Denim Dropwing (Trithemis donaldsoni)

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.

Trithemis donaldsoni – Male
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.

Habitat – Mkuze River, KwaZulu-Natal
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/

Dragonfly Atlas: Megan Loftie-Eaton, Sally Hofmeyr, Ryan Tippett & Les Underhill
Dragonfly Atlas: Megan Loftie-Eaton, Sally Hofmeyr, Ryan Tippett & Les Underhill
Megan Loftie-Eaton is our communications, social media and citizen science coordinator. Prior to her work for the BDI, she coordinated OdonataMAP, the Atlas of African Odonata. Sally Hofmeyr has many years' experience in the academic world, writing her own material and editing the work of others. Her academic background is in the natural sciences: her PhD and first postdoc in ornithology and environmental change (Animal Demography Unit, University of Cape Town). Ryan Tippett is an enthusiastic contributor to Citizen Science and has added many important and interesting records of fauna and flora. He has been a member of the VMU since 2014 and has currently submitted over 11000 records. He is also on the expert identification panel for the Odonata Map project. Prof Les Underhill has been Director of the Animal Demography Unit (ADU) at the University of Cape Town since it started in 1991. Although citizen science in biology is Les’s passion, his academic background is in mathematical statistics.