Arlekar, who was elected in the March 3 polls from the Pernem constituency in North Goa (the only constituency in Goa reserved for Scheduled Castes), was the only legislator in the 40-member house, whose name had been proposed for the post.
The election was held on the first day of the three-day budget session which got underway Monday. Arlekar was administered the oath of office by protem speaker Mahadev Naik.
The Congress has nominated former chief minister Pratapsingh Rane as the leader of opposition.
The 40 member Goa legislative assembly has 21 BJP legislators, with two regional parties – the Maharashtrawadi Gomantak Party (3 legislators) and the Goa Vikas Party (2 legislators) – and five independents backing the BJP while. The opposition Congress has nine members.