The feeding strategy of the predatory Gyrineum natator (Gastropoda: Neotaenioglossa: Ranellidae) in the Cape d’Aguilar Marine Reserve,Hong Kong,with a review of sulphuric acid use in prey access by the Tonnoidea and experimentally derived estimates of consumption

Under conditions of otherwise enforced starvation in filtered seawater and with only oysters (Saccostrea mordax) to feed on, an individual of Gyrineum natator consumed > 98%, on average, of its body weight of oyster tissues each week (> 14% per day). When other potential food, such as sediment, organic debris and other newly settled sessile organisms, was available to a similar-sized conspecific living in conditions of unfiltered seawater (in addition to oysters), the oysters only accounted for 1.52% of its average weekly diet (0.21% per day). This was because of the 12 proffered oysters, only four were consumed in contrast to the 12 eaten by the individual in filtered seawater. All the oysters were accessed through large holes made in their shells. It is generally understood that the salivary glands of confamilial ranellids produce secretions of sulphuric acid from greatly enlarged salivary glands and this is demonstrated herein for G. natator also. It is believed that it was these secretions that made the holes in the oyster shells. It, therefore, seems that G. natator uses sulphuric acid to attack prey only when more easily obtained food is not available. It may also be used in defence. A comparison of consumption rates for a range of scavenging and predatory gastropod taxa shows that representatives of the Nassariidae consume (much) more than predators because of their opportunistic lifestyles. Gyrineum natator generally eats similar amounts to other predators, although the increased difference in estimated consumption (~10%) between this species and another similar-sized ranellid, Linatella caudata, might be because the latter did not use sulphuric acid to access its prey. Its enforced use in this study of G. natator, therefore, might represent the increased costs of using the acid to access the proffered oyster prey.     

Symbiotic associations between hermit crabs and bryozoans from the Otago region,southeastern New Zealand

Thirteen species of bryozoans (six cyclostomes and seven cheilostomes) occurring off the Otago Peninsula (southeastern New Zealand) form symbiotic, possibly mutualistic, associations with hermit crabs. For all but one of these bryozoan species, such an association has not been reported previously. At most only 3 of the 13 bryozoans are obligate symbionts of hermit crabs. Associations are apparently initiated when a bryozoan larva settles on a gastropod shell occupied by a juvenile hermit crab and develops to form a colony which encrusts the whole shell and then continues to grow out beyond the shell aperture in the form of a helicospiral tube. The tube-building bryozoan colony grows in step with the crab, and tube development appears to be controlled by crab morphology and activity. Of the six species of hermit crabs found occupying bryozoan tubes, four were regular tube occupants, although they could also be found in other shelter types. Hermit crabs occupying bryozoan tubes very rarely indulged in shell exchanges or shell fights. There appear to be no clear cut pairwise correlations between hermit crab species and tube-forming bryozoan species. The following bryozoan species are described for the first time: Heteropora parapelliculata, Borgiola otagoensis, Disporella gordoni, Osthimosia monilifera and O. socialis.     

Pattern of shell occupation by the hermit crab Pagurus exilis (Anomura,Paguridae) on the northern coast of São Paulo State,Brazil

The purpose of this study was to determine the shell occupation pattern of Pagurus exilis using the percentage of shell types that were occupied and the morphometric relationship between hermits and occupied shells. Specimens were collected monthly from July 2001 to June 2003. A total of 1737 individuals were collected, occupying 19 gastropod shell species. Buccinanops gradatum (82%) was the most occupied shell, followed by Natica isabelleana (6.4%), Stramonita haemastoma (3.2%), and Cymatium parthenopeum (2.2%). There was a differential shell utilization pattern between sexes; males occupied larger and heavier shells while the non‐ovigerous females occupied the lightest ones. Pagurus exilis occupied more bare shells instead of incrusted ones. Buccinanops gradatum was the most occupied shell species as a function of its availability in the survey, and this occupation is strongly associated with the higher internal volume presented by these shells.     

Reproduction,planula development,and substratum selection in three species of Stylactaria (Cnidaria: Hydrozoa) from Hokkaido,Japan

Modes of reproduction, morphology and behaviour of planulae, and substratum specificity were studied and compared in three species of the hydrozoan genus Stylactaria from Hokkaido, S. conchicola, S. uchidai, and S. multigranosi. Observed differences in these attributes provide additional characters for discrimination of the three species. Stylactaria conchicola is oviparous, its planulae are sedentary, and its hydroid is substratum specific (living only on shells of the gastropod Homalopoma amussitatum). Stylactaria uchidai differs in being ovoviviparous, in having crawling planulae, and in being a substratum generalist. Stylactaria multigranosi is parthenogenetic, its planulae are sedentary, and it is substratum specific (occurring exclusively on the gastropod Nassarius multigranosus). Only female colonies of S. multigranosi are known, and gonophores of this species differ from those of S. conchicola and S. uchidai in being eumedusoid rather than styloid. Correlations were noted between attributes of the planula larva and substratum specificity in the three species. The cnidome differences between the species suggest that penetrant nematocysts are particularly important for sedentary planulae colonizing moving substrata. These characters are also considered useful in the taxonomy of species of Stylactaria. The phylogenetic significance of different gonophore types in the genus is considered.     

Gastropod shell utilisation pattern by the hermit crab Clibanarius symmetricus (Anomura: Diogenidae) in an Equatorial Amazon estuary

Clibanarius symmetricus is a diogenid hermit crab that is highly abundant in rocky intertidal environments, including the rock outcrops of Amazon estuaries. This study characterises the C. symmetricus shell utilisation pattern in the Marapanim River estuary, Pará, Equatorial Amazon, based on the hypothesis that occupancy patterns would differ, in relation to biometry and diversity of occupied shells, from those of other regions in the range of this species due to the distinct and unique environmental characteristics of equatorial estuaries. Monthly samplings were carried out from August 2006 to July 2007, in the upper and lower areas of the mid-littoral during low tides. A total of seven gastropod species were found as shells occupied by hermit crabs: 93.33% were Thaisella trinitatensis shells, 2.00% Nassarius vibex, 2.00% Neritina virginea, 1.33% Natica marochiensis, 0.67% Parvanachis obesa, and, occasionally, Littorina flava and Phalium granulatum shells, each with only one occurrence (0.33%). Juveniles [cephalothoracic shield length (CL) of less than 3.6 mm] occupied a higher variety of shells, while adults occupied shells with larger meristic variation. Males occupied larger shells. The length of the animal was influenced by shell measurements (total width, aperture width and weight). Clibanarius symmetricus showed occupancy patterns generally similar to those of specimens of the same species previously studied in the Brazilian subtropical region, and this occupancy is explained by shell availability, shell size and weight, and hermit size. However, this study showed lower occupied shell species diversity, and the species with highest occupancy frequency (T. trinitatensis) was not reported in any previous studies on this hermit crab. In addition, the studied population differed in occupancy patterns, with differences between males and females, and between juveniles and adults.     

Larval development and emigration behaviour during sea-to-land transition of the land hermit crab Coenobita brevimanus Dana, 1852 (Crustacea: Decapoda: Anomura: Coenobitidae) under laboratory conditions

To determine the early life history of the land hermit crab Coenobita brevimanus Dana, 1852, larvae were cultured individually in the laboratory. The zoeal and the megalopal stages are described and illustrated. The larvae developed through four planktonic zoeal stages to the megalopal stage. The major differences in the zoeal characters between C. brevimanus and other described Coenobita species were found in the armature of the pleomeres, whereas the character of pleomeres of C. brevimanus zoeae is the same as that of the coconut crab Birgus latro, a different genus in the same family. Morphological similarity was also found in segmentations of antennules and antennae in megalopae between C. brevimanus and the coconut crab. Megalopae of C. brevimanus were cultured in containers holding seawater and a hard substrate. These crabs migrate from the sea to land after developing a habit of acquiring gastropod shells.     

Protozoan ciliate epibionts on the freshwater apple snail Pomacea figulina (Spix, 1827) (Gastropoda,Ampullariidae) in an urban stream of south‐east Brazil

The objective of this study was to record and analyze the prevalence of ciliated protozoa associated with prosobranchian snails of the species Pomacea figulina collected from an urban stream in south‐eastern Brazil. Four collections were carried out between December, 2005, and March, 2006, from which 23 snails and 10 ‘empty’ shells were obtained. The shells and opercula were scraped over Petri dishes and the ciliates were observed using bright field and phase contrast microscopy. Seven species of ciliates were recorded on the snails of P. figulina. Of the 23 snails analyzed, 82.60% (n = 19) were infested with at least one species of ciliate. No ciliates were found on the ‘empty’ shells and opercula. The results are discussed in terms of ecological aspects involved in this association.     

XXII.—On the structure of the palate and mandible of Archegosaurus decheni,Goldfuss

Summary

The genus Helixotionella is introduced for three species of spirally budded, free-living, lunulitiform bryozoans from Australia, H. spiralis (Chapman), H. rubra (Bretnall) and H. scutata sp. nov. H. spiralis, the type species, has a fossil history extending from the Upper Oligocene of Victoria, but like H. scutata, has been found to occur in Recent samples from Western Australia. H. rubra is known only from the Recent of New South Wales. All species have minute colonies and the majority of specimens has been revealed only after detailed examination of very fine fractions of bottom sediments, which themselves include a high proportion of bryozoan skeletal material.     

Notes on astogeny of some Petraliellidae (Bryozoa) from Australia

Members of the bryozoan family Petraliellidae share the capacity to develop basal rhizoids, which anchor the unilaminar, semi-repent parts of the colonies above the substratum, and enable them to overgrow other, competing sessile forms. Little is known of the larval behaviour and settlement, or the early astogeny of species. Ancestrulate colonies of the Australian Tertiary lunulitiform species Smittia biincisa are referred to the genus Riscodopa, and together with Riscodopa paucipora sp. nov. are described and compared with the Recent species R. cotyla and R. parva from New Zealand, and with R. hyalina sp. nov. from New South Wales, Australia. All the Recent species are known to develop basal rhizoids, and an early astogeny similar to that of many other small, rooted bryozoans, comprising the post-metamorphosis development of a binary complex, including rhizoid and feeding elements, is inferred for Riscodopa. Observations on living Hippopetraliella magna from Queensland suggest that both the ancestrular morphology and early astogeny show a capacity for semi-repent growth, even though they do not include rhizoid development. Larvae metamorphose without direct attachment, and the ancestrula develops elongated, partially calcified supporting processes, which raise the early stages of growth above the substratum. A similar kind of ancestrula has been found in preserved specimens of Mucropetraliella ellerii.     

XII.—The upper Valentian trilobite fauna of Shropshire

Summary

Records of ten species of Sosylus collected in Nigeria are given, with details of distribution, host trees and platypodid associates. The Sosylus fauna of Nigeria appears to lie between that of Ghana and the Congo in species composition. Comment is made on the close association that some Sosylus species have with their platypodid hosts.     

The systematic positions of Orsodacne Latr. and Syneta Lac. (Coleoptera Chrysomelidae), in relation to characters of larvae,internal anatomy and tarsal vestiture

Summary

The male and female reproductive systems, gut and Malpighian tubules, and ventral nerve cord are described and figured for Orsodacne cerasi L. and Syneta betulae F.; the first instar larva of O. lineola is described and figured, and compared with already described larvae of Syneta betulae and other Chrysomelidae. The adhesive setae of the adult tarsi are described for both species and for representatives of Aulacoscelinae, Megascelinae, Megalopodinae, Sagrinae, Eumolpinae, Hispinae and Camptosomata. The mouthparts of adult Orsodacne and Aulacoscelis are described and figured, with consideration of pollen-eating adaptations in the family. It is concluded that Orsodacne is an isolated and primitive type whose nearest existing relative may be Cucujopsis Crowson in Australia, while Syneta may be allied to both Eumolpinae and Galerucinae. A new key to subfamilies of chrysomelid larvae is provided, and a phyletic dendrogram of the family is figured and discussed.     

LXI.—Notes on insects collected in West Greenland by the Oxford University Greenland expedition, 1936. With descriptions of a new species of Angitia (Hymenoptera,Ichneumonidæ)by A. Roman,and of Fannia (Diptera,Anthomyidæ) by J. E. Collin

Summary

A population of Chaetogaster limnaei limnaei Gruffydd, living on various molluscs in the Worcester-Birmingham canal, was studied from February 1971 to February 1973 in the course of a detailed study of the digeneans parasitizing the molluscs.

The incidence of C. l. limnaei on each of its hosts was recorded for each month during the sampling period.

The incidence of the worms was high during the winter months on Physa fontinalis (and Lymnaea peregra) but low during the summer, and was high during the summer and low during the winter on Bithynia tentaculata.

It is postulated that this pattern of incidence may have been due to a migration of the worms from the pulmonate hosts to B. tentaculata in late spring, when the large pulmonates died after breeding, and a return migration to the pulmonates the following autumn.

There was found to be no association between the digeneans parasitizing the molluscs and the occurrence of the oligochaetes, and it is suggested that in this case the oligochaetes have no influence on the parasitic burden of the molluscs.     

II.—Association between sessile colonial hydroids and fishes

Résumé

1. 1. There is a symbiosis between Sertularia operculata and Squalus acanthias, and between Seralia lendigera and Hippocampus ramulosus—there being but a single case reported for each pair of organisms. It is probable that these associations are entirely accidental.

2. 2. Of Stylactis minoi and Minous inermis, no fewer than twenty-nine specimens of the fish (presumably all ever taken) wherever found—and they have been taken from five widely distant stations on both coasts of India, and from Japan—were infested with the hydroid. Furthermore, so far as known, this particular hydroid has never been found save on this particular fish (inermis). These facts would seem to indicate that this is a purposive or obligate symbiosis.

3. 3. About one hundred specimens of Hypsagonus quadricornis were taken in Puget Sound. Thirty-seven of these were preserved, and ten of them were found to be sparsely covered with Perigonimus pugetensis. Other specimens of the fish taken outside Puget Sound and in Behring Sea all lacked the hydroid. Consideration of all these facts leads to the conclusion that the association is symbiotic and more or less accidental.

4. 4. One case has been presented of Hydrichthys mirus attached to Seriola zonata in Narragansett Bay. Parasitism is alleged, but the proofs offered, that there was some apparent degeneration on the part of the hydroid and some slight evidence of wasting away of the muscles of the fish at the point of attachment, are at best inconclusive, there being no evidence from sections presented to show actual anastomosis of the tissues of the two organisms. From the evidence presented one must conclude that this is only a case of symbiosis.

5. 5. One case is known of the attachment of a Nudiclava to a fish, Monacanthus, from the Andaman Sea. Parasitism is alleged in the title of the paper, but disclaimed in the text, since, in sections cut through the basal plate and the skin to which it was attached, such was not proven. Furthermore, the finding of food in the hydranths discounts the idea of parasitism. This case also must be classed as a symbiosis.

6. 6. True parasitism has been repeatedly shown to exist between an aberrant hydroid, Polypodium hydriforme, and the ovarian eggs of the Volga sterlet, Acipenser ruthenus. This has been definitely established by the work of four investigators, extending in time from 1872 to 1922—a half century. Except in its earliest stages, Polypodium has the nutritive cell-layer of its stolon, the endoderm, on the outside bathed in the egg-yolk. Later this becomes inverted and a large amount of yolk is carried into the common cavity. The egg is used up in nourishing the parasite.

7. 7. True parasitism has been shown between Hydrichthys boycei and numerous individuals of three species of fishes—Ambassis natalensis, Mugil sp., and an undetermined fish belonging to the Glyphidodontidæ—in Durban Bay, South Africa. The parasites were attached to various parts of the fishes, especially the fins. At the points of attachment, haustoria were sent down into flesh and into blood-vessels, and by means of these the parasite fed on the tissues of its host. Furthermore, on none of the hydranths were tentacles ever found, nor was any food ever found in them. Strange to say, the parasite never covers any large area of the fish, and apparently presently drops off leaving a scar behind.

     

An association between komokiacean foraminifers (Protozoa) and paludicelline ctenostomes (Bryozoa) from the abyssal Northeast Atlantic

Summary

Large collections of komokiacean foraminifers have been obtained from epibenthic sledge samples taken at bathyal and abyssal depths in the north-east Atlantic. Eight of the 32 species so far recognized have been found to form an association with paludicelline bryozoans. Approximately 4% of the > 12000 komokiaceans studied were involved in the association. The bryozoan colonies intergrow as networks with the komokiacean tubules and only the elongated peristomes protrude from the tubule mass. The distribution of ctenostome peristomes in relation to the tubule mass, and the length of the zooidal tentacle sheaths, suggest that these komokiacean species live together with their bryozoan associates at, or near the sediment surface.     

Microhabitat diversity of Svalbard Bryozoa

Bryozoans are one of the major macrofaunal groups of the high polar regions. Here we present data on the nature of bryozoan assemblages in the Svalbard Archipelago sampled over 6 years between 1997 and 2002. Samples were collected with use of Van Veen grab, dredge and Scuba diving at depths ranging from 0 to 268?m. Among examined material (5026 items) bryozoans were present on one type of abiotic (stones) and 40 types of biotic substrata. The biotic substrata we investigated included algae (12 taxa) and invertebrates (28 taxa: Hydrozoa, Gastropoda, Bivalvia, Polychaeta, Crustacea, Ascidiacea, other Bryozoa). Both a priori ANOSIM (Global R?=?0.512, P?=?0.001) and cluster analyses reveal differences between the assemblages on different types of substrata. Cluster analyses distinguish two distinct groups of substrata. The first (stable) included stones, molluscs and Balanus balanus whilst the second (flexible) consisted of algae, hydrozoans and bryozoans. Bryozoan assemblages which colonized different substrata, varied in terms of species composition and their dominance. Bryozoan species were categorized as generalists, low‐specificity epibiotic species or locally abundant background species. No species were found to be substratum‐specific to any type. Among substrata with the richest bryozoan fauna were stones (156 taxa), Chlamys islandica (68) and Balanus balanus (62). There were clear patterns in the distribution of substrata colonized by bryozoans within the fjord system: those shallow near the mouth were rich whilst those in deeper water were depauperate. We consider environmental gradients such as siltation and processes related to depth to be responsible for such patterns.     

Variation in shell geometry in the genus Lacuna (Prosobranchia: Lacunidae)

Summary

A range of species of the genus Lacuna have been numerically described in terms of the geometry of their shells.

Species are uniquely distinguishable on this basis.

Interspecific affinities and relationships defined here agree with those suggested by conventional classification, by general external appearance, and by presumed ecological pressures associated with zonation. Geometrical analysis may prove an accurate systematic aid at the specific or varietal level.     

L.—Two new Bittacidæ (Mecoptera)

Summary

The host-parasite relationships of Leptomonas ctenocephali from Ctenocephalides canis and Leptomonas sp. from Orchopeas h. howardi and Palaeopsylla m. minor are described. The latter two species of fleas are new host records for kinetoplastid flagellates. Attachment to pylorus and hindgut is by modification of the flagellum; hemidesmosomes are formed on the inner leaflet of the flagellar membrane and flagella-flagella desmosomes anchor adjacent flagella; a palisade of several layers of promastigote forms line the hindgut. Many individual flagellar membranes were found to extend around 3·0 μm and up to a maximum of 3·9 μm along the cuticular surface to which they were attached. In the rectum a specific association between the flagellates and the rectal ampullae is described; flagellates are attached to this surface covering completely each of the ampullae in heavy infections; again several layers of parasites coat the rectal ampullae. Attachment to the rectal ampullae is by the same mechanism as in the hindgut. Few parasites are attached to the rectal wall itself but rosettes of parasites attached by their flagella are observed in the lumen. The structure of the rectal ampullae are briefly described and the host-parasite relationships are discussed in the context of other described systems.     

A case of biodiversity overestimation in the Balkan Belgrandiella A. J. Wagner, 1927 (Caenogastropoda: Hydrobiidae): molecular divergence not paralleled by high morphological variation

Belgrandiella A. J. Wagner, 1927 is a genus comprising minute snails with conic or turriform shells that are facultative stygobionts, inhabiting subterranean waters and springs. Few specimens or even empty shells of this taxon can be found, so the taxonomy is based mostly on the shell morphology and geographic distribution. Anatomy is known for a few taxa, and its usefulness is restricted. This, coupled with a popular idea that isolation is the first factor shaping divergence and speciation of the spring/cave fauna, resulted in dozens of nominal species of Belgrandiella, known from shells at a given locality. Herein we present shells, anatomy and four molecular markers (nuclear H3, 18S and 28S and mitochondrial cytochrome oxidase subunit I) in Belgrandiella from 16 localities in Slovenia, northern Croatia, and Bosnia and Herzegovina. Five sites are type localities of Boleana umbilicata, Belgrandiella kusceri, Belgrandiella krupensis, Belgrandiella zermanica and Belgrandiella robusta, respectively. Considering the shell and geographic distribution, we have determined B. cf. robusta Belgrandiella cf. croatica, Belgrandiella cf. fontinalis, Belgrandiella cf. kuesteri, Belgrandiella cf. pageti and Belgrandiella cf. koprivnensis The shells of all, as well as penes and female reproductive organs of two putative, species have been illustrated. Molecular analysis indicates four distinct clades, most probably of species rank for B. kusceri, B. cf. kuesteri, B. cf. fontinalis and B. cf. koprivnensis. Four nominal species (B. krupensis, B. robusta, B. umbilicata and B. zermanica) and one genus (Boleana) must be synonymised with Belgrandiella kusceri, and there are no more than four valid, biological species in the studied Belgrandiella. The molecular divergence is completely unmirrored by high morphological variability. Hence the level of endemism is markedly overestimated in these snails.