Trophic ecology of the dusky catshark Bythaelurus canescens (Günther, 1878) (Chondrychthyes: Scyliorhinidae) in the southeast Pacific Ocean

Feeding and stable isotope analyses for Bythaelurus canescens individuals were conducted to describe the diet of B. canescens as well as infer their potential prey species in the community. Stomach content analysis and mixing models by ratio isotopes composition were used to infer the food habits and calculate the trophic level of the dusky catshark, B. canescens. The results showed siphonophores and cephalopods as the most important food in the diet (67.9 and 20.2%, respectively). Calculated trophic level was 3.9, indicating that B. canescens is a meso‐predator in the upper continental slope communities off Chile. By mixing models based on isotope data it can be inferred that the probabilities of the consumption cephalopods and siphonophores would be 36.7 and 15.2%, respectively.     

Long-term effects of prey-availability, partnering and temperature on overall egg capsule output of 'New Zealand flatworms', Arthurdendyus triangulates

Arthurdendyus triangulatus is an invasive terrestrial flatworm that preys on earthworms. To assess A. triangulatus egg capsule production, flatworms were maintained in ventilated polypropylene tubs (7.5 L) kept in controlled environment (CE) chambers or outdoors in the ground. Controlled environment chambers were maintained at 8°C or 14°C, flatworms kept singly or paired within tubs and offered Eisenia fetida according to a weight equalling one‐eighth or one‐half of the mean flatworm weight, or left unfed. The tubs were a successful method for keeping flatworms, with some surviving for over one year. The greatest number of egg capsules produced by an individual A. triangulatus was nine over a 16 week period for a flatworm kept at 14°C and fed at the one‐half regime (0.56 egg capsules flatworm^‐1 week^‐1). Although the effects of treatments varied with CE chambers, there was some evidence from flatworms kept outdoors, that feeding affected egg capsule output, with those flatworms fed at the one‐half regime tending to produce more egg capsules (P= 0.057). Flatworms at the one‐eighth regime or that were unfed produced progressively lighter egg capsules and substantially declined in weight themselves. Nevertheless, even unfed flatworms continued to produce egg capsules for 18 weeks. The lightest egg capsule weighed 8 mg, whilst the heaviest was 180 mg. In the CE chambers at 14°C, there was evidence for two different reproductive/survival strategies. Some flatworms produced cumulatively more egg capsules the longer they survived, whereas others lived longer but produced fewer egg capsules. Flatworms kept without a partner still produced egg capsules up to 35 weeks later. Egg capsules contained a mean of 4.14 (CE chambers) or 4.62 (outdoors) juveniles, with a maximum of 11. Overall, juveniles were 45% of the weight of egg capsules, although larger egg capsules had more juveniles, which comprised a greater proportion of the egg capsule. The conversion of earthworm prey to egg capsule production was estimated at 13%.     

Three new genera of nematodes (Strongyloidea: Cloacininae) from the redlegged pademelon,Thylogale stigmatica Gould (Marsupialia: Macropodidae) from eastern Australia

Summary Cassunema exigua n.g., n.sp., Monilonema lacunosa n.g., n.sp. and Foliostoma macropodis n.g., n.sp. are described from the stomach of the redlegged pademelon, Thylogale stigmatica Gould, 1860 (Marsupialia: Macropodidae), from north Queensland, Australia. All three genera belong to the subfamily Cloacininae Stossich, 1899 and to the tribe Macropostrongylinea Lichtenfels, 1980. The genus Cassunema is characterized by a poorly sclerotized buccal capsule with longitudinal ridges formed by the lining of the anterior part of the capsule. The genus Monilonema is characterized by a leaf-crown like flange at the mouth opening, a bulbous cervical collar, and paired dorsal and ventral tubular structures running internally and posteriorly from the collar. The genus Foliostoma is characterized by a leaf crown of tiny elements at the mouth opening, and oesophagus with short narrow anterior part, wide posterior part, bulb narrower than corpus and a heavily sclerotized ring between buccal capsule and oesophagus. A revised definition of the tribe Macropostrongylinea is given together with a key to the genera. ac]19810101     

Distinct Ca2+ channels maintain a high motility state of the sperm that may be needed for penetration of egg jelly of the newt,Cynops pyrrhogaster

Activation state of sperm motility named “hyperactivation” enables mammalian sperm to progress through the oviductal matrix, although a similar state of sperm motility is unknown in non‐mammalian vertebrates at fertilization. Here, we found a high motility state of the sperm in the newt Cynops pyrrhogaster. It was predominantly caused in egg jelly extract (JE) and characterized by a high wave velocity of the undulating membrane (UM) that was significantly higher at the posterior midpiece. An insemination assay suggested that the high motility state might be needed for sperm to penetrate the egg jelly, which is the accumulated oviductal matrix. Specific characteristics of the high motility state were completely abrogated by a high concentration of verapamil, which blocks the L‐type and T‐type voltage‐dependent Ca²⁺ channels (VDCCs). Mibefradil, a dominant blocker of T‐type VDCCs, suppressed the wave of the UM at the posterior midpiece with separate wave propagation from both the anterior midpiece and the posterior principal piece. In addition, nitrendipine, a dominant L‐type VDCC blocker, weakened the wave of the UM, especially in the anterior midpiece. Live Ca²⁺ imaging showed that, compared with the intact sperm in the JE, the relative intracellular Ca²⁺ level changed especially in the anterior and posterior ends of the midpiece of the blocker‐treated sperm. These suggest that different types of Ca²⁺ channels mediate the intracellular Ca²⁺ level predominantly in the anterior and posterior ends of the midpiece to maintain the high motility state of the newt sperm.     

Comparative morphology of the egg of the castniid palm borer,Paysandisia archon (Burmeister, 1880) (Lepidoptera: Castniidae)

Paysandisia archon (Burmeister, 1880) is an attractive neotropical castniid moth whose presence in Europe was recently reported. Its larvae are endophagous, feeding inside the trunks and branches of several species of palm trees (Arecaceae). The present paper deals with the morphology and biometry of the egg of this moth, comparing them with those of other castniid species.

The egg is a typical castniid egg, fusiform, upright sensu Döring, light cream or creamy pink when freshly laid, 4.69 ± 0.37 mm long and 1.56 ± 0.11 mm wide. Larvae emerge by gently splitting the chorion along one of the longitudinal ridges, on the half closer to the micropyle. SEM, TEM and LSCM photographs showing ultrastructural details of the egg are shown for the first time. The micropylar rosette (c. 54 μm in diameter) has generally 14–17 cells; in its centre lies the micropylar pit (c. 6 μm in diameter) which bears 12–16 micropylar canal openings (= micropyles) around its periphery. The pathways followed by those canals through the chorion have been figured. Eggs sampled in the wild (so laid by several females) were found to have a slightly variable number of ridges: most bore seven ridges (68.87%), although a significant portion (30.46%) bore eight and 1 egg (0.67%) bore only six; this against the currently accepted rule of five‐ridged eggs for Castniini (i.e. Neotropical castniids) to which Paysandisia archon belongs. It has also been found that the same female specimen has the capability of producing six‐, seven‐ or eight‐ridged eggs. Five types of egg irregularities affecting the longitudinal ridges are also figured and described. Transverse striae on the egg of P. archon are about 122. Aeropyles (c. 4 μm in diameter) occur on the ridges, at the intersections between the latter and two contiguous (left and right of the ridge) transverse striae, amounting to c. 854 on a seven‐ridged egg and to c. 976 on an eight‐ridged egg. Occasionally minute aeropyles ('microaeropyles') (c. 1.96–3.13 μm in diameter) also occur on transverse striae located close to both egg poles.

The chorion of P. archon shows the typical ditrysian fine structure with very thin basal layer (C‐1), 0.3–0.2 μm thick, gas‐filled trabecular layer (C‐2), c. 0.9 μm thick, and lamellar layer (C‐3), its thickness varying between 18.5 and 13 μm due to the bumpy external surface of the chorion. Aeropylar canals, that penetrate layer C‐3, connect the air‐containing inner chorionic meshwork (the trabecular layer C‐2) with the surrounding air; their outer part forms a big bulbous cavity (which opens to the outside through the small opening seen in external SEM images) and, underneath, a narrow canal follows, leading into the trabecular layer (C‐2).     

Cylicospirura advena n.sp. (Nematoda: Spirocercidae) a stomach parasite from a cat in New Zealand,with observations on related species

Summary Cylicospirura (Cylicospirura) advena n.sp. described from specimens obtained from a feral cat in New Zealand is characterized by the presence of toothless rounded knobs on the anterior ends of the longitudinal supporting ribs in the buccal capsule; a vulva either anterior or posterior to the oesophago-intestinal junction; its small size (less than 6 mm) and the presence of a thin, disc-like process on the tip of the short spicule. Additional figures are provided of Cyathospirura dasyuridis Mawson, 1968, and the presence of conspicuous lateral alae of Cylicospirura (C.) heydoni (Baylis, 1927) is noted for the first time. ac]19810222     

Two new species ofOdilia (Nematoda: Heligmonellidae) from Australian rodents,with comments onO. bainae Beveridge & Durette-Desset, 1992

Odilia tasmaniensis n. sp.,O. praeputialis n. sp. andO. bainae Beveridge & Durette-Desset, 1992 from the small intestine of Australian murids are described and illustrated. The two new species are distinguished from the other eight species in the genus, namelyO. mackerrasae (Mawson, 1961),O. brachybursa (Mawson, 1961),O. emanuelae (Mawson, 1961),O. melomyos (Mawson, 1961),O. polyrhabdote (Mawson, 1961),O. uromyos (Mawson, 1961),O. mawsonae (Durette-Desset, 1969) andO. bainae Beveridge & Durette-Desset, 1992.O. tasmaniensis n. sp. fromRattus lutreolus is characterised by the longitudinal cuticular ridges being continuous, the presence of 18 ridges in cross-section in the middle region of the body, the joined distal ends of the spicules forming a curved bluntly rounded tip, a short genital cone with a single ventral papilla and a pair of laterally curving dorsal raylets and the posterior end of the female tapering sharply.O. praeputialis n. sp. fromZyzomys woodwardi is characterised by continuous longitudinal cuticular ridges, the presence of 22–35 ridges in cross-section in the middle of the body, the sharply pointed joined distal tips of the spicules, a complex genital cone with a flat membraneous proconus, a ventral papilla projecting from an extension of the body wall, a pair of short straight dorsal raylets and the presence of a praepuce on the posterior end of the female.O. bainae is characterised by the longitudinal cuticular ridges being continuous, the presence of 17–22 ridges in cross-section in the middle region of the body, the joined distal ends of the spicules surrounded in an oval transparent cap, a long genital cone with a single ventral papilla and a pair of laterally curving dorsal raylets, and the absence of a praepuce on the posterior end of the female.Rattus lutreolus and the pseudomyine rodentsPseudomys higginsi andMastacomys fuscus are new host records for this species.     

Life history of Littorina scutulata and L. plena, sibling gastropod species with planktotrophic larvae

Abstract. The intertidal, sibling species Littorina scutulata and L. plena (Gastropoda, Proso‐branchia) are sympatric throughout most of their ranges along the Pacific coast of North America. Both species release disc‐shaped, planktonic egg capsules from which planktotrophic veliger larvae hatch. Here I review existing data and present new observations on these species' life history, including age at first reproduction, spawning season, maximum fecundity rates, capsule morphology, egg size and number, pre‐hatching development, larval growth at three food concentrations, potential settlement cues, planktonic period, and protoconch size. Previous classification of egg capsule morphologies used to distinguish the species is inaccurate; instead, capsules can be categorized into three types of which each species may produce two. Females of L. scutulata produced capsules with either two rims of unequal diameter or one rim, while females of L. plena produced capsules with one rim or two rims of nearly equal diameter. Females of each species spawned sporadically from early spring to early fall in Puget Sound. Larvae of L. plena hatched one day earlier than those of L. scutulata, and both species grew fastest in the laboratory at intermediate food concentrations. Larvae metamorphosed in the presence of a variety of materials collected from their adult habitat, including conspecific adults, algae, rocks, and barnacle tests. This is the first report of planktotrophic larvae in this genus metamorphosing in the laboratory. The total planktonic period of 8 larvae of L. scutulata raised in the laboratory was 37–70 days, and a single larva of L. plena metamorphosed after 62 days. Protoconch diameter of shells collected from the field was 256–436 μm and did not differ significantly between the species. Previous allozyme and mitochondrial DNA work has suggested high levels of genetic variability in both species and greater genetic population structure in L. plena, despite the long spawning season and long‐lived larvae in both species. The interspecific life history differences described here appear insufficient to produce consistent differences in gene flow patterns.     

Surface ultrastructure of the egg chorion in the dragonfly,Ictinogomphus rapax (Rambur) (Odonata : Gomphidae)

Scanning electron microscopic examination of the egg chorion in Ictinogomphus rapax (Rambur) (Odonata : Gomphidae) shows hexagonal reticulation throughout the surface. The anterior pole of the egg bears a small rounded micropylar stalk with a group of 6 orifices arranged radially around a central boss, while the posterior pole consists of a sessile, truncated cone formed of 50–60 long, coiled filaments. The functional, taxonomic, and phylogenetic significance of various microstructures of the eggshell are discussed.     

The fowl tick, <Emphasis Type="Italic">Argas (Persicargas) persicus</Emphasis> (Ixodoidea: Argasidae): Description of the egg and redescription of the larva by Scanning Electron Microscopy

This scanning electron microscopy study revealed that the egg of Argas persicus was covered with chorion which appeared as a wrinkled layer containing regions of three textures. The first had elevated parts of slightly rough surface. The second had irregular smooth elevations; each carried numerous parallel horizontal foldings with vertical ridges. The last region had rough surface with irregularly shaped projections. Following the removal of the chorion, shell was observed to have one polar micropyle and numerous slit like openings. Length (L), width (W) and L/W ratio of the egg were measured. Investigation of larvae revealed extensively folded integument of idiosoma and spherical or elongated tubercles on dorsal plate. Mouth enclosed between ventral hypostome and two dorsal chelicerae. Hypostome carried four longitudinal rows of conical denticles. Each chelicera was made up of two segments; the basal one appeared as a pocket for the distal one. Haller’s organ consisted of an anterior pit containing seven sensilla and a posterior capsule with four apertures. Distribution of chemo- and mechano-sensilla on the body was examined. Measurements of whole body, idiosoma, dorsal plate, capitulum, hypostome, palp and different types of sensilla both on the body and Haller’s organ are also presented.     

SALMFamide2 and serotonin immunoreactivity in the nervous system of some acoels (Xenacoelomorpha)

Acoel worms are simple, often microscopic animals with direct development, a multiciliated epidermis, a statocyst, and a digestive parenchyma instead of a gut epithelium. Morphological characters of acoels have been notoriously difficult to interpret due to their relative scarcity. The nervous system is one of the most accessible and widely used comparative features in acoels, which have a so‐called commissural brain without capsule and several major longitudinal neurite bundles. Here, we use the selective binding properties of a neuropeptide antibody raised in echinoderms (SALMFamide2, or S2), and a commercial antibody against serotonin (5‐HT) to provide additional characters of the acoel nervous system. We have prepared whole‐mount immunofluorescent stainings of three acoel species: Symsagittifera psammophila (Convolutidae), Aphanostoma pisae, and the model acoel Isodiametra pulchra (both Isodiametridae). The commissural brain of all three acoels is delimited anteriorly by the ventral anterior commissure, and posteriorly by the dorsal posterior commissure. The dorsal anterior commissure is situated between the ventral anterior commissure and the dorsal posterior commissure, while the statocyst lies between dorsal anterior and dorsal posterior commissure. S2 and serotonin do not co‐localise, and they follow similar patterns to each other within an animal. In particular, S2, but not 5‐HT, stains a prominent commissure posterior to the main (dorsal) posterior commissure. We have for the first time observed a closed posterior loop of the main neurite bundles in S. psammophila for both the amidergic and the serotonergic nervous system. In I. pulchra, the lateral neurite bundles also form a posterior loop in our serotonergic nervous system stainings.     

The Fine Structure of Rhynchocystis pilosa (Sporozoa, Eugregarinida)

SYNOPSIS. The trophozoite of Rhynchocystis pilosa obtained from the seminal vesicles of the earthworm Lumbricus terrestris was studied by light and electron microscopy. The trophozoite's cortical organization is particularly interesting because of its unusual evaginations and associated fibrillar structures. The pellicle is formed by 2 concentric membranes elevated into 60–70 alternating primary and secondary ridges extending posteriad. Numerous long ‘hairs’ or cytopilia originate along the primary ridges and each contains a system of fibrils originating from an underlying longitudinal myoneme. Longitudinal rows of pores lie between adjacent pollicular ridges. Three systems of fibrils lie in the cortex of the trophozoite. A longitudinal myoneme consisting of 12–18 fibrils lies below each primary pellicular ridge. Circular myonemes lie below the pellicle in a parallel array along the length of the organism. Each myoneme consists of 4–8 fibrils structurally similar to those of the longitudinal myonemes. Pairs of fine filaments also lie in the inner pellicular membrane along the apex of each ridge. The trophozoite's anterior end is modified as an attachment organelle consisting of 30–35 delicate pellicular folds which originate at the base of an anterior papilla. The folds extend approximately 15 μ posteriad where they become continuous with the primary pellicular ridges. The nucleus lies in the cytoplasm near the posterior level of the attachment organelle and is surrounded by a double membrane perforated by numerous pores. The cytoplasm contains numerous small vesicles which may be found in dense aggregations. These aggregations often occur in proximity to Golgi complexes and certain membrane-bound bodies. Mitochondria are abundant in the cytoplasm as are large, ovoid paraglycogen bodies. Occasionally layers of granular membranes are arranged parallel to the surface of the paraglycogen bodies but also occur thruout the cytoplasm.     

Temperature‐mediated trade‐offs and changes in life‐history integration in two slipper limpets (Gastropoda: Calyptraeidae) with planktotrophic development

Intraspecific variation in egg size and hatching size, and the genetic and environmental trade‐offs that contribute to variation, are the basis of the evolution of life histories. The present study examined both univariate and multivariate temperature‐mediated plasticity of life‐history traits, as well as temperature‐mediated trade‐offs in egg size and clutch size, in two planktotrophic species of marine slipper limpets, Crepidula. Previous work with two species of Crepidula with large eggs and lecithotrophic development has shown a significant effect of temperature on egg size and hatching size. To further examine the effect of temperature on egg size in Crepidula, the effects of temperature on egg size and hatching size, as well as the possible trade‐offs with other the life‐history features, were examined for two planktotrophic species: Crepidula incurva and Crepidula cf. marginalis. Field‐collected juveniles were raised at 23 or 28 °C and egg size, hatching size, capsules/brood, eggs/capsule, time to hatch, interbrood interval, and final body weight were recorded. Consistent with results for the lecithotrophic Crepidula, egg size and hatching size decreased with temperature in the planktotrophic species. The affects of maternal identity and individual brood account for more than half of the intraspecific variation in egg size and hatching size. Temperature also showed a significant effect on reproductive rate, with time to hatch and interbrood interval both decreasing with increasing temperature. However, temperature had contrasting effects on the number of offspring. Crepidula cf. marginalis has significantly more eggs/capsule and therefore more eggs per brood at 28 °C compared to 23 °C, although capsules/brood did not vary with temperature. Crepidula incurva, on the other hand, produced significantly more capsules/brood and more eggs per brood at the lower temperature, whereas the number of eggs/capsule did not vary with temperature. The phenotypic variance–covariance matrix of life‐history variables showed a greater response to temperature in C. incurva than in C. cf. marginalis, and temperature induced trade‐offs between offspring size and number differ between the species. These differences suggest that temperature changes as a result of seasonal upwelling along the coast of Panama will effect the reproduction and evolution of life histories of these two co‐occurring species differently. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??.     

Chondrichthyan egg cases from the south-west Atlantic Ocean

Egg cases of 21 oviparous chondrichthyan species from the south-west Atlantic Ocean are described and compared. The catshark Schroederichthys bivius has a cigar-shaped egg case with curled tendrils only at the posterior end. Egg cases of the elephant fish Callorhinchus callorynchus are spindle-shaped with anterior and posterior tubular extensions and lateral flanges. The skate Amblyraja doellojuradoi presents medium-sized egg cases (71 mm in length) with a lateral keel extending to the first portion of the horns. The endemic skate species of the genus Atlantoraja have medium to large egg cases (69-104 mm in length) and present relatively large posterior horns. Egg cases of the genus Bathyraja have a medium size, 75-98 mm in length, and are characterized by a very similar morphology, a relatively smooth to rough surface case and posterior horns strongly curved inwards. Egg cases of the genera Dipturus and Zearaja are very large, 115-230 mm in length, and have a well-developed posterior apron. Despite the problematical identification of skates at species level, the egg capsules of the endemic genus Psammobatis are easily diagnosed; the capsules are small (25-53 mm in length), those of Psammobatis rutrum being the smallest known to date in the world. Egg cases of Rioraja agassizi have a medium size, 61-68 mm in length, relatively straight sides, a smooth surface and silky attachment fibres placed in the lateral keel next to each horn. Those of the genus Sympterygia are small to medium sized, 51-86 mm in length, and display the thickest lateral keel and the longest posterior horns among the skates of the world. Egg cases can be a useful tool for identifying species and egg-laying areas; therefore, a provisional key for the south-west Atlantic Ocean chondrichthyan capsules is presented.     

Diverse oxyporine rove beetles from the Early Cretaceous of China (Coleoptera: Staphylinidae)

Two new genera and species, Protoxyporus grandis gen. et sp.n. and Cretoxyporus extraneus gen. et sp.n. , are described and figured on the basis of two well‐preserved impression fossils from the Lower Cretaceous Yixian Formation of China. The two genera display a combination of traits that are diagnostic of the extant staphylinid subfamily Oxyporinae: large and prominent mandibles, distinctly separated mesocoxae, abdominal tergites III–VII each with a pair of basolateral ridges, and abdominal intersegmental membranes with ‘brick‐wall’ pattern. Protoxyporus differs from extant Oxyporus in retaining the following plesiomorphic features: an elongate intercoxal process (or longitudinal carina) between metacoxae, relatively narrowly separated mesocoxae, less developed metaventral anterior process, and long infraorbital ridges. Cretoxyporus is morphologically very similar to Oxyporus, but retains distinct elongate infraorbital ridges. The discovery of two new oxyporine genera suggests that the early oxyporines were more diverse and their evolutionary history more complicated than previously documented. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:11503976‐D577‐45D2‐ACCB‐8226782EF817 .     

The surface ultrastructure of the egg capsule of Transversotrema patialense (Transversotrematidae: Digenea)

Bundy D. A. P. 1981. The surface ultrastructure of the egg capsule of Transversotrema patialense (Transversotrematidae : Digenea). International Journal for Parasitology11: 19–22. Scanning and transmission electron micrographs show that the egg capsule of the digenean Transversotrema patialense bears thread-like extensions 3 μm long and 0.12 μm in diameter at a density of one per μm^?2. These extensions trap bacteria and detritus against the egg capsule surface. The ultrastructural topography of the egg capsules of this species differs from the forms previously described for other parasitic platyhelminths. It is suggested that the capsular sculpturing arises as an incidental consequence of moulding effects at the egg capsule-reproductive tract interface during ovogenesis.     

Seamount egg‐laying grounds of the deep‐water skate Bathyraja richardsoni

Highly localized concentrations of elasmobranch egg capsules of the deep‐water skate Bathyraja richardsoni were discovered during the first remotely operated vehicle (ROV) survey of the Hebrides Terrace Seamount in the Rockall Trough, north‐east Atlantic Ocean. Conductivity–temperature–depth profiling indicated that the eggs were bathed in a specific environmental niche of well‐oxygenated waters between 4·20 and 4·55° C, and salinity 34·95–35·06, on a coarse to fine‐grained sandy seabed on the seamount's eastern flank, whereas a second type of egg capsule (possibly belonging to the skate Dipturus sp.) was recorded exclusively amongst the reef‐building stony coral Solenosmilia variabilis. The depths of both egg‐laying habitats (1489–1580 m) provide a de facto refuge from fisheries mortality for younger life stages of these skates.