due to limitations in the reference database, the researchers can't be sure of the exact location of origin. Researchers have noted a number of limb deformities in the introduced populations found throughout the United Kingdom, which are likely linked to small founder population sizes. Systematics The common midwife toad, (Alytes obstetricans) has four subspecies within its distribution, A. o. almogavarii, A. o. boscai, A. o. obstetricans, and A. o. pertinax. A. o. obstetricans is the subspecies with the largest distribution, spreading from the Iberian Peninsula northward into the rest of its range. The other three subspecies are local to the Iberian Peninsula. These subspecies formed during glacial refugia conditions during the Plio-Pleistocene climatic fluctuations. Due to the genetic differences of these populations, their individual conservation is highly important. Recently, A. o. almogavarii has been recommended as an independent incipient species Alytes almogavarii as it has been shown to be moving towards total impermeable gene flow. Behaviour When threatened, the midwife toad inflates, filling itself with air so as to make it appear as large as possible. It may also rear up on all four limbs, raise its rump and stand in a threatening posture with its head down and eyes shut. Reproduction takes place in spring and summer. The female seeks out a male and invites him to mate. Females are more prone to selecting larger males due to fitness preference. He proceeds to hold her round the flanks and uses his toes to stimulate her cloaca. After about half an hour he squeezes her sides firmly, whereby she stretches her hind legs and ejects a mass of eggs embedded in strings of jelly. The male releases her and inseminates the egg mass with his sperm. A little later, he begins to pull and pummel the egg mass, teasing it out so that he can wrap the strings around his back legs. He can mate again while the eggs are twined round his limbs and can carry up to three clutches of eggs at a time, a total of about 150 eggs. He looks after them until they hatch, in 3 to 8 weeks. He keeps them moist by lying up in a damp place during the day and by going for a swim if there is risk of them drying out. He may secrete a substance through the skin that protects the eggs from infection. When the eggs are