Further revisions of the Sabellidae subfamilies and cladistic relationships among the Fabriciinae (Annelida: Polychaeta)

Cladistic relationships of the sabellid subfamilies Fabriciinae and Sabellinae are examined in light of recent revisions of fabriciin taxa. The potential placement of Caobangia in the Sabellinae is suggested from an initial analysis of selected fabriciin species and genera. Subsequent cladistic analyses at the family level produced over 1800 cladograms, among which Caobangia is the most plesiomorphic taxon of either the Fabriciinae or Sabellinae. Successive approximations weighting reduced this ambiguity, consistently placing Caobangia in the Sabellinae. Subfamilies are emended on the basis of these results. Cladistic relationships of fabriciin taxa, exclusive of Caobangia , display topological instability among some genera and species. Genera are, however, monophyletic in all topologies. Incorporating ontogenetic data for branching ventral filamentous appendages in Augeneriella reduces ambiguity among genera and suggests alternative transformation series for ventral filamentous appendages.     

Factors influencing latitudinal pattern of biodiversity: An example using Sabellidae (Annelida, Polychaeta)

The latitudinal gradient of biodiversity hypothesis was tested utilising the geographical distribution of species taxa belonging to the family Sabellidae (Annelida: Polychaeta), one of the polychaete families studied by only a few specialists around the world. An increase in species richness towards the Tropical region was revealed, with an asymmetric distribution between the two hemispheres. Data show that most of the species were found in Northern latitudes, producing a Northern area much richer than the Southern one. The Atlantic-Mediterranean Region was particularly rich, with the number of species close to those from the Indo-Pacific Region. Mediterranean species richness is discussed in the light of the particular history of the basin, also emphasising the importance of naturalistic studies that have made the Mediterranean marine flora and fauna one of the best known in the world. The existence of extrinsic factors that obscure the real pattern of distributions is hypothesised. Differences found between the two hemispheres could be attributed primarily to the higher number of specialists working in the Boreal Domains, including the Mediterranean area. Global trends produced by some representative genera are also discussed with respect to the distribution of the taxonomic specialists.     

Contrasting scaling of ciliary filters in swimming larvae and sessile adults of fan worms (Annelida: Polychaeta)

Abstract. Both larval and adult fan worms capture particles with opposed bands of cilia. While the larvae use one of the opposed bands (the prototroch) for both feeding and swimming, the sessile adults rely partly on ambient currents to bring food particles to the ciliary bands. The scaling of length of prototrochal cilia with larval body size contrasts with scaling of the opposed latero-frontal cilia with adult body size. In the larva of the serpulid Hydroides elegans , the length of prototrochal cilia increased from 28 to 42 μm in early to late-stage larvae. In contrast, latero-frontal cilia did not increase in length (23 μm) during postlarval development of H. elegans. Among adults of 5 fan-worm species, lengths of latero-frontal cilia ranged from 22 to 35 μm and were weakly correlated with body size. The total area of ciliary filter nevertheless increased with increasing body dry weight of worms with an allometric exponent similar to exponents reported for gill and lophophore areas vs. body weight within species of suspension-feeding bivalves, brachiopods, and gastropods. The similar scaling was remarkable given the striking differences in distribution and function of the ciliary filters. In adult fan worms, increases in filter area depended largely on increases in number and length of radioles; differences in branching of radioles had little effect. Radioles were commonly in 2 or more rows in series, implying refiltration in still water by downstream radioles. Since the allometry of worms' filter area with body size depends on filters in series, it depends on ambient currents that overwhelm ciliary currents.     

Parasabella Bush, 1905, replacement name for the polychaete genus Demonax Kinberg, 1867 (Annelida, Polychaeta, Sabellidae)

Parasabella Bush, 1905 is reintroduced as a replacement name for Demonax Kinberg, 1867 (Annelida: Polychaeta: Sabellidae) which is a junior homonym of Demonax Thomson, 1860 (Insecta: Coleoptera: Cerambycidae).     

Redescription of Fabriciola tonerella Banse, 1959, and a new record of Novafabricia infratorquata (Fitzhugh, 1983) from the Mediterranean Sea, with a key for the Fabriciinae (Annelida: Polychaeta) of the Mediterranean Sea and the north-east Atlantic

The fabriciin sabellid species Fabriciola tonerella Banse, 1959 living on gastropod shells inhabited by hermit crabs collected in the western Mediterranean Sea is redescribed. Another species of Fabriciinae, Novafabricia infratorquata (Fitzhugh, 1983), is recorded for the first time from the Mediterranean Sea and found in the same habitat is described as well. The variability of characters depending on size and geographical distribution is given for both species. Moreover, selected characters for all known species of Fabriciola and Novafabricia as well as a simple key for all Fabriciinae of the Mediterranean Sea and the north-east Atlantic are provided.     

The influence of salinity on fertilization and larval development of Nereis virens (Polychaeta, Nereidae) from the White Sea

Effect of salinity on fertilization and early development of the polychaeta Nereis virens (Sars) from the White Sea was examined in laboratory experiments. The comparison of salinity resistance of different developmental stages of N. virens showed gradual increase of euryhalinity during ontogenesis—from fertilized eggs to juveniles.Successful fertilization and effective development (≥70-75%) was possible in narrow salinity range 22-34‰. The salinity range of successful development for trochophore and nectochaete larvae reached 14-45‰. This increase of the limits of salinity tolerance in trochophore and nectochaete larvae probably was due to the formation of protonephridium system.Rate of metamorphosis of N. virens was tested under temperature 5, 10, 17 and 23 °C and salinity 22-14‰. The highest rate of metamorphosis was marked at the temperature of 23 °C in salinities higher than 14‰.Our data confirms that N. virens originates from warm seas with oceanic salinity.     

Evidence of regenerative ability in Myxicola infundibulum (Annelida,Sabellida): evolutionary and systematic implications

Members of only a few species of annelids are reported as being incapable of regeneration; of these, Myxicola infundibulum is the only example in the family Sabellidae. Interestingly, its congener Myxicola aesthetica exhibits noteworthy regenerative ability. Unambiguously identifying non‐regenerating species is critical to reconstructing how regenerative abilities evolved within the phylum. However, studies designed specifically to assess the regenerative potential of M. infundibulum have never been performed. In this study, we aimed to confirm the lack of regeneration ability of M. infundibulum, reported previously for Atlantic specimens, or to determine the extent to which regeneration occurs. Our results showed that individuals from the Mediterranean Sea (Adriatic Sea) do undergo regeneration of lost body parts, although to a lesser extent than do other sabellids. Therefore, M. infundibulum should no longer be considered a non‐regenerating species. At present, uncertainties regarding phylogenetic relationships of Sabellidae prevent inferences about the polarity of change in M. infundibulum. Since our findings are counter to those of previous studies which describe Atlantic specimens as non‐regenerating, more extensive analysis is required to ascertain if they could actually belong to a different species than Mediterranean M. infundibulum, accounting for these differences in reported regenerative capacity.     

Morphological comparison of the regeneration process in Sabella spallanzanii and Branchiomma luctuosum (Annelida,Sabellida)

Within Annelida, the family Sabellidae is a particularly interesting clade in which to carry out comparative studies of regeneration, as its members vary in regeneration potential, with some even lacking this ability completely. However, data on the regenerative potential of sabellids are available only for a few species investigated early in the last century, and even for those, many aspects of regenerative ability are yet to be determined. In the present study, we compared the morphology of the regeneration process of anterior and posterior ends in Sabella spallanzanii and Branchiomma luctuosum, two sabellids that belong to closely related genera. Members of S. spallanzanii exhibited lower mortality in response to wounding and greater regenerative ability, with amputees able to complete the regeneration process more rapidly than in B. luctuosum. Moreover, results from this study suggest that adults of S. spallanzanii and B. luctuosum use different mechanisms to restore lost anterior body parts. In S. spallanzanii, both morphallaxis and epimorphosis appear to be important in anterior end regeneration, but in B. luctuosum, only epimorphosis appears to be important. Such variation among closely related taxa sharing similar body plans has rarely been reported, but might be profitably examined using molecular approaches in these and other species of sabellids. Results of such studies interpreted in the context of phylogeny may ultimately provide insight into the evolution of regeneration.     

The development of the serpulid Pomatoleios kraussii (Annelida, Polychaeta)

The development of Pomatoleios kraussii is extremely similar to that of Pomatoceros triqueter , and is completed under laboratory conditions in 1–3 weeks at 25–27°C. Mature larvae settle and metamorphose preferentially on the shells of adult conspecifics.     

Giant pelagic larvae of Phyllodocidae (Polychaeta,Annelida)

The microscopic anatomy of giant pelagic larvae of Phyllodocidae was studied using routine histological, SEM, and TEM techniques. The larvae consist of two distinct regions: a large spherical trochophore measuring up to 2 mm in diameter and a posterior, long (up to 10 mm length), narrow rudiment of the adult body with up to 120 segments. The larvae have an unusual mixture of larval and adult features, including a very complex, well-developed brain and ganglia in the ventral nerve cord, and only a single pair of protonephridia located in the hyposphere of the trochophore. A muscular pharynx is not developed. The intestinal wall, especially in the trochophore region, consists of endodermal cells containing considerable nutritive material in the form of yolk-like globular inclusions. The digestive tract of all larvae was empty. The position of the frontal sensory organ and the prototroch, the structure of the parapodia and setae, and the three pairs of tentacular cirri dictate inclusion of the larvae in the family Phyllodocidae. The relatively enormous size and unusual pattern of development of the adult body may be adaptations for a long pelagic life and rapid settlement of the species, which inhabits slopes of islands and underwater mounts located far apart. J. Morphol. 238:93–107, 1998. © 1998 Wiley-Liss, Inc.     

Phylogenetic affinities of the Flabelligeridae (Annelida, Polychaeta)

Cirratuliformia includes Acrocirridae, Cirratulidae, Ctenodrilidae, Flabelligeridae, Flotidae and Sternaspidae. The phylogenetic affinities have not been settled due to a limited availability of type or non-type material and the relationship between acrocirrids and flabelligerids have been problematical. In our study, the type material of all type species for all flabelligerid, and most acrocirrid genera have been studied and the morphological features have been used in a phylogenetic analysis. The results indicate that Acrocirridae, Ctenodrilidae, Fauveliopsidae, Flabelligeridae and Flotidae are monophyletic and that Sternaspidae falls within Cirratulidae; however, the latter conclusion might be reversed through increased taxon-sampling. The flabelligerid genera Brada, Flabelligera, Pherusa and Stylarioides each consists of several monophyletic groups and may be split. Conversely, Bradiella includes Diversibranchius, and the pelagic Buskiella includes Flota. The generic affinities of Poeobius remain uncertain, collecting better materials may resolve this issue.     

Male reproductive traits, semen cryopreservation, and heterologous in vitro fertilization in the bobcat (Lynx rufus)

There is limited information on bobcat ejaculate traits and sperm cryopreservation and fertilizing ability. Bobcats were electroejaculated under general anesthesia in November (autumn) and April (spring), and endocrine and sperm traits were characterized. Testosterone (mean ± SEM: 0.90 ± 0.15 ng/mL) was not different between sampling times, but cortisol (average: 13.95 ± 1.73 μg/dL) was significantly higher in April. Average number of spermatozoa was 10.0 ± 3.4 × 10⁶ sperm/ejaculate, with values being significantly higher in April. Sperm motility (average 55.7 ± 5.8% motile sperm) was not different between sampling times. The proportion of normal spermatozoa in the ejaculate (average: 14.7 ± 2.1%) was significantly higher in April, but the percentage of spermatozoa with intact acrosomes (average: 43.7 ± 3.8%) was significantly higher in autumn. Spermatozoa were cryopreserved in a Tes-Tris-based diluent (TEST) or Biladyl, both containing 20% egg yolk and 4% glycerol. Diluted sperm were loaded into straws, refrigerated using a programmable thermoblock with a dry chamber, frozen in nitrogen vapors, thawed, and incubated in F-10 medium with 5% fetal bovine serum for up to 3 h. After cryopreservation in TEST, there were about 50% motile sperm upon thawing, and survival was high during incubation post-thaw. Cryopreservation in Biladyl led to similar results, but motility decreased substantially during incubation post-thaw. Bobcat spermatozoa fertilized domestic cat oocytes matured in vitro. Fertilization rates were higher for sperm collected in April and cryopreserved in TEST (46%) than for those cryopreserved using Biladyl (<3%). Fertilized oocytes cleaved in culture, and some (27%) reached the morula stage. This study has allowed us to gain further baseline information on bobcat reproduction, explore sperm cryopreservation conditions, and show that fertilizing capacity can be tested using in vitro-matured cat oocytes. These results will be important for future conservation efforts.     

Comparative internal structure of dorsal lips and radiolar appendages in sabellidae (Polychaeta) and phylogenetic implications

Fan worms (Sabellidae) possess paired modified prostomial structures at the base of the radiolar crown, dorso‐lateral to the mouth, called dorsal lips. The dorsal lips are involved in the sorting of particles collected by the radiolar crown. The range of variation in the morphology of dorsal lips is extensive, and probably this is not only due to adaptations to different environments and feeding preferences but also due to phylogenetic constraints. In this study, we describe and compare the morphology of dorsal lips in a range of sabellid taxa based on histological cross‐sections of these structures, and compare our data and terminology with those of previous studies. Dorsal lips are maintained erect in most taxa by a modified radiole fused to them known as dorsal radiolar appendage. We suggest that dorsal radiolar appendages with an internal supporting axis (cellular or acellular) and probably also the ventral lips are synapomorphies of the family. J. Morphol., 2011. © 2010 Wiley‐Liss, Inc.     

Clonal domains in postlarval Platynereis dumerilii (Annelida: Polychaeta)

Following an enzymatic procedure for softening the egg envelope, blastomeres in the embryo of the polychaete Platynereis dumerilii were injected with TRITC-dextran. Injection was successful in the following blastomeres: AB, CD, A, B, C, D, 1a-1d, 1A-1D, 4d, and 4d(1). The distribution of fluorescent label was recorded by confocal laser scanning microscopy of young, three-segmented worms after 3 or 4 days of development, in some cases also in 1-day-old trochophore larvae. Results were documented by single optical sections, by stacking a limited number or a complete set of optical sections, and by computer-generated surface views of both the labeled tissue domains and the body contours from complete image stacks of whole worms. With respect to their descent from the embryonic cell pattern, five major compartments can be distinguished which together compose the body of the young worm: 1) The epispheric, epidermal, and neural region of the head, composed of four domains arranged as quasi-radial sectors derived from micromeres 1a, 1b (left and right ventral), and 1c and 1d (right and left dorsal). 2) A posttrochal epidermal region of the head originating from micromeres 2a(1)-2c(1) and constituting the ventral and lateral posttrochal epidermis of the head. 3) A stomodeal-ectomesodermal region of the head, including the stomodeum (micromeres 2a(2) and 2c(2)), its mesodermal envelope, and head mesoderm (micromeres 3a-3d). 4) A solid cone composed of the four terminal macromeres 4A-4D, forming the core of the trunk as the endoderm anlage. 5) An epidermal and mesodermal coating of the trunk originating from the dorsal micromeres 2d and 4d. The region of the so-called (first, anterior) peristomial cirri at the posterior flanks of the head is also composed of 2d- and 4d-derived trunk tissue, thus corroborating the postulated descent of this region and its appendages from a cephalized anteriormost trunk segment and its parapodia. The cell-lineage domains of the first and third micromere tiers are arranged left or right of the sagittal plane, while two micromeres of the second quartet are in a lateral and, initially, two in a median position (2b ventral and 2d dorsal). The offspring of micromere 2d expand from a dorsal position toward the ventral midline and those of cell 4d from a posterior-dorsal site toward the anterior, initially forming two lateral bands. In the epispheric part of the head, part of the neurectodermal tissue derived from micromeres 1a and 1b interweaves in a medio-sagittal bar, and part of the first micromere offspring of all four quadrants (1a-1d) combine in forming a central brain neuropil. Each of the latter sends neurites through both of the circumesophageal connectives. Paired muscle tracts extend through the head toward the base of the antennae and are probably derived from micromeres 3a and 3b. A mesodermal envelope of the stomodeum is probably built by the 3c and 3d micromeres. The formation of symmetry and the nature of the body axes in the embryo and adult of Platynereis dumerilii are discussed. J. Morphol.     

Morphological variation in Polydora ciliata complex (Polychaeta: Annelida)

Intraspecific variation in Polydora ciliata (Johnston) was assessed on the basis of evidence from morphological characters, which were studied by scanning electron microscopy. Differences were observed between populations of P. ciliata with respect to the setae of the fifth modified segment and in the caruncle. Two other species, namely P. ligni Webster and P. limicola (Annenkova), were also studied in order to assess interspecific variation. The two forms of P. ciliata , that is boring and non-boring, were found to be different morphologically.     

Ultrastructure and mineral composition of serpulid tubes (Polychaeta,Annelida)

We have studied the tube ultrastructure of 44 recent species from 36 serpulid genera. Twelve distinct ultrastructures are identified. Serpulids possess very diverse tube ultrastructures, in contrast with the traditional point of view. Most species show single‐layered tubes, but 34% of these species have between two and four ultrastructurally different layers. Tubes are mostly bimineralic, and are composed of aragonite and calcite; however, one of the polymorphs is always dominant. All the studied single‐layered tubes with a lamello fibrillar tube ultrastructure are exclusively calcitic; prismatic structures, both in regular or irregular orientation, are either calcitic or aragonitic in composition. There is no correlation between tube mineralogy, and ultrastructure, and marine, brackish, and freshwater environments. We find that 47% of the serpulid species studied possess a unique combination of tube structure characters. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 633–650.     

The effects of salinity,temperature and mercury on mortality of the trocophore larvae of Serpula vermicularis L. (Annelida: Polychaeta)

Using response surface methods 4-day old larvae of Serpula vermicularis L. were shown to be more euryplastic with respect to salinity and temperature than were gastrulae and 1-day old larvae. Significant interaction was found between the effects of temperature and reduced salinity on mortality of the larvae at each age tested. Four-day old trocophore larvae were more resistant to reduced salinity at low temperatures than were gastrulae and 1-day old larvae. The change in tolerance with age was in resistance rather than capacity adaptation and, since the larvae were acclimated at 16 °C, this change was genetic.Mercuric ions did not show synergistic effects with reduced salinity but merely acted additively. The concentrations of mercury found to be toxic were much higher than those that are likely to be found in coastal waters where S. vermicularis occurs.