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The land snail taxon Helix straminea Briganti, 1825 has been reintroduced as a valid species in 2014. We provide here a comprehensive account of its taxonomy, distribution, anatomy, phylogeny and karyology in Italy. An overview of the historical views on the validity of the species is presented and faunistic data are reviewed and implemented with new records from Campania and Basilicata. A lectotype is fixed for H. straminea from the syntypes stored in the Muséum d’Histoire Naturelle of Genève, as well as for three other taxa (Helix straminiformis Bourguignat, 1876, Helix yleobia Bourguignat, 1883 and Helix straminea ssp. elongata Bourguignat, 1860). Genital system, radula and karyotype are described for the first time. Molecular analysis of two mitochondrial genes combining GenBank data and the new sequences presented in this paper showed no differentiation between the northern and southern Italian populations. The conservation status of the species and its possible threats are discussed.

In the Mediterranean basin 23 species of cetaceans are known: 11 are regular and live, breed and feed and 12 are irregular, rare or accidental. These species are common in all the oceans of the globe (cosmopolitan species) and therefore none of them is endemic. In the inshore coastal waters of the Cilento, Vallo di Diano and Alburni National Park, five of the 23 Mediterranean species are regularly sighted; they are: one species of Mysticeti, the fin whale Balaenoptera physalus (Linnaeus, 1758) (family Balaenopteridae) and four species of Odontoceti, including the sperm whale Physeter microcephalus Linnaeus, 1758 (= P. catodon) (Family Physeteridae), the striped dolphin Stenella coeruleoalba (Meyen, 1833), the Common bottlenose dolphin Tursiops truncatus (Montagu, 1821) and the Risso’s dolphin Grampus griseus (G. Cuvier, 1812), (the last three species belonging to the family Delphinidae). A sixth species has recently been registered for the Park boundaries, the Dwarf Sperm Whale, Kogia sima (Owen, 1866), based on finding of a dead-stranded individual within the study area. Regarding the cetofauna of the coastal waters of the Gulf of Salerno, there are other two records and they are: the long-finned pilot whale Globicephala melas (Traill, 1809) and the Common Minke whale Balaenoptera acutorostrata Lacépède, 1804 (Mysticeti: Balaenopteridae). The former species is documented exclusively by bibliographical and museal data. The latter species is considered as “irregular” in Mediterranean Sea since there is no certainty that it reproduces, but it is possible that it attends this marine area for some periods of the year. This guide begins with the evolutionary history of Cetaceans. The following chapters are devoted to the general characteristics and biology of these animals, to the area of study and research methodology. It was considered interesting to include also a chapter with a brief historical overview on Cetacean researches in Campania. Then, a presentation is given for each of the species found in the Park boundaries and neighbouring, including notes on taxonomy, general description and diagnosis, notes on biology and ecology, general and local distribution, status and conservation, and some curiosities in the relationship with the man. In total the occurrence of eight species was herein documented in the survey area representing approximately the 73% of the estimated fauna of Campania Region (11 species) and about the 47% of the estimated Italian cetofauna (17 species: eight regular, four “irregular” and five occasional). The guide concludes with two chapters on recent laboratory researches on specimens from Cetofauna inhabiting coastal waters of the Cilento, Vallo di Diano and Alburni National Park. The first research concerns the preliminary results of a study on age determination of individuals stranded along the Cilento coast by counting the incremental growth lines observed in the tooth sections. The other research concerns molecular analysis to determine the origins of the stranded individuals. Cetaceans are protected at international level by CITES (Appendices I and II), by the Habitats Directive (Council Directive 92/43/EEC of 21 May 1992) on the conservation of natural habitats and of wild fauna and flora (annex II and IV), and a lot of species are mentioned on the IUCN Red List of Threatened Species. At European level some species are protected by the “Barcelona Convention” on the Protection of the Marine Environment and the Mediterranean Coast (and its new Application Protocol relative to Special Protection Zones and the Biological Diversity in the Mediterranean adopted on 1995), the “Bonn Convention” on the Conservation of Migratory Species of Wild Animals, the “Bern Convention” relative to the Conservation of European Wildlife and Natural Habitats, and by the Agreement on the Conservation of Cetaceans in the Black Sea Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS). For these reasons the Cetaceans are protected by special laws in many countries.

The knowledge of demographic traits such as longevity, growth rates and age at sexual maturity is crucial for understanding the structure of a population in its natural environment and implementing appropriate strategies for its management and conservation. Based on counts of growth layer groups in sections of decalcified teeth using the paraffin technique, we estimated the age and growth of 25 individuals of striped dolphin (Stenella coeruleoalba) found dead stranded along the coast of Campania and Calabria (south Italy, central-western Mediterranean) from 2013 to 2018. Seven individuals, with TL of 100–110 cm, were calves under 1 year old. The oldest male and female individuals were 19 and 14 years old, respectively. Growth curve estimated using the Gompertz growth model (GGM) showed that in S. coeruleoalba male growth trajectories are partly in accordance with those reported in other studies on the same species from different Mediterranean areas. The high frequency (28%) of calves strongly suggests that females of this species use the marine area all around the south-western Italian coasts to give birth to their offspring. Furthermore, a comparison with the estimated age of striped dolphins from other Mediterranean marine areas shows that the longevity of the individuals examined in this study is much lower. Our study provides information toward understanding the demographic traits of S. coeruleoalba from Mediterranean Sea. The results reported here can be useful for future research aimed at understanding population structure, mortality patterns and the effects of anthropogenic activity on the survival of this species in this marine area.

Simple Summary The Lycian salamanders of the genus Lyciasalamandra are characterized by a debated taxonomy and phylogenetic relationships. They have been the subject of various molecular and phylogenetic analyses, but their chromosomal diversity is completely unknown. We here present a comparative cytogenetic analysis on five out of the seven described species and seven subspecies of Lyciasalamandra, providing the first karyological assessment on the genus and comparing them to closely related representatives of the genus Salamandra. We analyzed the occurrence and distribution of different conserved (chromosome number and morphology) and highly variable karyological features. We found an impressive diversity in the configuration of nucleolus organizing regions (NORs), which alternatively occur either as heteromorphic or homomorphic loci on distinct regions of different chromosome pairs. We highlight that the observed peculiar taxon-specific pattern of chromosome markers supports the taxonomic validity of the different studied evolutionary lineages and is consistent with a scenario of synchronous evolution in the Lycian salamanders. Abstract We performed the first cytogenetic analysis on five out of the seven species of the genus Lyciasalamandra, including seven subspecies, and representatives of its sister genus Salamandra. All the studied species have a similar karyotype of 2n = 24, mostly composed of biarmed elements. C-bands were observed on all chromosomes, at centromeric, telomeric and interstitial position. We found a peculiar taxon-specific NOR configuration, including either heteromorphic and homomorphic NORs on distinct regions of different chromosomes. Lyciasalamandra a. antalyana and L. helverseni showed two homomorphic NORs (pairs 8 and 2, respectively), while heteromorphic NORs were found in L. billae (pairs 6, 12), L. flavimembris (pairs 2, 12), L. l. luschani (pairs 2, 12), L. l. basoglui (pairs 6, 12), L. l. finikensis (pairs 2, 6) and S. lanzai (pairs 8, 10). Homomorphic NORs with an additional supernumerary site were shown by S. s. salamandra (pairs 2, 8) and S. s. gigliolii (pairs 2, 10). This unexpected highly variable NOR configuration is probably derived from multiple independent NOR translocations and paracentric inversions and correlated to lineage divergence in Lyciasalamandra. These results support the taxonomic validity of the studied taxa and are consistent with a hypothesized scenario of synchronous evolution in the genus.

The data presented in this paper stand as supplementary information of the associated article “Karyological characterization of the common chameleon (Chamaeleo chamaeleon) provides insights on the evolution and diversification of sex chromosomes in Chamaeleonidae” [1] . This work provides (i) raw experimental data on the karyology of the common chameleon Chamaeleo chamaeleon and (ii) the results of bioinformatic analysis on sex-specific and repeated DNA sequences found in the same species. The karyological information here presented includes traditional staining method (Giemsa staining) and sequential C-banding + fluorochromes performed on Tunisian samples of the species. The sequence data include the alignments of the isolated DNA sequences with homologous sequences found in squamate Short Read Archives (SRAs) and the results of searches in public nucleic acid databases.

Information on demographic and life-history traits of endangered vertebrate species, such as sea turtles, is crucial for planning management and conservation actions. We applied skeletochronology of phalanges to estimate the age of loggerhead turtles, Caretta caretta, found dead stranded along the beaches of Campania (western Mediterranean) from 2013 to 2017. To obtain maturity data, we examined gonads from a subsample of 7 males and 11 females. Overall, curved carapace length (CCL) ranged from 5.6 to 90.8 cm, but for most turtles (89%) it was 50–79.9 cm. Predominance of stranded females (62%) was recorded. Ten out of the eighteen histologically examined gonads allowed estimating maturity. Based on the lines of arrested growth counting, the estimated age of the examined specimens ranged from 0 (hatchling) to 26 years. The modal age was 14 years for males and 17 years for females. The smallest male with spermatogenetic activity had a CCL of 65 cm and was estimated to be 16 years old. The smallest female with follicular development stage, characterising the transition towards adulthood, had a CCL of 69.5 cm and was estimated to be 20 years old. Anthropogenic factors were responsible for 36% of the mortality of individuals, followed by parasitic/infective pathologies (20%).

Sexual differentiation (SD) during development results in anatomical, metabolic, and physiological differences that involve not only the gonads, but also a variety of other biological structures, such as the brain, determining differences in morphology, behavior, and response in the breeding season. In many reptiles, whose sex is determined by egg incubation temperature, such as the leopard gecko, Eublepharis macularius, embryos incubated at different temperatures clearly differ in the volume of brain nuclei that modulate behavior. Based on the premise that "the developmental decision of gender does not flow through a single gene", we performed an analysis on E. macularius using three approaches to gain insights into the genes that may be involved in brain SD during the thermosensitive period. Using quantitative RT-PCR, we studied the expression of genes known to be involved in gonadal SD such as WNT4, SOX9, DMRT1, Erα, Erβ, GnRH, P450 aromatase, PRL, and PRL-R. Then, further genes putatively involved in sex dimorphic brain differentiation were sought by differential display (DDRT-PCR) and PCR array. Our findings indicate that embryo exposure to different sex determining temperatures induces differential expression of several genes that are involved not only in gonadal differentiation (PRL-R, Wnt4, Erα, Erβ, p450 aromatase, and DMRT1), but also in neural differentiation (TN-R, Adora2A, and ASCL1) and metabolic pathways (GP1, RPS15, and NADH12). These data suggest that the brains of SDT reptiles might be dimorphic at birth, thus behavioral experiences in postnatal development would act on a structure already committed to male or female.

The faunistic data on the recent land molluscs of Vesuvius National Park (Naples, Southern Italy) and neighbouring areas sampled during field surveys from 2005 to 2006 are reported here. The data were obtained through a careful research on museum collections and literature and were supplemented with observations from field surveys. Up to now, only 23 land snails species were known from the Vesuvius National Park through bibliographical data. The faunistic research, carried out in 25 stations of different environment typologies, allowed us to discriminate 31 species: 15 of these species are reported here for the first time for the study area. The presence of 16 species was confirmed by other field investigations. Other 19 taxa are reported in the literature, but not confirmed in our research - Helix turriculatella O. G. Costa, 1839 (obsolete nomenclature), Trochoidea trochoides Poiret, 1789, Hygromia cinctella (Draparnaud, 1801), Campylaea planospira (Lamarck, 1822), Vitrea sp. (cf. contracta (Westerlund, 1871)), Cecilioides acicula (O. F. Müller, 1774), Cochlicella acuta (O. F. Müller, 1774), Theba pisana O. F. Müller, 1774). Another 12 taxa are highly doubtful, because of possibilities for confusion with species living in other European or Italian regions, as well as previous misidentifications (Deroceras agreste (Linnaeus, 1758), Monacha gregaria (Rossmässler, 1839), Cochlicella barbara (Linnaeus, 1758), Monachoides incarnatus (O. F. Müller, 1774),Cernuella (Cernuella) cisalpina (Rossmässler, 1837), Cernuella aradasii (Pirajno, 1842), Oxychilus cellarius (O. F. Müller, 1774), O. alliarius (J. S. Miller, 1822), Zonitoides nitidus (O.F. Müller, 1774), Hyalina pseudohydatina, Ferussacia lubrica, Aegopinella nitens (Michaud, 1831); it was impossible in these cases to refer to their current specific name. Eobania vermiculata (O. F. Müller, 1774), Rumina decollata (Linnaeus, 1758), Papillifera papillaris (O. F. Müller, 1774) appear to be the most common species. Interesting are the records of Marmorana muralis (O.F. Müller, 1774), Helix cf. ligata (O.F. Müller, 1774) and Charpentiera gibbula gibbula (Rossmässler, 1836). Charpentieria gibbula honii (Tiberi, 1878) needs genetic investigations in order to confirm its taxonomic status. One allochthonous species (Paralaoma servilis (Shuttleworth, 1852)) was surveyed for the first time in the study area. A Red List of Threatened Species is proposed and the species are classified according to the IUCN criteria (Version 2019-2.1). The malacofauna of Vesuvius - Somma Mountain Complex is composed by 38 land mollusc species and represents 36.2% of the total species present in Campania (about 105 species, personal data) and 12.8% of the Italian fauna (about 530 species of land molluscs extrapolated from the list of Bank (2017). It is assumed that the poor biodiversity of the Vesuvian land malacofauna can be attributed essentially to the scarcity of calcareous substrates and the absence of permanent water sources.

Chameleons display high karyological diversity in chromosome number (from 2n = 20 to 62), morphology, heterochromatin distribution and location of specific chromosomal markers, making them unique study models in evolutionary cytogenetics. However, most available cytogenetic data are limited to the description of the chromosome number and morphology. Concerning sex chromosomes, our knowledge is limited to ZZ/ZW and Z1Z1Z2Z2/Z1Z2W systems in the genus Furcifer and the isolation of sex-linked, male-specific, sequences in Chamaeleo calyptratus, but the putative XY chromosomes have still to be identified in Chamaeleo and the conservation of male heterogamety in the genus needs confirmation from other species. In this study we performed a molecular and a cytogenetic analysis on C. chamaeleon, using standard, banding methods and molecular cytogenetics to provide a throughout karyological characterization of the species and to identify and locate the putative XY chromosomes. We confirm that the chromosome formula of the species is 2n = 24, with 12 metacentric macrochromosomes, 12 microchromosomes and NORs on the second chromosome pair. Heterochromatin was detected as weak C-bands on centromeric regions, differently from what was previously reported for C. calyptratus. Fluorescence in situ hybridization (FISH) showed the occurrence of interspersed telomeric signals on most macrochromosomes, suggesting that ancient chromosome fusions may have led to a reduction of the chromosome number. Using a combination of molecular and FISH analyses, we proved that male specific Restriction site-Associated DNA sequences (RADseq) isolated in C. calyptratus are conserved in C. chamaeleon and located the putative XY chromosomes on the second chromosome pair. We also identified different transposable elements in the focal taxa, which are highly interspersed on most chromosome pairs.

The common lizard (Zootoca vivipara) displays characteristic cytogenetic, reproductive, molecular, and biogeographic variability. This species comprises oviparous and viviparous populations with disjunct distribution and sex chromosome polymorphisms, from simple ZZ/ZW to complex Z1Z1Z2Z2/Z1Z2W systems with different morphologies of the W chromosome. In this study, we used the primers SINE A and SINE B and a newly designed primer pair to (1) obtain information on the presence and distribution of transposable elements (TEs) in 8 squamate families and (2) assess the chromosomal location of SINE Squam elements in Z. vivipara. PCR amplification with SINE A and SINE B produced single or multiple products in different Z. vivipara populations, subsequently used to design the SINE-Zv primers. Using the newly designed SINE-Zv primers, we identified 2 sequences of about 700 and 300 bp (SINE-Zv 700 and SINE-Zv 300) in all the investigated populations of Z. vivipara. Fluorescence in situ hybridizations showed a preferential localization of SINE-Zv sequences in the peritelomeric regions of almost all chromosomes, with the exception of the W. Both sequences contained a distinct segment of SINE Squam2. SINE-Zv 700 appeared to be restricted to Z. vivipara, while SINE-Zv 300 contained a partial Gypsy sequence that is highly conserved among Squamata and showed high identity values (72-93%) with several transcripts from different species. Using the same primers, we also highlighted the presence of another highly conserved Gypsy-like fragment in snakes which displayed significant similarity with the stomatin-like protein 2 of colubrids. Our results suggest that SINEs and the Gypsy-like elements are widely distributed among squamates and may have played an active role in their genomic evolution and differentiation.

The demand for caviar is growing as is its price on the market. Due to the decline of true caviar production from sturgeons, eggs from other fish species and other animals have been used as substitutes for caviar. The labels on these products should indicate the species from which the eggs were derived, but the label can be misleading in some cases. In this context, species identification using DNA analysis is crucial for traceability and authentication of caviar products. In this work, we applied the COIBar-RFLP procedure to obtain species-specific endonuclease restriction patterns useful to discriminate &ldquo, caviar&rdquo, species. The tested caviar products were identified as originating from eight species: Acipenser transmontanus, A. gueldenstaedtii, A. stellatus, A. baerii, Mallotus villosus, Huso huso, Cyclopterus lumpus and Eumicrotremus orbis. The results demonstrated that 14% of the caviar products examined have a label that does not indicate the species from which the eggs were originated. The MboI restriction enzyme produced specific profiles discriminating the eight species, confirming that the COIBar-RFLP is a useful approach for routine screening of seafood products due to its ease and rapid execution, as the results of screening can be obtained within 7 h, by-passing the need for sequencing.

Due to their particular phylogenetic position and biological characteristics, squamate reptiles and, in particular, snakes are becoming an increasingly important model for fields such as evolutionary biology, molecular ecology and adaptation. Recently, during a study to analyze the evolutionary history of European whip snakes, we found a LINE1 (L1)-like sequence (GenBank accession no. LM644476), herein called TRL1L, and while there are data on the abundance of L1 in snakes, their genomic and chromosome localization is still largely unexplored. We therefore performed a study to obtain information on TRL1L abundance, distribution and conservation in snake species, belonging to the Colubridae, Lamprophiidae and Viperidae families, using quantitative dot-blot and fluorescence in situ hybridization (FISH). TRL1L showed a high identity with homologous segments of L1s of lizards the Anolis carolinensis and Lacerta agilis and the zebrafish Danio rerio. The discovered sequences are truncated L1 elements which occur with a low copy number, about 0.1% of the genome of the species studied. This evidence suggests that L1 retroposons have a similar landscape in lizard and snake genomes, probably because similar processes limited L1 distribution in their genomes. TRL1L showed a non-random chromosome distribution pattern. It was scarcely located on autosomes and on the euchromatic W chromosome of Cerastes vipera, while mostly found on the heterochromatic W chromosome of Hierophis carbonarius and Elaphe quatuorlineata. Our data support the hypothesis that a ‘purifying selection’ against the accumulation of L1 elements takes place in recombining regions and highlight the possible role of these elements in the differentiation processes of the snake heterochromatic W chromosome. Interestingly, the preferential distribution of TRL1L on the heterochromatic W chromosomes of the studied snakes appears to be similar to that observed in mammals for L1 accumulation on differentiated Y chromosomes. This finding suggests that a convergent process may have taken place in the differentiation of vertebrate heterochromatic sex chromosomes

A cytogenetic study was carried out by means of standard and NOR-FISH staining methods on the chromosomes of four Alopiinae door snails, two species of the Delimini tribe (Siciliaria paestana and Papillifera bidens) and two species of Medorini tribe (Leucostigma candidescens and Medora sp.). The two Delimini species and Medora sp. showed similar karyotypes, concerning the number of chromosomes, 2n = 62, and the first metacentric pair of chromosomes clearly bigger than the other pairs, but differed in the number of the telocentric pairs: none in P. bidens, four in S. paestana and, even, 21 in Medora sp. Leucostigma candidescens had 2n = 48, all biarmed chromosomes. Loci of NORs were on a single medium small chromosome pair in all the four studied species. The obtained results evidence a relevant degree of intergeneric karyotypic diversity in Alopiinae, concerning both chromosome number and/or shape. The data allow us to make a hypothesis on the evolutionary chromosome trends for this door snail subfamily.

Sexual differentiation (SD) during development results in anatomical, metabolic, and physiological differences that involve not only the gonads, but also a variety of other biological structures, such as the brain, determining differences in morphology, behavior, and response in the breeding season. In many reptiles, whose sex is determined by egg incubation temperature, such as the leopard gecko, Eublepharis macularius, embryos incubated at different temperatures clearly differ in the volume of brain nuclei that modulate behavior. Based on the premise that "the developmental decision of gender does not flow through a single gene", we performed an analysis on E. macularius using three approaches to gain insights into the genes that may be involved in brain SD during the thermosensitive period. Using quantitative RT-PCR, we studied the expression of genes known to be involved in gonadal SD such as WNT4, SOX9, DMRT1, Erα, Erβ, GnRH, P450 aromatase, PRL, and PRL-R. Then, further genes putatively involved in sex dimorphic brain differentiation were sought by differential display (DDRT-PCR) and PCR array. Our findings indicate that embryo exposure to different sex determining temperatures induces differential expression of several genes that are involved not only in gonadal differentiation (PRL-R, Wnt4, Erα, Erβ, p450 aromatase, and DMRT1), but also in neural differentiation (TN-R, Adora2A, and ASCL1) and metabolic pathways (GP1, RPS15, and NADH12). These data suggest that the brains of SDT reptiles might be dimorphic at birth, thus behavioral experiences in postnatal development would act on a structure already committed to male or female.

Blindsnakes are poorly studied reptiles from the karyological point of view since chromosomal data are only known for eight out of more than 420 species. The present paper shows the results of a karyological study conducted by means of standard and banding staining (Ag-NOR-banding and C-banding plus CMA and DAPI fluorochromes) on three typhlopid species, Madatyphlops arenarius, Xerotyphlops vermicularis and the parthenogenetic blindsnake, Indotyphlops braminus . Madatyphlops arenarius has conserved the primitive snake karyotype of 2n = 36 with 16 biarmed macro- and 20 microchromosomes and NORs on a microchromosome pair. The karyotype of X . vermicularis differed in showing a reduced number of microchromosomes (16) and NORs on the long arms of the third macrochromosome pair. The parthenogenetic I . braminus exhibited a triploid karyotype of 3n = 42 with seven macro- and seven microtriplets and NORs on a microtriplet. Comparison with chromosome data from the available literature suggests that the primitive snake karyotype of 2n = 36 occurred in the common ancestor of Leptotyphlopidae + Typhlopidae and in the common ancestor of Typhlopidae. In the latter family chromosome evolution may well have proceeded towards a decrease in the chromosome number from 2n = 36, 34, 32 until it reached 2n = 28, mainly involving micro- to microchromosome and/or macrochromosome translocations. Furthermore, these chromosome rearrangements occurred independently and repeatedly in the different evolutionary lineages of this family and are partially concordant with phylogenetic relationships. Cytologically identifiable sex chromosomes were not revealed by either standard or C-banding staining.

Karyological studies continue to clarify the evolutionary history of many taxa. We report here on the first chromosome survey of the frog Pseudhymenochirus merlini (Pipidae) in comparison with the related species Hymenochirus boettgeri . In addition to the 2 n = 20 regular (A) chromosomes (eight metacentric and two subtelocentric pairs), H. boettgeri has an accessory B chromosome in about half of the scored karyotypes (2 n = 21). P. merlini showed a karyotype of 2 n = 20 chromosomes, differing from the set of A chromosomes of H . boettgeri by three inversions. Other differences are in the location of the nucleolus organizer regions (NORs), on the 10th chromosome pair in P. merlini instead of the 4th pair in H. boettgeri . Heterochromatin is less abundant in P. merlini , and localized in centromeric and telomeric regions of all chromosomes. The patterns in H. boettgeri resemble those of another pipid species, Silurana tropicalis , as to chromosome number (2 n = 20), morphology, and G-banding patterns. We propose that these characteristics are symplesiomorphic in Pipidae, allowing us to present a scenario for the chromosome evolution in this family. Our results identify a third mechanism of increase in chromosome numbers among pipid frog species, the addition of B chromosomes in Hymenochirus , besides the known processes of polyploidization in Xenopus / Silurana , and centric fission in Pipa .

The aim of this work is to investigate the sequence conservation and the evolution of repeated DNA in related species. Satellite DNA is a component of eukaryotic genomes and is made up of tandemly repeated sequences. These sequences are affected by high rates of mutation that lead to the occurrence of species-specific satellite DNAs, which are different in terms of both quantity and quality. In this work, a novel repetitive DNA family, named PjHhaI sat, is described in Pecten jacobaeus. The quantitative analyses revealed a different abundance of this element in the molluscan species investigated in agreement with the "library hypothesis" even if, in this case, at a high taxonomic level. In addition, the qualitative analysis demonstrated an astonishing sequence conservation not only among scallops but also in six other molluscan species belonging to three classes. These findings suggest that the PjHhaI sat may be considered as the most ancients of DNA described so far, which remained "frozen" during molluscan evolution. The widespread distribution of this sat DNA in molluscs as well as its long evolutionary preservation open up questions on the functional role of this element. A future challenge might be the identification of proteins or molecules which interact with the PjHhaI sat.

Within the scope of a project on the characterization of satellite DNAs in polar mollusks, the Antarctic chiton Nuttallochitonmirandus (Thiele, 1906) was analyzed. Two novel families of tandemly repeated DNAs, namely NmH and NmP, are described in their structure and chromosomal localization, and, furthermore, their presence was analyzed in related species. Data reported here display a particular variability in the structural organization of DNA satellites within this species. Processes driving satellite evolution, which are likely responsible for the intriguing variability of the identified satellite DNAs, are discussed.