In Tamil literature, Sujatha is a familiar name. It was the Pseudonym of Rangarajan. He is an Engineer by profession, worked at Bharath Electronics. He supervised the Electronic Voting Machine's design and production, which we are currently using in Indian elections.
Sujatha is his wife's name. He started to write with a pen name, because, there was already another Rangarajan in the Vikatan publications. But the choice of the name Sujatha may be, because of his love for his wife. He has written more than 100 novels, 250 short stories, screen plays to movies and also penned dialogues to few of Manirthnam and Shankar's movies. Roja is one among them. Since he is an Engineer and interested in science and computers, his science fiction novels and stories are remarkable. He is a versatile writer.
Apart from Sujatha, I remembe Sarath Chandra Chatterjee, a Bengali writer. His pen name is also a female name Anila Devi. He lived in 1850's and his writings were mainly about the life style of village people and the tragedies they face on everyday life, especially because of the social practices prevailed in Bengal at that time.
I believe, writers choose the pen name based on their literature work. Choosing a female name by a male writer might be for giving the output of their work in female version. When they concentrate much to bring out the life practices of some people, (we all aware of the sufferings that females undergone during that period), looking them from female version is important. It adds more impact to the content. Also, few other male writers, who fought for women liberty also wrote in the name of female given names. It is denote, "for the women, by the women".
So, male choosing female pen name and female choosing male pen name is closely related to the content they work on. There are some exceptional, they write in the name of their loved one.