The Bombay night frog � scientists revealed recently � favours a mating position previously unknown among the amphibian group�s 7,000 species, only the seventh catalogued in what might be called the �Kamasutra for frogs�. Dubbed the �dorsal straddle�, the new sex position is an evolutionary case study in how sexual selection always finds a way � no matter how contorted or acrobatic � for sperm and egg to hook up. Scientists led by SD Biju, a professor at the University of Delhi, staked out a dense forest near Humbarli village in the state of Maharashtra, western India, for 40 nights to catch their tiny quarry, the Nyctibatrachus humayuni, in flagrante delicto. Shorn of its context, their description of the exotic act could have been lifted from a 1970s sex manual. �The male does not embrace the female, but straddles over her back with his hands holding, or resting, on a leaf, branch or tree,� they write, setting the scene. At this point, the female � preparing for the next move � releases her eggs onto the leaf upon which the couple is perched. Things get pretty kinky from there. �The male ejaculates on the female�s dorsum and the sperm subsequently runs from her back and hind legs, before fertilising the eggs,� the researchers explain in a study, published in the scientific journal PeerJ.