Ngcobo set for Blitzbok debut
Brown's exclusion from the squad paves the way for the experienced Philip Snyman to don the captain's armband for the first time while playmaker Cecil Afrika continues to nurse the hamstring injury he picked up in the season-opening Dubai tournament last December.
Springbok Sevens coach Neil Powell said his team will focus on consistency in Wellington and Sydney.
"In the past we struggled to regain our best form after playing in Dubai and in our home tournament, so our mental focus will be a key aspect for us on this tour.
"We are building towards the Olympics Games in Rio, so it is important that we perform well in the World Series. These two tournaments will offer us another opportunity to rotate some players and introduce a new one. Stix [Sandile] has been knocking on the door for a while now and I know he is excited and very keen to play on the World Series circuit," Powell said.
In a rotational change, Carel du Preez comes in for Dylan Sage - who made his Springbok Sevens debut in Cape Town.
South Africa are the top seeds in Pool A in Wellington, where they will feature in group matches against Scotland, Russia and tournament hosts New Zealand. The Wellington Sevens takes place at the Westpac Stadium on January 30 and 31, and will be followed by the Sydney event a week later on February 6 and 7 at the Allianz Stadium.
Springbok Sevens squad: Chris Dry, Philip Snyman (captain), Carel du Preez, Kwagga Smith, Sandile Ngcobo, Francois Hougaard, Cheslin Kolbe, Ryno Benjamin, Justin Geduld, Rosko Specman, Seabelo Senatla, Juan de Jongh.