Parasitic nematodes of marine fishes from Palmyra Atoll, East Indo-Pacific, including a new species of Spinitectus (Nematoda, Cystidicolidae)

Abstract

Here, we present the results of a taxonomic survey of the nematodes parasitizing fishes from the lagoon flats of Palmyra Atoll, Eastern Indo-Pacific. We performed quantitative parasitological surveys of 653 individual fish from each of the 44 species using the intertidal sand flats that border the atoll’s lagoon. We provide morphological descriptions, prevalence, and mean intensities of the recovered seven species of adult nematode (Pulchrascaris chiloscyllii, Capillariidae gen. sp., Cucullanus bourdini, Cucullanus oceaniensis, Pseudascarophis sp., Spinitectus (Paraspinitectus) palmyraensissp. nov., Philometra pellucida) and three larval stages (Pulchrascaris sp., Hysterothylacium sp., Cucullanus sp.). We recorded: Pulchrascaris chiloscyllii from Carcharhinus melanopterus; Capillariidae gen. sp. from Chaetodon lunula, Lutjanus fulvus, and Ellochelon vaigiensis; Cucullanus bourdini from Arothron hispidus; Cucullanus oceaniensis from Abudefduf sordidus; Pseudascarophis sp. from Chaetodon auriga, Chaetodon lunula, and Mulloidichthys flavolineatus; Spinitectus (Paraspinitectus) palmyraensissp. nov. from Albula glossodonta; Philometra pellucida from Arothron hispidus; and three larval forms, Pulchrascaris sp. from Acanthurus triostegus, Acanthurus xanthopterus, Rhinecanthus aculeatus, Platybelone argalus, Carangoides ferdau, Carangoides orthogrammus, Caranx ignobilis, Caranx melampygus, Caranx papuensis, Chaetodon auriga, Chanos chanos, Amblygobius phalaena, Asterropteryx semipunctata, Valencienea sexguttata, Kyphosus cinerascens, Lutjanus fulvus, Lutjanus monostigma, Ellochelon vaigiensis, Mulloidichthys flavolineatus, Upeneus taeniopterus, Gymnothorax pictus, Abudefduf septemfasciatus, Abudefduf sordidus, and Stegastes nigricans; Hysterothylacium sp. type MD from Acanthurus triostegus, Carangoides ferdau, Chaetodon lunula, Chanos chanos, Kyphosus cinerascens, Abudefduf sordidus, and Arothron hispidus; and Cucullanus sp. from Caranx ignobilis. Spinitectus (Paraspinitectus) palmyraensissp. nov. (Cystidicolidae) is described from the intestine of roundjaw bonefish Albula glossodonta. All the nematode species reported in this study represent new geographical records. We discuss how our survey findings compare to other areas of the Indo-Pacific, and the way the relatively numerical dominance of trophically transmitted larval stages likely reflect the intact food web of Palmyra Atoll, which includes a large biomass of large-bodied top predator sharks and ray-finned fishes.

Characterization of Pseudoterranova ceticola (Nematoda: Anisakidae) larvae from meso/bathypelagic fishes off Macaronesia (NW Africa waters)

“…These species appear to show a caecum equal or longer than the ventricle, even in juvenile specimens of P. ceticola reported from the final hosts (Table 5 ) 27 , 42 , 44 , 47 . Therefore, the relationship between caecum length and ventricle length in larvae from intermediate or transport hosts may not reflect the adult morphology, contrary to the arguments of González Solís et al 31 . In addition, these species from kogiid whales are small compared to adult males maturing in pinnipeds.…”

“…type 1 and 2 larvae sensu Cannon 8 from teleost paratenic hosts have been molecularly found to include Pulchrascaris australis and Terranova pectinolabiata (now Euterranova pectinolabiata ) from Australian shark definitive hosts, respectively 4 , 8 , 29 , 30 . Gonzalez-Solis et al 31 used morphology alone to identify Terranova type 1 larvae from Hawaiian fishes as Pulchrascaris sp. In general, larvae of Pulchrascaris spp.…”

“…and Terranova spp. that are present in teleost paratenic hosts and mature in elasmobranchs, show very long and slender ventricles, alongside an even longer caecum, and they have conical pointed tails without mucron 5 , 8 , 31 , 32 . The Terranova -like larvae described in the present study however have shorter more oval ventricles, accompanied by caeca that rarely exceed the ventricle in length.…”

Parasite diversity at isolated, disturbed hydrothermal vents

“…We compared our vent data to similar dissection datasets from two other marine benthic ecosystems: kelp forests on the coast of Santa Barbara, California [51] and the intertidal lagoon sandflats of Palmyra Atoll, Line Islands Archipelago [52][53][54][55][56] (figure 1). Here, we consider benthic species to include those living on the surface of the seabed as well as those living just above, following the convention of the MarLIN BIOTIC database [60].…”

“…Its location on a fast-spreading plate boundary that experiences large-scale eruptive disturbance every 10-20 years [35] allows us to examine how features of parasite species richness and composition differ in an island-like and disturbed environment. We compare our data to coastal marine benthic ecosystems that differ in their degree of disturbance and isolation, and for which parasitological data were collected using similar methods: kelp forests on the coast of Santa Barbara, California, USA [51] and the lagoon sandflat of Palmyra Atoll in the Line Islands Archipelago [52][53][54][55][56].…”