Abstract
Purpose:
The present paper describes two new genera and species of the parasitic copepod family Chondracanthidae Milne Edwards, 1840 based on specimens collected from two species of deep-sea fishes at a depth of 212 m off Suruga Bay, Japan. Avatar nishidai gen. et sp. nov. is described from the host fish Chaunax abei Le Danois, 1978 (Chaunacidae). Kokeshioides surugaensis gen. et sp. nov. is described from the host fish Setarches longimanus (Alcock, 1894) (Setarchidae).
Methods:
Fresh specimens of chondracanthids were collected from the buccal cavity of two species of deep-sea fishes (fish hosts were frozen), Chaunax abei Le Danois, 1978 (Lophiiformes: Chaunacidae) and Setarches longimanus (Alcock, 1894) (Perciformes: Setarchidae), caught at a depth of 212 m in Suruga Bay, Japan (34° 37′48.87″ N, 138° 43′2.958″ E). Both the species are described and illustrated based on ovigerous females.
Results:
The genus Avatar gen. nov. can readily be distinguished from all other chondracanthid genera by the following combination of features: cephalothorax slightly wider than long with anterior pair of large and posterior pair of small lateral lobes, and two pairs of ventro-lateral processes; the very posteriormost part of the first pedigerous somite contributes to the neck; cylindrical trunk with two pairs of blunt proximal fusiform processes; antennule with small knob terminally; antenna bearing distal endopodal segment; labrum protruding ventrally; two pairs of biramous legs each with 2-segmented rami. Kokeshioides gen. nov. has the following combinations of features that distinguish it from other chondracanthid genera: body flattened, without lateral processes; cephalothorax much wider than long, with paired anterolateral and posterolateral lobes, folded ventrally; the very posteriormost part of the first pedigerous somite contributes to the neck; mandible elongate; legs unique, heavily sclerotized, represented by two pairs of acutely pointed processes.
Conclusion:
With the addition of two new genera presently reported, the family Chondracanthidae currently includes 52 valid genera. Among the described genera Avatar gen. nov. seems to be very primitive, while Kokeshioides gen. nov. is highly advanced. The deduced evolutionary history of chondracanthid genera is also discussed.
Keywords: Avatar, Chondracanthids, Copepoda, Fish parasite, Kokeshioides
Taxonomy
Order Cyclopoida Burmeister, 1834
Family Chondracanthidae Milne Edwards, 1840
Genus Avatar gen. nov.
Etymology: The generic name is derived from a world-famous epic science fiction film, James Cameron’s “Avatar”, in which the dragon-like aerial predator “Mountain Banshee” with two pairs of wings reminds us of the present new taxon with two pairs of lateral processes on the trunk. Gender feminine.
Avatar nishidai gen. et sp. nov.
Etymology: The specific name of the new species, ‘nishidai’, is dedicated to Mr. Yusuke Nishida (Hiroshima University) who found this enigmatic chondracanthid in the Suruga Bay, Japan. It is a noun in the genitive case.
Genus Kokeshioides gen. nov.
Etymology: The generic name is derived from a Japanese traditional wooden toy called “Kokeshi” and the Latin suffix -oides meaning “like”. Gender masculine.
Kokeshioides surugaensis gen. et sp. nov.
Etymology: The specific name is derived from the type locality, Suruga Bay, Japan. It is in the nominative singular, gender masculine.
Conclusions:
New material collected from two different species of deep-sea fishes of Suruga Bay, Japan were found to be different from all other known chondracanthid genera, and based on the clear morphological features we described two new monotypic genera. Accordingly, we described Avatar nishidai gen. et sp. nov. from Chaunax abei Le Danois, 1978 (Chaunacidae) and Kokeshioides surugaensis gen. et sp. nov. from Setarches longimanus (Alcock, 1894) (Setarchidae). By the description of two new genera in the presently reported study, the family Chondracanthidae currently includes 52 valid genera. Among the described genera Avatar gen. nov. seems to be very primitive, while Kokeshioides gen. nov. is highly advanced. The deduced evolutionary history of chondracanthid genera is also discussed in the present paper.
Panakkool Thamban Aneesh, Susumu Ohtsuka, Yusuke Kondo & Ameri Kottarathil Helna. 2024. Two New Genera and Species of the Parasitic Copepod Family Chondracanthidae Milne Edwards, 1840 (Copepoda: Cyclopoida) from Deep-Sea Fishes Off Suruga Bay, Japan. Acta Parasitologica. DOI: 10.1007/s11686-024-00820-3
