Octorhopalona saltatrix, a New Genus and Species (Hydrozoa, Anthoathecata) from Japanese Waters

Approximately 300 species of cnidarian jellyfish have been reported in Japanese waters. However, many specimens remain unidentified. In this study, taxonomic investigations, including morphological observations and molecular 16S phylogenetic analyses, were conducted on unknown specimens collected of...

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Bibliographic Details
Published in:Animals (Basel) 2022-06, Vol.12 (13), p.1600
Main Authors: Toshino, Sho, Yamamoto, Gaku, Saito, Shinsuke
Format: Article
Language:English
Subjects:
Anthoathecata
Cnidaria
Collectors
Diagnostic systems
Halimedusa
Halimedusidae
Hydrozoa
identification
Knobs
Maximum likelihood method
Morphology
Museums
New genera
new species
Phylogenetics
Phylogeny
Physical characteristics
Polyps
Public health
Taxonomy
Tentacles
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Summary:Approximately 300 species of cnidarian jellyfish have been reported in Japanese waters. However, many specimens remain unidentified. In this study, taxonomic investigations, including morphological observations and molecular 16S phylogenetic analyses, were conducted on unknown specimens collected off Oarai, Sagami Bay, and Tosa Bay, Japan. The specimens have the following morphological characteristics: distinct peaks in jelly above the base of the manubrium, a red band on the manubrium, and cylindrical marginal bulbs, each with an abaxial ocellus that is common to the family Halimedusidae. However, the specimens can be distinguished from other Halimedusidae species by their eight radial canals, eight tentacles with numerous stalked nematocyst knobs, and eight nematocyst tracks on the exumbrella. Moreover, molecular phylogenetic analyses revealed that the Kimura two-parameter distance between the specimens and other species was 0.066-0.099, which is considered to represent intergeneric variability. Based on this result, we described it as a new species and established a new genus for taxonomic stabilization. We also emended the diagnostic characters of the family Halimedusidae owing to the establishment of the new genus. Halimedusidae comprises five species in four genera. This paper provides taxonomic keys for the identification of species in the family Halimedusidae.
ISSN:2076-2615
2076-2615
DOI:10.3390/ani12131600