YNU identifies species of luminous Collembola identified as Lobella sauteri — Glows green in forest soil

A research group led by Dr. Atsuko Ohira (graduate student at the time of research, now a curator at the Tamarokuto Science Center) and Associate Professor Taizo Nakamori of the Graduate School of Environmental and Information Sciences at Yokohama National University (YNU), in collaboration with the Tamarokuto Science Center, Nagoya University, and Chubu University, has revealed for the first time that the true identity of the luminous Collembola (previously designated as Lobella sp.), a mystery for over 300 years, is Lobella sauteri. This identity was determined through DNA barcoding, which matches species-specific short gene markers to a database, and from the arthropod's morphological characteristics. The world's first successful video recording of Collembola luminescence has scientifically confirmed that L. sauteri glows green. The results were published in the 7 Aug. 2023 issue of the international academic journal Zootaxa.

With the body of a few millimeters long, Collembola is the world's smallest luminous arthropod on land. It is abundant in forest soils and also found in soils in parks, shrines, and planters. Collembola species differ from insects in that they have six legs, and a unique abdominal organ called a mucous tube. It is known that there are approximately 9000 species globally and about 400 species in Japan.

The luminous Collembola collected in Japan is the only one in the world that has been photographed glowing when stimulated and is expected to become a new material for the study of bioluminescence. Although DNA barcodes are obtained as clues for the identification of species, as in the case of many Collembolans, the species name had not been determined owing to taxonomic confusion.

The research group clarified the true identity of the luminous Collembola as Lobella sauteri on the basis of its DNA barcode and morphological characteristics. The first record of the luminous Collembola appeared in Japan's first book on herbalism, 'Yamato Honzo,' published in 1709, and it is possible that the same arthropod is the true identity of the species. Additionally, a total of 12 species collected in Tokyo-Okinawa Prefecture were tested for luminescence, using an originally developed method. Three new species were found among the known species, bringing the total number of luminous Collembola species in Japan to four.

Furthermore, the researchers developed a method to evaluate the luminous capacity with some precision using an acoustic device with which the same stimuli can be provided by anyone. They found that there is a luminous species in the genus Vitronura (viz., Vitronura giselae), which is a separate lineage (another subfamily) from L. sauteri. The researchers tested the luminous capacity of all known species of the Japanese genus Vitronura and found that Vitronura pygmaea and Vitronura mandarina did not luminesce. By contrast, Vitronura giselae and Vitronura kunigamiensis were found to be luminescent. It is rare for a genus to contain both luminescent and non-luminescent species.

The Tohoku species, erroneously named Lobella sauteri, was renamed Lobella monstrum sp. nov. on the basis of a specimen collected in Mount Osore. Whether or not this species is luminescent has not been tested.

L. sauteri glows when stimulated and has also been shown to produce defensive substances when strongly stimulated. Although it is not yet known why Collembolans glow, it is thought that they are a separate lineage from insects, appeared on Earth earlier than insects, and acquired the luminescent ability independently of fireflies. This luminous Collembola is expected to be used as research material for unraveling the diversity and origin of luminescent organisms.

Ohira said, "Research on luminous Collembola has only just begun. From now on, I would like to find out how many species of luminous Collembola there are in Japan and in which areas they are distributed."

Journal Information
Publication: Zootaxa
Title: Contribution to the taxonomy of Lobellini (Collembola: Neanurinae) and investigations on luminous Collembola from Japan
DOI: 10.11646/ZOOTAXA.5325.1.4