A new mtDNA M lineage has been detected among a Malagasy fisherman ethnicity: the Vezo (4/101 = 4%). It's been named M16 and appears to hang directly from the M node. Three other individuals with this lineage have been found among African Americans (though it has not yet been detected in mainland Africa). M16 has also been found in one citizen of Dubai (UAE) and one (1/127 = 0.8%) among the Mikea hunter-gatherers/horticulturalists of SW Madagascar, believed to be a remnant of pre-Austronesian colonization of the island.
Haplogroup M16 is characterized by 11 coding region mutations and 8 control region ones. M16 has two subclades: M16a (found only in one Vezo individual) and M16b (including all other carriers). They estimate (following the new refined method of Soares et al. - but notice that they give a very recent age to the relevant Pan-Homo split: only 6.5 Mya, when it can well be of 8 and even 10 Mya for what I know) that the MRCA of this lineage lived some 9500 years ago (CI: 1.9-17 Kya), with that of M16b having lived 1700-3900 years ago (CI: 0-8.2 Kya).
Both Mikea and Vezo also show other ineages that are absent among the central Merina ethnicity (arguably a more direct descendant of Austronesian colonists), namely: M*, M7c3 and F3b.
Francois-X Ricaut et al., A new deep branch of eurasian mtDNA macrohaplogroup M reveals additional complexity regarding the settlement of Madagascar. BMC Genomics, 2009. Open access.