Aborjinia corallicola sp. n., a new nematode species (Nematoda: Marimermithidae) associated with the bamboo coral Acanella arbuscula (Johnson)

Rickard Westerman,Oleksandr Holovachov,Bárbara De Moura Neves,Mohammed Ahmed

doi:10.1007/s11230-021-09996-y

Rickard Westerman, Oleksandr Holovachov + Show 2 more

Open Access

https://doi.org/10.1007/s11230-021-09996-y

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Abstract

A new species of Aborjinia Özdikmen, 2010 is described from the tissues of the cold-water bamboo coral Acanella arbuscula (Johnson) from the northwest Atlantic. Aborjinia corallicolasp. n. is characterized by 18.4–33.2 mm long body in adults; outer labial and cephalic sensilla papilliform and located 14–21 µm from anterior end, amphideal aperture located 22–41 µm from anterior end, excretory pore indistinct, rectum and anal opening functional, convex-conoid tail with broadly rounded terminus, spinneret subventral. It is placed in the genus Aborjinia based on the combination of the following characters: outer labial and cephalic sensilla papilliform in shape and located in one circle, contrary to Marimermis Rutsov & Platonova, 1974 (outer labial and cephalic sensilla setiform) and Ananus Rubtsov, 1977 and Thalassonema Ward, 1933 (outer labial and cephalic sensilla in separate circles, if known). From Aborjinia eulagiscae Tchesunov & Spiridonov, 1985 the new species differs in much shorter body, much shorter tail, presence of caudal glands and spinneret in adults, different host species. Our finding represents the first report of a nematode in a parasitic relationship with a cold-water octocoral. Phylogenetic relationships between Aborjinia and other nematodes are analyzed based on 18S rDNA sequences. Summary of all presently known species and genera of the family Marimermithidae is also given.

Highlights

Marimermithidae Rubtsov & Platonova, 1974 is a small group of marine nematodes
Nematodes were found during inspection of Acanella arbuscula colonies collected mostly during multispecies trawl surveys (HiBio-B-2019-A was collected using rock dredge) conducted by the Department of Fisheries and Oceans Canada (DFO) and additional material collected by fisheries observers in commercial fishing vessels (Table 1)
Phylogenetic position of Marimermithidae: The results from the phylogenetic analysis based on 18S rRNA gene (Fig. 7) suggest that the closest relatives to the Aborjinia corallicola sp. n. are the family Leptosomatidae Filipjev, 1916

Summary

Introduction

Marimermithidae Rubtsov & Platonova, 1974 is a small group of marine nematodes. They are widespread and have been recorded in south-western Indian Ocean, north and south Atlantic and in the north and south Pacific. Forty years later, in 1974, Rubtsov and Platonova discovered and described two new genera of nematodes These new nematodes were parasites of marine invertebrates and the authors proposed a new family Marimermithidae for their finds. This new family included three genera: Thalassonema Ward, 1933, Marimermis and Trophomera and the genus Marimermis included three new species, Marimermis maritima Rubtsov & Platonova, 1974, Marimermis kergelensis Rubtsov & Platonova, 1974, and Marimermis littoralis Rubtsov & Platonova, 1974 (Rubtsov & Platonova, 1974) These new findings included six females of Marimermis maritima which were found at 10 m depth in the gravel off the coast of the Pacific side of Simushir Island, Kuril archipelago. We describe yet another marimermithid species Aborjinia corallicola sp. n. found associated with the cold-water bamboo coral Acanella arbuscula (Johnson) from the Grand Banks of Newfoundland, Labrador, and Davis Strait (Northwest Atlantic)

Materials and Methods

Findings

Discussion