According to Jain tradition, the concept of the "Aara" refers to the time cycles (kalachakra) in Jain cosmology. Each Aara has its own characteristics, and the 5th Aara (Dushamā) is considered to be a period of sorrow and spiritual decline.

Regarding Acharyas (spiritual leaders) in the 5th Aara, Jain scriptures mention that the last Kevali (omniscient being), Jambu Swami, attained moksha 64 years after Mahavira's nirvana, which occurred near the end of the 4th Aara and beginning of the 5th Aara. After the time of the last Kevali, the succession of Shrut Kevalis (those who knew all Jain scriptures) and then Acharyas (head monks) continued for some generations.

According to the Digambara tradition:

• The last Shrut Kevali was Bhadrabahu Swami.
• After Bhadrabahu, the succession continued with Acharyas who were knowledgeable but not Shrut Kevalis.
• According to some Digambara texts, Vishakhacharya is considered the last Acharya of the 5th Aara. After him, the tradition of Acharyas as described in the scriptures is said to have ended, and true monastic discipline and scriptural knowledge gradually declined.

According to the Shwetambara tradition:

• The lineage continued with Acharyas for several generations, but specific names for the "last Acharya of the 5th Aara" are not universally agreed upon.

In summary: Vishakhacharya is commonly regarded in Digambara Jain tradition as the last Acharya of the 5th Aara. After him, it is believed that the tradition of true Acharyas as per scriptural standards ended.

If you would like detailed names of Acharyas in the succession, please specify the Jain sect (Digambara or Shwetambara).