Egg capsules, eggs and embryos of the southwestern Atlantic gastropod Coronium coronatum (Gastropoda: Muricidae)

The egg capsules, eggs and embryos of the muricid gastropodCoronium coronatum are described for the first time. Capsulesare sessile, bulliform, semi-circular, with a plug in the dorsalcenter. Sutures split the capsule into two asymmetrical halves.Recently laid capsules showed the presence of 3639 (n = 2) uncleavednurse eggs with a diameter of 180–210 µm (mean= 197.4 ± 8.9). The number of early embryos was 9–11.The size of the embryos was 320 x 320 to 820–880 µm.Nine pre-hatching embryos of 3.94 mm (n = 8, SD = 0.32)were found inside the older capsule. SEM illustrations of embryosand radulae are provided. Comparison of shell and radula ofembryos with the protoconch and radulae of adults of C. coronatumrevealed that the capsule belongs to this species. (Received 18 March 2006; accepted 10 October 2006)     

Energetics of the muricid gastropod Thais (Nucella) lapillus (L.)

Multivariate analysis of the physiological energetics of Thais (Nucella) lapillus (L.) was used to predict combinations of salinity and temperature at which scope for growth and reproduction will be positive. The scope for growth correlated positively with change in energy content at 15 and 20°C. The results suggest that energetic constraints set limits to capacity adaptation at ≈ 22‰ salinity, in agreement with field observations of the species distribution limit within estuaries. The zone of resistance adaptation is limited to salinities 15‰, probably because of an inefficiency in volume regulation at lower salinities. Growth of these dogwhelks is suppressed at minimum winter (5°C) and maximum summer (20°C) temperature, largely due to suppression of feeding. Constraints imposed by physiological energetics are important for an understanding of the ecology of this species, and may explain some features of seasonal change in behaviour, e.g. aggregations for purposes of egg-laying in the winter.     

Detection of Minchinia sp., in rock oysters Saccostrea cuccullata (Born, 1778) using DNA probes

Haplosporidian parasites infect various invertebrate hosts including some commercially important shellfish. Haplosporidium nelsoni (along with Perkinsus marinus) has severely affected Eastern oyster production on the eastern seaboard of the United States and flat oyster production in Europe has been severely impacted by Bonamia ostreae. These parasites are also often present at a very low prevalence and there are a variety of morphologically similar species that can be difficult to differentiate during cytological or histological diagnosis hence the need to develop specific tests. Recently, a Minchinia sp. was described affecting rock oysters (Saccostrea cuccullata) in north Western Australia. In this study, two in situ hybridisation (ISH) assays and a PCR assay have been developed and optimised for use in investigating these parasites. The first ISH assay used a 166bp polynucleotide probe while the second used a 30bp oligonucleotide probe. The specificity of each ISH assay was assessed by applying each probe to a variety of haplosporidian (5), a paramyxian (1) or ciliophora (1) parasites. The polynucleotide probe produced strong hybridisation signals against all of the haplosporidian parasites tested (Minchinia sp., Minchinia teredinis, Bonamia roughleyi, H. nelsoni and Haplosporidium costale) while the oligonucleotide probe recognised only the Minchinia sp. Both probes failed to detect the paramyxian (Marteilia sp.) or the Rhynchodid-like ciliate. The PCR assay amplifies a 220bp region and detected Minchinia sp. DNA from 50ng of genomic DNA extracted from the tissues of infected oysters and 10fg of amplified Minchinia sp. DNA. The assay did not react to oysters infected with H. nelsoni or H. costale. The ability of the PCR and oligonucleotide ISH assay to diagnose Minchinia sp. infected oysters was compared to histological examination from a sample of 56 oysters. The PCR assay revealed 26 infections while histological examination detected 14 infections. The oligonucleotide ISH assay detected 29 infections. The oligonucleotide ISH and PCR assays were found to be significantly more sensitive than histology for detecting the parasite.     

Spore ornamentation of Minchinia occulta n. sp. (Haplosporidia) in rock oysters Saccostrea cuccullata (Born, 1778)

A Minchinia sp. (Haplosporidia: Haplosporidiidae) parasite was identified infecting rock oysters and morphologically described by Hine and Thorne (2002) using light microscopy and transmission electron microscopy (TEM). The parasite was associated with up to 80% mortality in the host species and it is suspected that the parasite would be a major impediment to the development of a tropical rock oyster aquaculture industry in northern Western Australia. However, attempts to identify the parasite following the development of a specific probe for Haplosporidium nelsoni were unsuccessful. The SSU region of the parasite's rRNA gene was later characterized in our laboratory and an in situ hybridization assay for the parasite was developed. This study names the parasite as Minchinia occulta n sp. and morphologically describes the parasite using histology, scanning electron microscopy and transmission electron microscopy. The non-spore stages were unusual in that they consisted primarily of uninucleate stages reminiscent of Bonamia spp. The parasite's spores were ovoid to circular shaped and measured 4.5 microm-5.0 microm x 3.5-4.1 microm in size. The nucleus of the sporoplasm measured 1.5-2.3 microm and was centrally located. The spores were covered in a branching network of microtubule-like structures that may degrade as the spore matures.     

Genotypic diversity and gene flow in brooding and spawning corals along the Great Barrier Reef, Australia

Marine organisms exhibit great variation in reproductive modes, larval types, and other life-history traits that may have major evolutionary consequences. We measured local and regional patterns of genetic variation in corals along Australia's Great Barrier Reef to determine the relative contributions of sexual and asexual reproduction to recruitment and to infer levels of gene flow both locally (among adjacent sites, < 5 km apart) and regionally (among reefs separated by 500-1,200 km). We selected five common brooding species (Acropora cuneata, A. palifera, Pocillopora damicornis, Seriatopora hystrix, and Stylophora pistillata) and four broadcast spawners (Acropora hyacinthus, A. cytherea, A. millepora, and A. valida), which encompassed a wide range of larval types and potential dispersal capabilities. We found substantial genotypic diversity at local scales in six of the nine species (four brooders, two spawners). For these six, each local population displayed approximately the levels of multilocus genotypic diversity (Go) expected for outcrossed sexual reproduction (mean values of Go:Ge ranged from 0.85 to 1.02), although consistent single-locus heterozygous deficits indicate that inbreeding occurs at the scale of whole reefs. The remaining three species, the brooder S. hystrix and the spawners A. valida and A. millepora displayed significantly less multilocus genotypic diversity (Go) than was expected for outcrossed sexual reproduction (Ge) within each of several sites. Acropora valida and A. millepora showed evidence of extensive localized asexual replication: (1) a small number of multilocus (clonal) genotypes were numerically dominant within some sites (Go:Ge values were as low as 0.17 and 0.20): (2) single-locus genotype frequencies were characterized by both excesses and deficits of heterozygotes (cf. Hardy-Weinberg expectations), and (3) significant linkage disequilibria occurred. For the brooding S. hystrix Go:Ge values were also low within each of four sites (x = 0.48). However, this result most likely reflects the highly restricted dispersal of gametes or larvae, because levels of genetic variation among sites within reefs were extremely high (FSR = 0.28). For all species, we detected considerable genetic subdivision among sites within each reef (high FSR-values), and we infer that larval dispersal is surprisingly limited (i.e., Nem among sites ranging from 0.6 to 3.3 migrants per generation), even in species that have relatively long planktonic durations. Nevertheless, our estimates of allelic variation among reefs (FRT) also imply that for all four broadcast spawning species and three of the brooders, larval dispersal is sufficient to maintain moderate to high levels of gene flow along the entire Great Barrier Reef (i.e., Nem among reefs ranged from 5 to 31). In contrast, widespread populations of S. hystrix and S. pistilata (the two remaining brooders) are relatively weakly connected (Nem among reefs was 1.4 and 2.5, respectively). We conclude that most recruitment by corals is very local, particularly in brooders, but that enough propagules are widely dispersed to ensure that both broadcast spawning and brooding species form vast effectively panmictic populations on the Great Barrier Reef.     

Food selection of a corallivorous butterflyfish Chaetodon austriacus in the Red Sea, with particular emphasis on size and fish symbionts of corals

The exquisite butterflyfish Chaetodon austriacus feeds mainly on Acropora , Pocillopora , Montipora and Stylophora in the northern Red Sea. Large colonies of Acropora are preferred over smaller colonies and other coral genera, whereas avoidance is indicated for corals that are occupied by certain coral-associated gobiid fishes of the genus Gobiodon . It is suggested that, apart from coral identity, colony size and potential repellent effects of particular coral symbionts are both important sources of variation in the food selectivity of corallivorous chaetodotids.     

Species delimitation of common reef corals in the genus Pocillopora using nucleotide sequence phylogenies, population genetics and symbiosis ecology

Stony corals in the genus Pocillopora are among the most common and widely distributed of Indo-Pacific corals and, as such, are often the subject of physiological and ecological research. In the far Tropical Eastern Pacific (TEP), they are major constituents of shallow coral communities, exhibiting considerable variability in colony shape and branch morphology and marked differences in response to thermal stress. Numerous intermediates occur between morphospecies that may relate to extensive hybridization. The diversity of the Pocillopora genus in the TEP was analysed genetically using nuclear ribosomal (ITS2) and mitochondrial (ORF) sequences, and population genetic markers (seven microsatellite loci). The resident dinoflagellate endosymbiont (Symbiodinium sp.) in each sample was also characterized using sequences of the internal transcribed spacer 2 (ITS2) rDNA and the noncoding region of the chloroplast psbA minicircle. From these analyses, three symbiotically distinct, reproductively isolated, nonhybridizing, evolutionarily divergent animal lineages were identified. Designated types 1, 2 and 3, these groupings were incongruent with traditional morphospecies classification. Type 1 was abundant and widespread throughout the TEP; type 2 was restricted to the Clipperton Atoll; and type 3 was found only in Panama and the Galapagos Islands. Each type harboured a different Symbiodinium'species lineage' in Clade C, and only type 1 associated with the 'stress-tolerant'Symbiodinium glynni (D1). The accurate delineation of species and implementation of a proper taxonomy may profoundly improve our assessment of Pocillopora's reproductive biology, biogeographic distributions, and resilience to climate warming, information that must be considered when planning for the conservation of reef corals.     

Genetic distinctness of three widespread and morphologically variable species of Drupella (Gastropoda,Muricidae)

Corallivorous gastropods of the genus Drupella have caused considerable damage to corals at widely separated reefs in the Indo-Pacific. Morphological variability of Drupella species within and between areas has caused taxonomic confusion. To clarify the relationships, we examined allozyme variation at 16 gene loci in samples from Western Australia, Queensland and Japan. Within sites, the species D. cornus, D. rugosa and D. fragum were distinguishable individually by each of 9 to 11 loci, with average genetic identities of about 0.25. The differences extended across sites, whereas the conspecific genetic identities over distances up to 6000 km were 0.86 to 1.00, supporting the view that there are three widespread species of Drupella. Nevertheless, there is much variation within species for allozymes, size, shape and colour.     

Symbiont footprints highlight the diversity of scleractinian‐associated Zanclea hydrozoans (Cnidaria,Hydrozoa)

Hydrozoans of the genus Zanclea have been acknowledged only recently as a fundamental component of the highly diverse fauna associated with reef‐building scleractinian corals. Although widely distributed in coral reefs and demonstrated to be important in protecting corals from predation and diseases, the biodiversity of these hydrozoans remains enigmatic due to the paucity of available morphological characters, incomplete morphological characterisations and the possible existence of cryptic species. Recently, molecular techniques have revealed the existence of multiple hidden genetic lineages not yet supported by diagnostic morphological characters. In this work, we further explore the morpho‐diversity of three genetic lineages, namely Zanclea associated with the coral genera Goniastrea (clade I), Porites (clade II) and Pavona (clade VI). Aside from providing a complete classical characterisation of the polyp and medusa stage of each clade, we searched for new potential taxonomic indicators either on symbiotic hydroids or on host corals. On the hydroids, statistical analyses on almost 7,000 nematocyst capsules revealed a significant difference in terms of nematocyst size among the three Zanclea clades investigated. On each host coral genus, we identified peculiar skeletal modifications related to the presence of Zanclea symbionts. Lastly, we discussed the potential diagnostic value of these footprints in the characterisation of Zanclea–scleractinian associations.     

Cladogenesis of the European brown hare (Lepus europaeus Pallas, 1778)

A substantial portion of today’s biodiversity is attributed to the climatic oscillations of the Pleistocene Ice Ages. Gradual but dramatic climate changes were accompanied by expansion, contraction, and isolation of populations, promoting the accumulation of genome differences and adaptations in refugial populations and resulting in allopatric differentiation in a variety of taxa. In the present study, partial mitochondrial DNA sequences of the widely distributed European brown hare (Lepus europaeus) were analyzed to test whether the species’ present genetic structure is the result of postglacial re-colonization of Europe from Asia Minor (clade A) and the Balkans (clade B) only, as suggested previously, or if additional refugia are likely. Analyses indicated the presence of an additional refugium (Italy, clade I). The genealogic network of Italian hares displayed the tree-like structure expected from refugial populations, whereas central European brown hare haplotypes revealed a clear star-phylogeny indicative of past-bottleneck population growth. This population size expansion, which was confirmed by mismatch analysis, was estimated to have occurred ∼50–55 thousand years ago (kya). The divergence of clade A* from the remaining matrilines is estimated at 239 kya, whereas the divergence of the ancestors of clades B* and I from A* occurred about 128 kya. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Egg capsules and larval development of Nassarius burchardi (Philippi, 1849) and Nassarius jonasii Dunker, 1846 and comparisons with other Nassariidae (Caenogastropoda)

Adult Nassarius burchardi and N. jonasii were maintained in a laboratory, allowed to spawn and their early life stages described. N. burchardi veligers hatched from bulliform, oval capsules and N. jonasii veligers hatched from circular capsules with axial ridges. The capsules are compared with those described for other Nassariidae. All eggs developed within the capsules and hatching occurred within six to eight days in the laboratory. The planktotrophic veligers developed in four to five weeks before settling and metamorphosing. The veligers of both species were of comparable size and morphology and spent similar times developing as other Nassarius species from temperate waters. The two species differ in protoconch microsculpture.     

Egg capsules of the dusky catshark Bythaelurus canescens (Carcharhiniformes,Scyliorhinidae) from the south‐eastern Pacific Ocean

The external morphology of the egg capsule of Bythaelurus canescens and its fixation to the substratum are described. Bythaelurus canescens egg capsules are typically vase‐shaped, dorso‐ventrally flattened, pale yellow in colour when fresh and covered by 12–15 longitudinal ridges. The anterior border of the capsule is straight, whereas the posterior border is semicircular. Two horns bearing long, coiled tendrils arise from the anterior and posterior ends of the capsule. The presence of longitudinal ridges and long coiled tendrils at both anterior and posterior ends of the capsule readily distinguish these egg capsules from those of other chondrichthyans occurring in the south‐east Pacific Ocean.     

Development of coral and zooxanthella‐specific microsatellites in three species of Pocillopora (Cnidaria,Scleractinia) from French Polynesia

Since the building of coral reefs results from the association of corals and zooxanthellae, their intracellular algal symbionts, genetic markers for both organisms are essential for studying the contribution of their respective dispersal to the resilience of endangered reef ecosystems. Very few microsatellites have been obtained in corals thus far. Here we report the successful cloning of six polymorphic microsatellites (allele number: 5–15) from Pocillopora verrucosa, P. meandrina and P. damicornis. Four of them amplified coral, and two amplified zooxanthella DNA.     

The systematics of the radula-less gastropod Clathromangelia (Caenogastropoda, Conoidea)

On the basis of foregut anatomy and embryonic/larval shell morphology, the radula-less conoidean gastropod genus Clathromangelia Monterosato, 1884 is transferred to the subfamily Daphnellinae (family Turridae). The Lower Pliocene to Recent species arc reviewed. The type species is Pleurotoma granum Philippi, 1844, Recent from Sicily. C. quadrillum Dujardin, 1837 a fossil species described from the Miocene (and ranging to the Lower Pliocene) is here considered a distinct species, with planktotrophic larval development. Clathromangelia strigillata Pallary, 1904 from the Gulf of Gabè (Tunisia) is figured and redescribed. Clathromangelia loiselieri Oberling, 1970 (lectotype here selected) is a senior synonym of C. fehrae (emend. pro C. fehri ) Aartsen & Zenetou, 1987. Three new species are described and figured from the Italian Pliocene: C. tavianii sp. n., C. elvirae sp. n. and C. marinae sp. n.     

产卵次序对山麻雀卵色、卵大小和重量的影响

产卵次序可对鸟类卵黄中的营养成分、卵壳色素以及卵壳厚度等产生影响。一些鸟类可通过产卵次序对不同卵的资源进行分配,从而实现繁殖成效的最大化。本研究对不同产卵次序下山麻雀(Passer cinnamomeus)的卵色、卵大小和卵重量进行分析,结果表明,山麻雀的卵重和卵大小随着产卵次序并无显著变化,卵色与卵的大小和重量均无显著相关性,但卵背景的色度随产卵次序有明显下降趋势,而卵斑点密度则呈相反的变化。卵背景的色度随产卵次序下降可能是山麻雀有限的色素在卵中不均匀分配的结果,而卵斑点密度的增加则可能是对后期卵壳厚度变薄的一种补偿。     

The phylogeography and connectivity of the latitudinally widespread scleractinian coral Plesiastrea versipora in the Western Pacific

Whereas terrestrial animal populations might show genetic connectivity within a continent, marine species, such as hermatypic corals, may have connectivity stretching to all corners of the planet. We quantified the genetic variability within and among populations of the widespread scleractinian coral, Plesiastrea versipora along the eastern Australian seaboard (4145 km) and the Ryukyu Archipelago (Japan, 681 km) using sequences of internal transcribed spacers (ITS1-2) from ribosomal DNA. Geographic patterns in genetic variability were deduced from a nested clade analysis (NCA) performed on a parsimony network haplotype. This analysis allowed the establishment of geographical associations in the distribution of haplotypes within the network cladogram, therefore allowing us to deduce phylogeographical patterns based under models of restricted gene flow, fragmentation and range expansion. No significant structure was found among Ryukyu Archipelago populations. The lack of an association between the positions of haplotypes in the cladogram with geographical location of these populations may be accounted for by a high level of gene flow of P. versipora within this region, probably due to the strong Kuroshio Current. In contrast, strong geographical associations were apparent among populations of P. versipora along the south-east coast of Australia. This pattern of restricted genetic connectivity among populations of P. versipora on the eastern seaboard of Australia seems to be associated with the present surface ocean current (the East Australian Current) on this side of the south-western Pacific Ocean.