Morphological and morphometric study of Spirocerca lupi

The present study provides a detailed morphological redescription of Spiroc erca lupi (Rudolphi, 1809) by means of light and scanning electron microsco py (SEM). The present redescription agrees with previous descriptions excep t in some aspects that have been considered as individual anomalies. The st udy also includes a comprehensive morphometric analysis of several specimen s of S. lupi in red foxes (Vulpes vulpes) from the Iberian Peninsula. The a bsolute growth rate of the oesophagus of S. lupi is higher in males than in females. The body region of S. lupi showing the most marked growth is the reproductive zone, which contains all the reproductive organs. In juvenile females, the vulva is located at the level of the oesophagus but in older s pecimens it is post-oesophageal. The left spicule grows with age, whereas t he right spicule reaches its fall development in young (less than 25 mm len gth) specimens.