Amplexus (Latin "embrace") is a form of pseudocopulation in which a male frog grasps a female with his front legs while she lays her eggs. At the same time, he fertilizes them with the fluid containing sperm.
This mostly happens in the water, but some more terrestrial anurans like the disc-tongued frogs (Discoglossidae) perform amplexus on land. In more advanced anurans like the true frogs (Ranidae), the tree frogs (Hylidae) and the true toads (Bufonidae) the amplexus is axillary (in the armpits), while in less derived anurans (the Archaeobatrachia) and frogs in the Myobatrachidae family it is lumbar (abdominal, in front of the hindlegs). The Sooglossidae show inguinal amplexus where the male holds the female at the waist just anterior to her hind legs. Some species show cephalic amplexus where the head of the female is held while others show complete lack of amplexus.
In most anurans the males deposit sperm onto the eggs as they are being laid, however males of the genus Ascaphus possess an intromittent organ, unique among anurans, for internal fertilization. Internal fertilization does occur in a few other genera, including Nectophrynoides, Mertensophryne, and Eleutherodactylus.
Observations of Interspecific Amplexus between Western North American Ranid Frogs and the Introduced American Bullfrog (Rana Catesbeiana) and an Hypothesis concerning Breeding Interference
Jul 01, 2005; ABSTRACT.- Introduced American bullfrogs (Rana catesbeiana) come in contact with native amphibians on four continents and are...