Sphyriidae C. B. Wilson, 1919

Nagasawa, Kazuya, 2024, Rediscovery of a Deep-sea Fish Parasite Lophoura cornuta (Copepoda: Sphyriidae) in the Western North Pacific off Hokkaido, Northern Japan, Species Diversity 29 (1), pp. 37-42 : 38-40

publication ID	https://doi.org/ 10.12782/specdiv.29.37
persistent identifier	https://treatment.plazi.org/id/E42787A3-FFB8-FFDE-FE97-7C42FD649E8A
treatment provided by	Felipe
scientific name	Sphyriidae C. B. Wilson, 1919
status

Treatment

Family Sphyriidae C. B. Wilson, 1919 View in CoL

[New Japanese name: Uoyadori-soramame-mushi-ka] Genus Lophoura Kӧlliker in Gegenbaur, Kӧlliker, and Müller, 1853 [New Japanese name: Uoyadori-soramame-mushi-zoku] Lophoura cornuta (C. B. Wilson, 1919) [New Japanese name: Irakoanago-yadori-soramame-mushi] ( Figs 2–3 View Fig View Fig )

Rebelula cornuta C. B. Wilson, 1919: 582–585 View in CoL , pl. 55, figs 46–53.

Lophoura cornuta View in CoL : Yamaguti 1963: 309, pl. 310, fig. 1; Kabata 1979: 321; Boxshall 1989: 215–216, fig. 9; Boxshall and Halsey 2004: 819; Sebone and Dippenaar 2023: 355–356, fig. 7.

Excluded record.

Lophoura cornuta View in CoL : Cohen 1973: 632.

Material examined. Two post-metamorphic adult females (no attached males) (NSMT-Cr 31508 and 31509).

Host and localities. Kaup’s arrowtooth eel Synaphobranchus kaupii Johnson, 1862 ( Anguilliformes : Synaphobranchidae ) captured in the western North Pacific at a depth of 550 m (42º41′N, 144º47′E) off Cape Shirepa, eastern Hokkaido (locality 2 in Fig. 1 View Fig ) and at a depth of 620 m (42º14′N, 142º00′E) off Shin-Hidaka, central Hokkaido (locality 3 in Fig. 1 View Fig ), northern Japan.

Site in host. Anterior part of body embedded in host (no detailed information on the attachment sites was obtained from the collectors).

Description of post-metamorphic adult females. Body ( Figs 2A View Fig , 3A View Fig ) comprising cephalothorax, neck, and trunk bearing posterior processes. Total body length (TBL, excluding posterior processes) of two specimens 43.7mm ( Fig. 2A View Fig ) and 23.0mm ( Fig. 3A View Fig ). Trunk length and width 20.5× 14.4mm and 14.1× 8.6mm.

Cephalothorax soft, almost cylindrical, and transversely wrinkled ( Figs 2A–C View Fig , 3A, B View Fig ). In larger specimen, cephalothorax truncated anteriorly with mouth opening near two slightly sclerotized, conical protuberances on anterior surface ( Fig. 2D View Fig ), whereas in smaller specimen, anterior cephalothoracic portion chestnut-shaped with two slightly sclerotized, conical protuberances on anterior margin ( Fig. 3C, D View Fig ). Neck heavily sclerotized, cylindrical, slightly wider near junction with trunk; holdfast organ comprising four trunks bearing some slender, elongated, irregularly curved branches of different lengths ( Figs 2A–C View Fig , 3A, B View Fig ). Trunk (genitoabdomen) slightly longer than wide, swollen, dorsoventrally flattened, with two longitudinal rows of four depressions on dorsal and ventral surfaces ( Figs 2A View Fig , 3A View Fig ). Paired genital apertures raised ventrally from posterior end of trunk ( Fig 2A View Fig ). Posterior processes attached lateral to swelling on posterior tip of trunk, comprising long stalk and many, slen- der, elongated, mostly posteriorly extending cylinders arising from stalk ( Figs 2A View Fig , 3A View Fig ).

Color. Yellow ( Fig. 3A View Fig , ethanol-preserved specimens).

Japanese names. The new Japanese name of the family Sphyriidae is a combination of a Japanese adjective (“Uoyadori”) meaning fish-infecting and three Japanese nouns (“soramame-mushi-ka”), each meaning the shape of the trunk resembling a broad bean, a parasite, and a family. The new Japanese name of the genus Lophoura is similar to that of the family, but “zoku” means a genus. The first word (“Irakoanago”) in the new Japanese name of L. cornuta is the host name in Japanese.

Remarks. The morphological characters of the two post-metamorphic adult female specimens collected in this study correspond to the original description of L. cornuta by Wilson (1919), and the specimens are herein identified as this species. A single post-metamorphic adult female with a male attached was used in the original description, and this female was 32 mm in TBL.

Currently, two types of enlarged processes (antennary and maxillary processes) have been reported to be present on the anterior surface of the cephalothorax in several species of Lophoura including L. cornuta ( Sebone and Dippenaar 2023) . In the two adult female specimens examined in this study, two conical protuberances forming the antennary processes are found, but the maxillary processes are not clearly recognized ( Figs 2D View Fig , 3C View Fig ).

Lophoura cornuta is a poorly known fish parasite. There is only one paper on L. cornuta from Japan, which is the description of the species published more than 100 years ago ( Wilson 1919). One of the two specimens reported herein was collected off Cape Shirepa , eastern Hokkaido (locality 2 in Fig. 1 View Fig ) . This locality is close to the type locality of L. cornuta , which is off Cape Ochiishi, eastern Hokkaido (locality 1 in Fig. 1 View Fig ).

When L. cornuta was described by Wilson (1919), the host fish was reported as “ Synaphobranchus affinis ”. However, three Synaphobranchus species ( S. affinis , S. kaupii , and S. brevidorsalis ) occur in the western North Pacific off northern Japan ( Matsubara and Ochiai 1951; Shinohara et al. 1996, 2009), where S. kaupii predominates among these species ( Imamura et al. 1999; Watanabe 2014). Thus, it is possible that the host fish reported by Wilson (1919) was not S. affinis but S. kaupii .

Lophoura cornuta was redescribed by Boxshall (1989) from three adult (two post-metamorphic and one metamorphosing) female specimens taken from a synaphobranchid eel S. cf. brevidorsalis in the western South Pacific off New Caledonia. The adult female specimens were much smaller (about 7.5 and 5.5 mm in TBL) than those of the Japanese adult female specimens (23.0– 43.7 mm in TBL) ( Wilson 1919; this paper). Although Boxshall (1989) stated that no significant differences were found between the New Caledonian material and that of Wilson (1919), the cephalothorax of his specimens was, unlike that of the Japanese specimens ( Figs 2A–C View Fig , 3A, B View Fig ; see also Wilson 1919: pl. 55, fig. 46), smooth and not transversely wrinkled ( Boxshall 1989: fig. 9A, B). Furthermore, the holdfast organ of his larger specimen possessed many, slender, branching, or simple processes ( Boxshall 1989: fig. 9A), but that of the Japanese specimens has four trunks with some slender, elongated, irregularly curved branches of different lengths ( Figs 2A–C View Fig , 3A, B View Fig ; see also Wilson 1919: pl. 55, fig. 46). At present, it is unknown whether such morphological differences are due to local or body size-dependent intraspecific variations of L. cornuta , and specimens of about 10–20 mm in TBL are necessary to answer this question.

Recently, Sebone and Dippenaar (2023) reported the morphology of L. cornuta based on one adult female specimen (28.4 mm in TBL) taken from a hairy conger B. albescens in the Indian Ocean off the south coast of South Africa. As mentioned by these authors, the South African specimen differs from the western Pacific specimens reported by Wilson (1919) and Boxshall (1989) in the size and morphology of posterior processes: their specimen has posterior processes shorter than the trunk and cylinders (reported as stalks) extending laterally on the stalks (as peduncles) ( Sebone and Dippenaar 2023: fig.7a), but the western Pacific specimens have posterior processes longer than or as long as the trunk and cylinders extending mostly posteriorly on the stalks ( Wilson 1919: pl. 55, fig. 46; Boxshall 1989: fig. 9A). In the present study, we have also confirmed these differences between our specimens ( Figs 2A View Fig , 3A View Fig ) and the South African specimen. Moreover, the hosts reported from the western Pacific belong to the family Synaphobranchidae ( Wilson 1919; Boxshall 1989; this paper), whereas that from South Africa belongs to Congridae ( Sebone and Dippenaar 2023) . According to Boxshall (1998), each Lophoura species occurs on only one family of fish hosts. Therefore, from the viewpoint of the parasite’s morphology and host utilization, further taxonomic work is needed for the Lophoura copepod infecting the hairy conger off South Africa.

Slender codling Halargyreus johnsonii Günther, 1862 ( Gadiformes : Moridae ) is known to have an infection of “ Lophoura cornuta ” in the western North Atlantic and the Southern Ocean ( Cohen 1973). One of the specimens of this copepod was earlier reported as “a large parasitic copepod, tentatively assigned to the Caligoida” from a slender codling caught in the New York Bight ( Haedrich and Horn 1970). However, as stated above, L. cornuta usually infects synaphobranchid eels ( Wilson 1919; Boxshall 1989; this paper), and it is thus very likely that the parasitic copepod reported by Cohen (1973) from the morid fish (slender codling) is not L. cornuta but a different species. To date, two species of Lophoura ( L. magna Szidat, 1971 and L. tetraphylla Ho, 1985 ) have been reported from morid fishes ( Boxshall and Halsey 2004), and Patagonian codling Lepidion ensiferus (Günther, 1887) ( Szidat 1971, its scientific name misspelled as “ L. euriferus ”) and blue antimora Antimora rostrata (Günther, 1878) ( Ho 1985; Hogans 1986) are the hosts of these two parasites, respectively. Cohen (1973) pointed out that the above “ L. euriferus ” is not L. ensiferus but H. johnsonii .

Kingdom	Animalia
Phylum	Arthropoda
Class	Copepoda
Order	Siphonostomatoida
Family	Sphyriidae