Mega diversity means exhibiting great diversity. The main criteria for megadiverse countries is endemism at the level of species, genera and families. A megadiverse country must have at least 5,000 species of endemic plants and must border marine ecosystems. 

(from wikipedia)

Unable to swim.

From super small to super big frogs.

Endemic to Southern Africa. They inhabit fast-moving streams. 

Family Bufonidae.

Largest snake: African rock python, non-venomous
Venomous snakes: black mamba (one of the most deadly snakes in the world), eastern green mamba, boomslang, Cape cobra and rinkhals. 
Snakes are important for rat population control.

SW corner of Western Cape
Habitat type: renosterveld (part of the Fynbos Biomes, a vegetation zone characterized by a Mediterranean climate)

Habitat decline due to agriculture utilization and urban development (less than 3% of its original size) 

*leaves, geophytes, flowers, and shoots of indigenous fynbos and renosterveld plant and grass species. 

*aestivation June through September
*female digs a hole in the ground and covers it with grass to lay eggs
 

*CE in IUCN Red List
*Appendix I of CITES (international trade prohibition) 

https://en.wikipedia.org/wiki/Geometric_tortoise
https://www.iucnredlist.org/species/18398/111553007

*SE South Africa
*found up to 900 m above sea level
*ground-coastal bush and gallery bush: especially afforestation strips along rivers
 

mates in streams
eggs attached to branches hanging over the water, in egg clutches that looks like bales of foam
after hatching, the tadpoles fall down into the water 

Deterioration of reproduction water 
habitat pollution
habitat decline due to sugarcane plantations, forestry and cultivation

overpopulation
sprawling development patterns
deforestation

alien species invasions

hunting of (endangered) species

scarce water resources

Climate change effects
warming
drying 
greater frequency and intensity of extreme weather events (heat waves, flooding, drought)

According to computer-generated climate modelling produced by the South African National Biodiversity Institute, parts of southern Africa will see an increase in temperature by about 1 °C (1.8 °F) along the coast to more than 4 °C (7.2 °F) in the already hot hinterland such as the Northern Cape in late spring and summertime by 2050. Drought, increased intensity and frequency of fire, and climbing temperatures are expected to push many rare species towards extinction. 

https://en.wikipedia.org/wiki/South_Africa