A team of scientists from Cambodia and France has identified a new species of giant mosquito in the genus Toxorhynchites.
Toxorhynchites domrey: (A) thorax; (B) abdomen; (C) habitus; (D) lateral view of thorax. Image credit: Maquart et al., doi: 10.1016/j.aspen.2023.102064.
Toxorhynchites is the sole genus of the mosquito tribe Toxorhynchitini.
It consists of 90 species divided into four subgenera: Afrorhynchus, Ankylorhynchus, Lynchiella and Toxorhynchites.
While the first subgenera is restricted to the Afrotropical region, Ankylorhynchus and Lynchiella are present in the New World and Toxorhynchites is restricted to the Old World.
Members of the genus are large mosquitoes, with a wingspan reaching up to 1.2 cm.
They are often nicknamed elephant mosquitoes due to their large size and bent proboscis.
They are usually very colorful with a body covered with iridescent metallic-colored scales.
“Both sexes possess a large downwardly curved proboscis and are phytophagous, feeding exclusively on nectar or other sugary substances during daytime,” said Dr. Pierre-Olivier Maquart, a researcher in the Medical and Veterinary Entomology Unit at the Institut Pasteur du Cambodge, and his colleagues.
“The larval instars of Toxorhynchites species are predators, feeding primarily on the larvae of other mosquito species, as well as Chironomidae and Tipulidae larvae, dragonfly nymphs or aquatic worms.”
“Due to the peculiar feeding habit of their larvae, Toxorhynchites have been suggested, throughout the second half of the 20th century, to be used as a potential alternative method for vector-control,” they added.
“However, this practice only generated little results.”
In 2021, the authors collected several larvae of Toxorhynchites inside pitchers of the carnivorous plant Nepenthes smilesii during a survey conducted in Veun Sai Siem Pang National Park and in Kirirom National Park in Cambodia.
“The carnivorous plant Nepenthes smilesii is widespread throughout the Indochinese Peninsula and has been recorded from sea level up to 1,000 m in Cambodia, Laos, Thailand and Vietnam,” they said.
“It is a pyrophyte plant that is usually found in seasonally wet habitats such as open sandy savannahs and grasslands.”
Upon investigation, the Toxorhynchites larvae were proven to belong to a new species, named Toxorhynchites domrey.
“Upon investigating a previously unrecorded location of Nepenthes smilesii in the Veun Sai Siem Pang National Park in northeast Cambodia, and the entomological content of their pitchers, we found several Toxorhynchites larvae that, when reached adulthood, appeared to belong to a new species,” the researchers said.
“Several months later, following the same procedure, the same species was collected again in Kirirom National park in Kampong Speu Province, within the same carnivorous Nepenthes species.”
“Nepenthes smilesii and other Nepenthes plants use the apex of modified leaves as pitchers to attract, drown and digest prey,” they added.
“Since the water contained inside these pitchers never dries out as the plant constantly replenishes the fluid inside the trap, it represents a valuable aquatic resource for many organisms relying on it.”
“For instance in Peninsular Malaysia, botanists investigated the content of the Nepenthes pitchers, and demonstrated that more than 90% of the plants hosted at least one associated living arthropod, and more than 150 species were found to live in the pitchers.”
“Amongst the arthropods living in the pitchers, three different types of relationships can be distinguished: the Nepenthexen that are primarily associated with other habitats but that can live in pitchers opportunistically; the Nepenthophiles which are frequently found in pitchers, but do not entirely rely on the plant at any stage (i.e. crabs, spiders…) and the Nepenthobiont.”
“The latter category includes organisms that rely exclusively on these habitats for their development.”
“Several species of Culicidae fall into this category. Most likely Toxorhynchites domrey falls in this category as well, since the larvae have so far only been found in the pitchers of Nepenthes smilesii.”
The discovery is reported in a paper in the Journal of Asia-Pacific Entomology.
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Pierre-Olivier Maquart et al. 2023. Description of a new species of Toxorhynchites (Diptera: Culicidae) from Nepenthes pitchers in Cambodia. Journal of Asia-Pacific Entomology 26 (2): 102064; doi: 10.1016/j.aspen.2023.102064
Source : Breaking Science News