Stellenbosch University researchers discover new species of lice, chigger mites

Prof Sonja Matthee from Stellenbosch University collected six new species of chigger mites and helped name them. JC Bothma, who discovered two new lice species near Fraserburg. The chiggermyt Schoutedenichia horaki which was named after Professor Ivan Horak from the University of Pretoria.

By Engela Duvenage

Two new lice species and six new chigger mite species, collected by a postgraduate student and a researcher from Stellenbosch University (SU) respectively, have been named and their discovery announced. It just goes to show how rich the diversity of parasites in South Africa are, and how many are still waiting to be discovered, says Prof Sonja Matthee of the SU Faculty of AgriSciences’ Department of Conservation Ecology and Entomology, who collected and named the chigger mites.

The two new lice species were discovered by JC Bothma from Bellville, during his MSc studies in Zoology. At the time, he was researching the evolutionary relationship between parasites and their hosts in terms of the lice found on four South African mouse species. Bothma, who obtained his degree cum laude last year, sampled mice and lice from more than twenty localities in the country and discovered the two new species in the Fraserburg area.

News about the new lice species recently appeared in the Journal of Parasitology. Lice expert Prof Lance Durden from Georgia Southern University in the USA conducted the technical investigations and description of the new species.

He has been working regularly with Prof Sonja Matthee on various projects since 2003. He was visiting Stellenbosch University in 2018 to present a lice identification course for her students when Bothma showed him some of the lice he found during a fieldtrip in the Karoo.

Among them were two unknown species, barely larger than 1 mm each, which Bothma had removed from a pair of Grant’s rock mice (Micaelamys granti). At this stage, the Stellenbosch team already knew that the lice were genetically distinct from any other known louse species found on rodents in South Africa. Durden took them back to the USA, where he went through the step-by-step process of analysing and describing the new species.

The species are named Hoplopleura granti and Polyplax megacephalus. The two blood-sucking parasites spend their whole lifecycle – from the egg stage to adulthood – only on the body of a Grant’s rock mouse.

Hoplopleura granti is so named because of its host, Grant’s rock mice. Polyplax megacephalus was named for its fairly large (“mega” in Latin) head (“cephalus”), compared to most of the other 550 lice species found worldwide.

Bothma conducted his studies under the guidance of molecular ecologist Prof Conrad Matthee from the Department of Botany and Zoology in the SU Faculty of Science, and Prof Sonja Matthee of the SU Faculty of AgriSciences.

Prof Sonja Matthee also recently collaborated with a Russian colleague, Prof Alexandr Stekolnikov of the Zoological Institute of the Russian Academy of Sciences, to identify six new chigger mite species. She found the mites on field mice near Hoedspruit in Mpumalanga. The announcement about the new species was made in the journal Systematic and Applied Acarology.

Most of the 80 South African chigger mite species described (there are 440 known species worldwide) are to be found in KwaZulu-Natal, but few surveys elsewhere in the country have been done.

Chigger mites are at less than a millimetre by no means easy to spot or to identify. They fall into the larger Arachnida class to which spiders, ticks and scorpions also belong.

Chigger mites are to be found on hosts during their larval stage, and then fall off the host to continue developing through their different live stages in the vegetation. Larvae that feed on hosts such as humans, livestock and pets can cause irritating, itchy bites.

Most of the 80 South African chigger mite species described (there are 440 known species worldwide) are to be found in KwaZulu-Natal, but few surveys elsewhere in the country have been done.

Two of Prof Matthee’s mentors were honoured in the naming of the new species, Ascoschoengastia ueckermanni and Schoutedenichia horaki. They are the South African acarologists (mite and tick experts) Prof Eddie Ueckermann from North-West University and Professor Ivan Horak from the University of Pretoria. Both have been retired for several years (currently Ueckermann is 69 years old and Horak 86) but are still engaged in research in their respective fields. A third species, Trombicula walkerae, was named after the late Dr Jane Walker, who was an expert on Africa’s tick species, and among others helped write guides on tick species to be found in Botswana and Kenya.

Fleas, lice, mites and ticks are all external parasites that occur on the bodies of host animals and feed on their blood at some point during their life cycle. Internal parasites include tapeworms, flatworms and roundworms. For every animal species, there is usually a specific set of parasites that are very unique to them.

Prof Matthee believes more effort should be made with surveys on the distribution of parasite species and their description, as each plays a unique role in ecosystems. Further, parasites make up a significant part of biodiversity on earth as more that 50% of all animal species are either parasites or exhibit some form of parasitism as part of their lifecycle. Because some can also transmit diseases to humans and animals, it is therefore necessary to know where in the country different species occur.

“Parasite research is a very neglected field of study in South Africa,” says Prof Matthee, who has been involved in such work for the past two decades. “There is a shortage of local experts and that is why we regularly use overseas colleagues to help us describe new species.”

One of Prof Matthee’s former doctoral students, Dr Andrea Spickett of the Agricultural Research Council’s Onderstepoort Veterinary Institute, surveyed the internal parasites found in 13 mice species across South Africa as part of her studies. In the process she found at least 13 unknown species of worms. These must first be formally studied to confirm whether they are perhaps new species.

Source: Stellenbosch University

Image source: Stellenbosch University

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