A generic revision of the Dorvilleidae (Polychaeta), with six new species from the deep North Pacific

PETER A. JUMARS
The Dorvilleidae are divided into eight genera: Dorvillea, Schistomeringos (new name), Protodorvillea, Meiodorvillea (new genus), Exallopus (new genus), Ophryotrocha, Parophryotrocha , and Apophryotrocha (new genus). Periodic maxillary replacement is found to occur in a manner which makes many often cited maxillary characters taxonomically unreliable. Therefore, the pharyngeal characters of all the type-species are redescribed or newly described. The discovery of new forms and the present interpretation of hard jaw parts permit construction of a phylogenetic scheme with Dorvillea as the most primitive genus containing living species. Suggestions are given for the advantageous use of the phenomenon of maxillary replacement in autecoiogical investigation.
Evidence is presented against the cosmopolitan distribution of Schistomeringos rudolphi , a species often noted in nearshore pollution studies. Newly described species are Dorvillea batia, Schistomeringos mediofurca, Meiodorvillea apalpata, Exallopus cropion, Ophryotrocha profunda , and Apophryotrocha mutabiliseta , all from the deep North Pacific. A key to the genera is provided, as are listings of all the known species within each genus.     

The ontogeny of feeding behavior and cranial morphology in the leopard shark Triakis semifasciata (Girard 1854): A longitudinal perspective

While much is known about the ecological and functional morphology of feeding in lower vertebrates, studies of elasmobranch feeding over ontogeny are broadly lacking. In this study, the ontogeny of feeding behavior and morphology were investigated in neonatal and young-of-the-year leopard sharks Triakis semifasciata using morphometric measurements of growth and high-speed videography in a longitudinal study. Five food types were used during filming sessions to facilitate differentiation of modulation and variation over ontogeny. Functional aspects of muscle and buccal volume scaling were investigated through dissection. Growth over ontogeny was shown to influence numerous kinematic variables, while intra- and inter-individual variability was the dominant factor affecting feeding behavior. Modulation of feeding behavior based on food size and elusiveness was present for timing variables and predator motion during the strike, but not for food motion or the relative extent of buccal expansion. Allometric growth occurred in all aspects of external cranial morphology measured, resulting in a shallower head profile, anterior displacement of the mouth, and relatively larger jaw musculature over ontogeny. While the degree to which morphology constrains or enhances behavior cannot be directly quantified, variability in behavior greatly exceeds variability in morphology over early ontogeny. Maintenance of a behaviorally and morphologically versatile feeding apparatus throughout ontogeny is proposed to enhance the exploitation of resources and facilitate a diverse diet in T. semifasciata under variable environmental conditions.     

Jaw morphology and ontogeny in five species of Ophryotrocha

Detailed scanning electron microscopy of jaws within the genus Ophryotrocha (Dorvilleidae, Annelida) was performed on 871 jaw parts. The investigations resulted in new understandings of the ontogeny and jaw morphology and have systematic implications for the family. Five species in the genus (Ophryotrocha alborana, O. diadema, O. gracilis, O. hartmanni, and O. labronica pacifica) were kept in culture, and the development of the jaws was studied by sampling throughout their life history. Ophryotrocha species have mandibular plates that remain the same throughout ontogeny, whereas the posterior shafts elongate. Both mandibular plate morphology and shaft ontogeny have species‐specific distinctions. In Ophryotrocha, the maxillae can be assigned to three to four distinct types, which are replaced by moulting. The maxillary morphology and developmental stages at which moults occur are species specific, although with broad intervals. A redefinition is given for some of the basic jaw elements, and new homologies are proposed for structures that are also present across other dorvilleid taxa. J. Morphol. 2010. © 2009 Wiley‐Liss, Inc.     

Morphological and ultrastructural characterization of olfactory sensilla in Drosophila suzukii: Scanning and transmission electron microscopy

Drosophila suzukii is a serious horticultural and quarantine pest, damaging various berry crops. Although the active use of olfactory communication in D. suzukii is well-known, their olfactory sensory system has not been comprehensively reported. Therefore, the present study was carried out to understand the morphology, distribution and ultrastructure of olfactory sensilla present in the antennae and maxillary palps of D. suzukii, through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The olfactory sensilla on the antennae of D. suzukii in both sexes could be classified into three major morphological types, basiconic, trichoid and coeloconic sensilla, according to their shapes. The antennal basiconic sensilla were further divided into three subtypes and the antennal trichoid sensilla into two subtypes, respectively, according to the size of individual sensillum. In contrast to the antennal olfactory sensilla showing diverse morphology, basiconic sensilla was the only type of olfactory sensilla in the maxillary palps of D. suzukii. The basiconic sensilla in the maxillary palps could be further classified into three subtypes, based on their size. Our SEM and TEM observations indicated that multiple nanoscale pores are present on the surface of all types of olfactory sensilla in the antennae and maxillary palps, except coeloconic sensilla. The difference in the morphological types and the distribution of olfactory sensilla suggests that their olfactory functions are different between antennae and maxillary palps in D. suzukii. The results of this study provide useful information for further studies to determine the function of olfactory sensilla in D. suzukii and to understand their chemical communication system.     

Do sharks exhibit heterodonty by tooth position and over ontogeny? A comparison using elliptic Fourier analysis

Tooth morphology is often used to inform the feeding ecology of an organism as these structures are important to procure and process dietary resources. In sharks, differences in morphology may facilitate the capture and handling of prey with different physical properties. However, few studies have investigated differences in tooth morphology over ontogeny, throughout the jaws of a single species, or among species at multiple tooth positions. Bull (Carcharhinus leucas), blacktip (Carcharhinus limbatus), and bonnethead sharks (Sphyrna tiburo) are coastal predators that exhibit ontogenetic dietary shifts, but differ in their feeding ecologies. This study measured tooth morphology at six positions along the upper and lower jaws of each species using elliptic Fourier analysis to make comparisons within and among species over their ontogeny. Significant ontogenetic differences were detected at four of the six tooth positions in bull sharks, but only the posterior position on the lower jaw appeared to exhibit a functionally relevant shift in morphology. No ontogenetic changes in morphology were detected in blacktip or bonnethead sharks. Intraspecific comparisons found that most tooth positions significantly differed from one another across all species, but heterodonty was greatest in bull sharks. Additionally, interspecific comparisons found differences among all species at each tooth position except between bull and blacktip sharks at two positions. These morphological patterns within and among species may have implications for prey handling efficiency, as well as in providing insight for paleoichthyology studies and reevaluating heterodonty in sharks.     

Morphological description of the mouthparts of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae)

Scanning (SEM) and transmission (TEM) electron microscopy were used to elucidate the morphology of the rostrum, as well as the mandibular and maxillary stylets of the psyllid Diaphorina citri, vector of phloem-inhabiting bacteria associated with citrus huanglongbing (HLB) disease. D. citri has a cone-shaped rostrum that extends behind the pair of prothoracic coxae. The stylet bundle comprises a pair of mandibular (Md) and maxillary (Mx) stylets with a mean length of 513.3 μm; when retracted, their proximal portions form a loop and are stored in the crumena (Cr). Serial cross-sections of the rostrum revealed that the mandibles are always projected in front of the maxillary stylets. The two maxillary stylets form the food and salivary canals, with diameters of 0.9 μm and 0.4 μm respectively. These two canals merge at the end of the stylets forming a common duct with a length of 4.3 μm and a mean diameter of 0.9 μm. The acrostyle, a distinct anatomical structure present in the common duct of aphid maxillary stylets, was not observed by TEM in the ultrathin cross-sections of the common duct (CD) of D. citri. This study provides new information on D. citri mouthparts that may help to understand the feeding behaviour of this important vector of HLB-associated bacteria.     

Hidden in the mangrove forest: the cryptic intertidal mite Carinozetes mangrovi sp. nov. (Acari,Oribatida, Selenoribatidae)

The small archipelago of Bermuda is a geologically young landmass in the Western Atlantic Ocean and recently turned out to be inhabited by a number of intertidal oribatid mites. One newly described species, Carinozetes bermudensis, showed an unusual vast range of habitats like sandy beaches, rocky substrate and mangroves. In the present study, 13 Bermudian populations of C. bermudensis were analysed to verify species integrity of specimens from different microhabitats. A morphometric analysis of 17 continuous variables as well as a molecular genetic investigation of the mitochondrial cytochrome oxidase subunit I revealed the existence of a new species Carinozetes mangrovi sp. nov., inhabiting exclusively intertidal algae growing on mangrove roots. Although both species are morphologically nearly identical, the configuration of the genus-specific ventral carinae represents a clear diagnostic character. The high genetic divergence of approximately 12 % of the cytochrome oxidase subunit I gene sequence between C. bermudensis and C. mangrovi sp. nov. suggests that these two species diverged before the emergence of the Bermuda islands. Accordingly, both of them are older than the geologically young archipelago of Bermuda.     

Vertebrate head development: Segmentation,novelties, and homology

Vertebrate head development is a classical topic lately invigorated by methodological as well as conceptual advances. In contrast to the classical segmentalist views going back to idealistic morphology, the head is now seen not as simply an extension of the trunk, but as a structure patterned by different mechanisms and tissues. Whereas the trunk paraxial mesoderm imposes its segmental pattern on adjacent tissues such as the neural crest derivatives, in the head the neural crest cells carry pattern information needed for proper morphogenesis of mesodermal derivatives, such as the cranial muscles. Neural crest cells make connective tissue components which attach the muscle fiber to the skeletal elements. These crest cells take their origin from the same visceral arch as the muscle cells, even when the skeletal elements to which the muscle attaches are from another arch. The neural crest itself receives important patterning influences from the pharyngeal endoderm. The origin of jaws can be seen as an exaptation in which a heterotopic shift of the expression domains of regulatory genes was a necessary step that enabled this key innovation. The jaws are patterned by Dlx genes expressed in a nested pattern along the proximo-distal axis, analogous to the anterior–posterior specification governed by Hox genes. Knocking out Dlx 5 and 6 transforms the lower jaw homeotically into an upper jaw. New data indicate that both upper and lower jaw cartilages are derived from one, common anlage traditionally labelled the “mandibular” condensation, and that the “maxillary” condensation gives rise to other structures such as the trabecula. We propose that the main contribution from evolutionary developmental biology to solving homology questions lies in deepening our biological understanding of characters and character states.     

Ophryotrocha longidentata sp.n. and Dorvillea erucaeformis (Malmgren) (Polychaeta, Dorvilleidae) from the West Coast of Scandinavia

Ophryotrocha longidentata sp.n. is described from the Skagerak, West Coast of Sweden. The species lives on muddy bottoms at a depth of about 100 m. It is distinguished by having biarticulated palps and by the structure of the jaw apparatus. Dorvillea erucaeformis (Malmgren) from the West Coast of Norway is redescribed and re-established. This species was earlier considered identical with D. rubrovittata (Grube).     

Ultrastructural studies of the patterns of conidiogenesis in Dacrymyces stillatus nees: Fries (basidiomycete)

New patterns of conidial formation on basidiospores and vegetative hyphae are identified, illustrated and described. The mechanisms of conidial ontogeny so far unsatisfactorilly studied are elucidated and now better understood. Several types of conidiogenous cells are described and their ontogeny better illustrated and explained. Arthroconidia of the fungi are for the first time studied at ultrastructural level and their mode of formation and secession as well better understood. Likewise, chlamydospores of D. stillatus are for the first time investigated at ultrastructural level, what enables a better observation of their structure and morphology and as well a better understanding of their origin and various modes of formation.     

Genetic divergence and isolation by distance in the West Atlantic sea anemone Actinia bermudensis (McMurrich, 1889)

The sea anemone Actinia bermudensis [Proc. Acad. Nat. Sci. Philadelphia 41 (1889) 102] has a widespread distribution over the Western Atlantic, where it has been reported from Bermuda and Bahamas to southern Brazil. Nonetheless, reproductive features of this species, which broods asexually produced offspring, suggest that it has low dispersal capabilities. This raises a question about the specific status of the Brazilian population of A. bermudensis. The aim of this paper was to evaluate the taxonomic status of the Brazilian population, by genetically comparing it with the type locality (Bermuda) population. For this, we used allozyme electrophoresis to analyze samples from both populations. Thirteen enzyme systems (16 loci) yielded interpretable results for all populations. A high differentiation was encountered for the Western Atlantic A. bermudensis population (F_ST=0.434), partially due to the presence of a diagnostic locus (LAP) between Bermuda and Brazilian populations. This result could be taken as an indication that the Brazilian population should be elevated to a specific status. We do expect some genetic differentiation, however, between natural populations separated over wide geographic distances. Finally, since Mantel and regression analyses did not rule out the isolation by distance model, we have conservatively decided to maintain the specific status of A. bermudensis from Brazil.     

The morphology and post-hatching development of the skull of Bolitoglossa nicefori (Caudata: Plethodontidae): developmental implications of recapitulation and repatterning

The cranial morphology of the direct-developing salamander Bolitoglossa nicefori and its post-hatching development are described and compared with that of other urodeles. Four stages of cranial development are defined on the basis of conspicuous events that occur during post-hatching ontogeny. The adult skull morphology of B. nicefori is similar to that of other plethodontids; however, some regions show interspecific variation. The post-hatching ontogeny of the skull and the stage of ossification observed in the hatchlings of B. nicefori show two important ontogenetic features: (1) a mosaic of early larval, metamorphic and post-metamorphic skull features in hatchlings, and (2) absence of characteristic larval elements in skull and hyoid apparatus. The distinctive stage of ossification in the hatchlings of B. nicefori could be caused by heterochronic changes in the ossification sequence, compared to the ontogeny of metamorphic salamanders. The possible heterochronic changes and the absence of larval traits are perhaps due to ontogenetic repatterning, yet without an obvious impact on the adult skull morphology (absence of morphological novelties). This might indicate a compartmentalized development. Further studies should be performed in order to establish the possible occurrence of recapitulatory patterns or ontogenetic repatterning in the skull morphogenesis of B. nicefori during its embryonic development.     

Interaction between Foxc1 and Fgf8 during Mammalian Jaw Patterning and in the Pathogenesis of Syngnathia

Syngnathia (bony fusion of the upper and lower jaw) is a rare human congenital condition, with fewer than sixty cases reported in the literature. Syngnathia typically presents as part of a complex syndrome comprising widespread oral and maxillofacial anomalies, but it can also occur in isolation. Most cartilage, bone, and connective tissue of the head and face is derived from neural crest cells. Hence, congenital craniofacial anomalies are often attributed to defects in neural crest cell formation, survival, migration, or differentiation. The etiology and pathogenesis of syngnathia however remains unknown. Here, we report that Foxc1 null embryos display bony syngnathia together with defects in maxillary and mandibular structures, and agenesis of the temporomandibular joint (TMJ). In the absence of Foxc1, neural crest cell derived osteogenic patterning is affected, as osteoblasts develop ectopically in the maxillary prominence and fuse with the dentary bone. Furthermore, we observed that the craniofacial musculature is also perturbed in Foxc1 null mice, which highlights the complex tissue interactions required for proper jaw development. We present evidence that Foxc1 and Fgf8 genetically interact and that Fgf8 dosage is associated with variation in the syngnathic phenotype. Together our data demonstrates that Foxc1 – Fgf8 signaling regulates mammalian jaw patterning and provides a mechanistic basis for the pathogenesis of syngnathia. Furthermore, our work provides a framework for understanding jaw patterning and the etiology of other congenital craniofacial anomalies, including temporomandibular joint agenesis.     

Shape analysis of the jaws between two minnow species over ontogeny

This study compares sand shiner (Notropis stramineus ) and silverjaw (Ericymba buccata ) minnows, in terms of the morphological shape changes of the upper, lower, and pharyngeal jaws over ontogeny. These two species of minnows initially feed on midge larvae and undergo an ontogenic prey shift. The traditional morphometrics measured—total length, snout‐to‐vent length, eye diameter, premaxilla length, lower jaw length, gape—were regressed onto total length to test for allometry. Digital pictures were processed with tpsDig and further analyzed with MorphoJ utilizing a regular geometric morphometrics procedure using principle component analyses. We examined gut contents for 16 fish of each species. For the silverjaw minnows, we found all jaw variables to exhibit positive allometric growth with increasing total length, while most of the jaw variables for the sand shiner exhibited negative allometric growth with increasing total length. This correlates with an ontogenic prey shift for both species. Sand shiner minnows have been found to be more omnivorous, feeding on algae later in life, while silverjaw minnows undergo a prey shift to larger invertebrates. These species lack oral dentition causing an increased reliance on the pharyngeal apparatus. Principle component analyses revealed elongation of pharyngeal jaw elements in the silverjaw minnows and a relative shortening and bulking of pharyngeal jaws in the sand shiner minnows. The ontogenic dietary shifts observed in these two species provide possible explanation for the morphological changes over ontogeny in jaw elements, which are likely enabling these species to occupy the same habitat with little niche overlap.     

Micropropagation of calla lily (<Emphasis Type="Italic">Zantedeschia albomaculata</Emphasis>) via <Emphasis Type="Italic">in vitro</Emphasis> shoot tip proliferation

Summary A method for the micropropagation of Zantedeschia albomaculata is presented using shoot tip proliferation onto Murashige and Skoog (MS) medium supplemented with different plant growth regulator concentrations and combinations. Of the four cytokinins tested, 6-benzyladenine (BA) and thidiazuron (TDZ) were found to be more effective. An optimal concentration of BA (8.87 μM) or TDZ (4.54 μM) developed an average of 3.8 and 3.2 shoots per explant, respectively, but increasing concentrations of cytokinins often led to lower proliferation rate and stunted growth. Addition of auxins to the MS medium supplemented with 8.87 μM BA slightly enhanced multiple shoot formation in the explants. Multiplication of six cultivars of Zantedeschia genus comprising different flower types and colors were tested and achieved using only one regeneration medium (MS+8.87 μMBA+2.46 μM IBA). Different MS medium strength, air temperature (15, 20, 25, and 30°C) and light quality [fluorescent, red + blue, red and blue light provided by a LED (light-emitting diode) system] were used (without phytohormone) with the aim of stimulating in vitro shoot and root development. Half-strength MS or MS and cultures maintained at 25°C were found to be equally suitable for shoot tip culture of Z. albomaculata. Shoot elongation as well as fresh and dry weight were significantly increased when cultures were kept under red or blue light.     

Microencapsulation of Neuroblastoma Cells and Mesenchymal Stromal Cells in Collagen Microspheres: A 3D Model for Cancer Cell Niche Study

There is a growing trend for researchers to use in vitro 3D models in cancer studies, as they can better recapitulate the complex in vivo situation. And the fact that the progression and development of tumor are closely associated to its stromal microenvironment has been increasingly recognized. The establishment of such tumor supportive niche is vital in understanding tumor progress and metastasis. The mesenchymal origin of many cells residing in the cancer niche provides the rationale to include MSCs in mimicking the niche in neuroblastoma. Here we co-encapsulate and co-culture NBCs and MSCs in a 3D in vitro model and investigate the morphology, growth kinetics and matrix remodeling in the reconstituted stromal environment. Results showed that the incorporation of MSCs in the model lead to accelerated growth of cancer cells as well as recapitulation of at least partially the tumor microenvironment in vivo. The current study therefore demonstrates the feasibility for the collagen microsphere to act as a 3D in vitro cancer model for various topics in cancer studies.     

Do Changes in Morphology and Prey-Capture Movements Facilitate a Dietary Transition in Juvenile Colorado pikeminnow, Ptychocheilus lucius?

Ontogenetic diet shifts in juvenile fishes are sometimes associated with proportional changes to the feeding mechanism. In addition, many piscivorous teleosts transition from invertebrate-prey to fish-prey when the mouth attains a specific diameter. Allometric (disproportionate) growth of the jaws could accelerate a young fish’s ability to reach a critical gape diameter; alternately by opening the lower jaw to a greater degree, a fish might increase gape behaviorally. We investigated the ontogeny of feeding morphology and kinematics in an imperiled piscivore, the Colorado pikeminnow (Ptychocheilus lucius) in a size range of individuals across which a diet shift from invertebrate-prey to prey-fishes is known to occur. We predicted that: (1) the feeding apparatus of the fish would grow proportionally with the rest of the body (isometric growth), that (2) anatomical gape diameter at the known diet transition would be a similar gape diameter to that observed for other piscivorous juvenile fishes (15–20 mm) and (3) feeding kinematic variables would scale isometrically (that is, change in direct proportion to body length) as juvenile pikeminnow became larger. Furthermore, we also asked the question: if changes in feeding morphology and kinematics are present, do the changes in morphology appear to generate the observed changes in kinematics? For juvenile Colorado pikeminnow, the majority of the morphological variables associated with the skull and jaws scale isometrically (that is, proportionally), but seven of eight kinematic variables, including functional gape, scale with negative allometry (that is, they became disproportionately smaller in magnitude). In contrast with the overall trend of isometry, two key aspects of feeding morphology do change with size; the lower jaw of a young Colorado pikeminnow becomes longer (positive allometry), while the head becomes shallower (negative allometry). These findings do not support the hypothesis that morphological ontogenetic changes directly generate changes in feeding kinematics; in fact, allometric jaw growth would, a priori, be expected to generate a larger gape in older fish—which is the opposite of what was observed. We conclude that ontogenetic morphological changes produce a more streamlined cranium that may reduce drag during a rapid, anteriorly directed strike, while concomitant behavioral changes reduce the magnitude of jaw movements—behavioral changes that will facilitate a very rapid opening and closing of the jaws during the gape cycle. Thus, for juvenile pikeminnow, speed and stealth appear to be more important than mouth gape during prey capture.     

Structure and Growth Pattern of Pseudoteeth in Pelagornis mauretanicus (Aves,Odontopterygiformes, Pelagornithidae)

The extinct Odontopterygiformes are the sole birds known to possess strong and sharp bony pseudoteeth, the shape and location of which are closely mimetic of real teeth. The structure of the pseudoteeth is investigated here in a late Pliocene/early Pleistocene species, Pelagornis mauretanicus, using X-ray microtomography and thin sections. The results are interpreted with regard to the pseudotooth mode of growth, and have implications concerning aspects of Pelagornis ecology. The larger pseudoteeth are hollow and approximately cone-shaped, and the smaller ones are rostro-caudally constricted. The walls of pseudoteeth are composed of bone tissue of the fibro-lamellar type, which is intensively remodeled by Haversian substitution. The jaw bones display the same structure as the pseudoteeth, but their vascular canals are oriented parallel to the long axis of the bones, whereas they are perpendicular to this direction in the pseudoteeth. There is no hiatus or evidence of a fusion between the pseudoteeth and the jaw bones. Two possible models for pseudotooth growth are derived from the histological data. The most plausible model is that pseudotooth growth began after the completion of jaw bone growth, as a simple local protraction of periosteal osteogenic activity. Pseudotooth development thus occurred relatively late during ontogeny. The highly vascularized structure and the relative abundance of parallel-fibered bone tissue in the pseudoteeth suggest poor mechanical capabilities. The pseudoteeth were most likely covered and protected by the hardened, keratinized rhamphotheca in the adult during life. The late development of the pseudoteeth would involve a similarly late and/or partial hardening of the rhamphotheca, as displayed by extant Anseriformes, Apterygiformes and some Charadriiformes. This would add support to the hypothesis of a close phylogenetic relationship between Odontopterygiformes and Anseriformes. The late maturation of the Pelagornis feeding apparatus, and hence the delayed capability for efficient prey catching, suggests that Pelagornis was altricial.     

Patterns of growth of the mandibular corpus in spotted hyenas (Crocuta crocuta) and cougars (Puma concolor)

Differences in jaw morphology among adult carnivorans are well established, but the ontogenetic mechanisms by which these differences arise are largely unexplored. Mandibular ontogeny in Crocuta crocuta and Puma concolor is analysed biomechanically using principles of beam theory. In each species, the development of cross-sectional properties of the mandibular corpus associated with rigidity under loading follows a biphasic pattern of growth. In early postnatal growth, deposition of cortical bone appears to be constrained by the overall weaker tissue with which juvenile skeletons are constructed and by the need to volumelrically accommodate the developing teeth within their bony crypts. Thus, this stage of growth is characterized by a net periosteal deposition of bone and a swelling of the medullary cavity. In late postnatal growth, the constraints on endosteal deposition of bone are relieved as the permanent teeth erupt; thus, cortical thicknesses increase sharply by periosteal expansion as well as medullary contraction. Finally, it is noted that basic differences in jaw construction between Crocuta and Puma appear to develop prenatally as they are largely in place at birth. Hence, postnatal development enhances, but does not soley contribute to, the biomechanical differences in the jaws of these species.