Erection of Euterranova n. gen. and Neoterranova n. gen. (Nematoda, Anisakidae), with the description of E. dentiduplicata n. sp. and new records of two other anisakid nematodes from sharks off New Caledonia.

František Moravec,Jean-Lou Justine

doi:10.1051/parasite/2020053

Abstract

Helminthological examinations of three species of sharks, Galeocerdo cuvier, Triaenodon obesus (both Carcharhinidae, Carcharhiniformes) and Stegostoma fasciatum (Stegostomatidae, Orectolobiformes) from New Caledonian waters, carried out during 2003–2005, revealed the presence of three species of adult anisakid nematodes referable to Terranova Leiper et Atkinson, 1914. However, this genus can no longer be considered valid, because its type species has been designated a species inquirenda. Therefore, the present nematodes are assigned to two newly established genera, Euterranova n. gen. [type species E. dentiduplicata n. sp.] and Neoterranova n. gen. [type species N. scoliodontis (Baylis, 1931) n. comb.], based mainly on different labial structures. Euterranova dentiduplicata n. sp. from the stomach of S. fasciatum is mainly characterized by the presence of lips with two rows of denticles. Innominate specimens of Euterranova (a female and a third-stage larva) were collected from the digestive tract of T. obesus. Specimens of N. scoliodontis were recorded from G. cuvier. The two named species are described based on light and scanning electron microscopical examinations. Neoterranova scoliodontis has previously been recorded in New Caledonian waters from the same host species. Species previously attributed to Terranova are transferred to Euterranova (5 species), Neoterranova (4 species) or considered species inquirendae (10 species). Since Pseudoterranova Mozgovoy, 1950 was found to be a nomen nudum according to the International Code of Zoological Nomenclature (ICZN), the available name of this genus is Pseudoterranova Mozgovoy, 1953. A key to Porrocaecum-like nematode genera (Porrocaecum, Pseudoterranova, Pulchrascaris, Euterranova, and Neoterranova) is provided.

Highlights

As stated by Moravec and Justine [29], the taxonomy of anisakid nematodes parasitizing elasmobranchs remains rather confused, mainly because of the inadequate descriptions of many species, and this unsatisfactory situation still exists
The only adult anisakid nematode so far reported from elasmobranchs in New Caledonian waters is Terranova scoliodontis (Baylis, 1931), found in the tiger shark Galeocerdo cuvier (Péron et Lesueur) (Carcharhinidae) [29]
Specimens used for scanning electron microscopical (SEM) examination were postfixed in 1% osmium tetroxide, dehydrated through a graded acetone series, critical-point-dried and sputtercoated with gold; they were examined using a JEOL JSM7401F scanning electron microscope at an accelerating voltage of 4 kV (GB low mode)

Summary

Introduction

As stated by Moravec and Justine [29], the taxonomy of anisakid nematodes parasitizing elasmobranchs remains rather confused, mainly because of the inadequate descriptions of many species, and this unsatisfactory situation still exists. This mainly concerns representatives of the controversial genus Terranova Leiper et Atkinson, 1914, which contains many species parasitic in elasmobranchs, teleosts, crocodilians, colubrid snakes and, previously, marine mammals The taxonomic status of Terranova is questionable and, as indicated by Gibson [14], Deardorff [11] and Bruce and Cannon [10], important interspecific morphological features, such as lip characters, spicule differences or the presence or absence of plectanes, indicate the need for a new generic conception for these species. In the same region, unidentified larvae attributed to Terranova have been reported from different species of teleosts [22, 37, 38] and, based on sequence data, some of them were later identified as Terranova pectinolabiata Shamsi, Barton et Zhu, 2019 [35] or Pulchrascaris australis Shamsi, Barton et Zhu, 2020 [36]

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