Mapidian is a moribund Arawakan language of Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

 and formerly of Guyana

Guyana

Guyana , officially the Co-operative Republic of Guyana, previously the colony of British Guiana, is a sovereign state on the northern coast of South America that is culturally part of the Anglophone Caribbean. Guyana was a former colony of the Dutch and of the British...

.

Kaufman (1994) classified Mapidian as a dialect of Wapishana

Wapishana language

Wapishana is an Arawakan language of Guyana and Brazil.Kaufman considered Wapishana, Atorada, and Mapidian to be dialects. Aikhenvald separates Mapidian. Ethnologue notes that Atorada has 50% lexical similarity with Wapishana and 20% with Mapidian, and that Wapishana and Mapidian share 10%....

, whereas Aikhenvald (1999) separates them. Ethnologue (2009) notes they have a "lexical similarity" of 10%.

Aikhenvald had included Mawayana

Mawayana language

Mawayana is an Arawakan language of Guyana.Aikhenvald lists Mawayana as an alternate name of Mapidian. However, Hicks reports that it has no "semantic" similarity with Mapidian or the other Wapishanan languages; it is thus left unclassified here....

as a variant of Mapidian, but Hicks (2002) reports they are not similar.