Did the Indo-Pacific leptomedusa Lovenella assimilis (Browne, 1905) or Eucheilota menoni Kramp, 1959 invade northern European marine waters? Morphological and genetic approaches

Jean-Michel Brylinski,Lies Vansteenbrugge,Dorothée Vincent,Elvire Antajan,Stefan Hoffman,Luen-Luen Li,Karl Ginderdeuren

doi:10.3391/ai.2016.11.1.03

Abstract

Hydromedusae, morphologically resembling the Indo-Pacific leptomedusa Lovenella assimilis (Browne, 1905) (Cnidaria: Hydrozoa: Lovenellidae), are reported for the first time in both the eastern English Channel and the southern bight of the North Sea. Analyses of past zooplankton samples from a long-term monitoring program suggest that this non-indigenous species has been present in the eastern English Channel at least since 2007. Genetic analyses identified specimens as Eucheilota menoni based on nearly identical 18S ribosomal RNA gene, mitochondrial cytochrome oxydase subunit gene I (COI) sequences, and 16S Ribosomal RNA gene. Consequently, published morphological descriptions of L. assimilis and E. menoni were compared, and their species status is discussed with regard to morphological and genetic evidence. In conclusion we suggest synonymizing these 2 indistinguishable species.

Highlights

The Leptomedusa Lovenella assimilis (Browne, 1905) (Cnidaria: Hydrozoa: Lovenellidae) has been reported from tropical to temperate regions in Indo-Pacific waters (Kramp, 1968, cf. in Pires-Miranda et al 2013; Figure 2) such as SriLanka (Browne 1905; original description), the Bay of Bengal (Navas-Pereira and Vannucci 1991), China and Philippines (Chow and Huang 1958; Kramp 1961; Xu et al 2008), Papua New Guinea (Bouillon 1984), New Zealand (Bouillon 1995), Japan (Hirano and Yamada 1985) and Red Sea (Schmidt 1973)
We report for the first time the occurrence of medusae morphologically closely resembling Lovenella assimilis in the eastern English Channel and southern bight of the North Sea
Gonad shape, number of marginal bulbs, occurrence of cirri, number of statocysts and their concretions, and the cnidome, all studied specimens were identified as Lovenella assimilis

Summary

Introduction

The Leptomedusa Lovenella assimilis (Browne, 1905) (Cnidaria: Hydrozoa: Lovenellidae) has been reported from tropical to temperate regions in Indo-Pacific waters (Kramp, 1968, cf. in Pires-Miranda et al 2013; Figure 2) such as SriLanka (Browne 1905; original description), the Bay of Bengal (Navas-Pereira and Vannucci 1991), China and Philippines (Chow and Huang 1958; Kramp 1961; Xu et al 2008), Papua New Guinea (Bouillon 1984), New Zealand (Bouillon 1995), Japan (Hirano and Yamada 1985) and Red Sea (Schmidt 1973). Lovenella assimilis was never been reported outside the Indo-Pacific. We report for the first time the occurrence of medusae morphologically closely resembling Lovenella assimilis in the eastern English Channel and southern bight of the North Sea. Morphological and genetic analyses allowed to discuss: (i) the taxonomic, diagnostic characteristics; (ii) the validity of the taxonomic status from another lovenellid hydromedusa, Eucheilota menoni Kramp, 1959, which was already reported as an introduced species in European waters (Altuna 2009); and (iii) the correctness of available DNA sequences of both species in the online repositories

Methods

Results

Conclusion