Croton sapiifolius Müll.Arg. In: a new occurrence for the State of Espírito Santo, Brazil¹

ABSTRACT

While studying Croton material collected in Espírito Santo, we found several specimens of Croton sapiifolius, a species previously restricted to the State of Bahia. The present paper updates our knowledge about the taxonomy, habitat and geographic distribution of C. sapiifolius. This finding increases the number of known Croton species occurring in Espírito Santo State to 20 and contributes to the knowledge of Croton of the Brazilian Atlantic Forest.

Keywords:
Atlantic Forest; Crotoneae; Flora; Restinga vegetation

RESUMO

Durante visita aos herbários do Estado do Espírito Santo, foram encontrados espécimes de C. sapiifolius para este Estado, uma espécie conhecida até o momento apenas para o Estado da Bahia. Neste trabalho são apresentados dados atuais sobre a taxonomia e distribuição geográfica de C. sapiifolius. Essa nova ocorrência eleva para 20 o número de espécies conhecidas de Croton no Estado do Espírito Santo. O presente trabalho contribui para enriquecer o conhecimento sobre as espécies de Croton na Floresta Atlântica e no Brasil.

Palavras-chaves:
Crotoneae; Flora; Floresta Atlântica; Restinga

Introduction

Croton L., the second largest genus of Euphorbiaceae, comprises about 1.200 species distributed worldwide (Berry et al. 2005). Brazil has 316 species of the genus, which ranks Croton as the 4^th largest Angiosperm genus in the country (BFG 2015). It occurs in almost all types of vegetation, but most species grow in dry and open vegetation, secondary forests and disturbed sites (van Ee et al. 2011, Gomes-Pompa 1971, Caruzo et al. 2011).

Croton sapiifolius was described by Müller Argoviensis (1865) as the only species of section Quadrilobus Müll.Arg. Webster (1993) mentioned that the species was poorly known because until then it was only known from the type collection. Riina et al. (2010) updated the description of Croton sapiifolius, designated a lectotype, and recorded new specimens, however, until that moment it was known to occur only in moist forests of southern Bahia.

During studies conducted on the genus Croton at the herbarium of the Universidade Federal do Espírito Santo (VIES; acronym following Thiers 2016), several collections of C. sapiifolius from the State of Espírito Santo were found. According to Dutra et al. (2015), there were 19 species of Croton in the State of Espírito Santo (ES). The present paper documents the first record of Croton sapiifolius for this State, increasing to 20 the number of Croton species known for Espírito Santo and extending the distribution of this species to southeastern Brazil.

Material and methods

This study was based on the analysis of collections deposited in the following herbaria: ALCB, CVRD, MBML, SP, VIES (acronyms according to Thiers 2016).

Morphological characters were observed using a stereomicroscope and the terms used in the description are following Hickey (1973), Stearn (1992), and Webster et al. (1996).

Results and Discussion

Important characters for recognizing Croton sapiifolius are the following: trees up to 14 m tall, monoecious or apparently dioecious, glabrescent or covered by sparse indumentum of stellate, stellate-lepidote or stellate-porrect trichomes; leaves coriaceous, elliptic or oblong, margin entire to sinuous or dentate, with discoid glands in the sinuses; venation brochidodromous; acropetiolar glands 2(-4), sessile and globose, visible from the adaxial side of the leaf. Staminate inflorescences axillary; staminate flowers shortly pedicellate, 4-merous, valvate, sepals ovate, petals oblong; stamens 10-15. Pistillate inflorescences terminal; pistillate flowers pedicellate; 4(-6)-merous, sepals triangulate, filiform petals sometimes present; ovary 2(-3)-locular; styles 3, with 6(-8) terminal arms. Capsules obovate to oblong; seeds obovoid, carunculate (see illustration in Riina et al. 2010).

Croton sapiifolius is endemic to the Atlantic Forest (figure 1), where is found in 'restinga' forests of Espírito Santo State and in moist forests of southern Bahia, from 100 to 200 m elevation (Riina et al. 2010). Flowering from August to October and fruiting in May, October and November.

Figure 1
Geographic distribution of Croton sapiifolius (Guarapari, Vila Velha, Vitória: Espirito Santo, Brazil; Uruçuca, Itagibá, Jussari, Uruçuca, Una: Bahia, Brazil). Map showing previously known localities (circles) and new locality records (diamonds). BA: Bahia. ES: Espírito Santo.

Selected material examined: BRAZIL. Espírito Santo: Guarapari, Setiba, 27-IX-1982, O.J. Pereira et al. 195 (VIES, SP); Vila Velha, Interlagos, 1-VI-1995, O.J. Pereira et al. 5459 (VIES, SP); ibid., 8-VIII-1995, O. Zambom & F.S. Sá 1522 (VIES, SP); Vitória, Reserva Ecológica de Camburi, 28-XI-1997, A.M. Assis & I. Weiler Júnior 298 (VIES, SP); ibid., 1-X-1998, A.M. Assis 638 (VIES, SP). Bahia: Itagibá, Mata da Botinha, 6-I-2009, M.L. Guedes et al. 16508 (ALCB); ibid, 10-VII-2009, M.L. Guedes et al. (ALCB).

Specimens of Croton sapiifolius from Espírito Santo provide new data and additional morphological variation for the species. For this reason, the current description (Riina et al. 2010) should be complemented with the following features: occurrence of monoecious individuals; presence of stellate-porrect trichomes in other parts of the plant besides the pistillate flowers; presence of reduced petals in the pistillate flowers; styles bifid, with terminal tips sometimes divided once more.

Specimens of Croton sapiifolius were erroneously identified at VIES as C. polyandrus Spreng. Although both species occur sympatrically in 'restinga' forests of the State of Espírito Santo, they can be easily distinguished by their habit (arborescent in C. sapiifolius vs shrubby in C. polyandrus), foliar margin (sinuous or entire in C. sapiifolius vs crenate in C. polyandrus), number of carpels (usually two in C. sapiifolius vs three in C. polyandrus) and inflorescence sexuality (unisexual in C. sapiifolius vs bisexual in C. polyandrus). Another species found in 'restinga' forests of the State of Espírito Santo is Croton sphaerogynus Baill., which differs from Croton sapiifolius in several morphological features (see table 1).

Table 1
Main characters distinguishing Croton sapiifolius, C. polyandus and C. sphaerogynus.

Character/Species	Croton sapiifolius	Croton polyandrus	Croton sphaerogynus
Habit	tree	shrub	shrub
Leaf margin	sinuous	crenate	serrate
Number of carpels	2	3	3
Inflorescence sexuality	unisexual	bisexual	bisexual
Pistillate flower	campanulate	subcampanulate	flask-shaped
Styles	6(-8) terminal arms	6 terminal arms	12 terminal arms

The present paper increases the number of known species of Croton in the State of Espírito Santo to 20 and contributes to the knowledge of Croton species in Brazil.

• 1
  Parte da Dissertação de Mestrado da primeira Autora

Acknowledgements

The authors want to thank the following herbaria: ALCB, CVRD, MBML, SP, and VIES for providing access to their collections. Financial support was provided to RFS by Coordenação de aperfeiçoamento de Pessoal de Nível Superior (Capes). MBRC thanks 'Conselho Nacional de Desenvolvimento Científico e Tecnológico' (CNPq) for the research grant provided (process 441049/2014-1).

Literature cited

• Berry, P.E., Hipp, A.L., Wurdack, K.J., van Ee, B.W. & Riina, R. 2005. Molecular phylogenetics of the giant genus Croton and tribe Crotoneae (Euphorbiaceae sensu stricto) using ITS and trnL-trnF DNA sequence data. American Journal of Botany 92: 1520-1534.
• BFG. 2015. Growing Knowledge: an overview of Seed Plant diversity in Brazil. Rodriguésia 66: 1085-1113.
• Caruzo, M.B.R., van Ee, B.W., Cordeiro, I., Berry, P.E. & Riina, R. 2011. Molecular phylogenetics and the character evolution in "Sacaca" clade: novel relationships of Croton section Cleodora (Euphorbiaceae). Molecular Phylogenetics and Evolution 60: 193-206.
• Dutra, V.F., Alves-Araújo, A. & Carrijo, T.T. 2015. Angiosperm Checklist of Espírito Santo: using electronic tools to improve the knowledge of an Atlantic Forest biodiversity hotspot. Rodriguésia 66: 1145-1152.
• Gomes-Pompa, A. 1971. Possible papel de la vegetación secundaria en la evolución de la flora tropical. Biotropica 3: 125-135.
• Hickey, L.J. 1973. Classification of the architecture of dicotiledonous leaves. American Journal of Botany 60: 17-33.
• Riina, R., Cordeiro, I., Amorim, A.M. & Berry P.E. 2010. Croton thomasii Riina & P. E. Berry (Euphorbiaceae), a new species from the Atlantic Forest in the State of Bahia (Brazil) and typification of Croton sapiifolius Müll Arg. Candollea 65: 101-107.
• Stearn, W.T. 1992. Botanical Latin. 4 ed. Timber Press, Portland.
• Thiers, B. 2016 [continuously updated]. Index Herbariorum: A global directory of public herbaria and associated staff. New York Botanical Garden's Virtual Herbarium. Available in http://sweetgum.nybg.org/ih/ (access in I-VI-2015).
  » http://sweetgum.nybg.org/ih/
• van Ee, B.W., Riina, R., Berry, P.E. 2011. A new infrageneric classification and molecular phylogeny of New World Croton (Euphorbiaceae). Taxon 60: 791-823
• Webster, G.L. 1993. A provisional synopsis of the sections of the genus Croton (Euphorbiaceae). Taxon 42: 793-823.
• Webster, G.L., Del-Arco-Aguilar, M.J. & Smith, B.A. 1996. Systematic distribution of foliar trichome types in Croton (Euphorbiaceae). Botanical Journal of the Linnean Society 121: 41-57.

Publication Dates

• Publication in this collection
  Oct-Dec 2016

History

• Received
  13 June 2016
• Accepted
  26 Aug 2016