The field photographs provided were made by the late Jean-Noël Labat and downloaded from the Muséum National d'Histoire Naturelle (Paris) website. The distribution maps were prepared using QGIS Desktop 3.2.2. Conservation assessments are based on the IUCN Red List Categories and Criteria (IUCN 2012(IUCN , 2017. Area of occupancy (AOO) and extent of occurrence (EOO) were calculated with GeoCAT, a geospatial conservation assessment tool (Bachman et al. 2011; http://geocat.kew.org/), using a 2 × 2 km grid cell size as recommended by IUCN (2012IUCN ( , 2017. All the taxonomic and biogeographical information about Acalypha is available online in the regularly updated "Acalypha Taxonomic Information System" website (Cardiel et al. 2020;www.acalypha.es). style divided into 5-8 slender, fimbriate segments. Capsules 3-locular, c. 3 mm diam., echinate and hispid, with simple, straight, erect to antrorse trichomes c. 0.5 mm long, and conical projections c. 0.75 mm long. Seeds pyriform, 2 × 1.5 mm, smooth.
Distribution and habitat. Acalypha gillespieae is known only from a small area between 200 and 300 m elevation on the north side of Montagne des Français (Fig. 2). This limestone massif, including the area where A. gillespieae grows, is covered with dry deciduous forest (Moat and Smith 2007, Goodman et al. 2018).
Etymology. The proposed epithet honors the botanist Lynn J. Gillespie, research scientist at the Canadian Museum of Nature. In addition to studying Arctic plants and Poaceae, she has worked on the systematics of Euphorbiaceae worldwide, including in Madagascar. She collected all the known specimens of this species, either alone or as leader of a team of botanists.
Conservation status. Acalypha gillespieae is known from three collections from the same locality. Montagne des Français has been relatively well collected (P. Lowry, pers. comm.), so the dearth of collections suggests this species is rare, even there. Its apparent rarity could also, at least in part, reflect it being quite inconspicuous and thus easily overlooked. The extent of occurrence (EOO) could not be calculated. Its area of occupancy (AOO) is estimated to be 8000 km 2 . Montagne des Français is a category V protected area (Dudley 2008). Its habitat is somewhat threatened by wood-cutting, primarily for charcoal, but mainly on its lower slopes, below where A. gillespieae is found. Acalypha gillespieae is assigned a preliminary IUCN conservation status of Critically Endangered: CR B2ab(ii,iii,iv).
Distribution and habitat. Acalypha leandrii is known from two localities in western Madagascar, in the area east of Antsalova. They are both from the karstic massif of Mesozoic limestones known as Tsingy de Bemaraha, in the Melaky Region. This region has dry climates, and the primary vegetation is dry deciduous forest (Schatz 2000, Moat and Smith 2007. The altitudinal range of A. leandrii is from 100 to 300 m. (Fig. 2).
Etymology. The proposed epithet honors the French botanist Jacques Désiré Leandri (1903Leandri ( -1982. He worked extensively in the Euphorbiaceae family from Madagascar, including writing the last taxonomic treatment of Acalypha from the island, in which he described numerous new species (Leandri 1942). Leandri collected the type specimen of this species.
Conservation status. Acalypha leandrii is known from three collections. The extent of occurrence (EOO) could not be calculated. Its area of occupancy (AOO) is estimated to be 8 km 2 . The Tsingy de Bemaraha lies within a national park and a nature reserve that has been IUCN category II and Ia protected areas (Dudley 2008) since 1927 and a UNESCO World Heritage Site since 1990 . The forest of this area has local anthropogenic pressures such as fire associated with the renewal of zebu (cattle) pastures, logging for construction and deforestation for new agricultural lands. Bemaraha has lost more forest habitat from 2006 to 2016 compared to 1996 to 2006 . No specimens of this species have been collected for 60 years, so we cannot rule out that this species has become extirpated from one or both areas. In conclusion, due to habitat loss and the absence of recent collections, A. leandrii is assigned a preliminary IUCN conservation status of Critically Endangered: CR B2ab(ii,iii).
Distribution and habitat. Acalypha mayottensis is endemic to Mayotte, a French overseas department in the Comoros Archipelago, and presumably restricted to the Mbouzi islet (Fig. 2). Mbouzi is a small, volcanic, unoccupied islet, of 82 ha, located east of the main island (Grande-Terre). It has a tropical humid climate, with two seasons: one cool and dry, the other hot and wet, resulting from shifts in the Intertropical Convergence Zone. Mbouzi is mainly covered by secondary dry deciduous forest (Boullet and Traclet 2018). According to the specimens' labels, A. mayottensis is a common deciduous bush on the islet, growing in deciduous forest, in ravines and stony areas, from 10 to 90 m elevation.
Etymology. The proposed epithet refers to Mayotte island, to which the small Mbouzi islet belongs.
Conservation status. Acalypha mayottensis is only known from Mbouzi islet. The extent of occurrence (EOO) is estimated to be 0.017 km 2 . Its area of occupancy (AOO) is estimated to be 8 km 2 . Mbouzi islet was declared a "Réserve Naturelle Nationale" in 2007, a category IV protected area (Dudley 2008). In the 1990s the islet had lost 70% of its original forests due to agricultural activities. Mbouzi currently conserves 10% of its natural and subnatural forest (Boullet and Traclet 2018). Currently, the most serious threat is invasive species, both animals, such as Eulemur fulvus, and plants, such as Antigonon leptopus, Lantana strigocamara, Leucaena leucocephala, Litsea glutinosa, Spathodea campanulata and Furcraea foetida (Boullet andTraclet 2018, Quintard et al. 2019). A. mayottensis is assigned a preliminary IUCN conservation status of Critically Endangered: CR B1ab(i,iii) + B2ab(ii,iii).
Additional specimen examined (  Notes. Five other species of Acalypha are known from Mayotte: Acalypha chibomboa Baill., A. indica L., A. lanceolata (Müll.Arg.) Radcl.-Sm., A. paxii Aug.D.C., and A. richardiana Baill. A. mayottensis does not strongly resemble any of them. The only other Acalypha species known from Mbouzi islet is A. richardiana, which differs mainly by having sessile androgynous inflorescences and mature female bracts subrounded, c. 7 × 6 mm (vs. pedunculate androgynous inflorescences and mature female bracts subreniform, c. 19 × 21 mm in A. mayottensis). The herbarium specimens of A. mayottensis had been previously identified as A. claoxyloides Hutch., endemic to the Seychelles Archipelago, but it clearly differs by having flattened resinous glands on lower leaf surface, female bracts and flowers, and smooth capsules (vs. resinous glands absent and echinate capsules in A. mayottensis).  Fig. 6.
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 km 2 . Loky-Manambato is a category V  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. Acalypha nusbaumeri is assigned a preliminary IUCN conservation status of Critically Endangered: CR B2ab(ii,iii).