Redescription of Orcinocyamus orcini (Amphipoda: Cyamidae) from Orcinus orca Stranded at East Java Island, Indonesia
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Published on: June 16, 2020
Marina Hassan1, Aditya Yudhana2, Mohammad Faizal Ulkhaq3
1Institute of Tropical Aquaculture and Fisheries, Universiti Malaysia Terengganu, 21030, Kuala Nerus, Terengganu, Malaysia. marina@umt.edu.my.
Background:
Orcinocyamus orcini (Leung, 1970) is a cyamid amphipod specific to the killer whale (Orcinus orca). This study redescribes O. orcini from Indonesia using morphological and molecular approaches and provides the first DNA sequences for the species.
Methods:
Specimens collected from skin lesions of an O. orca in East Java, Indonesia, were examined using light and scanning electron microscopy. Molecular characterization was based on partial mitochondrial cytochrome c oxidase subunit I (COI) sequence and phylogenetic analysis.
Results:
Morphological examination confirmed the specimens as O. orcini and revealed diagnostic features including anterodorsal epaulette-like processes, ventral abdominal spines, and paired double, sausage-shaped, non-fasciculate gills on segments 3 and 4. The first COI sequences of O. orcini (GenBank accession numbers PX513872 and PX513873) differed by 17.8-21.3% from those of 10 other sequenced cyamid species and formed a distinct lineage in the phylogenetic analysis.
Conclusions:
The study provides an updated morphological characterization and the first molecular reference data for O. orcini, facilitating its future identification and expanding its documented geographic distribution to the tropical Indo-Pacific.
