Croton aemulus Barbosa & Carn., sp. nov.
Creators: name: Barbosa, Bárbara Laís Ramos
name: Oliveira, Reyjane Patrícia
name: Mascarenhas, Ana Angélica Silva
name: Dórea, Marcos Da Costa
name: Martins, Fabiano Machado
name: Carneiro-Torres, Daniela Santos
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Malpighiales
Euphorbiaceae
Croton
Croton aemulus

description: Croton aemulus Barbosa & Carn. -Torres, sp. nov. (Fig. 1, 2 A–E, 3 A–F, 4 B)   
 Type:— BRAZIL: Minas Gerais: Jequitinhonha. Serra de areia no topo da serra, 16º20’11.2”S, 41º5’25.4”W, 1088 m, 21 November 2015, B.L.R. Barbosa, D.S. Carneiro-Torres, M.S. Silva & J.F.C. Oliveira 19 (holotype HUEFS!; isotypes ALCB!, K!, M!, MBM!, MO!, NY!, P!, RB!, SP!, SPF!).   
 Diagnosis:— Croton aemulus differs from C. longibracteatus by having leaf blades with a pubescent adaxial surface, leaf margins with 3–4 glands at the apex of each tooth, staminate and pistillate flowers with smaller stamens and bracts, and sepals of pistillate flowers with short-stipitate glands (vs. leaf blades with a subglabrous adaxial surface, leaf margins with one sessile gland at the apex of each tooth, staminate and pistillate flowers with larger stamens and bracts, and sepals of pistillate flowers with long-stipitate glands).   
 Description:—Shrubs, monoecious, erect, to 1 m tall, foliage viscid, green-vinaceous, pubescent, trichomes stellate-rotate, porrect, radii 6–8. Leaves simple, alternate; stipules lanceolate, glandular, 1.5–4 × 1–2 mm; petiole 8.5–30 mm long, hirsute-pubescent, eglandular; blade ovate, 31.5–71 × 21–47 mm, apex acuminate, base cordate to subcordate, margin with 3–4 glands at the apex of each tooth, pubescent on both surfaces; venation actinodromous. Inflorescences terminal, bisexual, 25.5–83 mm long, hirsute, with proximal pistillate flowers and distal staminate flowers, distributed continuously along the rachis; bracts lanceolate, staminate flower bracts 1.5–4.5 mm long, pistillate flower bracts 1.5– 7 mm long, fimbriate-glandular, glands long-stipitate, concentrated at the base. Staminate flowers yellowish green, 5.5–7 mm long; pedicels 2–5 mm long; sepals 5, ovate, 2.5–4 × 1.5–2.5 mm; adaxial surface glabrous, abaxial surface pubescent with trichomes at the apex; petals 5, ovate, 3–4 × 2–3 mm; stamens 11–12, 4.5–6.5 mm long. Pistillate flowers green, 7.5–8 mm long; pedicels 3–4.5 mm long; sepals 5, lanceolate, 6.5–9 × 1–2 mm, pubescent, margin glandular, glands short-stipitate, reduplicate; petals absent; ovary globose, pubescent, styles 3, united at the base, multifid, with 8–11 terminal tips, glabrous. Capsules globose, 6.5–7 × 5.5–6 mm, pubescent; seeds globose, 3.5–4 × 2.5–3 mm, smooth, carunculate.   
 Etymology: —The epithet aemulus refers to the general and confusing morphology of this new species, which is quite similar to Croton longibracteatus and C. graomogolensis.   
 Morphological comments: —In general, Croton aemulus is morphologically similar to C. longibracteatus (Fig.5F–J). These species share several characters, such as lanceolate and glandular stipules, leaf blades with a dentate margin, and a similar number of stamens. They differ mainly because C. aemulus has leaf blades with a pubescent adaxial surface, margins with 3–4 glands at the apex of each tooth, pistillate flowers 7.5–8 mm long, and lanceolate sepals with short-stipitate glands (vs. leaf blades with a subglabrous adaxial surface, margins with one gland at the apex of each tooth, pistillate flowers 9–17.5 mm long, and lanceolate sepals with long-stipitate glands in C. longibracteatus). Although both species have some similar leaf anatomical characters, as discussed below, they also exhibit differences that support our taxonomic decisions.   
 Croton aemulus is also similar to C. graomogolensis (Fig. 2 F–L) by the size of pistillate and staminate flowers and small bracts (Tab. 2). Croton aemulus differs by having pubescent leaf blades on the adaxial surface, margins with 3–4 glands at the apex of each tooth, staminate flowers 5.5–7 mm long, and stamens 11–12 (vs. leaf blades glabrous to subglabrous on the adaxial surface, margin with 1–3 glands at the apex of each tooth, staminate flowers 3–4.5 mm long, and stamens often 15–17 in C. graomogolensis).   
 Geographic distribution, habitat and conservation: — Croton aemulus is restricted to the state of Minas Gerais, in southeastern Brazil, and is only known from the municipality of Jequitinhonha (Fig. 1). It was only found in the Mata Escura Biological Reserve, in cerrado de altitude vegetation (mountain savannah), which occurs from 1,088 to 1,134 m elevation and typically grows on sandy soil (Tab. 2). This species is here considered Endangered CR (B1 B2 ab (ii)), according to IUCN (2012) criteria, because it is only known from three locations and has an estimated area of occupancy (AOO) of less than 15 km 2.   
 Paratypes:— BRAZIL. Minas Gerais: Jequitinhonha, Reserva Biológica da Mata Escura, 16º26’2”S, 41º0’12”W, 31 December 2004, R. de Mello-Silva et al. 437 (RB, SP, SPF); Reserva Biológica da Mata Escura, 16º20’18”S, 41º05’23”W, 25 March 2008, T.E. Almeida et al. 1308 (BHCB).
description: Published as part of Barbosa, Bárbara Laís Ramos, Oliveira, Reyjane Patrícia, Mascarenhas, Ana Angélica Silva, Dórea, Marcos Da Costa, Martins, Fabiano Machado & Carneiro-Torres, Daniela Santos, 2018, Croton aemulus and C. graomogolensis (Euphorbiaceae): Two new species from Minas Gerais, Brazil, based on distinct lines of evidence and their relation to C. muscicapa and C. longibracteatus, pp. 259-272 in Phytotaxa 365 (3) on page 262, DOI: 10.11646/phytotaxa.365.3.4, http://zenodo.org/record/13704505