Tantã is a very important and well-known brazilian instrument that replaces surdo when in small gatherings, such as "rodas de samba" or "rodas de choro".

Here is the related wikipedia page, in english:

https://en.wikipedia.org/wiki/Tan-tan

For further information (such as pictures, links and alternative names, displayed in bold), refer to the portuguese version of the wikipedia page:

https://pt.wikipedia.org/wiki/Tantã