Ringed Cascader (Zygonyx torridus)

View the above photo record (by John Wilkinson) in OdonataMAP here.

Find the Ringed Cascader in the FBIS database (Freshwater Biodiversity Information System) here.

Family Libellulidae

Zygonyx torridus RINGED CASCADER

(Kirby, 1889)

Identification

Large size

Length up to 61mm; Wingspan attains 102mm.

The sexes are alike.

Most similar to Zygonoides fuelleborni, the Southern Riverking. The two have similarly coloured and patterned abdomens. However, Zygonoides fuelleborni has blue rather than black eyes, and bulbous basal segments on the abdomen. The two species also display very different behaviour, making them easy to seperate.

Could also be mistaken for a female Zygonyx natalensis but that species shows far less yellow on the abdomen.

Click here for more details on identification.

Zygonyx torridus – Male
Tswaing Nature Reserve, Gauteng
Photo by Gerhard Diedericks

Habitat

Their preferred habitat is that of rivers and streams in both open and wooded landscapes. Favours fast flowing waters but also hunts over nearby slow flowing sections. Most regular along rocky stretches of river, but is not limited by this.

Habitat – Oribi Gorge Nature Reserve, KwaZulu-Natal
Photo by Ryan Tippett

Behaviour

A distinctly aerial species that spends long periods in flight coursing up and down a chosen route. Occasionally seen perched when it will hang vertically with wings outstretched. Often seen hovering over white water and has a great change of speed as it darts off to snatch prey or chase off a rival. Females and immatures are regularly found away from water in the surrounding woodlands.

Status and Conservation

Locally common. Listed as of Least Concern in the IUCN Red List of Threatened Species. Zygonyx torridus makes little use of man-made habitats as it is reliant on flowing rivers. It is however a fairly hardy species that can inhabit somewhat degraded rivers provided its habitat requirements are met.

Distribution

A very widespread species. Zygonyx torridus is found throughout most of Sub-Saharan Africa and also occurs in southern Europe, parts of the Middle East and western Asia.

In Africa it is only absent from the arid and semi-arid regions that lack perennial, flowing rivers and streams.

The South African distribution is mostly confined to the North and East where it is widespread.

Below is a map showing the distribution of records for Ringed Cascader 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.

Ringed Cascader OdonataMAPped by Gregg Darling: http://vmus.adu.org.za/?vm=OdonataMAP-83845

Further Resources

Virtual Museum (OdonataMAP > Search VM > By Scientific or Common Name)

More common names: Kringklatertjie (Afrikaans)

Type Locality: Sierra Leone, no locality data available.

Recommended citation format: Loftie Eaton. M; Hofmeyr S; Tippett RM; Underhill L – Ringed Cascader Zygonyx torridus. Biodiversity and Development Institute. Available online at http://thebdi.org/2020/02/19/ringed-cascader-zygonyx-torridus/

Dragonfly Atlas: Megan Loftie-Eaton, Ryan Tippett, Rene Navarro & Les Underhill
Dragonfly Atlas: Megan Loftie-Eaton, Ryan Tippett, Rene Navarro & Les Underhill
Megan Loftie-Eaton is our communications, social media and citizen science projects coordinator. Prior to her work for the BDI, she coordinated OdonataMAP, the Atlas of African Odonata. 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 OdonataMAP project. Rene Navarro is the genius behind the Virtual Museum. 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.