Croton spica Baillon (1864: 362)

Da Silva, Marcos J., Sodré, Rodolfo C. & Berry, Paul E., 2015, An enigmatic species of Croton (Euphorbiaceae) is rediscovered after more than 100 years in midwestern Brazil, Phytotaxa 221 (1), pp. 83-88 : 83-87

Croton spica Baillon (1864: 362) ( Figs. 1 and 2)

Type:— BRAZIL. Matto Grosso: without locality, 1833, C. Gaudichaud 249 (holotype: P [ P 00634647 image!], isotype F!).

Subshrubs 0.4–0.9 m tall, arising from a xylopodium, erect, cespitose, monoecious, latex hyaline. Stem and branches canescent-green or yellowish-green, tomentose, covered with stellate-porrect trichomes (same as on the petiole, inflorescence axis, both surfaces of the bracts of both flower sexes, external surface of the pistillate sepals and gynoecium). Stipules 0.6–1.1 × 0.3–0.6 mm, ovate to oblong, margins entire; petiole 0.6–2.2 cm long, tomentose, with two patelliform, sessile to or subsessile glands at the apex, each 1–1.2 mm diameter; blade 4.3–8.3 × 2.3–5.2 cm, elliptic, oblong or ovate, base distinctly cordate or sometimes obtuse, margin serrate to crenate with patelliform glands in the sinuses and globose glands on the tip of the teeth, apex obtuse to apiculate, membranous, discolorous, upper surface light green, lower surface whitish; venation brochidodromous, with 5–10 pairs of secondary veins at an angle more than 45º in relation to the midrib; the two basalmost pairs reaching less than half the length of the blade. Thyrses 2.5–6.2 cm long, terminal, flowers continuous along the inflorescence axis, the pistillate flowers 2–5 distributed in the basal ¼ of the axis; staminate bracts 4–6 × 0.15–0.2 mm, at least twice the size of the buds; pistillate bracts 6–7 × 0.4–0.5 mm, both linear, acute at the apex. Staminate flowers 3.8–5 mm long; pedicel 1–2 mm long; sepals 5, 2.3–2.5 × 1.3–1.4 mm, ovate, acute at the apex, densely tomentose externally and glabrous to glabrescent internally, discretely united at the base; petals 5, 2.8–3 × 0.7–0.8 mm, lanceolate to oblong, obtuse to acute at the apex, villous on both surfaces, barbellate; stamens 11, one in the central portion of the flowers surrounded by the rest, glabrous; disk 5-segmented, segments oblong, receptacle villous. Pistillate flowers 7–11 mm long; pedicel 1–2 mm long; sepals 5, conspicuously unequal, the two largest 6–9 × 3.8–8.5 mm, obovate to widely elliptic, obtuse to acuminate at the apex, the two median ones 4.5–6.5 × 1.3–3.7 mm, ovate, obovate or lanceolate, acute to obtuse at the apex, and the smallest one 4.5–5 × 1.1–1.4 mm, lanceolate, all serrate-margined, foliaceous, and densely stellate-pubescent on both surfaces, petals 2–3 × 0.1–0.2 mm, linear to lanceolate, with long-rayed stellate trichomes along the margins, with an apical gland; ovary 1.3–2 × 2–2.8 mm, subgloboid; styles 3.5–6 mm long, 2-fid, with 6 terminal tips; disk 5-lobed, lobes quadrangular, receptacle glabrous. Capsule with a pedicel of 2.2 mm; 5–5.5 × 4.5–5 mm, globoid to oblongoid, the mericarps not protruding, whitish-green, styles and sepals persistent, the sepals accrescent and foliaceous. Seeds 4–4.3× 2.6–2.7 mm, oblongoid to ovoid, discretely foveolate, brownish with dark brown or cream splotches, caruncle more or less triangular, pale yellow.

Additional specimens examined:— BRAZIL. Distrito Federal: Brasília, imediações do Samambaia, a direita do km 11 da BR 060 , em direção a porção central de Brasília, 20 February 2014, (fl, fr), R. C. Sodré et al. 1207 ( IBGE, M, UFG). Goiás: Alto Paraíso de Goiás, Parque Nacional da Chapada dos Veadeiros, ca. 3.5 km a noroeste do Morro do Buracão, 14°07’25.4”S, 47°44’12.1”W, 1189 m, 10 May 2013, (fl, fr), R. C. Sodré et al. 719 ( UFG), R. C. Sodré et al. 720 ( UFG), R. C. Sodré et al. 721 ( UFG) ; próximo a bifurcação da estrada de terra que leva a Cachoeira das Sete Quedas, 14°07’25.4”S, 47°44’12.1”W, 1189 m, 14 December 2013, (fl), M. J. Silva & R. C. Sodré 5660 ( K, UFG), M. J. Silva & R. C. Sodré 5661 ( P, UFG), M. J. Silva & R. C. Sodré 5662 ( R, UFG), M. J. Silva & R. C. Sodré 5663 ( M, UFG), M. J. Silva & R. C. Sodré 5664 ( IBGE, UFG) ; 1 km a partir da bifurcação que leva a Cachoeira das Sete Quedas, 14°07’30”S, 47°44’24.6”W, 1182 m, 14 December 2013, (fl), M. J. Silva & R. C. Sodré 5666 ( P, UFG), M. J. Silva & R. C. Sodré 5667 ( M, UFG) ; 2.5 km a noroeste do Morro do Buracão, 14°07’39.2”S, 47°44’11.6”W, 1191 m, 14 December 2013, (fl), M. J. Silva & R. C. Sodré 5676 ( UFG). Cristalina, a aproximadamente 7 km da BR 050 , em direção a RPPN Linda Serra dos Topázios, 16°44’55,3”S, 47°40’33,6”W, 1098 m, 24 January 2014, (fl), R. C. Sodré et al. 1127 ( IBGE, M, P, UFG). Leopoldo de Bulhões, 600 m antes do Posto da Polícia Rodoviária Federal em direção a Silvânia, 16°38’36.9”S, 48°43’21.4”W, 1048 m, 27 November 2013, (fl, fr), M. J. Silva et al. 5591 ( IBGE, K, UFG). Silvânia, Floresta Nacional de Silvânia , cerca de 2 km a noroeste da sede da reserva, após uma porteira de ferro interditada, 7 December 2012, (fl), M. J. Silva et al. 4591 ( UFG), M. J. Silva et al. 4592 ( UFG), M. J. Silva et al. 4597 ( UFG), M. J. Silva et al. 4598 ( IBGE, UFG), R. C. Sodré et al. 328 ( M, UFG), R. C. Sodré et al. 333 ( UFG), R. C. Sodré et al. 334 ( UFG), R. C. Sodré et al. 335 ( UFG), R. C. Sodré et al. 336 ( UFG) ; same locality, 24 May 2013, (fl, fr), M. J. Silva et al. 4948 ( UFG) ; GO 330 , próximo ao posto da Polícia Rodoviária Federal, entre os municípios de Silvânia e Leopoldo de Bulhões, 16°38.717’S, 48°42.996’W, 1060 m, 14 March 2013, (fl, fr), R. C. Sodré et al. 621 ( R, UFG), R. C. Sodré et al. 622 ( P, UFG), R. C. Sodré et al. 623 ( K, UFG, K), R. C. Sodré et al. 624 ( M, UFG) ; same locality, 25 May 2013, (fl, fr), M. J. Silva et al. 4954 ( R, UFG), M. J. Silva et al. 4955 ( P, UFG), M. J. Silva et al. 4956 ( K, UFG), M. J. Silva et al. 4957 ( M, UFG) ; Floresta Nacional de Silvânia , imediações da propriedade do Senhor Cícero, cerca de 2 km a noroeste da sede da FLONA, 16°38’6.4”S, 48°40’36.4”W, 1056 m, 27 November 2013, (fl), M. J. Silva et al. 5598 ( UFG), M. J. Silva et al. 5599 ( UFG), M. J. Silva et al. 5601 ( UFG), M. J. Silva et al. 5606 ( UFG). Pirenópolis, Serra dos Pireneus, subida para o Parque, 15°49’1’’S, 48°53’38”W, 1085 m, 18 January 2005, (fl), J. Paula-Souza et al. 4134 ( ESA). Mato Grosso: entroncamento das rodovias, Cuiabá Santarém e Porto Velho, arredores do aeroporto, 15°38’56”S, 56°11’42”W, 4 February 1979, (fl, fr), M. G. da Silva & A. Pinheiro 4433 ( NY) .

Notes:— Croton spica was described by Baillon (1864) based on the sole collection of Gaudichaud 249 from Mato Grosso state (“Province de Matto Grosso”) in Brazil. Until recently it was a poorly known and collected species. However, analyzing specimens of the genus from the midwestern region of Brazil, we have found one collection of this species at NY from Mato Grosso state, and other 37 specimens collected in Goiás state and the Distrito Federal. In Goiás the species can be found in the Chapada dos Veadeiros National Park, in the National Forest of Silvânia, in the Private Reserve of Natural Heritage Linda Serra dos Topázios and in the Pireneus State Park, while in the Distrito Federal it occurs in the neighboring region of Brasilia municipalities. In all known localities, it grows in cerrado s. str. on sandy, stony and clayey soil, or in cerrado rupestre close to damp places in stony soil between 1060 and 1190 m of elevation. In the Silvânia National Forest it frequently occurs in small populations together with C. abaitensis Baillon (1864: 337) , while in the Chapada dos Veadeiros National Park it is sympatric with C. desertorum Müller Argoviensis (1873: 265) . It is known to produce flowers and fruits from November to May.

Although Croton spica is still found in a few locations we believe that it is a common species in the Midwest region because the vegetation types where it grows are also widespread in central Brazil. Thus, we consider it to be a Least Concern species according to the IUCN Red List Category ( IUCN 2014).

In taxonomic terms, Croton spica is placed here in Croton sect. Geiseleria ( Gray 1856: 391) Baillon (1858: 359) by virtue of its subshrubby habit, stellate trichomes, glands at the apex of the petiole and along the margins of the blade, and pistillate flowers with free and unequal sepals ( van Ee et al., 2011). Along with Croton abaitensis , C. agoensis Baillon (1864: 348) , C. longinervius Müller Argoviensis (1873: 215) , C. mucronifolius Müller Argoviensis (1873: 216) and C. pycnadenius Müller Argoviensis (1873: 216) , this species shares inconspicuous stipules, leaves that are subsessile or shortly petiolate with the base usually distinctly cordate and the lower surface whitish, as well as persistent and linear bracts, pistillate flowers with 5 sepals with stellate hairs on both surfaces, bifid styles and an androecium usually with 11 stamens. Croton spica differs from all of these species by the combination of the petiole with mostly sessile patelliform glands; leaf blades with 5–10 pairs of secondary veins; and pistillate flowers with two large sepals 6–9 mm long with conspicuously serrate margins. In contrast, the other species have petioles with stipitate-patelliform, cupuliform or turbinate glands, leaf blades with just 2–3(–4) pairs of secondary veins, and pistillate flowers with sepals up to 5 mm long and with entire margins. Since C. spica has previously been confused in herbaria material with its related species, we provide the following key to help differentiate the species of Croton sect. Geiseleria from Goiás with which it could be confused.