Conservation planning for the extraordinary and Endangered Spesbona damselfly

Abstract

The damselfly Spesbona angusta is one of the world’s rarest insects, is Red Listed as Endangered, and occurs today at only one known locality in the Cape Floristic Region (CFR), South Africa. It has some unusual characteristics, including rapid and reversible colour change in both sexes, and a larva with frilled lamellae that lives in a micro-habitat free of competitors and large anisopteran enemies. We define here the characteristics of its habitat and record some other unusual behavioural traits, including the adult male’s ability to sail on the water surface, very strong site selection for oviposition, and female approach to males, all in the context of its conservation. We used satellite imagery to determine the location of habitats within its locality. We further used infrared imagery to identify warmer and cooler habitats within the area. Details of its occurence were mapped, based on observational data acquired throughout the flight season. From this, we were able to establish that its population moves around its locality, and we also establish its environmental requirements for conservation. We also indicate its umbrella value for representing two other threatened odonate species, Endangered Proischnura polychromatica and Vulnerable Syncordulia legator, as well as some other CFR endemic odonates. Conservation of this species requires continual monitoring and removal of invasive alien trees as a priority. Translocation should also be considered as various risks to this one locality are high. A potential site is identified.