La Plena Puerto Rican music has been heavily influenced by African rhythms. The Bomba developed directly from ritual slave dances. The Plena is a blend of different cultures but relies heavily on African tradition. Both elements developed in those coastal areas with a concentration of African descendants. Afro traits in Puerto Rican music include: collective participation in which there is no distinct line between musicians and audience. Everyone is welcomed and encouraged to participate. An emphasis on rhythm and percussion rich in melody. Widespread use of call and response. La Plena Puertorriqueña developed in Ponce approximately 100 years ago. La Plena is also known as "el periodico catao" (the sung newspaper) because the songs are about currents issues. Plena musicians often poke fun at mundane everyday occurrences or the antics of politicians. The Plena rhythm has strong African roots but it is also influenced by other music genres such as Taíno, jíbaro, danzas, and other European styles. Plena instruments include a large tambourine like instrument called pandero. A pandero is a very short drum that looks like a tambourine without jingles, and bigger in diameter than a tambourine. The pandero was introduced in Spain by the Moors Of particular importance are "classical" Puerto Rican pieces such as "Temporal", "Mamita Llego el Obispo", "La Bandera", "Mataron a Elena", pieces from the early period of the plena and pieces distinctively interpreted by Rafael Cortijo with Ismael Rivera.