Jayanti has become the twelfth subgenus, or species, of cricket identified under the genus Arachnomimus Saussure, 1897. Found in the Kurra caves of Chhattisgarh in April 2021 by a team of zoologists headed by Dr Ranjana Jaiswara of the Zoology Department of Panjab University, Chandigarh, the new subgenus was named Jayanti after Professor Jayant Biswas, one of the leading cave explorers in the country, who assisted the team. The new find has been published in the reputed journal Zootaxa this month.
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Arachnomimus is the genus name given by Swiss Entomologist Henri Louis Frédéric de Saussure in 1878 to crickets that resembled spiders. The word Arachnomimus is derived from two Ancient Greek words — ἀράχνη (arákhnē, means “spider”) and μῖμος (mîmos, means “imitator, actor”). This is apt because crickets of this group are commonly called spider crickets because of their smaller body size and long legs.
The newly discovered subgenus, Indimimus, is different from the two subgenera, Arachnomimus and Euarachnomimus, because of the male genitalia structure, explains Dr Jaiswara. Insects have a lock-and-key model genitalia structure which is unique to each subgenus. Genus and subgenus are taxonomic levels created by taxonomists to classify organisms. A genus is represented by a set of diagnostic characters. Certain variations in characters compel taxonomists to divide the genus into subgenus and document the variation.
Crickets are noticeable for their loud calls, especially at night. Male crickets produce this sound by rubbing their wings against each other to attract females. The females listen to these calls using ears located on their legs and approach the males for mating and reproduction.
Interestingly, males of the new Jayanti subgenus cannot produce sound and their females don’t have ears. The crickets were found on the walls of the Kurra caves which don’t have light inside. They may be communicating by beating their abdomen or any other body part on the cave walls. Vibrational communication is one of the softest but fastest modes of signal transmission. Further studies on their skills of vibrational communication may help in designing hearing aids for human which can capture quietest signals and amplify to an audible hearing range, the researchers explain.
With the discovery of Jayanti from India, the genus Arachnomimus is now known from 12 species. Distribution of these species is very wide, ranging from Brazil to Malaysia. In India, the diversity of spider crickets is still unexplored. Given India is home to four biodiversity hotspots, and all the hotspots have unexplored caves, there is significant scope for many more discoveries.
“Merely 1 per cent of the total caves in India have been explored till now. Areas like northeast have thousands of caves with huge potentials for discoveries,” Dr Biswas added.