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Despite the oligotrophic conditions of the southeastern Levantine Sea and northern Red Sea, six lobster species—five slipper lobsters (Scyllaridae) and one spiny lobster (Palinuridae)—maintain permanent, reproducing populations in the study area. Additionally, there are isolated records of four other sporadic lobster species. In the southeastern Mediterranean, permanent species include the Mediterranean slipper lobster,Scyllarides latus, small European locust lobster, Scyllarus arctus, and pygmy locust lobster, Scyllarus pygmaeus. In the northern Red Sea, they include the clamkiller slipper lobster, Scyllarides tridacnophaga, Lewinsohn locust slipper lobster, Eduarctus lewinsohni, and pronghorn spiny lobster, Panulirus penicillatus. This review synthesizes current knowledge of their biology and ecology, including distribution, habitat, reproduction and development, feeding, predators and anti-predatory adaptations, behavior, sensory modalities, environmental impacts, threats, and conservation. Recent advances focus mainly on larger, commercially valuable species (S. latus, S. tridacnophaga, P. penicillatus), while major gaps remain for oceanic post-embryonic stages and the nektonic nisto postlarva, as well as for smaller, often cryptic species (S. arctus, S. pygmaeus, E. lewinsohni). Addressing these gaps will require targeted research, using modern methodologies, in coastal, deep, and open waters, coupled with citizen-science surveys. While many Indo-Pacific decapods have been established in the Mediterranean, no immigrant lobster species have successfully colonized Levant waters, despite rare records of three non-indigenous species (NIS). However potential NIS predators and shifts in mollusk compositions, the main prey of some native lobsters, may affect the latter. Large lobsters remain targeted by fisheries despite protective regulations, which are not always effective or obeyed. No-take marine protected areas (MPAs) or nature reserves can be effective if sufficiently large and well-managed. Habitat loss from marine construction can be partly compensated by stable, environmentally safe artificial reefs tailored to lobster behavioral ecology. The categories of the studied lobsters’ species in the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, last updated over fifteen years ago, should be re-evaluated.

The slipper lobster Scyllarus arctus is an important fishery resource in Galicia (NW Iberian Peninsula), with a large reduction of its populations in recent decades in the North-east Atlantic and Mediterranean, but only limited information on its reproduction. This study provides an analysis of the reproductive potential of this scyllarid during two breeding cycles (2008 and 2009) in the NE Atlantic (43°20′N 8°50′W). We studied several reproductive traits (fecundity, brood weight, egg weight and volume) in broods with eggs both in an early and late embryonic stage, in relation to female size and temporal variations. Total output (fecundity and weight) and egg weight were closely linked to maternal size, and this relationship remained in broods with late-stage eggs. In relation to temporal variations, our data revealed an important seasonal variability in fecundity and egg weight, showing an inverse pattern in the reproductive strategy in the first two seasons of the reproductive period, with a maximum egg weight in winter (December–February) and a maximum number of eggs produced in spring (April–May). A predictive model for realized fecundity was developed: log (FE) = 0.064 + 2.907 log (length)−0.018 Month2 + 0.174 Month, which accounted for over 90% of variation in the total data.

Advanced stages of Scyllarus phyllosoma larvae were collected by demersal trawling during fishery research surveys in the western Mediterranean Sea in 2003–2005. Nucleotide sequence analysis of the mitochondrial 16S rDNA gene allowed the final-stage phyllosoma of Scyllarus arctus to be identified among these larvae. Its morphology is described and illustrated. This constitutes the second complete description of a Scyllaridae phyllosoma with its specific identity being validated by molecular techniques (the first was S. pygmaeus). These results also solved a long lasting taxonomic anomaly of several species assigned to the ancient genus Phyllosoma Leach, 1814. Detailed examination indicated that the final-stage phyllosoma of S. arctus shows closer affinities with the American scyllarid Scyllarus depressus or with the Australian Scyllarus sp. b (sensu Phillips et al., 1981) than to its sympatric species S. pygmaeus.

Phyllosoma larvae of the Palinura lack a branchial cavity and gills. In the phyllosoma, gas and ion exchanges that occur at the level of the gill in the adult must occur in other parts of the body or through the entire body. The objective of this study was to localize epithelia bordering the body of the phyllosoma larvae that had features comparable to those of the gill epithelia of adult decapods. The first phyllosoma instar of the small Mediterranean slipper lobster Scyllarus arctus was studied. First, we used a silver nitrate staining method to identify parts of the body with high ionic permeability. Confocal laser scanning microscopy with a fluorescent vital stain for mitochondria, dimethylaminostyrylmethylpyridiniumiodine (DASPMI), was then used to localize cells with a high density of mitochondria. Next, an ultrastructural study of selected epithelia was carried out. A thick (5 microns) mitochondria-rich epithelium covers the ventral side of the cephalic shield; its cells are characterized by the presence of well-developed apical infoldings adjacent to the cuticle. This part of the body has a high ionic permeability as indicated by a positive silver nitrate staining. The ventral mitochondria-rich epithelium might be involved in active ion transport. The rest of the body, particularly the dorsal side of the shield and the appendages, shows a lower ionic permeability (no positive silver nitrate staining) and is limited by a thin (1 micron) epithelium with low numbers of mitochondria. This epithelium exhibits features of a typical respiratory epithelium.

The distribution, abundance, and interannual variation of scyllarid phyllosoma larvae were studied in waters of the Balearic Sea (Western Mediterranean) from plankton samples collected between 2001 and 2005. Over the study period, 342 phyllosomas were collected, all belonging to Scyllaridae. Scyllarus arctus (Linnaeus, 1758) was the most abundant (89%), with representation of all developmental stages (I-X), except stage IX, plus two nistos. Scyllarus pygmaeus (Bate, 1888) phyllosoma included middle stages (IV-VII) and two final stages X. Finally, a stage II phyllosoma of Scyllarides latus (Latreille, 1802) was recorded for the first time in the Western Mediterranean. The majority of the phyllosomas were early stage S. arctus found in near shore stations, while advanced stages were common farther away from the coast, especially to the south of the Balearic Sea. That was also the case of S. pygmaeus, most of which stage V, observed to the southwest of the archipelago. Phyllosomas were scarce in low salinity (S<37.2) water masses of recent Atlantic origin, and interannual differences in distribution reflected the intrusions of low salinity Atlantic water from the South.

The evolutionary pathway of Palinuridae (Crustacea, Decapoda) is still controversial, uncertain and unexplored, expecially from a karyological point of view. Here we describe the South African spiny lobster Jasus lalandii karyotype: n and 2n values, heterochromatin distribution, nucleolar organizer region (NOR) location and telomeric repeat structure and location. To compare the genomic and chromosomal organization in Palinuridae we located NORs in Panulirus regius, Palinurus gilchristi and Palinurus mauritanicus: all species showed multiple NORs. In J. lalandii NORs were located on three chromosome pairs, with interindividual polymorphism. In P. regius and in the two Palinurus species NORs were located on two chromosome pairs. In the two last species 45S ribosomal gene loci were also found on B chromosomes. In addition, the nature and location of telomeric repeats were investigated by FISH in J. lalandii, P. gilchristi, P. mauritanicus Palinurus elephas, and P. regius (Palinuridae, Achelata), and in Scyllarus arctus (Scyllaridae, Achelata): all these Achelata species showed the (TTAGG)n pentameric repeats. Furthermore, in J. lalandii these repeats occurred in all the telomeres and in some interstitial chromosomal sites, associated with NORs.

Issue Title: Themed Issue: Marine, Freshwater, and Wetlands Biodiversity Conservation Biological characterisation of the Santa Clara submarine tunnel in S. Miguel Island (Azores) is made. Spatial description of the cave is provided and zonation and stratification patterns of sessile epifauna are described. Profiles were based on sketches drawn in loco. Fauna census was conducted with non-destructive techniques: in loco observations complemented by still images. The tunnel is a 14-m long lava tunnel at 14 m depth. It is obstructed in the north end where a small opening permits light penetration and some water circulation. There are two entrances, two twilight zones and one middle dark zone. The floor of the tunnel is predominantly occupied by sponges, the polychaetes Pomatoceros triqueter and the coral Caryophyllia smithii. On vertical walls there were some encrusting sponges and a few corals such as C. inornata. On the ceiling the major groups found were individuals of C. inornata and Spirobranchus polytrema. Several crustacean species (e.g. Dromia marmorea, Scyllarus arctus and Stenopus spinosus) and fishes with sciaphylic habits (e.g. Apogon imberbis, Conger conger, Phycis phycis and Gaidropsarus guttatus) were also seen.[PUBLICATION ABSTRACT]