Teratological Cases of the Ocular Patterns in the South African Endemic Trapdoor Spider Genus Stasimopus Simon (1892) (Araneae, Mygalomorphae, Stasimopidae)

Teratology is the science that deals with the causes and patterns of deformities, abnormalities and defects in the physical development of animals. Teratological occurrences can be due to genetic or environmental conditions. Ocular teratologies are common in hypogean spiders. This communication reports on the occurrence of ocular teratologies of the South African endemic spider family, Stasimopidae. A total of 212 spiders from various museum collections were examined for cases of ocular teratologies. Six females and one male were found to display some form of teratology. The species found to exhibit these were Stasimopus patersonae, S. robertsi, S. insculptus peddiensis, S. griswoldi, and three unidentified specimens. The teratologies range from reduced eye size to numerous additional eyes. The exact cause of the teratologies is unknown. They could, however, be linked to embryonic trauma or developmental issues, juvenile injury, or unusual environmental conditions during embryonic development. The spiders all survived to adulthood, as in hypogeal spiders eye sight is not the most relied on sense. Understanding the causes of teratologies is important as it may enable researchers to predict the effect of increasing chemical use and global climate change on the embryology of spiders.