Croton graomogolensis Barbosa & Carn.

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, Phytotaxa 365 (3), pp. 259-272 : 264-265

Croton graomogolensis Barbosa & Carn. -Torres, sp. nov. ( Fig. 1 , 2 F–-L , 3 G–L , 4 D )

Type:— BRAZIL: Minas Gerais: Grão Mogol. Início da Trilha do Barão , lado esquerdo, 16º33’24.8”S, 42º53’27.6”W, 873m, 20 November 2015, B.L.R. Barbosa, D.S. Carneiro-Torres, M.S. Silva & J.F.C. Oliveira 17 (holotype HUEFS!; isotypes ALCB!, K!, M!, MBM!, MO!, NY!, P!, RB!, SP!, SPF!) .

Diagnosis:— Croton graomogolensis differs from C. muscicapa by its smaller pistillate flowers, 4–6 mm long, and stamens often 15–17 (vs. pistillate flowers 6–10 mm long and stamens 11–12 in C. muscicapa ).

Description:—Shrubs, monoecious, erect, 2 m tall, foliage viscid, green-vinaceous, glabrous. Leaves simple, alternate; stipules glandular, resembling a bunch of grapes, 1–1.5 × 1–1.5 mm; petiole 9–32.5 mm long, glabrous, eglandular; blade ovate, 19–48 × 15–37.5 mm, apex acute, base cordate, margin with 1–3 glands at the apex of each tooth, adaxial surface glabrous to subglabrous, abaxial surface pubescent to glabrous; venation actinodromous. Inflorescences terminal, bisexual, 12–59 mm long, glabrous, with proximal pistillate flowers and distal staminate flowers, distributed continuously along the rachis; bracts lanceolate, staminate flower bracts 1–2 mm long, pistillate flower bracts 1–3 mm long, fimbriate-glandular. Staminate flowers yellowish green, 3.5–4.5 mm long; pedicels 1–2.5 mm long; sepals 5, ovate, 3–4 × 1.5–2.5 mm, adaxial and abaxial surfaces glabrous; petals 5, oblong, 2–3.5 × 2–3 mm; stamens 15–17, 3–4 mm long. Pistillate flowers green, 4–6 mm long; pedicels 1.5–8.5 mm long; sepals 5, 3–4.5 × 1–2, lanceolate, glabrous, margin glandular, glands short-stipitate, not reduplicate; petals absent, ovary globose, glabrous, styles 3, united at the base, multifid, with 9–10 terminal tips, glabrous. Capsules globose, 4.5–5 × 4.5–5 mm, glabrous; seeds globose, 4.5–5 × 4–4.5 mm, smooth, carunculate.

Etymology: —The specific epithet refers to the municipality of Grão Mogol in Minas Gerais, Brazil, where the species was first collected.

Morphological comments: — Croton graomogolensis is morphologically similar to C. muscicapa ( Fig. 5 A-E) due to the glabrous to pubescent leaves, glandular stipules resembling a bunch of grapes, and leaf blades with a serrate margin ( Fig. 4 D ). Croton graomogolensis differs by having more stamens (often 15–17) and pistillate flowers 4–6 mm long (vs. 11–12 stamens and pistillate flowers 6–10 mm long in C. muscicapa ) ( Tab. 2). These species also have similar and different leaf anatomical characters, as discussed below.

Geographic distribution, habitat and conservation: — Croton graomogolensis is restricted to the state of Minas Gerais, in southeastern Brazil ( Fig. 1 ), and is only known from the municipalities of Grão Mogol and Serranópolis de Minas. It occurs in campo rupestre vegetation (rupestrian grasslands) from 873 to 1,100 m elevation ( Tab. 2). This species is here considered Endangered EN (B2 ab (ii)), according to IUCN criteria ( IUCN 2012), because it is only known from 11 localities in two municipalities and has an estimated AOO of less than 80 km 2. The species occurs within the Grão Mogol and Serra Nova state reserves. We found herbarium specimens collected in these areas in 2007; however, we did not find individuals of this species in these areas during recent fieldwork.

Paratypes:— BRAZIL. Minas Gerais: Grão Mogol, Serra do Grão Mogol , 12 November 1938, F. Markgraf 3517 ( RB) ; Serra do Espinhaço ca. 15 km oeste de Grão Mogol, 19 February 1969, H.S. Irwin et al. 23528 ( UEC 4602 ) ; Serra do Pipiri , 1 January 1980, G. Hatschbach 42882 ( MO) ; em direção nordeste da cidade, 16º32’S, 42º55’W, 22 May 1982, A.M. Giulietti et al. CFCR 3425 ( SP, SPF) ; próximo da saída na Estrada para São Francisco Sá , 7 January 1986, I. Cordeiro et al. CFCR 9049 ( SP, SPF) ; estrada para o Rio Ventania , rio temporário à leste da cidade, 25 July 1986, R. de Mello-Silva et al. CFCR 9952 ( SP, SPF) ; escarpas à direita do Riachão Ribeirão , 21 May 1987, R. de Mello-Silva & J.R. Pirani CFCR 10787 ( SP, SPF) ; trilha dos Garimpeiros , 14 July 1990, G. Hatschbach 54268 ( HUEFS, MBM) ; estrada da Serra do Barão, 16º32’S, 42º55’W, 22 March 2000, L.R. Lima et al 93 ( SPF). Serranópolis de Minas, Sete Quedas , 17 April 2007, O.S. Ribas & J.M. Silva 7755 ( MBM) .

Figures

FIGURE 1. Map showing known distribution of the four species.

FIGURE 2. C. aemulus and C. graomogolensis. A–E. C. aemulus (Barbosa et al.19, HUEFS). A. Habit; B. Stipules, glandular, lanceolate; C. Bracts; D. Staminate flower; E. Pistillate flower. F–L. C. graomogolensis (Barbosa et al. 17, HUEFS). F. Habit; G. Glandular stipules, resembling a bunch of grapes; H. Bracts in frontal view; I. Bracts in lateral view; J. Staminate flower; K. Pistillate flower; L. Ovary and styles. Drawing by Natanael Nascimento.

FIGURE 3. C. aemulus (Barbosa et al. 19, HUEFS) and C. graomogolensis (Barbosa et al. 17, HUEFS). A–F. C. aemulus. A. Habit; B. Inflorescences with staminate flowers and bracts; C. Inflorescences with flower buds, staminate and pistillate flowers; D. Leaf and stipules, branch pubescent; E, F. Pistillate flowers. G–L. C. graomogolensis. G. Habit; H. Inflorescences with flower buds and open staminate flower; I. Inflorescences with flower buds, staminate flowers, and fruit; J. Pistillate flowers and stipules; K. Pistillate flowers; L. Branch. Photos by D.S. Carneiro-Torres and B.L.R Barbosa.

FIGURE 4. Morphological comparison of species. Leaf margin, stipules, sepals, and bracts. A. C. longibracteatus (Barbosa et al. 11, HUEFS). B. C. aemulus (Barbosa et al. 19, HUEFS). C. C. muscicapa (Barbosa et al. 4, HUEFS). D. C. graomogolensis (Barbosa et al. 17, HUEFS). Scale bars = 1 mm.

FIGURE 5. C. muscicapa (Barbosa et al. 4, HUEFS) and C. longibracteatus (Barbosa et al. 11, HUEFS). A–E. C. muscicapa: A. Habit; B. Glabrous leaf; C. Glandular stipules, resembling a brunch of grapes; D. Staminate flower; E. Pistillate flower; F–J. C. longibracteatus. F. Habit; G. Leaf with details of the subglabrous adaxial surface and pubescent abaxial surface; H. Glandular, lanceolate stipules; I. Staminate flower; J. Pistillate flowers with one sepal removed. Drawing by Lucas Menezes.