Two new species of Acanthocotyle Monticelli, 1888 (Monogenea: Acanthocotylidae), parasites of two deep-sea skates (Elasmobranchii: Rajiformes) in the South-East Pacific

Luis A Ñacari,Marcelo E Oliva,Fabiola A Sepúlveda,Ruben Escribano

doi:10.1186/s13071-019-3756-5

Abstract

BackgroundParasites of deep-sea fishes from the South-East Pacific (SPO) are poorly known. Of c.1030 species of fish found in this area, 100–150 inhabit the deep-sea (deeper than 200 m). Only six articles concerning metazoan parasites of fish from deep-waters of SOP are known, and nine monogenean species have been reported. Currently, ten species are known in Acanthocotyle Monticelli, 1888 (Monogenea) and when stated, all of them are found in shallow waters (10–100 m). Acanthocotyle gurgesiella Ñacari, Sepulveda, Escribano & Oliva, 2018 is the only known species parasitizing deep-sea skates (350–450 m) in the SPO. The aim of this study was the description of two new species of Acanthocotyle from two Rajiformes.MethodsIn September 2017, we examined specimens of two species of deep-sea skates (Rajiformes), Amblyraja frerichsi (Krefft) and Bathyraja peruana McEachran & Myyake, caught at c.1500 m depth off Tocopilla, northern Chile, as a by-catch of the Patagonian tooth fish Dissostichus eleginoides Smitt fishery. Specimens of Acanthocotyle were collected from the skin of the skates. Morphometric (including multivariate analysis of proportional measurements, standardized by total length), morphological and molecular analyses (LSU rRNA and cox1 genes) were performed in order to identify the collected specimens.ResultsThe three approaches used in this study strongly suggest the presence of two new species in the genus Acanthocotyle: Acanthocotyle imo n. sp. and Acanthocotyle atacamensis n. sp. parasitizing the skin of the thickbody skate Amblyraja frerichsi and the Peruvian skate Bathyraja peruana, respectively. The main morphological differences from the closely related species Acanthocotyle verrilli Goto, 1899 include the number of radial rows of sclerites, the non-discrete vitelline follicles and the number of testes.ConclusionsThe two species of monogeneans described here are the only recorded parasites from their respective host species in the SPO. Assessing host specificity for members of Acanthocotyle requires clarifying the systematics of Rajiformes.

Highlights

Parasites of deep-sea fishes from the South-East Pacific (SPO) are poorly known
Ten valid species have been described to date: Acanthocotyle lobianchi Monticelli, 1888; A. elegans Monticelli, 1890; A. verrilli Goto, 1899; A. pacifica Bonham & Guberlet, 1938; A. pugetensis Bonham & Guberlet, 1938; A. williamsi Price, 1938; A. patagonica Kuznetsova, 1971; A. greeni Macdonald & Llewellyn, 1980; A. urolophi Kearn, Whittington, Chisholm & Evans-Gowing 2016 and A. gurgesiella Ñacari, Sepulveda, Escribano & Oliva, 2018
Traditional taxonomy based on morphology and morphometry and multivariate analyses based on morphometric data corrected for body length, strongly supports three species of Acanthocotyle detected in three different skates from SPO

Summary

Introduction

Parasites of deep-sea fishes from the South-East Pacific (SPO) are poorly known. Acanthocotyle gurgesiella Ñacari, Sepulveda, Escribano & Oliva, 2018 is the only known species parasitizing deep-sea skates (350–450 m) in the SPO. Knowledge of biodiversity in the Atacama Trench, closely associated to the high productive Humboldt Current Marine Ecosystem is limited; the assemblage of deepsea nematodes, the community of soft-shelled benthic foraminiferans and the presence of some amphipods have been described [4,5,6]. Ten valid species have been described to date: Acanthocotyle lobianchi Monticelli, 1888 (type-species); A. elegans Monticelli, 1890; A. verrilli Goto, 1899; A. pacifica Bonham & Guberlet, 1938; A. pugetensis Bonham & Guberlet, 1938; A. williamsi Price, 1938; A. patagonica Kuznetsova, 1971; A. greeni Macdonald & Llewellyn, 1980; A. urolophi Kearn, Whittington, Chisholm & Evans-Gowing 2016 and A. gurgesiella Ñacari, Sepulveda, Escribano & Oliva, 2018. Only two species, A. pacifica and A. gurgesiella were described from deep-sea skates

Objectives

Methods

Results

Discussion

Conclusion