Chubu University discovers a new parasitic nematode species, found in exotic millipede species that came to Japan from Taiwan — Fears of spread to native hosts

Professor Koichi Hasegawa of the College of Bioscience & Biotechnology, Chubu University, and Visiting Scientist Jans Morffe (a researcher at the Institute of Ecology and Systematic, Cuba) have jointly identified a new nematode species parasitizing the exotic millipede species Chamberlinius hualienensis Wang, 1956, which was introduced to Japan from Taiwan. They named the parasite Travassosinema viatorum n. sp. (meaning "traveler"). The results were published in the electronic edition of Zootaxa.

Although millipedes belong to the same family of polypods as centipedes and scutigeromorphs, they do not harm humans directly and are forest decomposers that feed on fallen leaves. There are approximately 12,000 registered millipede species distributed throughout the world. In Japan, they are found from Hokkaido to Okinawa. Most of them live quietly in the forests. However, in recent years, an exotic species, Chamberlinius hualienensis Wang, 1956, has invaded and established itself in Okinawa and Kagoshima prefectures, sometimes causing outbreaks and becoming a problem as an unpleasant pest. It is believed that this species, which is native to Taiwan, may have been brought to Japan along with soil and plants, and spread across the country.

According to the National Institute for Environmental Studies, this species has also been observed in Shizuoka and Kanagawa prefectures in Honshu. The research group studied the parasitic nematodes of Chamberlinius hualienensis Wang, 1956 in Okinawa prefecture and found a new species of the genus Travassosinema, which parasitizes Japanese and other world species of millipedes. Since it came to Japan from Taiwan along with Chamberlinius hualienensis Wang, 1956, it was given the species name (the name written following the genus name in its scientific nomenclature) viatorum (Latin for "traveler").

Molecular phylogenetic analysis suggests that this group of nematodes may have evolved through speciation (the process of formation of new species) by changing their host species of millipedes. Therefore, there is a possibility that the species that came from Taiwan in Chamberlinius hualienensis Wang, 1956 could spread to Japanese millipede hosts.

The Ishigaki and Iriomote islands in Okinawa prefecture are inhabited by the native millipede Chamberlinius uenoi Mukarakami, 1975, which is of the same genus as Chamberlinius hualienensis Wang, 1956. Therefore, this highlights the need to strengthen both the prevention of invasion by exotic species and the protection of organisms in the Yaeyama Islands of Okinawa.

Parasitic organisms introduced by exotic hosts can cause diseases in native species, sometimes resulting in the destruction of native ecosystems or the extinction of species, as in the case of pine wilt disease and chytridiomycosis. However, this group of nematodes may have an innate ability to switch hosts, and much remains to be learned about their negative effects on new hosts.

Journal Information
Publication: Zootaxa
Title: Morphological and molecular characterization of Travassosinema viatorum n. sp. (Nematoda: Oxyuridomorpha: Travassosinematidae) from the invasive millipede Chamberlinius hualienensis Wang, 1956 (Diplopoda: Polydesmida: Paradoxosomatidae) in Okinawa, Japan
DOI: 10.11646/ZOOTAXA.5318.4.4