Croton espinhacensis M. J. Silva & Sodre 2024, sp. nov.
Creators: name: Silva, Marcos José Da
name: Sodré, Rodolfo Carneiro
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Malpighiales
Euphorbiaceae
Croton
Croton espinhacensis

description: Croton espinhacensis M.J. Silva & Sodré, sp. nov. (Fig. 1)
Type:— BRAZIL. Minas Gerais: Fruta de Leite, Sítio 2, Ponto 1, 16°12’43”S, 42°28’52”W, 892 m, 30 November 2016 (fl., fr.), A. C. Sevilha, G. Pereira-Silva, J. B. Pereira & S. E. de Noronha 5890 (holotype: CEN 103263!; isotypes: CEN!, UFG!, UB!).
Diagnosis:—This new species has indumented anthers, an unusual feature in the genus Croton. It ressembles Croton harleyi Carn. -Torres & Cordeiro (in Carneiro-Torres et al. 2011: 128), from the Northeastern region of Brazil, by the shrubby habit, stems densely distally branched with leaves grouped at the apex of branches, bisexual thyrses with unisexual cymes and flowers of both sexes continuous, and staminate flowers with 11 stamens. However, C. espinhacensis differs especially in having leaf blades that are chartaceaeous, ovate-lanceolate, ovate-oblong or cordate, with stipitate patelliform nectary glands at the leaf base (vs. membranaceous, elliptic blades, and with cylindric nectary glands at the leaf base in C. harleyi), thyrses with 1(–2) pistillate flowers at the base (vs. 2–4), anthers indumeted (vs. glabrous), pistillate flowers pedicelate with plane sepals (vs. sessile with revolute sepals), and seeds oblong (vs. ellipsoid).
Description:—Subshrub or shrub 0.8–2 m tall, erect, monoecious, densely branched distally, adult branches darkish and glabrous and young branches ferrugineous or green-brownish, with stellate or mutiradiate trichomes, the first ones sessile, with 7–10 rays; the second ones multiradiate in 2 or 3 whorls, with stipe measuring 0.2–0.3 mm long, and rays up to 0.5 mm long; latex scarce, hyaline; stipules 0.9–1 × 0.3–0.4 mm, lanceolate or narrowly triangular with 4–8 ovoid and sessile nectary glands at the base, covered with stellate trichomes on both surfaces, the trichomes more densed externally. leaves entire, spirally alternate along the stems; petioles 0.5–1.4 cm long; blades 1.4–3.9 × 0.7–2.6 cm, ovate, ovate-lanceolate, ovate-oblong or cordate, with obtuse or slightly cordate base with 2 shortly stipitate patelliform glands 0.4–0.6 mm diam. on the abaxial surface, acute or shortly acuminate apex, entire or slightly serrate or serrulate margin, with sessile colleters in the sinuses, membranaceous, discolorous, adaxial surface light green and adaxial surface green-ferrugineous, the first ones with stellate trichomes with 6–10 rays, the second ones multiradiate in 2 or 3 whorls, with stipe 0.2–0.3 mm long, and rays up to 0.5 mm long, both, tomentose to the touch; venation brochidodromous, with 4–6 pairs of secondary veins, primary and secondary veins prominent on the abaxial surface and impressed on adaxial surface. Inflorescences bisexual, 0.9–1.5 cm long, terminal with 1(–2) pistillate flowers at the base axis, and 9 or 18 staminate flowers continuous along the inflorescence axis; bracts of staminate flowers 2.3–2.4 × 0.2–0.3 mm, lanceolate glabrous internally and pin-cushion externally; bracts of pistillate flowers 4–4.1 × 0.2–0.3 mm, lanceolate similar to the staminates ones. Staminate flowers 7–8 mm long, yellowish, actinomorphic; pedicels 4–4.1 mm long; calyx 5-lobed, lobes 2.1–2.2 × 1.4–1.5 mm, equal, oval, ovate-triangular, with acute apex, slightly united at the base, ventrally glabrous, dorsally stellate; petals 2.4–2.8 × 1–1.1 mm, elliptic, ovate-elliptic or elliptic-obovate, with a obtuse apex, villous externally with stellate trichomes along the midrib, ciliate on the margins, the longest cilia at the base; stamens 11, 3.7–3.8 mm long, with a sparsely pubescent indumentum of hispid trichomes on filaments and anthers, anthers oblong with 0.7–0.8 mm long; disk with 5 obovoid segments, yellowish with margin slightly crenulate; receptacle villous. Pistillate flowers 5.2–5.5 mm long; pedicels 3–3.1 mm long; sepals 5, subequal 4.8–5 × 1.6–1.8 mm, lanceolate or narrowly triangular, with acute apex, margin entire, plane, eglandular with multiradiate trichomes on both surfaces, the trichomes more densed externally, free, valvate prefloration; petals 5, glanduliform; ovary 2–2.1 × 2.2–2.3 mm globose, yellowish-ferrugineous with tomentose indumentum of stellate trichomes; stigmas 3, deeply bifid, 3.6−3.9 mm long, covered with stellate trichomes; disk 5-segmented, receptacle glabrous. Capsules 4.9–5 × 3.9–4 mm, oblongoid, ferrugineous, the trichomes multiradiate, sepals accrescent, similar to the length of the fruit, pedicels 2.3–2.5 mm long; seeds 4–4.1 × 1.9–2 mm, oblong, grayish, with discretely dark spots; caruncle hatshaped, sessile, yellow-whitish, visible on both surface of the seed.
Distribution and habitat:—The species is so far known from the Espinhaço Mountain Range, in the Brazilian states of Bahia and Minas Gerais (Fig. 2), where it grows in “cerrado rupestre” and “cerrado denso” in flat or hillside areas between 828 and 1391 m of altitude. It prefers sandy and litholics soils, as well as plinthosols or latossols.
Phenology: — Collected with flowers and fruits from November to May.
Preliminary conservation status:—Species with an estimated EOO and AOO of 7,825.856 km 2 and 48.000 km 2, respectively. Therefore, it is tentatively classified here as Vulnerable (EN) Criteria B1 subcriteria b(i, iv, v).
Etymology: — The specific epithet “ espinhacensis ” alludes to the region of the Espinhaço Range, state of Minas Gerais and Bahia, where the species lives.
Additional specimens examined (paratypes):— BRAZIL. Bahia: Mortugaba, ca. 8 km da cidade em direção a Jacaraci (“Jacarau” on the label), 14°53’7”S, 42°28’3”W, 1000 m, 16 March 1994 (fl.), V. C. Souza et al. 5527 (ESA, SPF). Minas Gerais: Fruta de Leite, Vale do Rio Peixe Bravo, 14 February 2020 (fl.), R. S. Fonseca et al. 1329 (MCCA). Monte Azul, Parque Estadual Caminho dos Gerais, 14°52’37”S, 43°2’15”W, 1046 m, 16 February 2017 (fl.), D. M. G. Oliveira et al. 124 (ALCB, BHCB). Rio Pardo de Minas, Areião, Ponto 5, 15°26’31”S, 42°28’52”W, 902 m, 23 May 2005 (fr), A. C. Servilha et al. 4305 (CEN); estrada de chão sentido entroncamento Novo Horizonte / Rio Pardo de Minas, 15°49’52”S, 42°25’42”W, 868 m, 21 April 2006 (fl., fr.), D. S. Carneiro-Torres et al. 695 (ESA, HUEFS); ib., Vereda Funda, 15°54’45”S, 42°28’32”W, 876 m, 10 December 2008 (fl., fr), A. C. Sevilha et al. 4951 (CEN); Parque Estadual da Serra Nova, trilha para o escorregador no Córrego da Velha, 15°36’53.9–57.3” S, 42°44’5.6–20.6” W, 834–858 m, 21 March 2012 (fl., fr.), J. A. Lombardi, M. N. Saka & D. A. Araújo 9029 (HRCB, UPCB); ib., trilha para o Gerais, 15°39’40”S, 42°45’57”W, 1391 m, 22 March 2012 (fl.), J. M. Costa et al. 1016 (BHCB). Rubelita, Sítio 2, Ponto 3, 828 m, 01 December 2016 (fl., fr), A. C. Sevilha et al. 5961 (CEN). Santo Antônio do Retiro, ca. 11 km da cidade em direção a Mato Verde, ca. 2 km do rio Mandaçaia, 15°22’41”S, 42°41’54”W, 1000 m, 17 March 1994 (fl.), C. M. Sakuragui et al. CFCR 15128 (SPF, K, R); Sucuriu, 15°20’18”S, 42°45’09”W, 986 m, 15 March 2017 (fl., fr), A. C. Sevilha et al. 6370 (CEN, UFG). Serranópolis de Minas, Parque Estadual de Serra Nova e Talhado, estrada de acesso aos Gerais Santana, cerca de 1 km a nordeste da Cidade das Pedras, 15°48’7”S, 42°46’7”W, 950 m, 04 April 2022 (fl.), M. Verdi et al. 8820 (RB, SPF, HUEFS).
Notes:— Croton espinhacensis is placed here in Croton sect. Geiseleria subsect. Geiseleria. This decision is based on the combination of the following character states: shrubby or subshrubby habit, alternate leaves no more than 2 to 3 times as long as wide, with sessile or stipitate nectary glands at the apex of the petiole or at the base of the blade and/or in the sinuses of the leaf margin, thyrses without a distinct gap between staminate and pistillate flowers, pistillate flowers with free sepals, glandular or eglandular equal or slightly unequal, developed or glandulifom petals, bifid styles with 6 terminal branch tips, and fruits with an irregularly fimbriate columella apex.
Among the species of this section present in Brazil, Croton espinhacensis ressembles C. harleyi (Carneiro et al. 2011), a species from the Caatinga vegetation of the Bahia state. Both species share the shrubby habit, the stems densely branched from the upper third, the leaves commonly grouped in terminations of the branches, leaf blades small up to 5 × 2.5 cm with nectaries on the base and margin, the thyrses up to 2 cm long with pistillate flowers continuous to the staminate flowers, the latter with 11 stamens. However, the characters listed in Table 1 certainly serve to differentiate both species.
Croton espinhacensis has been confused in herborized collections (see, e.g., C.M. Sakuragui CFCR 15128 from SPF, K and R; D.M.G. Oliveira 124 from ALCB, BHCB; and V.C. Souza et al. 5527 from ESA and SPF) with C. atrorufus, a species of Croton sect. Barhamia (Klotzsch 1853: 104) Baillon (1858: 367) subsect. Medea (Klotzsch 1841: 193) Pax (1890: 39: 367) that also can be foud in de Espinhaço Montain Range. In fact, both species sahres the same habit, colors of the branches and leaves, in some case, tha shape of the leaves, and estaminate disc 5-segmented. However, C. atrorufus has stipules laciniate-glandulose (vs. entire in C. espinhacensis), leaves without acropetiolar or basilaminar glands (vs. with a pair of basilaminar glands), pistillate sepals with margin laciniate-glandulose (vs. entire and without glands), anthers glabrous (vs. anthers indumented), styles 4 or 5-fids (vs. 2-fids), as well as seeds broadly elliptical with a rugose testa (vs. oblongoid and smooth).
With the description of this new species, C. carajasensis Sodré & Secco (2023: 134) and C. piriquetifolius M.J. Silva & Sodré (in Silva et al. 2024: 144), Croton sect. Geiseleria is now represented in Brazil by 57 species, 39 of which are endemic, which reinforces that Brazil is the center of diversity of this group.
description: Published as part of Silva, Marcos José Da & Sodré, Rodolfo Carneiro, 2024, A new species of Croton (Euphorbiaceae) from the Espinhaço Mountain Range, Brazil, pp. 87-94 in Phytotaxa 677 (1) on pages 88-92, DOI: 10.11646/phytotaxa.677.1.5, http://zenodo.org/record/14522214