Two new tapeworm species discovered in wild oval squid

Credit: Okinawa Institute of Science and Technology Graduate University

Researchers from the Physics and Biology Unit at the Okinawa Institute of Science and Technology (OIST) have discovered two species of tapeworms, or cestodes, in the guts and stomachs of wild-caught oval squid (Sepiotheutis lessoniana).

“The cestodes found in the squids were all in their larval stage, which suggests that they use the squids as intermediary hosts,” says Dr. Mehmet Arif Zoral. One is a newly described species, Nybelina enterika (“enter” is Greek and refers to the intestine, “ika” is the common name for squid in Japanese), and the other is an unknown member of the genus Phoreiobothrium.

“No cestodes were found outside the guts and stomachs of the squids, suggesting that they might be confined by the intestinal wall.”

In addition to describing the morphology of the two species, the researchers also described their mitogenomes and numerous nuclear genomic regions in a paper that was recently published in the Journal of Invertebrate Pathology.

Healthy, female Sepiotheutis lessoniana in the OIST Marine Science Station research tank. Credit: Mehmet Arif Zoral / OIST

As Dr. Zdenek Lajbner explains, “these sequences may serve as biomarkers for diagnosing infestations in future, especially considering the tiny size of the larvae, with the N. enterika measuring just one millimeter in length on average, and the Phoreiobothrium about half of that.”

“The danger of these cestodes to human health is yet unknown. However, the enzymes that they use to digest squid tissue are known to cause allergic reactions in humans,” adds Dr. Lucia Zifcakova.

When tested, the parasites were not found in squid raised in aquaculture.

More information:
Mehmet Arif Zoral et al, Infection of two cestode larvae, Nybelinia enterika sp. nov. and Phoreiobothrium sp. in oval squid Sepioteuthis lessoniana species complex, Journal of Invertebrate Pathology (2025). DOI: 10.1016/j.jip.2025.108329

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Okinawa Institute of Science and Technology Graduate University

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Two new tapeworm species discovered in wild oval squid (2025, April 10)
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