Aricidea fragilis (Annelida: Paraonidae) in the Mediterranean Sea: overlooked native or alien species?

J Langeneck,C Mazziotti,B Mikac,T Scirocco,A Castelli

doi:10.1080/24750263.2018.1484185

Abstract

The paraonid polychaete Aricidea fragilis Webster, 1879, a typically west-Atlantic species, is reported from the Mediterranean Sea on the basis of several individuals, from the Adriatic and Tyrrhenian Sea. Its differences with the other Mediterranean Paraonidae, and in particular with the morphologically close Aricidea suecica meridionalis Laubier & Ramos, 1974, are briefly discussed. The possible status of A. fragilis as an alien species in European waters is analysed. The scarcity of historical records, the relatively restricted distribution, and the population dynamics observed in European waters strongly support the hypothesis of an introduction, despite the wide temporal interval between the first record of the species in the 1930s and the currently ongoing range expansion and population explosion. Here we precautionarily suggest considering A. fragilis a cryptogenic species.

Highlights

The introduction of alien species represents a major threat for natural ecosystems, and may severely affect the functioning of ecosystems as well as anthropic activities (Vilà et al 2010), producing relevant economic losses (Pimentel et al 2001)
Despite being the first species of Aricidea to have been described (Webster 1879), as well as one of the largest and most conspicuous known Paraonidae, A. fragilis is poorly known from several points of view
The pattern of notopodial lobes in the pre-branchial region, the large size, the high number of branchiae and the shape of neuropodial chaetae in the post-branchial region are consistent between the original description and the subsequent redescriptions

Summary

Introduction

The introduction of alien species represents a major threat for natural ecosystems, and may severely affect the functioning of ecosystems as well as anthropic activities (Vilà et al 2010), producing relevant economic losses (Pimentel et al 2001). For this reason, monitoring of biological invasions represents a paramount tool in environmental management, in order to plan impact reduction and, where possible, eradication strategies (Wittenberg & Cock 2001). The Mediterranean polychaete fauna is overall well known, alien polychaetes in the Mediterranean are in need of comprehensive revision, and some species should probably be considered cryptogenic, rather than truly alien

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Conclusion