Insight into the cryptic diversity and phylogeography of the peculiar fried egg jellyfish Phacellophora (Cnidaria, Scyphozoa, Ulmaridae)

Abstract

The fried egg jellyfish Phacellophora camtschatica (senso lato) is a morphologically peculiar and conspicuous species occurring mostly in the cold waters of the North Pacific. It is less common in the cold waters of the NW Atlantic, and occasionally has been reported in the Mediterranean, Arctic, East and South Pacific, and E, SW and NE Atlantic. However, sightings of this scyphozoan jellyfish have intensified during the past two to three decades in Macaronesia, the Iberian Peninsula and the Mediterranean. These jellyfish are known to be voracious predators of other jellies, but also of other taxa, including fish of commercial interest. Therefore, Phacellophora aggregations may threaten local fisheries, aquaculture, and local biodiversity structuring. We report the first known occurrences of Phacellophora in the Azores Islands, which apparently become more frequent in recent years of the past decade. We confirm, through DNA barcoding of COI and 16S mitochondrial markers, the genetic identity of Phacellophora occurring in the Azores (NE Atlantic). We reveal, with COI sequence data, three (potentially four) cryptic species within the Phacellophora camtschatica complex. Two Phacellophora species co-occur in the North Pacific. In the North Atlantic (and possibly in the Mediterranean) one or two distinct species exist. Three nominal species of the genus that are currently synonymized, with type localities in the N Pacific, NW Atlantic, and the Mediterranean, need reassessment. The morphotypes previously defined for the four putative species names given for Phacellophora might be eventually differentiated by the number and disposition of the marginal lappets of umbrellae. This morphologic character has to be further inspected in vouchers of the four genetic lineages of Phacellophora, to decide between the description of new species, and the resurrection of junior synonyms through the designation of neotypes with DNA Barcodes, to validate the identity of the cryptic taxa detected. More haplotype sampling is necessary across the distribution of the genus to further investigate the genetic diversity and phylogeographic history of Phacellophora. The high genetic relatedness of Phacellophora from the cold NW Atlantic and the sub-tropical shores of the Azores, revealed by 16S and COI sequence data, suggests a recent invasion, in terms of geologic time, of the temperate waters of the NE Atlantic (and possibly of the Mediterranean). The medusivorous habits of Phacellophora, and especially its predation on the mauve stinger (Pelagia spp.) which frequently blooms in Macaronesia and Mediterranean waters, could relate to the recent reports of Phacellophora in the Azores, Madeira, Canary Islands, and the Mediterranean. More investment, including on scientific staff, is necessary to catalog, DNA barcode and monitor jellyfish dynamics more accurately worldwide.

DNA Barcoding of Moon Jellyfish (Cnidaria, Scyphozoa, Ulmaridae, Aurelia): Two Cryptic Species from the Azores (NE Atlantic, Macaronesia), and Evaluation of the Non-Indigenous Species (NIS)

“…Moon jellies may sting bathers (affecting tourism), and in high aggregations, may impact local power and desalination plants, net fisheries, fish farms [58], and ultimately trophic-web dynamics (e.g., [59,60]) with potential consequences on fisheries and natural habitat structuring. Therefore, given the pervasion of cryptic species diversity within the genus Aurelia (e.g., as noted in this study) and other jellyfish (e.g., [45]), it is advisable to monitor jellyfish blooms conjunctly with DNA barcoding to ascertain the native or exotic status of species and (try) to mitigate potential economic and/or ecological negative effects, particularly in the presence of NIS. The 16S marker is of special utility to DNA barcode jellyfish and determines phylogenetic associations, being much more easily amplified and sequenced than the COI and ITS1-5.8S markers.…”

“…The correspondent PCR products were tracked using a pool of 13 bp primer tags used for demultiplexing (cf. Moura et al [45]). The DNA barcodes generated were verified and eventually corrected, using Geneious Prime ® 2021.1, as described by Moura et al [45].…”

“…Moura et al [45]). The DNA barcodes generated were verified and eventually corrected, using Geneious Prime ® 2021.1, as described by Moura et al [45]. The three Aurelia samples collected in 2021 were processed posteriorly with similar methods, except for the PCR products that were purified separately and sequenced by an external company with a Sanger sequencer.…”

“…The DNA barcoding laboratory methods applied to the 25 Aurelia samples collected in 2019 are described in Moura et al [45], with the addition of the amplification and sequencing of ca. 420 bp of the nuclear region ITS1-5.8S using the primers ITSF (TAA-CAAGGTTTCCGTAGG) and ITSR (CTCAGACAGACATGCTCC) [22].…”

“…These samples were processed conjunctly with around 1000 samples of jellies and associated taxa (cf. methods in Moura et al [45]), to sequence, in two runs with a MinION sequencer (©Oxford Nanopore Technologies), the mitochondrial markers 16S (ca. 600 bp) and COI (ca.…”