Diversity and conservation status of South African dragonflies (Odonata)

Dragonflies are important conservation subjects and excellent indicators of terrrestrial and aquatic environmental conditions. To date, 155 spp, have been recorded in South Africa; 29 spp. (18.7%) are endemic. Metacnemis angusta and Paragomphus dicksoni are only known from female specimens and are of doubtful taxonomic status. Chlorolestes apricans, C, draconica, Ecchlorolestes nylephtha, E, peringueyi. Metacnemis valida, Pseudagrion inopinatum, P. unsingaziense, Enallagma polychromaticum, Ceratogomphus triceraticus, Syncordulia gracilis, S. venator: Orthetrum rubens and Urothemis,tis luciana are ecologically threatened. Chlorolestes apricans and LI, luciana are of particular concern. C, apricans, whose populations have declined in recent years, appears not to occur in any protected area, There are several significant sites/areas for Odon,: the Western Cape has several endemic spp., while the Amatola-Wintertberg mountain range of the Eastern Cape has 2. KwaZulu-Natal Drakensberg has one highly localized endemic. Greater St Lucia is rich in pan-African spp., as well as some highly localized endemics, The Kruger National Park has no indigenous spp., but is rich in spp. representing the typical southern African savanna, There are isolated localities such as Itala and Umtamvuna, which have unusual outlier assemblages. Nor all anthropogenic disturbance is harmful to Odon. Small dams play an important role in geographically increasing the overall density of many lentic spp. Similarly, the aquatic weed Pistia enhances local species richness in the Kruger National Park, Most major human disturbances however, are harmful to population levels. Exotic tree plantations within 30m of the: river's edge reduce species richness, The rainbow trout is implicated in causing range retraction of the very rare and threatened E. peringueyi, while removal of natural forest in the southern Cape has eliminated populations of the equally rare E. nylephtha. Cattle grazing, resulting in bank vegetation destruction, and black wattle infestations along Eastern Cape river banks have had a major adverse impact on C. apricans. These factors are synergistic with lowered water levels in causing population fragmentation. Of great concern from this survey is that presence of rare species in nature reserves does not necessarily guarantee their survival. Orthetrum robustum at St Lucia, and O. brachiale, O. guineense and O. hintzi at Mpenjati reserves were abundant in 1990 but absent in 1994 because the intervening dry years had dried out their pools. Management recommendations include avoidance of siltation, eutrophication, salination, cattle trampling of bunks, and planting of exotic trees on banks within 30m of edge. Recommendations also include maintaining a constant water level in lakes and reservoirs, encouraging an abundance of aquatic macrophytes, and maintaining a wide range of physical bank and shallow water conditions so that there is a variety of substrate types, vegetation structures and sun/shade conditions.