Cape Thorntail (Ceratogomphus triceraticus)

View the above photo record (by Jean Hirons) in OdonataMAP here.

Find the Cape Thorntail in the FBIS database (Freshwater Biodiversity Information System) here.

Family Gomphidae

Ceratogomphus triceraticusCAPE THORNTAIL

Identification

Medium-large size

Length attains 63mm; Wingspan reaches 72mm.

Females resemble the males but have reduced foliations and they are more robust with broader abdomens.

Similar to Ceratogomphus pictus, but is noticeably larger and darker. The abdomen segments are predominantly yellow in C. pictus, and mainly black in C. triceraticus.

The forwards projecting thorn on the abdomen is broader in this species. In addition, the foliations on the abdomen have thick black outer edges. Ceratogomphus pictus has thin black edging on the foliations.

Click here for more details on identification of the Cape Thorntail.

Ceratogomphus triceraticus – Male
Bloukrans Pass, Eastern Cape
Photo by Desire Darling

Habitat

Frequents shallow, rocky and fast flowing streams and rivers. Usually in fairly open and hilly countryside.

Habitat – Palmiet River, Western Cape
Photo by Corné Rautenbach

Behaviour

Mostly perches on the ground or on rocks, but also sits on low twigs and bushes. Mostly found at the river but sometimes encountered away from water, flying to and fro along a chosen route. This is a shy and weary species.

Status and Conservation

The Cape Thorntail is an uncommon and very localised species. It is listed as Near Threatened in the IUCN Red List of Threatened Species. This is due to its relatively small, restricted distribution and the fact that it is reliant upon undisturbed habitats.

Distribution

Ceratogomphus triceraticus is endemic to South Africa, where it is mostly restricted to the Western Cape province. It extends marginally into the Eastern Cape, reaching its eastern limit near Port Elizabeth.

Below is a map showing the distribution of records for Cape Thorntail 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.