Cnidoscolus Pohl (1827: 56)

Oliveira, Cellini Castro De, Melo, André Laurênio De & Silva, Marcos José Da, 2021, Synopsis of Cnidoscolus (Euphorbiaceae) in midwestern Brazil, including taxonomic updates, a new species, and a reestablishment of C. neglectus, Phytotaxa 500 (3), pp. 179-200 : 181

Cnidoscolus Pohl (1827: 56)

Herbs, annual or perennial, subshrubs, shrubs or trees; monoecious; stems erect or decumbent, cinereous, greenish or light green in the young parts; latex milky, abundant; indumentum composed of aciculiform or aculeiform multicellular stinging hairs in the vegetative and reprodutive parts, mixed or nor with pubescent, tomentose or villous indumentum; stipules persistent or tardilly caducous, triangular, papillose; leaves alternate, the leaf blade 3–5(–9)- palmatilobed, pinatisect, lyrate-pinnatisect or rarely unlobed, with or without acropetiolar or basilaminar glands; venation brochidodromous, cladodromous or hiphodromous. Inflorescences simple or compound dichasia, axillary or pseudo-axillary; flowers monochlamydeous, white or cream, unisexual; staminate flowers tubulose or urceolate at the ends of the dichasium branches, the androecium with 4–30 stamens in two to six whorls partially or completely joined in a column, or rarely free, and 0–5 filiform staminodes, disc extrastaminal; pistillate flowers gamotepalous or dialytepalous, found usually towards the base of the dichasium, ovary 3(–5)-carpelar, ovules 1 per locule, styles usually multifid, free or partially joined, disc annular. Fruits dehiscent septicidally or loculicidally, rarely indehiscent; seeds dry, carunculate, cinereous or darkish, spotted.

Cnidoscolus Pohl belongs to the tribe Manihoteae Pax (1890: 77) ( Webster 1994) , together with the genus Manihot Miller (1754 : [851]), from which it differs and can be recognized by the presence of stinging hairs, white or cream flowers in dichasia, the staminate ones with usually monadelphous androecium and an extrastaminal disc. In Brazil, the genus encompasses 41 species (BFG 2015, Maya-Lastra & Steinmann 2018) distributed especially in the Phytogeographic biomes of Caatinga and Cerrado. In the midwestern region of Brazil, before this work, Cnidoscolus was represented by 19 species (BFG 2015, Maya-Lastra et al. 2020). However, the review of species the genus for Brazil by Oliveira (2019), led us to recognize nine species of the same for the Midwest region (see the key below), one of which, C. macvaughii , is new to science. Additionally, we propose: a) the synonymizations of C. inaequalis Fernández Casas (2001: 35) and C. spathulatus Fernández Casas (2003 b: 95) under C. albomaculatus Johnston (1923: 86) ; C. loefgrenii (Pax & Hoffmann 1910: 107) Pax & Hoffmann (1931: 166) , C. calyptratus Fernández Casas (2001: 33) and C. monsato Fernández Casas (2004e: 235) under C. neglectus Pohl (1827: 60) ; and, C. calcareus Fernández Casas (2004a: 172) and C. mitis Fernández Casas (2005: 258) under C. vitifolius ( Miller 1768: Jatropha no. 5) Pohl (1827: 61); b) one neotype for C. paucistamineus ( Pax 1910: 110) Pax (1931: 166) ; and, c) the re-establishment of C. neglectus , a taxon historically synonymized under C. urens ( Linnaeus 1753: 1007) Arthur (1921: 11) , a species not yet found in the Midwest region.

In relation to other species of the genus (e.g., C. aculeatissimus (Colla 1836: 112) Fernández Casas (2002: 67) , C. oligandrus ( Müller Argoviensis 1874: 502) Pax (1931: 166) , C. sellowianus Klotzsch ex Pax (1910: 90) and C. urniger ( Pax 1910: 104) Pax (1931:166)) , cited for the Midwest region by BFG (2015) and Maya-Lastra et al. (2020) we propose that they were mistakenly identified, namely C. aculeatissimus and C. sellowianus confused with C. vitifolius , and C. urniger with C. cervii ; or they are not native such as C. oligandrus , found under cultivation in the Federal District, and are, therefore, not considered here.

All species treated here are compared in a dichotomous key, have their distributions discussed and mapped, are diagnosed morphologically, and seven of them are also represented by images.