First record of Croton echinocarpus ( Euphorbiaceae : Crotoneae ) in São Paulo state , Brazil

Croton is the second largest genus of Euphorbiaceae with about 1200 species worldwide. Brazil has around 350 species of Croton in all kinds of habitats, but with a great number of species concentrated in the eastern part of the country. The present work increases the number of Croton species in São Paulo to 38, due to our recent discovery of Croton echinocarpus in this state. We also provide comments on the taxonomy, photographs and a distribution map for this species.

Croton L. is a typical genus from dry and moist vegetation in the tropics and subtropics worldwide (van Ee et al. 2011).It is the second largest genus of Euphorbiaceae with about 1200 species (Govaerts et al. 2000), which ranks Croton as the 11 th largest Angiosperm genus (Frodin 2004).The most species-rich region for this genus is the Neotropics, with main centers of diversity in Brazil, the West Indies, and Mexico (Burger and Huft 1995).The genus has a great morphological diversity, ranging from herbs to trees, and occupies a wide range of habitats (Caruzo et al. 2011).Despite its great morphological diversity, Croton species can be easily recognized in the field due to its conspicuous stellate or lepidote trichomes, narrow or condensed thyrsoid inflorescences of unisexual flowers, clear or colored latex, frequent petiolar glands, and senescent leaves that turn orange before abscising (Riina et al. 2009).
In Brazil, Croton is represented by around 350 species, including herbs, shrubs, trees, and rarely lianas, in all kinds of habitats, but with a great number of species concentrated in the eastern part of the country (Caruzo et al. 2010).According to Caruzo and Cordeiro (2007), the genus is represented by 37 species in São Paulo state (SP).The present work documents the first record of Croton echinocarpus Müll.Arg.(Müller Argoviensis 1865: 88) in SP, which increases the number of Croton species that occur in this state to 38.
Our results were based on field observations, in addition to the examination of collections mainly from the following herbaria: BHCB, MBM, SP, SPF (abbreviations according to Thiers 2015).Croton echinocarpus was recorded by Müller Argoviensis (1873) only in Rio de Janeiro and Minas Gerais states, both in Southeastern Brazil.However, in March 2014 we discovered a population of C. echinocarpus in Atibaia municipality, thus extending the distribution range of this species to SP.This represents an increase of about 400 km relative to the formerly known distribution range of this species.
Croton echinocarpus belongs to Croton section

ACKNOWLEDGEMENTS
Thanks are due to Otávio Luis Marques da Silva for providing photos of Croton echinocarpus and for the help during fieldwork.The conservation status of Croton echinocarpus according to the IUCN criteria (2012) is Data Deficient (DD).Nevertheless, the only population found in SP occurs in a private area and it is not under legal protection, which increases the risk of extinction of C. echinocarpus in this state.Our finding provides an important contribution to the knowledge of Croton species distribution in Brazil that can help in future studies on the genus distribution in the country.Furthermore, the present work increases the number of known Croton species in SP to 38.

CheckFigure 1 .
Figure 1.Morphology of Croton echinocarpus.A: Branch showing immature fruits.B: Leaf and immature fruits.C: Detail of leaf, showing sessile petiolar glands.D: Detail of inflorescence axis, showing pistillate flowers.E: Young branch exuding brownish latex.F: Immature fruit.G: Detail of habit showing the crown.H: Habit.I: Detail of pistillate flower.J: Locality where C. echinocarpus was collected in Fazenda Paraiso, Atibaia -SP (images D, E, F, I, J by O.L.M. Silva and A, B, C, G, H by R.F.Santos and O.L.M. Silva).
Cyclostigma(Riina et al. 2009;van Ee et al. 2011) and is most similar to C. celtidifolius Baill.(Baillon 1864: 331), from which can easily be distinguished by its sessile petiolar glands (vs stipitate petiolar glands in C. celtidifolius), bifid styles, with 6 terminal tips (vs tetrafid styles, with 12 terminal tips in C. celtidifolius) and capsules echinate-muricate (vs smooth in C. celtidifolius).Another species morphologically similar to C. echinocarpus is C. urucurana Baill.(Baillon 1864: 335), however they can be distinguished from each other by the morphology of stipules (not foliaceus and subulate in C. echincarpus vs foliaceus and ovate with a long acuminate apex in C. urucurana) and capsules (echinatemuricate in C. echinocarpus vs smooth in C. urucurana).

Figure 2 .
Figure 2. Geographical distribution of Croton echinocarpus.The point represented by  shows how the population found in São Paulo state is far from formerly known distribution of the species (represented by ).A small map on right shows the location of Brazil in South America, highlighting the southeastern region of the country.Acronyms for each state: ES=Espírito Santo; MG=Minas Gerais; SP=São Paulo.