The First Report of Pennella (Crustacea: Copepoda) Infesting Stenella coeruleoalba Stranded in Malta: Morphological and Genetic Analyses.

Here, we document the stranding of a striped dolphin Stenella coeruleoalba (Meyen, 1833) (Mammalia: Delphinidae), which was found dead in Maltese waters in July 2020. The stranded dolphin exhibited a severe infestation of the mesoparasitic copepod, Pennella balaenoptera Koren and Danielssen, 1877 (Copepoda: Pennelidae). Parasites of this genus represent the largest known mesoparasites to infest cetaceans. Under normal circumstances, cetaceans may have a few P. balaenoptera individuals attached to them, but cetaceans with compromised health are more prone to heavy infestations. The identification of the parasite was accomplished through morphological and genetic analyses. This incident highlights the significance of monitoring mesoparasitic infestations, offering valuable insights into the health of cetacean populations and emphasizing the potential implications for conservation efforts in the region.

Conservation Genetics of the Loggerhead Sea Turtle, Caretta caretta, from the Central Mediterranean: An Insight into the Species' Reproductive Behaviour in Maltese Waters.

Loggerhead sea turtle, Caretta caretta (Linnaeus, 1758), nestlings were investigated through specimens found dead either after hatching or unhatched (n = 120) from eight nests around the Maltese islands (Central Mediterranean). Molecular genetics was used to conduct maternity and paternity tests of the collected specimens utilizing expanded mitochondrial DNA sequences from the control region (858 bp) and 25 microsatellite loci (12 dinucleotide loci and 13 tetranucleotide loci). Mitochondrial data produced two haplotypes, CC-A2.1 and CC-A3.1, with the most common haplotype being present in seven nests. Microsatellite data revealed the identity of six different females that were involved in the deposition of the eggs in the eight turtle nests analysed. This confirms that two females laid multiple nests. Additionally, microsatellite data allowed for the determination of multiple paternity, with one clutch being sired by two fathers. These results are useful for monitoring the genetic diversity of loggerhead sea turtle nestlings and of the turtle mothers and fathers contributing to future turtle offspring, which rely on Maltese sandy beaches for their successful start to life. Effective conservation management benefits from merging scientific knowledge with effective measures at potential nesting sites to avoid losses of nestlings caused by human negligence.

The first complete mitochondrial genomes for Serranus papilionaceus and Serranus scriba, and their phylogenetic position within Serranidae.

BACKGROUND: Butterfly-winged comber, Serranus papilionaceus Valenciennes, 1832, was recently resurrected and so it is no longer considered as a junior synonym of the Painted comber, Serranus scriba (Linneus, 1758). This calls for a more comprehensive phylogenetic assessment using mitochondria DNA genomes to better understand the relationship and delineate these two species. METHODS AND RESULTS: Next-generation Sequencing was applied to sequence the genome of these two Serranus species. The data generated was then used to construct the mitochondrial genome of these two species. This produced the first complete mitochondrial genomes for the genus Serranus here represented by Serranus papilionaceus and Serranus scriba. These two mitochondrial genomes are 16,514 bp and 16,512 bp respectively, and both contained the typical 37 genes found in vertebrates (13 protein-coding genes, two ribosomal RNAs, 22 transfer RNAs), together with the OL and the control region. CONCLUSIONS: These mitochondrial genomes provide a new insight into the phylogenetic and evolutionary connections between the various subfamilies within Serranidae, while providing new molecular data that can be applied to discriminate between the studied species.

Characterization of the complete mitogenome of Haifa grouper, Hyporthodus haifensis (Perciformes: Serranidae), and its phylogenetic position within Epinephelini.

The complete mitochondrial genome of the Haifa grouper, Hyporthodus haifensis (Ben-Tuvia, 1953), has been obtained, through Illumina next-generation sequencing, and annotated. This mitogenome was found to be 16,525 bp long and to contain 37 genes, a control region, and the L-strand replication origin. The overall base composition of the complete mitogenome for this species was found to be 28.55% A, 28.07% C, 16.32% G, and 27.06% T. This study also looked into the mitogenome phylogenetic relationships of H. haifensis within the tribe Epinephelini and adds to the genetic resources currently available for the species.

Resurrection of the Butterfly-winged Comber, Serranus papilionaceus Valenciennes, 1832 (Teleostei, Serranidae) and its phylogenetic position within genus Serranus.

The family Serranidae is represented by 92 genera and 579 valid species, with the genus Serranus Cuvier, 1816, containing 30 species. In this study, specimens of Butterfly-winged Comber, Serranus papilionaceus Valenciennes, 1832, were collected from the Canary Islands and compared morphologically and genetically to Painted Comber, Serranus scriba (Linnaeus, 1758), from the Mediterranean Sea. Morphological differences, especially in the colour banding pattern, were corroborated by genetic differences in mitochondrial (COI and ND2) and nuclear (Rhod and PTR) markers. The mitochondrial DNA markers revealed a high level of divergence and no shared haplotypes between the two species (interspecific divergence: COI 4.31%; ND2 8.68%), and a phylogenetic analysis showed that these two species are closely related sister species sharing common ancestry. This study is therefore offering to resurrect S. papilionaceus Valenciennes, 1832 as a valid species increasing the number of eastern Atlantic Serranus species to 11. This should direct new species-specific research, including its population conservation status assessment across its distribution.

Characterization and comparison of the complete mitochondrial genomes of two stingrays, Dasyatis pastinaca and Dasyatis tortonesei (Myliobatiformes: Dasyatidae) from the Mediterranean Sea.

This work represents the complete mitochondrial genomes of two stingrays, Dasyatis pastinaca and Dasyatis tortonesei, from the Mediterranean Sea. The mitogenomes of these two species were obtained through whole generation sequencing and annotated. These mitogenomes were found to be 17,713 bp and 17,630 bp respectively and each contained 37 genes, that is 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes and two ribosomal RNA (rRNA) genes, a control region and the origin of L-strand replication (OL). All PCGs begin with the codon ATG, except for cytochrome c oxidase subunit 1 (COX1) gene, while two PCGs end with an incomplete termination codon. All tRNA genes are able to fold into their typical cloverleaf secondary structures, except for tRNA-Ser1AGY which lacks the dihydrouracil arm. The control region was 1982 bp and 1889 bp for D. pastinaca and D. tortonesei respectively. Phylogenetic analysis using Bayesian Inference confirmed the occurrence of the genus Dasyatis within the monophyletic subfamily Dasyatinae. This study adds on genetic resources available for these two stingray species.

The complete mitogenome of the Critically Endangered smalltooth sand tiger shark, Odontaspis ferox (Lamniformes: Odontaspididae).

Here, we report the first complete mitochondrial genome for the smalltooth sand tiger shark, Odontaspis ferox (Risso, 1810). The circular mitochondrial genome was found to be 16,682 bp in length and contains 37 genes, a control region and the replication origin of the L-strand (OL). The base composition of this mitogenome is 32.6% A, 23.3% C, 12.8% G, and 31.3% T. Phylogenetic analysis of Lamniformes indicates that O. ferox did not group with Carcharias taurus and so the taxonomic classification of Odontaspididae needs to be revised. This study promotes conservation genetics for this poorly studied shark species which is listed critically endangered in the Mediterranean Sea.

A molecular approach towards taxonomic identification of elasmobranch species from Maltese fisheries landings.

The mitochondrial genome, through the application of DNA barcoding, provides a powerful tool for identifying species even when specimens are either incomplete or belong to species that exhibit cryptic diversity. In fisheries management accurate identification of whole or part of the specimens landed is a fundamental requirement for the conservation of species affected directly or indirectly by the fisheries activities. In this study cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 2 (ND2) sequences were used to genetically distinguish 36 elasmobranch species collected from Maltese (Central Mediterranean) commercial fisheries landings. Each species was analysed using these two mtDNA loci where COI (610bp) and ND2 (990bp) efficiently distinguished between the various species studied, leading to the identification of 101 haplotypes, with the intraspecific p-distance ranging between 0 and 0.75% (mean 0.10%, SD ±0.13%). This study enhances the molecular data available on elasmobranchs by providing new ND2 sequences for various species, while providing both COI and ND2 data for poorly studied Mediterranean species including: the large pelagic sharks Alopias vulpinus, A. superciliosus, Carcharhinus altimus, C. plumbeus, Carcharadon carcharias, Isurus oxyrinchus, Prionace glauca and Odontaspis ferox; the smaller demersal sharks Somniosus rostratus, Squatina aculeata, S. oculata and Squalus sp.; and the endemic stingray Dasyatis tortonesei. It also confirmed the landings of species whose identification relies strongly on molecular tools, namely Squalus sp. and D. tortonesei, which are both first confirmed records amongst Maltese fisheries landings. Morphologically, the latter two species, can be easily misidentified with S. blainville and D. pastinaca respectively. Additionally, this study evaluated the genetic differences between different polychromatic forms of Raja clavata, R. radula and Dipturus oxyrinchus. Based on the currently analysed specimens, no significant genetic differences were found between the various forms and thus no further speciation within the species was identified.

Population genetics of the deep-sea bluntnose sixgill shark, Hexanchus griseus, revealing spatial genetic heterogeneity.

Hexanchus griseus is a globally distributed deep-water shark species. It inhabits tropical and temperate waters throughout the world, including the Mediterranean Sea where it is by-caught by small-scale fisheries in the region. In this study, we analysed the genetic variation of H. griseus specimens collected from different areas within and outside the Mediterranean region, to assess its genetic connectivity. The mitochondrial DNA (mtDNA) sequence analysed in this study ranged from cytochrome b to 16S rRNA genes including the control region, the 12S rRNA gene and the interspersed tRNA genes in the region, covering a total of 3731 to 3914 nucleotides. Results have shown that this species exhibits geographically distinct maternal lineages, indicating population structure along geographical ranges. These findings reveal population subdivisions not only between the Pacific Ocean and the Atlantic Ocean, but also within the oceans and on a smaller scale within the Mediterranean Sea. This highlights the need to consider each population subdivision separately when designing management plans for the conservation of this species.