It looks like  Ipomoea cordatotriloba or I. carnea, which is found in Brasil :)

 Thank you very much, Dr. Pegman.

In fact leaves are similar to I. carnea but it doesn't seem to me that it looks like that species when you look at sepals and flowers, which are much darker and purple in this specimen than in carnea... Compare the sepals of carnea with these sepals, they are quite different: 

 https://lh4.googleusercontent.com/-ETNzs5V1-aU/T3IKVQWQm5I/AAAAAAAACpI/1bloBi_urcw/s1600/DSCN1238.jpg

Do you think they could be the same species??

In relation with I. cordatotriloba, sepals and flowers are closer to this plant, but still different:

http://www.bio.utexas.edu/courses/bio406d/images/pics/cnv/ipomoea_cordatotriloba.htm

Moreover, I haven't found any deeply lobed/shallowly lobed leaves, which are characteristic of the species. All leaves are not lobed at all... Is this possible in I. cordatotriloba?

 Anyhow, it seems more plausible it is related to I. cordatotriloba rather than to I. carnea...

Thanks a lot for your help, Dr. Pegman!

Best regards,

Juanma

I'd go for carnea :)

No, its not ipomoea carnea.

Thank you Mr. Kaur. What species is it, in your opinion?

Best regards.

Its sepals as well as seed are also not similar to ipomoea cordatotriloba.

Please send pics of open flowers and size of flowers.

good greeting

Please follow this link may be helpful in diagnosis and it explains the flowers of this species

Http://www.asergeev.com/pictures/k/Ipomoea_flower.htm

Thank you very much, Dr. Sosa.  The link is not opening. Could you check it out and send it again?

Best regards

Juanma

Try Ipomoea calantha

Thanks, Dr. Aigbokhan. I'll check it out.

Best regards,

Juanma

Maybe this plant is a Ipomoea pupurea (L.) Roth. You can check it in the next links: http://www.tropicos.org/ or http://www.tropicos.org/NameSearch.aspx?name=Ipomoea+purpurea&commonname=.

Also you can check Ipomoea indica (Burm.) Merr., in the next links: http://www.tropicos.org/NameSearch.aspx?name=Ipomoea+indica&commonname=, http://www.tropicos.org/Name/8500780 or http://www.theplantlist.org/tpl1.1/search?q=Ipomoea+indica.

Greetings

Vega-Muñoz

This is first times I see this plant! Thanks all

Thank you, Mr. Pham. Me too....

 Thank you Mr. Vega-Muñoz.  I don't think it is I. purpurea... Certainly it is not I.indica... 

 It looks like I. eriocarpa R. Br.

Thank you very much, Prof. Robert.

Some leafs are indeed similar to I. eriocarpa's, but in this plant, flowers are bigger (in I, eriocarpa the tubular corolla is up to 1cm long, whereas here is aprox. 4cm long), and moreover, I. erocarpa's seeds are completelly different: http://ts-den.aluka.org/fsi/img/size2/alukaplant/k/phase_01/k0002/kexp023010042.jpg

Best regards,

Juanma

I think this species belongs to Ipomoea indica and for farther information follow the link. http://www.flickr.com/photos/98799884@N00/1257846417/

Best regards

Gebru

It's not ipomoea eriocarpa nor ipomoea indica.

Por las  fotos, podria afirmar que se trata de  Ipomoea carnea,   en Peru tambien crece en la costa. 

Better to refer Flora of Ethiopia and Erothrean

Good luck

Gebru

Dear, Juanma, 

Maybe, 

Ipomoea batatas (L.) Lam. Convolvulaceae

Ipomea batatas L.