Morphology and cell division of the oxytrichids Architricha indica nov. gen., nov. sp., and Histriculus histrio (Müller, 1773), Corliss, 1960 (Ciliophora, Hypotrichida)

The oxytrichid ciliate Architricha indica nov. gen., nov. sp., isolated from the river Yamuna, Delhi, shows a new combination of characters. It possesses a flexible body, 18 frontal-ventral-transverse (FVT) cirri, 3 right and 2 left marginal cirral rows, 6 dorsal bristle rows and 3 caudal cirri (CC). The FVT cirri arise from 6 primordia, which utilize 6 parental cirri in their origin as is typical of Oxytricha species. Multiple marginal rows (MMR) develop through 5 independent marginal primordia arising "within-row", 1 in each parental marginal row. All the 5 marginal rows are thus morphogenetically active. Such a mode of formation of MMR has not been recorded among oxytrichids and has necessitated separation of A. indica at the generic level. Histriculus, on the other hand, has well-known characteristics, viz. rigid body, confluent marginal rows and absence of CC. The morphogenesis of Histriculus histrio has been described by Berger and Foissner [1997. Cladistic relationships and generic characterization of oxytrichid hypotrichs (Protozoa, Ciliophora). Arch. Protistenkd. 148, 125-155]. Reinvestigation of very early stages of development revealed that (i) the FVT cirral primordia utilize kinetosomes from 5 parental FVT cirri, (ii) the primordium II of the proter is of a composite origin: kinetosomes from the oral primordium merge with the primordium II that originates from the buccal cirrus II/2 and (iii) the FVT primordia V and VI for the 2 daughter cells arise sequentially from the parental cirrus V/4. Thus, the genus Histriculus exhibits a new combination of characters with respect to the origin of FVT cirri, an additional pattern to be added to the known 6 patterns of FVT development in oxytrichids [Berger and Foissner, 1997; Berger, H., 1999. Monograph of the Oxytrichidae (Ciliophora, Hypotrichida), Kluwer Academic Publishers, Dordrecht/Boston/London].     

Conjugation in the spirotrich ciliate Halteria grandinella (Müller, 1773) Dujardin, 1841 (Protozoa, Ciliophora) and its phylogenetic implications

The conjugation of Halteria grandinella was studied in protargol preparations. The isogamontic conjugants fuse partially with their ventral sides to a homopolar pair. The first maturation division generates dramatic transformations: (i) the partners obtain an interlocking arrangement; (ii) the number of bristle kineties decreases from seven to four in each partner; and (iii) the right conjugant loses its buccal membranelles, the left the whole adoral zone. The remaining collar membranelles arrange around the pair's anterior end and are shared by both partners; finally, the couple resembles a vegetative specimen in size and outline. The vegetative macronucleus fragments before pycnosis. The micronucleus performs three maturation divisions, but only one derivative each performs the second and third division. The synkaryon divides twice, producing a micronucleus, a macronucleus anlage, and two disintegrating derivatives. Scattered somatic kinetids occur during conjugation, but disappear without reorganization. An incomplete oral primordium originates in both partners. The conjugation of Halteria grandinella resembles in several respects that of hypotrich spirotrichs; however, the majority of morphological, ontogenetical, and ultrastructural features still indicates an affiliation with the oligotrich and choreotrich spirotrichs. Accordingly, the cladistic analysis still contradicts the genealogy based on the sequences of the small subunit rRNA gene.     

Margolisiella islandica sp. nov. (Apicomplexa: Eimeridae) infecting Iceland scallop Chlamys islandica (Müller, 1776) in Icelandic waters

Wild Iceland scallops Chlamys islandica from an Icelandic bay were examined for parasites. Queen scallops Aequipecten opercularis from the Faroe Islands and king scallops Pecten maximus and queen scallops from Scottish waters were also examined. Observations revealed heavy infections of eimeriorine parasites in 95–100% of C. islandica but not the other scallop species. All life stages in the apicomplexan reproduction phases, i.e. merogony, gametogony and sporogony, were present. Trophozoites and meronts were common within endothelial cells of the heart’s auricle and two generations of free merozoites were frequently seen in great numbers in the haemolymph. Gamonts at various developmental stages were also abundant, most frequently free in the haemolymph. Macrogamonts were much more numerous than microgamonts. Oocysts were exclusively in the haemolymph; live mature oocysts contained numerous (>500) densely packed pairs of sporozoites forming sporocysts.Analysis of the 18S ribosomal DNA revealed that the parasite from C. islandica is most similar (97.7% identity) to an unidentified apicomplexan isolated from the haemolymph of the giant clam, Tridacna crocea, from Japan. Phylogenetic analyses showed that the novel sequence consistently grouped with the Tridacna sequence which formed a robust sister clade to the rhytidocystid group.We propose the name Margolisiella islandica sp. nov., referring to both type host and type locality.     

Taxonomic and nomenclatural notes on Syrrhopodon gaudichaudii Mont. (Calymperaceae) and S. hawaiicus Müll.Hal.

Syrrhopodon gaudichaudii Mont. is lectotypified and its key features are discussed. A neotype is designated for Syrrhopodon hawaiicus Müll.Hal. and the taxon is placed in synonymy with S. gaudichaudii. A key to the species of Syrrhopodon occurring in the Hawaiian Islands is provided.     

Population growth of Lepadella patella (O. F. Müller, 1786) at different algal (Chlorella vulgaris) densities and in association with Philodina roseola Ehrenberg, 1832

Population growth of Lepadella patella was studied using Chlorella as the sole food at five concentrations ranging from 0.25 × 10⁶ to 4.0 × 10⁶ cells ml^–1 at 25 °C for 22 days. The population densities increased with increasing algal concentration up to 1.0 × 10⁶ cells ml^–1. The population growth of L. patella was lower at algal concentration of 2.0 × 10⁶ cells ml^–1 and above. In a separate experiment, we tested the influence of the bdelloid rotifer Philodina roseola on the population growth of L. patella at different ratios of initial inoculation densities using 1.0 × 10⁶ cells ml^–1 of Chlorella at 28 °C. Despite lower initial inoculation densities compared with those in the controls, both L. patella and P. roseola showed higher peak abundances when grown together. The maximum peak abundance values recorded for L. patella and P. roseola were 830 and 230 ind. ml^–1, respectively, at an inoculation ratio of 1:1.     

Morphology and phylogenetic position of the oxytrichid ciliates,Urosoma salmastra (Dragesco and Dragesco-Kernéis, 1986) Berger, 1999 and U. karinae sinense nov. sspec. (Ciliophora,Hypotrichia)

The morphology and infraciliature of two hypotrichous ciliates, Urosoma salmastra and U. karinae sinense nov. sspec., were investigated for populations collected from the surface of intertidal gravel in the Huguang Mangrove Forest, Zhanjiang, China and the upper 10 cm layer of soil in the Sangke Grass Land in the southern part of Gansu Province, China, respectively. Urosoma salmastra is characterized by its elongate-elliptical body with no tail-like structure; two macronuclear nodules; cortical granules colourless, less than 1 μm across, and arranged in short rows; adoral zone occupying 25% of body length in vivo; paroral conspicuously short and located in front of endoral. Urosoma karinae sinense nov. sspec. is characterized by its elongate-elliptical body with no tail; 2–4 macronuclear nodules; cortical granules colourless, less than 1 μm across, and arranged in short rows; adoral zone occupying 30% of body length in vivo; paroral shorter than, and located ahead of endoral. Phylogenetic analyses based on SSU rRNA gene sequence data suggest a close relationship between U. salmastra, U. karinae sinense nov. sspec. and Oxytricha granulifera within the Oxytrichinae assemblage.     

Effects of tissue extract of adults on metamorphosis in Ascidia mentula O.F. Müller and Ascidiella scabra (O.F. Müller)

Unhatched, but fully developed larvae of two solitary ascidians Ascidia mentula O.F. Müller and Ascidiella scabra (O.F. Müller) were incubated in a variety of adult tissue extracts, which an earlier study had shown to accelerate metamorphosis. Our study confirmed this observation and showed, furthermore, that tissue extracts induce tail resorption in unhatched larvae of Ascidiella. For both species, the most active induction of metamorphosis was obtained with tunic tissue extracts. The results indicate that chemical stimulation without the presence of tactile cues may initiate metamorphosis. We suggest that the ability of tunic extracts to induce metamorphosis may explain juvenile establishment on adult ascidians and their aggregated distribution found in nature.     

Observations on the clypeasteroid Echinocyamus pusillus (O. F. Müller)

The tiny echinoid Echinocyamus pusillus (O. F. Müller) is equipped with specialized external structures that suit it for a wide variety of environments. Special features include the ability to burrow in sediments of fine sand to shell gravel and to climb vertically.Specimens dredged off the west coast of Scotland were observed in aquaria and with the SEM. E. pusillus is characterized by three kinds of spines, and by two of pedicellariae. In contrast to sand dollars, the spines play a passive rôle in the feeding and burrowing operation, probably retaining a defensive nature as in the regular urchins. It is the podia that are chiefly involved in climbing, burrowing, righting, and probably feeding. Surface ciliary currents transport particles, but not to the mouth; they may have a respiratory or cleansing function. Experimental animals did not burrow in either very fine or very coarse sand, probably because a certain relationship exists between particle weight and podia size.E. pusillus shares behavioural and structural characteristics with regular and irregular urchins. It is not a true sand dollar, but may illustrate an evolutionary stage towards such a form.     

Morphology and molecular phylogeny of a new hypotrich ciliate,Anteholosticha songi nov. spec., and an American population of Holosticha pullaster (Müller, 1773) Foissner et al., 1991 (Ciliophora,Hypotrichia)

A new urostylid ciliate, Anteholosticha songi nov. spec., isolated from forest soil in Tibet, and an American population of Holosticha pullaster (Müller, 1773) Foissner et al., 1991, isolated from a freshwater pond in the USA, are investigated in terms of their morphology, ontogenesis, and molecular biology. Anteholosticha songi nov. spec. is characterized by a slender to ellipsoidal body measuring 160–205 × 40–55 μm in vivo; rod-shaped yellowish cortical granules arranged in irregular short rows; four dorsal kineties; adoral zone consisting of 35–40 membranelles; three frontal, one buccal, one parabuccal, two frontoterminal, two pretransverse, and four to six transverse cirri and 14–25 midventral pairs; 12–22 ellipsoidal macronuclear nodules longitudinally arranged in pairs left of cell mid-line. Supplemental information on morphogenesis in Holosticha pullaster is also presented. The phylogenetic relationship of Anteholosticha and Holosticha inferred from SSU rDNA sequence data are concordant with previous studies and showing that Holosticha is monophyletic whereas Anteholosticha is polyphyletic and should be split into two or more genera.     

Corynebacterium antarcticum sp. nov., Corynebacterium marambiense sp. nov., Corynebacterium meridianum sp. nov., and Corynebacterium pygosceleis sp. nov., isolated from Adélie penguins (Pygoscelis adeliae)

A taxonomic study was conducted on 16 bacterial strains isolated from wild Adélie penguins (Pygoscelis adeliae) from Seymour (Marambio) Island and James Ross Island. An initial screening by repetitive sequence-based PCR fingerprinting divided the strains studied into four coherent groups. Phylogenetic analysis based on 16S rRNA gene sequences assigned all groups to the genus Corynebacterium and showed that Corynebacterium glyciniphilum and Corynebacterium terpenotabidum were the closest species with 16S rRNA gene sequence similarities between 95.4 % and 96.5 %. Further examination of the strains studied with ribotyping, MALDI-TOF mass spectrometry, comprehensive biotyping and calculation of average nucleotide identity and digital DNA–DNA hybridisation values confirmed the separation of the four groups from each other and from the other Corynebacterium species. Chemotaxonomically, the four strains P5828^T, P5850^T, P6136^T, P7210^T representing the studied groups were characterised by C_16:0 and C_18:1 ω9c as the major fatty acids, by the presence of meso-diaminopimelic acid in the peptidoglycan, the presence of corynemycolic acids and a quinone system with the predominant menaquinone MK-9(H₂). The results of this study show that the strains studied represent four new species of the genus Corynebacterium, for which the names Corynebacterium antarcticum sp. nov. (type strain P5850^T = CCM 8835^T = LMG 30620^T), Corynebacterium marambiense sp. nov. (type strain P5828^T = CCM 8864^T = LMG 31626^T), Corynebacterium meridianum sp. nov. (type strain P6136^T = CCM 8863^T = LMG 31628^T) and Corynebacterium pygosceleis sp. nov. (type strain P7210^T = CCM 8836^T = LMG 30621^T) are proposed.     

Biological studies and phenology of the slug Deroceras reticulatum (Müller, 1774) (Pulmonata: Stylommatophora)

Summary

In the southeast of Buenos Aires Province (Argentina), slugs cause reductions in crop yield by killing seeds and seedlings, by destroying stems and growing points, and by reducing leaf area. Deroceras reticulatum (Müller, 1774) was introduced into Argentina a long time ago, but the biology and ecology of this species in this country are still unknown. The aim of this study was to determine how temperature affects growth rate, reproduction and survival of D. reticulatum and also to assess the seasonal phenology of this species. The life cycle of D. reticulatum was investigated at 12°C, 20°C and at a temperature which alternated between 12°C for 16 h and 20°C for 8 h. The light/dark regime during the experiment was LD: 8/16 h. Slug populations were sampled from grassland located at the Experimental Station of INTA Balcarce. Eggs hatched after 16.3 to 39.8 days and fertility varied between 83.9% and 91.1%. The mean time from hatching to oviposition was longer and fecundity lower at 20°C than 12°C and 12/20°C (p <0.05). The net reproductive rate was 1.49 to 70.53 and the mean generation time varied between the 27 and 30 weeks. In natural conditions, eggs of D. reticulatum were found from early winter until the end of the spring, when soil temperature was 8–15°C and humidity was above 15%. These results indicate that D. reticulatum has one generation per year, univoltine phenology, with peak densities of slugs from the beginning of winter to the end of spring, which coincides with the sowing and emergence of winter and summer crops.     

Description of Ulvella elegans sp. nov. and U. islandica sp. nov. (Ulvellaceae,Ulvophyceae) from Iceland – a study based on morphology of species in culture and tufA gene sequences

Two new Ulvella species, U. elegans R. Nielsen & K. Gunnarsson and U. islandica R. Nielsen & K. Gunnarsson are described. These microfilamentous marine green algae were found in the sublittoral zone in northern Iceland, epiphytic on Euthora cristata and associated with a calcareous polychaete tube, respectively. Unialgal cultures were established from field-collected material for morphological observations. In culture, Ulvella elegans was characterized by rosettes of monostromatic pseudoparenchyma consisting of radiating filaments with a margin of mutually free filaments. Each cell had one pyrenoid. Hairs were not observed. Ulvella islandica had a heterotrichous morphology, consisting of dense tufts of upright broad branches and much narrower, rhizoid-like branches. Acrochaete-type hairs occurred; these are hyaline non-septate merocytic extensions from a more or less bulbous base, which may be separated from the vegetative cell below. Most cells had one pyrenoid except for a few broad cells which had two or three. In a phylogenetic reconstruction based on the chloroplast-encoded tufA gene, the sequences for the two species were clearly distinct from any other Ulvella sequence available for this gene. Ulvella islandica was placed in a clade together with U. lens, U. wittrockii, U. reticulata and U. pseudorepens. Ulvella elegans occupied a branch deep in the phylogeny but the position was poorly supported.     

Rugiloricus bacatus sp. nov. (Loricifera ‐Pliciloricidae) and a ghost‐larva with paedogenetic reproduction

Abstract

A new species of Loricifera, Rugiloricus bacatus sp. nov. is described together with the diagnoses of two other Rugiloricus species, Rugiloricus sp. nov. A and B, from the Faroe Bank (North Atlantic). Characteristic for all three species is the presence of a new type of reduced larva, a ghost‐larva. This type of reduced larva was discovered in 1986 by Jeanne Renaud‐Mornant, but it was with the Faroe Bank material that it was first discovered that the ghost‐larvae belonged to the phylum Loricifera. The ghost‐larvae are eitherfound inside late instar Higgins‐larvae, called penultimate Higgins‐larvae, or in the sediment. The three types of Higgins‐larvae from the Faroe Bank can be distinguished by characters such as anterior setae, posterior setae and toes. The adults of Rugiloricus bacatus sp. nov. are characterised by a prominent ruff resembling a pearl necklace; two of the eight clavoscalids are modified in the 1st row; the 2nd row of leg‐shaped scalids are very large and robust, and the 9th row with 30 beak‐like scalids alternating with 30 alternating plates. The postlarvae are free‐living and their scalids on the introvert are reduced to protoscalids. Postlarvae and adult stages have not been found for Rugiloricus sp. nov. A and B and therefore only diagnoses of these two species are presented here.     

General morphology and ultrastructure of the radula of Testudinalia testudinalis (O. F. Müller, 1776) (Patellogastropoda,Gastropoda)

The radular morphology of the patellid species Testudinalia testudinalis (O. F. Müller, 1776) from the White Sea was studied using light, electron, and confocal microscopy. The radula is of the docoglossan type with four teeth per row and consisting of six zones. We characterize teeth formation in T. testidinalis as follows: one tooth is formed by numerous and extremely narrow odontoblasts through apocrine secretion; this initially formed tooth consists of numerous vesicles; the synthetic apparatus of the odontoblasts is localized in the apical and central parts of the cells throughout the cytoplasm and is penetrated by microtubules which are involved in the transport of the synthesized products to the apical part of the odontoblast; the newly formed teeth consist of unpolymerized chitin. Mitotic activity is located in the lateral parts of the formation zone. The first four rows contain an irregular arrangement of teeth, but the radular teeth are regularly arranged after the fifth row. The irregularly arranged teeth early on could be a consequence of the asynchronous formation of teeth and the distance between the odontoblasts and the membranoblasts. The morphological data obtained significantly expands our knowledge of the morphological diversity of the radula formation in Gastropoda.     

Description of Phaeobola aeris gen. nov., sp. nov (Rhizaria,Cercozoa, Euglyphida) Sheds Light on Euglyphida’s Dark Matter

The majority of Euglyphida species are characterised by shells with imbricated silica scales. Environmental surveys indicate a large unexplored diversity and recent efforts hinted at a certain diversity of yet undescribed, inconspicuous, scale-lacking Euglyphida. Here we describe Phaeobola aeris gen. nov., sp. nov. that shows a variety of morphological characters typical for the Euglyphida but lacks silica scales-instead, this species bears an agglutinated test. Neither its morphology nor phylogenetic placement allows its assignment to any currently described family. We erected the yet monospecific genus Phaeobola gen. nov., which with yet available data remain Euglyphida incertae sedis.