Can you identify this bulbous plant?

A couple of years ago I got some bulbs of a friend of mine. At his turn he got them from his mother. She visited some years earlier North Sumatra and brought these bulbs with here. Directly I saw that it was a representative of the Amaryllidaceae, but which one?

Soon after the bulbs were planted, they produced leaves. The glossy, linear leaves are about three mm wide and five to seven cm long. The leaves grow towards the surface of the soil. The plants grew prosperously, but they didn't form any flowers. I had resolved to give them one year. If they didn't flower in that year, I would throw them away. Well, at least one plant must have heart this. One plant flowered at the end of September 1999. Below you see two pictures of the flower. The pictures are taken on the second day of flowering. The flower was open for three days.

The solitary, suberect flower stands on a five cm long flower stem. The flower is two cm in diameter. The tepals are at the base united into a green coloured tube. The spreading perianth segments are white, to the tips changing into dark pink.

Directly the names Habranthus 'Alipore Beauty' and 'Mary' came to my mind. These crossings between Habranthus and Zephranthes come from India. A direct link with Sumatra! According to the description (Lancaster, 1913) 'Alipora Beauty' has the same size as Habranthus robustus. First conclusion: my plant is no 'Alipora Beauty'. Except to the length of the flower stem and the colour of the base of the flower stem, my flowering plant meets the description of 'Mary'. Is my flowering plant truly Habranthus 'Mary'? That's hard to say when you have only one flowering plant.

Who has the answer to the questions: 'Is this Habranthus 'Mary'. If it is not, what is it then?' If you know the answers, please send me a message.

Lancaster, S.P. Bi-generic Hybrids produced between Cooperia and Zephyranthus produced at the Agricultural Society's Gardens, Alipore, Calcutta. Journal of the Royal Horticultural Society, 1913 (38), 531-532.