I know that KBR mentions that their tudei is speculated to be Piper wichmannii, but it has not been established. From what I gather isa/tudei is just one strain of piper methysticum. It originated from PNG but because of it's intense effects it has become revered throughout the South Pacific and is grown in Vanuatu as well. In Vanuatu it is only used for special ceremonies .
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One of the most potent strains is called "Isa" in Papua New Guinea, and also called "Tuday" in Hawaii. In Vanuatu, it is considered a type of "Tudei" kava, pronounced as "two-day" because it is said to have effects lasting two days due to its chemical profile being high in the kavalactone dihydromethysticin. The plant itself is a strong, very hardy, fast-growing variety with multiple light to dark green stems covered with raised dark spots.
In Vanuatu, exportation of kava is strictly regulated. Only strains they deem as "noble" varieties that are not too weak or too potent are allowed to be exported. Only the most desirable strains for everyday drinking are selected to be noble varieties to maintain quality control. In addition, their laws mandate that exported kava must be at least five years old and farmed organically. Their most popular noble strains are "Boroguu" or "Boronggoru" from Pentecost Island. "Melomelo" from Ambae island, (called sese in North Pentecost) and "Palarasul" kava from Espiritu Santo Island. In Vanuatu, Tudei (two-days) kava is reserved for special ceremonial occasions and exporting it is not allowed. "Palisi" is a popular Tudei variety
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It sounds like tudei is a subcatagory and isa a member of that set or the same exact strain. To me it just sounds like a popular strain with a reputation for being really heavy and intoxocating.
