Complex sentence: Linguistically, Siculo-Arabic and therefore its descendant Maltese are considered Maghrebi Arabic closest to Tunisian Arabic, but it is no longer mutually intelligible with the varieties other than Tunisian spoken today in North Africa.
Split into simpler sentences: Linguistically, Siculo-Arabic, and therefore its descendant Maltese, are considered the Arabic varieties that are closest to Tunisian Arabic. It is no longer mutually intelligible with the Arabic varieties other than the Tunisian Arabic dialect spoken today in North Africa.