Gilli Smyth, the co-founder of the eccentric and influential space-rock-cum-prog-cum-psychedelic band Gong, has died aged 83, the Planet Gong website reports.

Smyth had been admitted to Byron Bay hospital in Australia on Monday with pulmonary pneumonia. On admission, her son Orlando Allen said on Facebook, she had been given a 30% chance if surviving the night. Planet Gong reported that she died at noon on 25 August.

Smyth, who was English, founded the band with Daevid Allen – Smyth’s husband and Orlando’s father – in 1967 in Paris. She often performed as Shakti Yoni, and described her style of singing as “musical landscaping”. In a 1971 interview, Allen said her style – which the band called “space whispers” – was “a totally original form of singing. In the end, Gilli is the only person in the band that is without precedent.”

“Her unique stage presence and vocals manifested and determinedly represented a vital, deeply fundamental feminine principle within the Gong universe,” Planet Gong said. “She last performed with the band in 2012.”

Smyth, rear, with Daevid Allen and the Banana Moon Band in 1968. Photograph: Photo 12/UIG via Getty Images

As with so many aspects of the Gong story, Smyth’s involvement with the group was – for outsiders, at least – confusing. She left Gong in 1974, releasing a solo album in 1978, and then forming a new group, Mother Gong, who at one point opened for Bob Dylan.

Allen himself was delighted that Gong generated satellite splinter groups – he was responsible for Planet Gong, New York Gong and Gongmaison himself.

Gong itself reunited in 1992, with Smyth rejoining in 1994. In addition to that, she embarked on two techno side-projects, Goddess Trance and Goddess T.

Smyth’s death follows that of Allen, who died in March 2015.