Two-striped Skimmer (Orthetrum caffrum)

The photo above (by Katharina Reddig) can be viewed in OdonataMAP here.

Orthetrum caffrum, commonly known as the Two-striped Skimmer is a dragonfly in the family Libellulidae.

Identification

Medium sized

Length up to 45mm; Wingspan attains 68mm.

Both sexes are among the more readily identified Orthetrum species, due to the two diagonal stripes on the sides of the thorax.

In fully pruinose males the diagnostic white stripes may become partially or completely obscured. These males are best identified by the shape of the secondary genitalia.

Most likely to be confused with the Epaulet Skimmer (Orthetrum chrysostigma), but that species has just one pale, diagonal stripe on the thorax sides.

Orthetrum caffrum – Male
Near Ixopo, KwaZulu-Natal
Photo by Ryan Tippett
Orthetrum caffrum – Female
Near Ixopo, KwaZulu-Natal
Photo by Ryan Tippett

Habitat

Most common in higher altitude or mountainous areas. The preferred habitats are open margins of rivers, pans, water-holes and dams. Usually frequents areas with low grassy or bushy growth and also bare exposed areas next to the water.

Behaviour

Often perches on the ground or on rocks, but also sits on twigs and other similar perches in or near the water. Hunts from a perch and quickly resettles again. Both sexes are found in the same vicinity.

Status and Conservation

Common and widespread in South Africa. It is listed as of Least Concern in the IUCN Red List of Threatened Species.

Distribution

Orthetrum caffrum is widespread throughout most of Southern, Central and East Africa. In South Africa it is only absent from the hot, humid areas of the lowveld and NE KwaZulu-Natal.

Below is a map showing the distribution of records for Two-striped Skimmer 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.

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.