The photo above (by John Wilkinson) can be viewed in OdonataMAP here.
Find the Denim Dropwing in the FBIS database (Freshwater Biodiversity Information System) here.
Family Libellulidae
Trithemis donaldsoni – DENIM DROPWING
(Calvert, 1899)
Identification
Medium-sized
Length up to 44mm; Wingspan reaches 71mm.
Males are recognisable by the uniformly pale blue body colouration and contrasting dark head and eyes. The black terminal segments on the abdomen are also a useful aid in identification.
Could be confused with several other all-blue dragonflies, such as Skimmers (Orthetrum spp.) and the other blue dropwings.
Most similar to Navy Dropwing (Trithemis furva), Highland Dropwing (Trithemis dorsalis), Silhouette Dropwing (Trithemis hecate) and Halfshade Dropwing (Trithemis aconita). The Denim dropwing can be told apart by its slightly larger size, paler blue colouration, contrasting black eyes and black terminal segments.
Click here for more details on identification of the Denim Dropwing.
Mkuze River, KwaZulu-Natal
Photo by Ryan Tippett
Habitat
Inhabits shallow, rocky and fast-flowing rivers. Mostly in hot savanna regions. Requires rocks in the mid-stream for perching on. Seldom found away from such sites.
Photo by Ryan Tippett
Behaviour
Males perch close to the water on rocks, mostly in the mid-stream. Occasionally sits on a plant stem over the water. They are alert and can be difficult to approach. Females are seldom encountered and spend most of their time far from water.
Status and Conservation
Localised and generally scarce, but listed as of Least Concern in the IUCN Red List of Threatened Species. Due to its habitat choice Trithemis donaldsoni does not make use of man made habitats.
Distribution
Widely distributed in Southern and East Africa, ranging from South
Africa up to Kenya and Uganda. Also occurs in Botswana and across to Namibia and Angola.
Below is a map showing the distribution of records for Denim Dropwing in the OdonataMAP database as at February 2020.
The next map below is an imputed map, produced by an interpolation algorithm, which attempts to generate a full distribution map from the partial information in the map above. This map will be improved by the submission of records to the OdonataMAP section of the Virtual Museum.
Ultimately, we will produce a series of maps for all the odonata species in the region. The current algorithm is a new algorithm. The objective is mainly to produce “smoothed” maps that could go into a field guide for odonata. This basic version of the algorithm (as mapped above) does not make use of “explanatory variables” (e.g. altitude, terrain roughness, presence of freshwater — we will be producing maps that take these variables into account soon). Currently, it only makes use of the OdonataMAP records for the species being mapped, as well as all the other records of all other species. The basic maps are “optimistic” and will generally show ranges to be larger than what they probably are.
These maps use the data in the OdonataMAP section of the Virtual Museum, and also the database assembled by the previous JRS funded project, which was led by Professor Michael Samways and Dr KD Dijkstra.
Further Resources
Virtual Museum (OdonataMAP > Search VM > By Scientific or Common Name)
More common names: Denimvalvlerkie (Afrikaans)
Type Locality: Erer River, Ethiopia
Recommended citation format: Loftie Eaton. M; Hofmeyr S; Tippett RM; Underhill L. Denim Dropwing Trithenis donaldsoni. Biodiversity and Development Institute. Available online at https://thebdi.org/2020/05/08/denim-dropwing-trithemis-donaldsoni/
