Molecular Insights Into the Ctenophore Genus Beroe in Europe: New Species, Spreading Invaders

Abstract

The genus Beroe Browne, 1756 (Ctenophora, Beroidae) occurs worldwide, with 25 currently-described species. Because the genus is poorly studied, the definitive number of species is uncertain. Recently, a possible new Beroe species was suggested based on internal transcribed spacer 1 (ITS1) sequences from samples collected in Svalbard, Norway. Another species, Beroe ovata, was introduced to Europe from North America, initially in the Black Sea and subsequently (and possibly secondarily) into the Mediterranean and Baltic Seas. In areas where ctenophores have been introduced, they have often had significant detrimental ecological effects. The potential for other cryptic and/or undescribed Beroe species and history of spread of some species in the genus give reason for additional study. When alive, morphological hallmarks may be challenging to spot and photograph owing to the animals' transparency and near-constant motion. We sampled and analyzed 109 putative Beroe specimens from Europe, using morphological and molecular approaches. DNA analyses were conducted using cytochrome oxidase 1 and internal transcribed spacer sequences and, together with published sequences from GenBank, phylogenetic relationships of the genus were explored. Our study suggests the presence of at least 5 genetic lineages of Beroe in Europe, of which 3 could be assigned to known species: Beroe gracilis Künne 1939; Beroe cucumis Fabricius, 1780; and Beroe ovata sensu Mayer, 1912. The other 2 lineages (here provisionally named Beroe "norvegica" and Beroe "anatoliensis") did not clearly coincide with any known species and might therefore reflect new species, but confirmation of this requires further study.

Comparative neuroanatomy of ctenophores: Neural and muscular systems in Euplokamis dunlapae and related species

“…In contrast to Euplokamis , other species from this study are representatives of quite derived ctenophore lineages (Dunn, ; Dunn, Leys, & Haddock, ; Johansson et al, ; Moroz et al, ; Whelan et al, ). Recent phylogenomic reconstructions, using transcriptomes of 37 ctenophore species, proposed that about 380–260 million years ago Ctenophora might undergo a substantial evolutionary bottleneck (Whelan et al, ) with the extinction of several early groups followed by adaptive radiation leading to extant lineages.…”

Toward a global reference database of COI barcodes for marine zooplankton

“…The most frequently-used gene region for species-level identification of marine zooplankton is a ~570 bp region of mitochondrial cytochrome oxidase I (COI; Hebert et al 2003;Bucklin et al 2011). Other gene regions used for species identification include the mitochondrial 16S ribosomal RNA (rRNA) gene, which is widely used for Cnidaria (Lindsay et al 2015) and Copepoda (Bucklin et al 1992;Lindeque et al 1999;Goetze 2010), and a portion of the nuclear Internal Transcribed Spacer (ITS) region, which has been used for Ctenophora (Johansson et al 2018).…”

“…While a few recent papers successfully used COI for delimitation of species in the benthic ctenophore family Coeloplaniidae (Alamaru et al 2017) and the genus Beroe (Johansson et al 2018), obtaining COI sequences has been challenging for many species, with standard primers failing to amplify COI sequences due to high intraspecific nucleotide diversity (Schultz et al 2020). Lack of sequenced mitochondrial genomes has complicated PCR primer design for ctenophores (Wang and Cheng 2019).…”

Pelagic deep-sea fauna observed on video transects in the southern Norwegian Sea

“…The habitus of the others points towards the unresolved species complex Beroe cf. cucumis (Bayha et al 2004;Mills and Haddock 2007;Johansson et al 2018), suggesting the presence of at least two species of Beroe in the study area. The lobate ctenophore Bolinopsis (Bolinopsis sp.…”