News & Event

PRESS RELEASE: Feather Mite Species Related to the Laysan Albatross Discovered in Japan

News & Event

Scientists present morphological redescriptions and new genetic information on two feather mite species associated with an endangered seabird species

Phoebastria immutabilis is a seabird species listed under the category of “Near Threatened” by the International Union for Conservation of Nature. Feather mites, specific to P. immutabilis, have not been reported in Japan in the last 50 years due to the population collapse of their host. Now, scientists in Japan report two such mite species, Diomedacarus gigas and Echinacarus petaliferus, for the first time in Japanese coastal waters, which could facilitate seabird conservation efforts.

Discovery of feather mite species from the Laysan Albatross, Phoebastria immutabilis.

Caption:  Two species of feather mites (both males) from the Laysan Albatross. A) Echinacarus petaliferus (Trouessart, 1898) and B) Diomedacarus gigas (Trouessart, 1895).
Credit:  Tsukasa Waki from Toho University, Japan.
License:  Original Content

Phoebastria immutabilis, commonly known as the Laysan Albatross, is a large seabird native to the North Pacific Ocean. Owing to the decrease in their population size, this species has been listed as “Near Threatened” in the Red List of the International Union for Conservation of Nature. Laysan Albatrosses, like other birds, have a symbiotic relationship with feather mites, a species of highly host-specific parasites that inhabit the feathers of the birds. 

Now, with the threat of extinction looming over P. immutabilis, the feather mites could be in danger, too. Changes in the population dynamics of either host or their symbiont (the organism living in symbiosis with the host) can lead to an ecological imbalance. However, their current population and infection status remains ambiguous in Japan. To bridge this gap, Professor Satoshi Shimano from Hosei University, along with Associate Professor Tsukasa Waki from Toho University and Professor Masaki Eda from Hokkaido University, all in Japan, investigated the current status of P. Immutabilis feather mites. They studied bird specimens from in and around Japanese coastal waters. Their recent work was published in Volume 28, Issue 1 of the journal Systematic and Applied Acarology on 19 January 2023.
Sharing the motivation behind their investigation, Prof. Shimano states, “The feather mite Compressalges nipponiae, which infects the Crested Ibis, is known to have become extinct with the disappearance of its host population in Japan. Therefore, information on the mite symbionts, thought to clean the host’s feathers, could be helpful in conserving the Layasan Albatross.” Their study and findings were published in the journal Systematic and Applied Acarology. 

Feather mites from three preserved P. immutabilis wing feathers were studied using microscopy and molecular analyses. The team identified 603 members of Diomedacarus gigas, and two adult males of Echinacarus petaliferus. Remarkably, this is the first study to report on the occurrence of D. gigas in Japan in the last 50 years, and the first-ever on E. petaliferus. The team provided a detailed morphological redescription of the isolated mites. Twenty D. giga and one E. petraliferus mites were selected for analysis of haplotype network – a method to determine genetic diversity and lineage.

Every organism has a unique set of genes that do not undergo much variation over time, which makes them a molecular fingerprint. Cytochrome Oxidase Subunit I (COI) was used as the target gene for haplotype analysis of D. gigas. The COI parsimony network revealed seven different haplotypes, of which six were unique to their hosts. The large proportion of unique COI haplotypes pointed to a greater genetic diversity and stable population of D. gigas. On the other hand, genetic information could not be obtained for E. petaliferus and additional research is expected for this species. The team concluded that E. petaliferus was a rare species in Japan, with a high risk of extinction. 

In summary, these findings highlight the strong correlation between the ecology of the mites and the population of P. immutabilis. Foreseeing possible future avenues for their work, Dr. Waki speculates, “We believe that the information on the Laysan Albatross and the distribution of its symbionts will enable better conservation planning and extinction risk assessment for this species. This knowledge will ultimately lead to a better preservation of ecosystems for future generations.” 

And we certainly hope his visions come true! 

Discovery of feather mite species from the Laysan Albatross, Phoebastria immutabilis.

Caption: Two species of feather mites (both males) from the Laysan Albatross. A) Echinacarus petaliferus (Trouessart, 1898) and B) Diomedacarus gigas (Trouessart, 1895).
Credit: Tsukasa Waki from Toho University, Japan.
License: Original Content


Authors: Tsukasa Waki 1, Masaki Eda 2, and Satoshi Shimano 3
Title of original paper: Two feather mite species (Alloptidae, Freyanidae) associated with the Laysan Albatross Phoebastria immutabilis (Rothschild, 1893) (Diomedeidae) from Japanese coastal waters
Journal: Systematic and Applied Acarology
DOI: 10.11158/saa.28.1.7
Abstract URL:
Article URL:
1 Faculty of Science, Toho University
2 Hokkaido University Museum, Hokkaido University
3 Science Research Center, Hosei University

About Professor Satoshi Shimano

Satoshi Shimano is an acarologist and a Professor at the Science Research Center at Hosei University in Japan. He obtained his master’s degree from Nagoya University and his doctoral degree from Yokohama National University, both in Japan. His research interests include systematics, taxonomy, soil zoology, acarology, and protistology. He has published 177 papers with over 1800 citations to his credit. Additionally, he is a recipient of several awards and has a patent to his name. 

About Associate Professor Tsukasa Waki

Tsukasa Waki is an Associate Professor at the Faculty of Science at Toho University, Japan. He earned his PhD from The University of Tokyo, and is currently pursuing research across field ecology, population ecology, pathogens and virulence, infection, and mortality. He has published 55 articles on diverse topics in the biological sciences since 2009.

About Hosei University

Hosei University is one of the leading private universities in Tokyo, Japan. The university offers international courses in many disciplines and has a long and rich history. Hosei University was founded as a school of Law in 1880 and evolved into a private university by 1920. 
It is also home to multiple research centers, which conduct advanced research on various fields, including nanotechnology, sustainability, ecology, and more. 
The university has three main campuses—Ichigaya, Koganei, and Tama, located across Tokyo. 

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