Sven Boström - Profile on Academia.edu (original) (raw)

Papers by Sven Boström

Description of two species of Chiloplectus Andrássy, 1984 (Nematoda: Plectidae) from Ukraine and a revised taxonomy of the genus

Nematology, 2000

Swedish Plectida (Nematoda). Part 6. Neocamacolaimus parasiticus gen. n., sp. n

Zootaxa, 2014

A new genus Neocamacolaimus gen. n., with one new species N. parasiticus gen. n., sp. n. is descr... more A new genus Neocamacolaimus gen. n., with one new species N. parasiticus gen. n., sp. n. is described from the benthic polychaete Sphaerosyllis cf. hystrix collected in the Skagerrak off the west coast of Sweden. Neocamacolaimus gen. n. is placed in the family Camacolaimidae and is particularly characterised by having annulated cuticle with lateral alae; setiform cephalic sensilla located at level with amphids; amphidial fovea ventrally spiral; buccal cavity without armament; pharynx muscular; nerve ring located at base of pharynx; male reproductive system diorchic with outstretched testes; spicules weakly arcuate with straight manubrium; gubernaculum absent; alveolar supplements located in the pharyngeal region; tubular supplements absent; tail conoid; caudal glands and spinneret present. Juveniles of this genus are particularly characterised by their parasitic lifestyle and the following unique morphological features: lips form a dorso-ventrally elongated perioral disc with intern...

Consensus nematode 18S ribosomal DNA primers were designed by aligning available 18S sequences an... more Consensus nematode 18S ribosomal DNA primers were designed by aligning available 18S sequences and identifying a variable region flanked by highly conserved regions. These primers were then used to amplify nematode 18S rDNA from whole soil community DNA extracted from a range of European grassland types. Cloning of the PCR amplicons (778 bp) followed by restriction digest analysis (RFLP) resulted in the recovery of 34 unique nematode sequences from the four grasslands studied. Comparison of these data with the limited number of 18S rDNA nematode sequences currently held in on-line databases revealed that all of the sequences could be assigned to known nematode taxa albeit tentatively in some cases. Two of the sequences recovered from the site in the Netherlands (wet, hay-grassland) were recovered in a clade that included a sequence of the genus Trichodorus whilst other sequences from this site showed similarity with 18S rDNA sequences of the genus Prismatolaimus (five sequences), Xiphinema (one sequence) and Enoplus (one sequence). Of the remaining sequences, two showed some affinity with Mylonchulus (UK, upland peat), four with Steinernema (UK) and one sequence with Mesorhabditis (Hungary, east European Steppe). Three sequences from the Netherlands and one from Hungary were recovered in a clade that included a sequence of the genus Pratylenchoides whilst three further sequences from the Netherlands and two from Hungary were recovered in a clade encompassing the genus Globodera. Of the remaining nine sequences, two (NL6, NL62) formed a distinct lineage within the Adenophorea with 90% bootstrap recovery in a paraphyletic clade that included sequences of Prismatolaimus and Trichodorus. Seven sequences (three from the Netherlands, three from the UK and one from Greece) were left unassigned though the tree topology suggested some relationship (58% bootstrap recovery) with the genus Cephalobus. To assess whether primers used to amplify 18S rDNA might be used to fingerprint genetic diversity in nematode communities in soil, the environmental sequence data were used to design a second set of primers carrying a GCclamp. These primers amplified a 469 bp fragment internal to the region flanked by the primer set used to derive the nematode trees and were used to amplify 18S rDNA for subsequent analysis using denaturing gradient gel electrophoresis (DGGE). DGGE analysis of six major European grassland types revealed considerable genetic diversity between sites. However, the relationships seen with the DGGE data were inconsistent with previous studies where the same soils had been characterized with respect to functional and morphological diversity. To confirm that this second set of primers was amplifying nematode sequences, selected bands on the DGGE gels were extracted, PCR amplified and sequenced. The final alignment was 337 bases. These analyses revealed the presence of sequence signatures from the genera Paratrichodorus, Plectus, Steinernema, Globodera, Cephalobus and Pratylenchoides. q

European Journal of Taxonomy, 2014

Populations of Stegelleta are described from California, New Zealand and Senegal. An amphimictic ... more Populations of Stegelleta are described from California, New Zealand and Senegal. An amphimictic population from California is identified as belonging to S. incisa and compared with type specimens from Utah and an amphimictic population from Italy. One population from New Zealand is close to S. incisa but considered to represent a new species, Stegelleta laterocornuta sp. nov. It is particularly characterised by a 379-512 µm long body in females and 365-476 µm in males; cuticle divided into 16 rows of blocks at midbody (excluding lateral field); lateral field with four incisures; three pairs of asymmetrical lips, U-shaped primary axils without guarding processes, each lip asymmetrically rectangular with a smooth margin, only lateral lips have slender acute tines; three labial probolae, bifurcated at half of their length; vulva without flap; spermatheca 17-31 µm long; postuterine sac 7-24 µm long; spicules 21.5-23.5 µm long. Other specimens from New Zealand are identified as belonging to S. tuarua. A parthenogenetic population from Senegal is identified as belonging to S. ophioglossa and compared with type specimens from Mongolia and records of several other populations of S. ophioglossa. The generic diagnosis is emended and a key to the species of Stegelleta is provided.

Temporal dynamics of soil nematode communities in a grassland plant diversity experiment

Soil Biology and Biochemistry, 2011

We report here on an 8-year study examining links between plant and nematode communities in a gra... more We report here on an 8-year study examining links between plant and nematode communities in a grassland plant diversity experiment, located in the north of Sweden on previous agricultural soil. The examined plots contained 1, 4 and 12 common grassland plant species from three functional groups; grasses, legumes and forbs. The same plant species composition was maintained in the plots

Plant and Soil, 1999

This investigation analyses whether soil nematode diversity is correlated with soil functional pa... more This investigation analyses whether soil nematode diversity is correlated with soil functional parameters to serve as bioindicator of soil functioning. The analysis focuses on the interrelations of nematofauna, microflora, and soil nitrogen pools. The sites studied represent six major European grassland types: Northern tundra, atlantic heath, wet grassland, seminatural temperate grassland, East European steppe, and mediterranean garigue. Continental and local climate gradients were combined to a wide and continuous range of microclimate conditions. Nematode richness, as indicated by the number of genera, was highest under temperate conditions and declined towards the climatic extremes. Differences in richness affected all nematode feeding types proportionally. Nematode richness was the only parameter among a range of 15 alternatives tested that exhibited consistent correlations with mass and activity parameters of both nematofauna and microflora in the mineral grassland soils (garigue, wet grassland, seminatural grassland, steppe). In the same soils, the nematode Maturity Index was the best indicator of nitrogen status. We conclude that a high nematode richness can generally be seen as a good indicator of an active nematofauna and microflora in mineral grassland soils, and hence as an indicator of the decomposition function. The prospects of exploiting nematode diversity as an indicator of soil functioning are critically discussed. © 2001 Éditions scientifiques et médicales Elsevier SAS bioindication / diversity-function relationship / microflora / nematodes / soil nitrogen

Swedish Plectida (Nematoda). Part 5. Rhadinema timmi (Vitiello, 1971) comb. n.

Zootaxa, 2014

Leptolaimus timmi Vitiello, 1971 is redescribed from bottom sediments collected in the Skagerrak ... more Leptolaimus timmi Vitiello, 1971 is redescribed from bottom sediments collected in the Skagerrak off the west coast of Sweden. New morphological data necessitate the transfer of this species to the genus Rhadinema Cobb, 1920. The main diagnostic characters of Rhadinema timmi (Vitiello, 1971) comb. n. include: 1.3-1.8 mm long body; rounded labial region weakly offset from body contour; cephalic setae 2-4 µm long; amphid located 12-19 µm from anterior end; first body pore located 22-30 µm from anterior end; lateral field absent; stoma tubular: cheilostom with six weakly cuticularised longitudinal rugae, gymnostom with sclerotized bar-shaped rhabdia, stegostom long, tubular; female without supplements, vagina without pars refringens, vulva midventral; male with 10-11 tubular and without alveolar supplements; spicules arcuate and 21-30 µm long.

Swedish Plectida (Nematoda). Part 4. The genus Leptolaimus de Man, 1876

Zootaxa, 2013

Twelve known and nine new species of Leptolaimus are described from bottom sediments collected in... more Twelve known and nine new species of Leptolaimus are described from bottom sediments collected in marine habitats of Sweden, including the Bothnian Sea and Bothnian Bay, the Baltic Sea proper, Gullmarn Fjord and the Skagerrak. Three of these species have been previously recorded in Sweden while nine are new records for the Swedish fauna. The following known species are redescribed: Leptolaimus papilliger de Man, 1876, L. cupulatus Lorenzen, 1972, L. danicus Jensen, 1978, L. donsi (Allgén, 1946) comb. n., L. mixtus Lorenzen, 1972, L. pellucidus (Southern, 1914) comb. n., L. venustus Lorenzen, 1972, L. lorenzeni (Boucher & de Bovée, 1972) comb. n., L. alatus Vitiello, 1971, L. macer Lorenzen, 1972, L. septempapillatus Platt, 1973, L. elegans (Schuurmans Stekhoven & De Coninck, 1933) Gerlach, 1958. Leptolaimus primus sp. n. is characterised by the 319-472 µm long body; rounded labial region continuous with body contour; cephalic setae 1.5-2.0 µm long; amphid located 7.0-11.5 µm from anterior end; first body pore located 18.5-28.0 µm from anterior end; lateral field originating 35 µm from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male without tubular and with four alveolar supplements, alveolar supplements without sclerotized inner ring; spicules arcuate and 13.5-16.0 µm long. Leptolaimus secundus sp. n. is characterised by the 576-645 µm long body; rounded labial region continuous with body contour; cephalic setae 2.0 µm long; amphid located 6.5-7.0 µm from anterior end; first body pore located 23.0-28.5 µm from anterior end; lateral field originating 18.0-23.0 µm from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male with single tubular and 9-15 alveolar supplements, tubular supplement weakly arcuate with blunt tips, alveolar supplements with sclerotized lining; spicules arcuate and 23.0-26.5 µm long. Leptolaimus tertius sp. n. is characterised by the 576-579 µm long body; rounded labial region continuous with body contour; cephalic setae 2 µm long; amphid located 4-5 µm from anterior end; first body pore located 21.0-23.5 µm from anterior end; lateral field originating 26-29 µm from anterior end; male with four tubular and 7-10 alveolar supplements, tubular supplements weakly arcuate with blunt tips, alveolar supplements with sclerotized inner ring; spicules arcuate and 25-26 µm long. Leptolaimus quartus sp. n. is characterised by the 597-686 mm long body; rounded labial region continuous with body contour; cephalic setae 2.0-3.5 µm long; amphid located 5.0-7.0 µm from anterior end; first body pore located 23.5-27.0 µm from anterior end; lateral field originating 19.0-27.0 µm from anterior end; male with three tubular and 8-9 alveolar supplements, tubular supplements straight with blunt expanded tips, alveolar supplements with sclerotized inner ring; spicules arcuate and 23.0-25.0 µm long. Leptolaimus quintus sp. n. is characterised by the 443-528 µm long body; rounded labial region continuous with body contour; cephalic setae 1.0-2.0 µm long; amphid located 7.0-10.0 µm from anterior end; first body pore located 18.0-28.5 µm from anterior end; lateral field originating 25.0-41.0 µm from anterior end; female with two tubular supplements (one just posterior to cardia and one in front of anus), vagina without pars refringens, vulva right-sublateral; male with 8-10 tubular and without alveolar supplements, tubular supplements weakly arcuate with anchor-like tips; spicules arcuate and 17.0-22.0 µm long. Leptolaimus sextus sp. n. is characterised by the 626-728 µm long body; truncated labial region offset from body contour; cephalic setae 1.5-2.0 µm long; amphid located 8.0-12.0 µm from anterior end; first body pore located 41.0-48.5 µm from anterior end; lateral field originating 28.0-41.0 µm from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male with five (rarely six) tubular and without alveolar supplements, tubular supplements weakly S-shaped with bifid tips; spicules arcuate and 39.0-46.0 µm long. Leptolaimus septimus sp. n. is characterised by the 679-850 µm long body; truncate labial region offset from body contour; cephalic setae 2.5-3.5 µm long; amphid located 8.5-11.5 µm from anterior end; first body pore located 37.0-44.0 µm from anterior end; lateral field originating 26.5-37.0 µm from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male with four (rarely five) tubular and without alveolar supplements, tubular supplements weakly S-shaped, with bifid or blunt tips; spicules arcuate and 31.0-33.5 µm long. Leptolaimus octavus sp. n. is characterised by the 541-638 µm long body; truncate labial region continuous with body contour; cephalic setae 1.5-2.0 µm long; amphid located 8.5-12.0 µm from anterior end; first body pore located 31.5-41.0 µm from anterior end; lateral field…

Soil Biology and Biochemistry, 2003

Consensus nematode 18S ribosomal DNA primers were designed by aligning available 18S sequences an... more Consensus nematode 18S ribosomal DNA primers were designed by aligning available 18S sequences and identifying a variable region flanked by highly conserved regions. These primers were then used to amplify nematode 18S rDNA from whole soil community DNA extracted from a range of European grassland types. Cloning of the PCR amplicons (778 bp) followed by restriction digest analysis (RFLP) resulted in the recovery of 34 unique nematode sequences from the four grasslands studied. Comparison of these data with the limited number of 18S rDNA nematode sequences currently held in on-line databases revealed that all of the sequences could be assigned to known nematode taxa albeit tentatively in some cases. Two of the sequences recovered from the site in the Netherlands (wet, hay-grassland) were recovered in a clade that included a sequence of the genus Trichodorus whilst other sequences from this site showed similarity with 18S rDNA sequences of the genus Prismatolaimus (five sequences), Xiphinema (one sequence) and Enoplus (one sequence). Of the remaining sequences, two showed some affinity with Mylonchulus (UK, upland peat), four with Steinernema (UK) and one sequence with Mesorhabditis (Hungary, east European Steppe). Three sequences from the Netherlands and one from Hungary were recovered in a clade that included a sequence of the genus Pratylenchoides whilst three further sequences from the Netherlands and two from Hungary were recovered in a clade encompassing the genus Globodera. Of the remaining nine sequences, two (NL6, NL62) formed a distinct lineage within the Adenophorea with 90% bootstrap recovery in a paraphyletic clade that included sequences of Prismatolaimus and Trichodorus. Seven sequences (three from the Netherlands, three from the UK and one from Greece) were left unassigned though the tree topology suggested some relationship (58% bootstrap recovery) with the genus Cephalobus. To assess whether primers used to amplify 18S rDNA might be used to fingerprint genetic diversity in nematode communities in soil, the environmental sequence data were used to design a second set of primers carrying a GCclamp. These primers amplified a 469 bp fragment internal to the region flanked by the primer set used to derive the nematode trees and were used to amplify 18S rDNA for subsequent analysis using denaturing gradient gel electrophoresis (DGGE). DGGE analysis of six major European grassland types revealed considerable genetic diversity between sites. However, the relationships seen with the DGGE data were inconsistent with previous studies where the same soils had been characterized with respect to functional and morphological diversity. To confirm that this second set of primers was amplifying nematode sequences, selected bands on the DGGE gels were extracted, PCR amplified and sequenced. The final alignment was 337 bases. These analyses revealed the presence of sequence signatures from the genera Paratrichodorus, Plectus, Steinernema, Globodera, Cephalobus and Pratylenchoides. q

Nematodes, rotifers and tardigrades from nunataks in Dronning Maud Land, East Antarctica

Polar Biology, 1995

... tude 1200-1300 m, size 500 x 200 m) on 31 January 1992. ... ca = Physcia caesia; Pr cr = Pras... more ... tude 1200-1300 m, size 500 x 200 m) on 31 January 1992. ... ca = Physcia caesia; Pr cr = Prasiola crispa; Ps mi =Pseudephebe minuscula; Rh me =Rhizoplaca melanophthalma; Xa ca = Xanthoria candelaria; Xa el = Xanthoria elegans; Um ap = Umbilicaria aprina; - = not present ...

Polar Biology, 2011

The endemic Antarctic nematode Scottnema lindsayae is described from specimens collected in Taylo... more The endemic Antarctic nematode Scottnema lindsayae is described from specimens collected in Taylor Valley, McMurdo Dry Valleys, Victoria Land. The recently collected material is compared with the original description and other subsequent descriptions of the species. A more complete scanning electron microscopy (SEM) study of the species is presented. The phylogenetic position of S. lindsayae is inferred using a secondary structure-based alignment of a partial sequence of nuclear Large Subunit (LSU) ribosomal DNA. Phylogenetic trees were inferred using base-paired substitution models implemented in PHASE 2 software and Bayesian inference, and show S. lindsayae as the sister group to Stegelletina taxa.

Description of Deleyia gen. n. with a discussion of its phylogenetic relationships to the genera Daubaylia Chitwood & Chitwood, 1934 and Myolaimus Cobb, 1920 (Nematoda: Rhabditida)

Nematology, 2006

The new genus Deleyia gen. n., including two new species, D. poinari gen. n., sp. n. and D. aspic... more The new genus Deleyia gen. n., including two new species, D. poinari gen. n., sp. n. and D. aspiculata gen. n., sp. n., is described from terrestrial material (rotting wood and moss) in Ukraine. The new genus is inter alia characterised by the outer cuticular layer being defoliated along most of the body, except for labial region and tail posterior to phasmid, forming a cuticular sheath around the body and a vulval cuticular sac in females, and reduced stoma and basal bulb. Deleyia poinari gen. n., sp. n. is separated from D. aspiculata gen. n., sp. n. by a shorter body (L = 600-831 vs 756-945 ¿m), a shorter PUS (7-18 vs 44-69 ¿m), longer tail in both females and males (40-50 vs 32-38 ¿m and 37-48 vs 35 ¿m, respectively), and presence vs absence of spicules and gubernaculum. The phylogenetic position of Deleyia gen. n. and its relationships to the genera Daubaylia and Myolaimus are discussed.

Panagrolobus vanmegenae, a new genus and species from The Netherlands and Ukraine, with taxonomic revision and two new species of the genus Teratolobus Andrássy, 1968 (Nematoda: Cephalobidae)

Nematology, 2006

Five species of the subfamily Acrolobinae, viz. Panagrolobus vanmegenae gen. n., sp. n., Teratolo... more Five species of the subfamily Acrolobinae, viz. Panagrolobus vanmegenae gen. n., sp. n., Teratolobus regulus Andrássy, 1968, T. obscurus sp. n., T. hamatus (Andrássy, 1986) comb. n. and T. similis sp. n., are described and illustrated from material collected in The Netherlands, Ukraine, Costa Rica, Mexico, Australia and South Africa. The new genus is characterised by a crown-shaped labial region

Nematology, 2003

A new species of the genus Nothacrobeles is described from natural areas (a salt lake) in the Sou... more A new species of the genus Nothacrobeles is described from natural areas (a salt lake) in the Southeast Iberian Peninsula. Nothacrobeles lanceolatus sp. n. is characterized by its body length, two rows of cuticular punctations per annulus, labial probolae bifurcate with divergent prongs, pharyngeal corpus 2.4 to 3.5 times isthmus length, spermatheca length, postuterine sac 0.5 to 1.1 times the corresponding body diameter ratio, female tail conical and bearing a spindle-shaped or conical mucro with acute terminus, phasmid at 8 to 17 µm posterior to the anus, male tail conical with acute mucro, spicules length, and gubernaculum length. In addition, Nothacrobeles cf. lunensis and Zeldia punctata are studied. Cervidellus capricornis is transferred to genus Nothacrobeles.

Description of Aulolaimus multipapillatus sp. n. and A. nannocephalus Andrássy, 1972 with notes on taxonomy and phylogeny of the genus (Nematoda: Aulolaimidae)

Nematology, 2007

One new and one known species of Aulolaimus are described, viz. A. multipapillatus sp. n. from Is... more One new and one known species of Aulolaimus are described, viz. A. multipapillatus sp. n. from Israel and A. nannocephalus from Ukraine. Aulolaimus multipapillatus sp. n. is particularly characterised by a cuticle bearing ca 60 distinct longitudinal ridges, cuticle with distinct ornamentation on ventral body side anterior and posterior to vulva, 6-11 midventral sensilla anterior to cloaca, and spicules ca

Morphology, molecular characterisation and systematic position of the genus Cynura Cobb, 1920 (Nematoda: Plectida)

Nematology, 2013

ABSTRACT Descriptions of three known species of Cynura, i.e., C. cerambus, C. klunderi and C. pap... more ABSTRACT Descriptions of three known species of Cynura, i.e., C. cerambus, C. klunderi and C. papillata, are given, including SEM micrographs of C. cerambus and a tabular compendium for all species of the genus. The phylogenetic relationships of C. klunderi are inferred from molecular data. Bayesian analyses of small subunit (SSU) of rRNA sequences support a position nested among the Plectidae suggesting the secondary simplification in the morphology of pharyngeal valvular apparatus in Cynura and the 'return' from a terrestrial to a marine environment in this genus.

Effects of plant species and plant diversity on soil nematodes – a field experiment on grassland run for seven years

Nematology, 2011

ABSTRACT Plant species identity and diversity may greatly influence the composition of the nemato... more ABSTRACT Plant species identity and diversity may greatly influence the composition of the nematode fauna. In this study the development of the nematode fauna was followed in a field experiment on arable soil with monocultures and mixtures of several plant species. Experimental plots were sown with one, four or 12 species of grass, legumes and forbs and were sampled four times in 7 years. Nematode diversity was little influenced by plant diversity. Due to a pronounced increase of Paratylenchus projectus populations, the Shannon diversity index decreased in several treatments towards the end of the experiment. Differences in nematode faunal composition among treatments increased with time. In spite of the rather long duration of the experiment, the faunal composition did not stabilise but changed continuously. The obligate plant feeders Tylenchorhynchus dubius, T. maximus and Pratylenchus spp. occurred in higher numbers in monocultures than in mixtures of several plant species. Among the microbivores, the abundance of some bacterial- and fungal-feeding nematode taxa seemed to be directly influenced by the plant species identity. In the plots with Trifolium spp. there was an increase of rapidly growing bacterial feeders belonging to Rhabditidae and Panagrolaimidae already after the first growing season. The abundances of some bacterial-feeding nematodes were correlated to total plant production. The numbers of the omnivorous Mesodorylaimus sp. appeared to be influenced by the degree of plant coverage. The abundance of several nematode taxa appeared to be little influenced by the composition of the vegetation. The plant feeder P. projectus and the bacterial feeder Prismatolaimus sp. reacted rather slowly and a distinct increase in numbers was only seen after 7 years, when P. projectus strongly dominated the fauna in several treatments. Among the bacterial feeders, some species with moderate growth rate belonging to Cephalobidae decreased with time in several treatments.

Effects of moisture on soil microorganisms and nematodes: A field experiment

Microbial Ecology, 1986

The effects of soil moisture changes on bacteria, fungi, protozoa, and nematodes and changes in o... more The effects of soil moisture changes on bacteria, fungi, protozoa, and nematodes and changes in oxygen consumption were studied in a field experiment. In one plot the soil was drip-irrigated daily for 10 days, while an adjacent plot experienced one rainfall and was then allowed to dry out. Oxygen consumption was the parameter measured which responded most rapidly to changes in soil moisture content. Lengths of fluorescein diacetate-active hyphae paralleled oxygen consumption in both plots. Total hyphal length was not affected by one rainfall but increased from 700 mg(-1) dry weight soil to more than 1,600 m in less than 10 days in the irrigated plot. In the rain plot, bacterial numbers doubled within 3 days and declined during the following period of drought. In the irrigated plot, numbers increased by 50% and then remained constant over the duration of the study. Only small changes in protozoan numbers were observed, with the exception of the last sampling date in the irrigated plot when large numbers of naked amoebae were recorded 2 days after a large natural rainfall. Nematode numbers, especially obligate root feeders, increased in both treatments. The increases were caused by decoiling rather than growth. The results indicate that fungal respiration was dominating, while bacteria, lacking a suitable source of energy, were less active, except for the first days.

Russian Journal of …, 2004

Summary. Descriptions of populations of Tylocephalus auriculatus, T. cephalatus, T. nimius, T. lo... more Summary. Descriptions of populations of Tylocephalus auriculatus, T. cephalatus, T. nimius, T. longicornis sp. n. and T. primitivus sp. n. are given on the basis of studies with light and scanning electron microscopy. T. longicornis sp. 11. is characterised by a body length of 540-560 pm, cervical cuticular expa~isions bearing 20-25 annules and extending well posterior to the level of "subcephalic" setae, cornua 13 pm long with filiform terminus, tail 43-45 pln long, 49-57 somatic and 7 caudal setae. T. primitivus sp. 11. is characterised by a body length of 300-450 ym, weakly developed cervical cuticular expansions bearing 7-1 1 annules and extending halfway to the level of "subcephalic" setae, cornua cylindrical and 3-5 pm long, tail 28-46 pm long, 10-16 somatic and 3-5 caudal setae. An emended diagnosis and a revised classification of the genus Tylocephalus, and a key for identification of species in the subfamily Wilsonematinae are given.

Polar Biology - POLAR BIOL, 1996

In a previous paper the occurrence of nematodes, rotifers and tardigrades in 29 samples from nuna... more In a previous paper the occurrence of nematodes, rotifers and tardigrades in 29 samples from nunataks in Dronning Maud Land, East Antarctica taken 1991/1992 was recorded. In this study, a more thorough description of animal distribution is possible by adding 64 new samples (1993/1994), thus increasing the total number from these studies to 93 soil samples from 11 nunataks. The number of species recorded from the area has now increased from 27 to 34. The populations were patchily distributed and the species composition differed between nunatak areas in Vestfjella and Heimefrontfjella. In most samples only one or a few species of nematodes or tardigrades were found. The number of rotifer species in a particular sample varied from nought to seven. Rotifers occurred in most of the samples (76%) with a maximum density of 750 specimens/gram dry weight. The nematode distribution was more restricted. Nematodes were found in high abundance on only four of the nunataks and occurred in 35% of ...

Description of two species of Chiloplectus Andrássy, 1984 (Nematoda: Plectidae) from Ukraine and a revised taxonomy of the genus

Nematology, 2000

Swedish Plectida (Nematoda). Part 6. Neocamacolaimus parasiticus gen. n., sp. n

Zootaxa, 2014

A new genus Neocamacolaimus gen. n., with one new species N. parasiticus gen. n., sp. n. is descr... more A new genus Neocamacolaimus gen. n., with one new species N. parasiticus gen. n., sp. n. is described from the benthic polychaete Sphaerosyllis cf. hystrix collected in the Skagerrak off the west coast of Sweden. Neocamacolaimus gen. n. is placed in the family Camacolaimidae and is particularly characterised by having annulated cuticle with lateral alae; setiform cephalic sensilla located at level with amphids; amphidial fovea ventrally spiral; buccal cavity without armament; pharynx muscular; nerve ring located at base of pharynx; male reproductive system diorchic with outstretched testes; spicules weakly arcuate with straight manubrium; gubernaculum absent; alveolar supplements located in the pharyngeal region; tubular supplements absent; tail conoid; caudal glands and spinneret present. Juveniles of this genus are particularly characterised by their parasitic lifestyle and the following unique morphological features: lips form a dorso-ventrally elongated perioral disc with intern...

Consensus nematode 18S ribosomal DNA primers were designed by aligning available 18S sequences an... more Consensus nematode 18S ribosomal DNA primers were designed by aligning available 18S sequences and identifying a variable region flanked by highly conserved regions. These primers were then used to amplify nematode 18S rDNA from whole soil community DNA extracted from a range of European grassland types. Cloning of the PCR amplicons (778 bp) followed by restriction digest analysis (RFLP) resulted in the recovery of 34 unique nematode sequences from the four grasslands studied. Comparison of these data with the limited number of 18S rDNA nematode sequences currently held in on-line databases revealed that all of the sequences could be assigned to known nematode taxa albeit tentatively in some cases. Two of the sequences recovered from the site in the Netherlands (wet, hay-grassland) were recovered in a clade that included a sequence of the genus Trichodorus whilst other sequences from this site showed similarity with 18S rDNA sequences of the genus Prismatolaimus (five sequences), Xiphinema (one sequence) and Enoplus (one sequence). Of the remaining sequences, two showed some affinity with Mylonchulus (UK, upland peat), four with Steinernema (UK) and one sequence with Mesorhabditis (Hungary, east European Steppe). Three sequences from the Netherlands and one from Hungary were recovered in a clade that included a sequence of the genus Pratylenchoides whilst three further sequences from the Netherlands and two from Hungary were recovered in a clade encompassing the genus Globodera. Of the remaining nine sequences, two (NL6, NL62) formed a distinct lineage within the Adenophorea with 90% bootstrap recovery in a paraphyletic clade that included sequences of Prismatolaimus and Trichodorus. Seven sequences (three from the Netherlands, three from the UK and one from Greece) were left unassigned though the tree topology suggested some relationship (58% bootstrap recovery) with the genus Cephalobus. To assess whether primers used to amplify 18S rDNA might be used to fingerprint genetic diversity in nematode communities in soil, the environmental sequence data were used to design a second set of primers carrying a GCclamp. These primers amplified a 469 bp fragment internal to the region flanked by the primer set used to derive the nematode trees and were used to amplify 18S rDNA for subsequent analysis using denaturing gradient gel electrophoresis (DGGE). DGGE analysis of six major European grassland types revealed considerable genetic diversity between sites. However, the relationships seen with the DGGE data were inconsistent with previous studies where the same soils had been characterized with respect to functional and morphological diversity. To confirm that this second set of primers was amplifying nematode sequences, selected bands on the DGGE gels were extracted, PCR amplified and sequenced. The final alignment was 337 bases. These analyses revealed the presence of sequence signatures from the genera Paratrichodorus, Plectus, Steinernema, Globodera, Cephalobus and Pratylenchoides. q

European Journal of Taxonomy, 2014

Populations of Stegelleta are described from California, New Zealand and Senegal. An amphimictic ... more Populations of Stegelleta are described from California, New Zealand and Senegal. An amphimictic population from California is identified as belonging to S. incisa and compared with type specimens from Utah and an amphimictic population from Italy. One population from New Zealand is close to S. incisa but considered to represent a new species, Stegelleta laterocornuta sp. nov. It is particularly characterised by a 379-512 µm long body in females and 365-476 µm in males; cuticle divided into 16 rows of blocks at midbody (excluding lateral field); lateral field with four incisures; three pairs of asymmetrical lips, U-shaped primary axils without guarding processes, each lip asymmetrically rectangular with a smooth margin, only lateral lips have slender acute tines; three labial probolae, bifurcated at half of their length; vulva without flap; spermatheca 17-31 µm long; postuterine sac 7-24 µm long; spicules 21.5-23.5 µm long. Other specimens from New Zealand are identified as belonging to S. tuarua. A parthenogenetic population from Senegal is identified as belonging to S. ophioglossa and compared with type specimens from Mongolia and records of several other populations of S. ophioglossa. The generic diagnosis is emended and a key to the species of Stegelleta is provided.

Temporal dynamics of soil nematode communities in a grassland plant diversity experiment

Soil Biology and Biochemistry, 2011

We report here on an 8-year study examining links between plant and nematode communities in a gra... more We report here on an 8-year study examining links between plant and nematode communities in a grassland plant diversity experiment, located in the north of Sweden on previous agricultural soil. The examined plots contained 1, 4 and 12 common grassland plant species from three functional groups; grasses, legumes and forbs. The same plant species composition was maintained in the plots

Plant and Soil, 1999

This investigation analyses whether soil nematode diversity is correlated with soil functional pa... more This investigation analyses whether soil nematode diversity is correlated with soil functional parameters to serve as bioindicator of soil functioning. The analysis focuses on the interrelations of nematofauna, microflora, and soil nitrogen pools. The sites studied represent six major European grassland types: Northern tundra, atlantic heath, wet grassland, seminatural temperate grassland, East European steppe, and mediterranean garigue. Continental and local climate gradients were combined to a wide and continuous range of microclimate conditions. Nematode richness, as indicated by the number of genera, was highest under temperate conditions and declined towards the climatic extremes. Differences in richness affected all nematode feeding types proportionally. Nematode richness was the only parameter among a range of 15 alternatives tested that exhibited consistent correlations with mass and activity parameters of both nematofauna and microflora in the mineral grassland soils (garigue, wet grassland, seminatural grassland, steppe). In the same soils, the nematode Maturity Index was the best indicator of nitrogen status. We conclude that a high nematode richness can generally be seen as a good indicator of an active nematofauna and microflora in mineral grassland soils, and hence as an indicator of the decomposition function. The prospects of exploiting nematode diversity as an indicator of soil functioning are critically discussed. © 2001 Éditions scientifiques et médicales Elsevier SAS bioindication / diversity-function relationship / microflora / nematodes / soil nitrogen

Swedish Plectida (Nematoda). Part 5. Rhadinema timmi (Vitiello, 1971) comb. n.

Zootaxa, 2014

Leptolaimus timmi Vitiello, 1971 is redescribed from bottom sediments collected in the Skagerrak ... more Leptolaimus timmi Vitiello, 1971 is redescribed from bottom sediments collected in the Skagerrak off the west coast of Sweden. New morphological data necessitate the transfer of this species to the genus Rhadinema Cobb, 1920. The main diagnostic characters of Rhadinema timmi (Vitiello, 1971) comb. n. include: 1.3-1.8 mm long body; rounded labial region weakly offset from body contour; cephalic setae 2-4 µm long; amphid located 12-19 µm from anterior end; first body pore located 22-30 µm from anterior end; lateral field absent; stoma tubular: cheilostom with six weakly cuticularised longitudinal rugae, gymnostom with sclerotized bar-shaped rhabdia, stegostom long, tubular; female without supplements, vagina without pars refringens, vulva midventral; male with 10-11 tubular and without alveolar supplements; spicules arcuate and 21-30 µm long.

Swedish Plectida (Nematoda). Part 4. The genus Leptolaimus de Man, 1876

Zootaxa, 2013

Twelve known and nine new species of Leptolaimus are described from bottom sediments collected in... more Twelve known and nine new species of Leptolaimus are described from bottom sediments collected in marine habitats of Sweden, including the Bothnian Sea and Bothnian Bay, the Baltic Sea proper, Gullmarn Fjord and the Skagerrak. Three of these species have been previously recorded in Sweden while nine are new records for the Swedish fauna. The following known species are redescribed: Leptolaimus papilliger de Man, 1876, L. cupulatus Lorenzen, 1972, L. danicus Jensen, 1978, L. donsi (Allgén, 1946) comb. n., L. mixtus Lorenzen, 1972, L. pellucidus (Southern, 1914) comb. n., L. venustus Lorenzen, 1972, L. lorenzeni (Boucher & de Bovée, 1972) comb. n., L. alatus Vitiello, 1971, L. macer Lorenzen, 1972, L. septempapillatus Platt, 1973, L. elegans (Schuurmans Stekhoven & De Coninck, 1933) Gerlach, 1958. Leptolaimus primus sp. n. is characterised by the 319-472 µm long body; rounded labial region continuous with body contour; cephalic setae 1.5-2.0 µm long; amphid located 7.0-11.5 µm from anterior end; first body pore located 18.5-28.0 µm from anterior end; lateral field originating 35 µm from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male without tubular and with four alveolar supplements, alveolar supplements without sclerotized inner ring; spicules arcuate and 13.5-16.0 µm long. Leptolaimus secundus sp. n. is characterised by the 576-645 µm long body; rounded labial region continuous with body contour; cephalic setae 2.0 µm long; amphid located 6.5-7.0 µm from anterior end; first body pore located 23.0-28.5 µm from anterior end; lateral field originating 18.0-23.0 µm from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male with single tubular and 9-15 alveolar supplements, tubular supplement weakly arcuate with blunt tips, alveolar supplements with sclerotized lining; spicules arcuate and 23.0-26.5 µm long. Leptolaimus tertius sp. n. is characterised by the 576-579 µm long body; rounded labial region continuous with body contour; cephalic setae 2 µm long; amphid located 4-5 µm from anterior end; first body pore located 21.0-23.5 µm from anterior end; lateral field originating 26-29 µm from anterior end; male with four tubular and 7-10 alveolar supplements, tubular supplements weakly arcuate with blunt tips, alveolar supplements with sclerotized inner ring; spicules arcuate and 25-26 µm long. Leptolaimus quartus sp. n. is characterised by the 597-686 mm long body; rounded labial region continuous with body contour; cephalic setae 2.0-3.5 µm long; amphid located 5.0-7.0 µm from anterior end; first body pore located 23.5-27.0 µm from anterior end; lateral field originating 19.0-27.0 µm from anterior end; male with three tubular and 8-9 alveolar supplements, tubular supplements straight with blunt expanded tips, alveolar supplements with sclerotized inner ring; spicules arcuate and 23.0-25.0 µm long. Leptolaimus quintus sp. n. is characterised by the 443-528 µm long body; rounded labial region continuous with body contour; cephalic setae 1.0-2.0 µm long; amphid located 7.0-10.0 µm from anterior end; first body pore located 18.0-28.5 µm from anterior end; lateral field originating 25.0-41.0 µm from anterior end; female with two tubular supplements (one just posterior to cardia and one in front of anus), vagina without pars refringens, vulva right-sublateral; male with 8-10 tubular and without alveolar supplements, tubular supplements weakly arcuate with anchor-like tips; spicules arcuate and 17.0-22.0 µm long. Leptolaimus sextus sp. n. is characterised by the 626-728 µm long body; truncated labial region offset from body contour; cephalic setae 1.5-2.0 µm long; amphid located 8.0-12.0 µm from anterior end; first body pore located 41.0-48.5 µm from anterior end; lateral field originating 28.0-41.0 µm from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male with five (rarely six) tubular and without alveolar supplements, tubular supplements weakly S-shaped with bifid tips; spicules arcuate and 39.0-46.0 µm long. Leptolaimus septimus sp. n. is characterised by the 679-850 µm long body; truncate labial region offset from body contour; cephalic setae 2.5-3.5 µm long; amphid located 8.5-11.5 µm from anterior end; first body pore located 37.0-44.0 µm from anterior end; lateral field originating 26.5-37.0 µm from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male with four (rarely five) tubular and without alveolar supplements, tubular supplements weakly S-shaped, with bifid or blunt tips; spicules arcuate and 31.0-33.5 µm long. Leptolaimus octavus sp. n. is characterised by the 541-638 µm long body; truncate labial region continuous with body contour; cephalic setae 1.5-2.0 µm long; amphid located 8.5-12.0 µm from anterior end; first body pore located 31.5-41.0 µm from anterior end; lateral field…

Soil Biology and Biochemistry, 2003

Consensus nematode 18S ribosomal DNA primers were designed by aligning available 18S sequences an... more Consensus nematode 18S ribosomal DNA primers were designed by aligning available 18S sequences and identifying a variable region flanked by highly conserved regions. These primers were then used to amplify nematode 18S rDNA from whole soil community DNA extracted from a range of European grassland types. Cloning of the PCR amplicons (778 bp) followed by restriction digest analysis (RFLP) resulted in the recovery of 34 unique nematode sequences from the four grasslands studied. Comparison of these data with the limited number of 18S rDNA nematode sequences currently held in on-line databases revealed that all of the sequences could be assigned to known nematode taxa albeit tentatively in some cases. Two of the sequences recovered from the site in the Netherlands (wet, hay-grassland) were recovered in a clade that included a sequence of the genus Trichodorus whilst other sequences from this site showed similarity with 18S rDNA sequences of the genus Prismatolaimus (five sequences), Xiphinema (one sequence) and Enoplus (one sequence). Of the remaining sequences, two showed some affinity with Mylonchulus (UK, upland peat), four with Steinernema (UK) and one sequence with Mesorhabditis (Hungary, east European Steppe). Three sequences from the Netherlands and one from Hungary were recovered in a clade that included a sequence of the genus Pratylenchoides whilst three further sequences from the Netherlands and two from Hungary were recovered in a clade encompassing the genus Globodera. Of the remaining nine sequences, two (NL6, NL62) formed a distinct lineage within the Adenophorea with 90% bootstrap recovery in a paraphyletic clade that included sequences of Prismatolaimus and Trichodorus. Seven sequences (three from the Netherlands, three from the UK and one from Greece) were left unassigned though the tree topology suggested some relationship (58% bootstrap recovery) with the genus Cephalobus. To assess whether primers used to amplify 18S rDNA might be used to fingerprint genetic diversity in nematode communities in soil, the environmental sequence data were used to design a second set of primers carrying a GCclamp. These primers amplified a 469 bp fragment internal to the region flanked by the primer set used to derive the nematode trees and were used to amplify 18S rDNA for subsequent analysis using denaturing gradient gel electrophoresis (DGGE). DGGE analysis of six major European grassland types revealed considerable genetic diversity between sites. However, the relationships seen with the DGGE data were inconsistent with previous studies where the same soils had been characterized with respect to functional and morphological diversity. To confirm that this second set of primers was amplifying nematode sequences, selected bands on the DGGE gels were extracted, PCR amplified and sequenced. The final alignment was 337 bases. These analyses revealed the presence of sequence signatures from the genera Paratrichodorus, Plectus, Steinernema, Globodera, Cephalobus and Pratylenchoides. q

Nematodes, rotifers and tardigrades from nunataks in Dronning Maud Land, East Antarctica

Polar Biology, 1995

... tude 1200-1300 m, size 500 x 200 m) on 31 January 1992. ... ca = Physcia caesia; Pr cr = Pras... more ... tude 1200-1300 m, size 500 x 200 m) on 31 January 1992. ... ca = Physcia caesia; Pr cr = Prasiola crispa; Ps mi =Pseudephebe minuscula; Rh me =Rhizoplaca melanophthalma; Xa ca = Xanthoria candelaria; Xa el = Xanthoria elegans; Um ap = Umbilicaria aprina; - = not present ...

Polar Biology, 2011

The endemic Antarctic nematode Scottnema lindsayae is described from specimens collected in Taylo... more The endemic Antarctic nematode Scottnema lindsayae is described from specimens collected in Taylor Valley, McMurdo Dry Valleys, Victoria Land. The recently collected material is compared with the original description and other subsequent descriptions of the species. A more complete scanning electron microscopy (SEM) study of the species is presented. The phylogenetic position of S. lindsayae is inferred using a secondary structure-based alignment of a partial sequence of nuclear Large Subunit (LSU) ribosomal DNA. Phylogenetic trees were inferred using base-paired substitution models implemented in PHASE 2 software and Bayesian inference, and show S. lindsayae as the sister group to Stegelletina taxa.

Description of Deleyia gen. n. with a discussion of its phylogenetic relationships to the genera Daubaylia Chitwood & Chitwood, 1934 and Myolaimus Cobb, 1920 (Nematoda: Rhabditida)

Nematology, 2006

The new genus Deleyia gen. n., including two new species, D. poinari gen. n., sp. n. and D. aspic... more The new genus Deleyia gen. n., including two new species, D. poinari gen. n., sp. n. and D. aspiculata gen. n., sp. n., is described from terrestrial material (rotting wood and moss) in Ukraine. The new genus is inter alia characterised by the outer cuticular layer being defoliated along most of the body, except for labial region and tail posterior to phasmid, forming a cuticular sheath around the body and a vulval cuticular sac in females, and reduced stoma and basal bulb. Deleyia poinari gen. n., sp. n. is separated from D. aspiculata gen. n., sp. n. by a shorter body (L = 600-831 vs 756-945 ¿m), a shorter PUS (7-18 vs 44-69 ¿m), longer tail in both females and males (40-50 vs 32-38 ¿m and 37-48 vs 35 ¿m, respectively), and presence vs absence of spicules and gubernaculum. The phylogenetic position of Deleyia gen. n. and its relationships to the genera Daubaylia and Myolaimus are discussed.

Panagrolobus vanmegenae, a new genus and species from The Netherlands and Ukraine, with taxonomic revision and two new species of the genus Teratolobus Andrássy, 1968 (Nematoda: Cephalobidae)

Nematology, 2006

Five species of the subfamily Acrolobinae, viz. Panagrolobus vanmegenae gen. n., sp. n., Teratolo... more Five species of the subfamily Acrolobinae, viz. Panagrolobus vanmegenae gen. n., sp. n., Teratolobus regulus Andrássy, 1968, T. obscurus sp. n., T. hamatus (Andrássy, 1986) comb. n. and T. similis sp. n., are described and illustrated from material collected in The Netherlands, Ukraine, Costa Rica, Mexico, Australia and South Africa. The new genus is characterised by a crown-shaped labial region

Nematology, 2003

A new species of the genus Nothacrobeles is described from natural areas (a salt lake) in the Sou... more A new species of the genus Nothacrobeles is described from natural areas (a salt lake) in the Southeast Iberian Peninsula. Nothacrobeles lanceolatus sp. n. is characterized by its body length, two rows of cuticular punctations per annulus, labial probolae bifurcate with divergent prongs, pharyngeal corpus 2.4 to 3.5 times isthmus length, spermatheca length, postuterine sac 0.5 to 1.1 times the corresponding body diameter ratio, female tail conical and bearing a spindle-shaped or conical mucro with acute terminus, phasmid at 8 to 17 µm posterior to the anus, male tail conical with acute mucro, spicules length, and gubernaculum length. In addition, Nothacrobeles cf. lunensis and Zeldia punctata are studied. Cervidellus capricornis is transferred to genus Nothacrobeles.

Description of Aulolaimus multipapillatus sp. n. and A. nannocephalus Andrássy, 1972 with notes on taxonomy and phylogeny of the genus (Nematoda: Aulolaimidae)

Nematology, 2007

One new and one known species of Aulolaimus are described, viz. A. multipapillatus sp. n. from Is... more One new and one known species of Aulolaimus are described, viz. A. multipapillatus sp. n. from Israel and A. nannocephalus from Ukraine. Aulolaimus multipapillatus sp. n. is particularly characterised by a cuticle bearing ca 60 distinct longitudinal ridges, cuticle with distinct ornamentation on ventral body side anterior and posterior to vulva, 6-11 midventral sensilla anterior to cloaca, and spicules ca

Morphology, molecular characterisation and systematic position of the genus Cynura Cobb, 1920 (Nematoda: Plectida)

Nematology, 2013

ABSTRACT Descriptions of three known species of Cynura, i.e., C. cerambus, C. klunderi and C. pap... more ABSTRACT Descriptions of three known species of Cynura, i.e., C. cerambus, C. klunderi and C. papillata, are given, including SEM micrographs of C. cerambus and a tabular compendium for all species of the genus. The phylogenetic relationships of C. klunderi are inferred from molecular data. Bayesian analyses of small subunit (SSU) of rRNA sequences support a position nested among the Plectidae suggesting the secondary simplification in the morphology of pharyngeal valvular apparatus in Cynura and the 'return' from a terrestrial to a marine environment in this genus.

Effects of plant species and plant diversity on soil nematodes – a field experiment on grassland run for seven years

Nematology, 2011

ABSTRACT Plant species identity and diversity may greatly influence the composition of the nemato... more ABSTRACT Plant species identity and diversity may greatly influence the composition of the nematode fauna. In this study the development of the nematode fauna was followed in a field experiment on arable soil with monocultures and mixtures of several plant species. Experimental plots were sown with one, four or 12 species of grass, legumes and forbs and were sampled four times in 7 years. Nematode diversity was little influenced by plant diversity. Due to a pronounced increase of Paratylenchus projectus populations, the Shannon diversity index decreased in several treatments towards the end of the experiment. Differences in nematode faunal composition among treatments increased with time. In spite of the rather long duration of the experiment, the faunal composition did not stabilise but changed continuously. The obligate plant feeders Tylenchorhynchus dubius, T. maximus and Pratylenchus spp. occurred in higher numbers in monocultures than in mixtures of several plant species. Among the microbivores, the abundance of some bacterial- and fungal-feeding nematode taxa seemed to be directly influenced by the plant species identity. In the plots with Trifolium spp. there was an increase of rapidly growing bacterial feeders belonging to Rhabditidae and Panagrolaimidae already after the first growing season. The abundances of some bacterial-feeding nematodes were correlated to total plant production. The numbers of the omnivorous Mesodorylaimus sp. appeared to be influenced by the degree of plant coverage. The abundance of several nematode taxa appeared to be little influenced by the composition of the vegetation. The plant feeder P. projectus and the bacterial feeder Prismatolaimus sp. reacted rather slowly and a distinct increase in numbers was only seen after 7 years, when P. projectus strongly dominated the fauna in several treatments. Among the bacterial feeders, some species with moderate growth rate belonging to Cephalobidae decreased with time in several treatments.

Effects of moisture on soil microorganisms and nematodes: A field experiment

Microbial Ecology, 1986

The effects of soil moisture changes on bacteria, fungi, protozoa, and nematodes and changes in o... more The effects of soil moisture changes on bacteria, fungi, protozoa, and nematodes and changes in oxygen consumption were studied in a field experiment. In one plot the soil was drip-irrigated daily for 10 days, while an adjacent plot experienced one rainfall and was then allowed to dry out. Oxygen consumption was the parameter measured which responded most rapidly to changes in soil moisture content. Lengths of fluorescein diacetate-active hyphae paralleled oxygen consumption in both plots. Total hyphal length was not affected by one rainfall but increased from 700 mg(-1) dry weight soil to more than 1,600 m in less than 10 days in the irrigated plot. In the rain plot, bacterial numbers doubled within 3 days and declined during the following period of drought. In the irrigated plot, numbers increased by 50% and then remained constant over the duration of the study. Only small changes in protozoan numbers were observed, with the exception of the last sampling date in the irrigated plot when large numbers of naked amoebae were recorded 2 days after a large natural rainfall. Nematode numbers, especially obligate root feeders, increased in both treatments. The increases were caused by decoiling rather than growth. The results indicate that fungal respiration was dominating, while bacteria, lacking a suitable source of energy, were less active, except for the first days.

Russian Journal of …, 2004

Summary. Descriptions of populations of Tylocephalus auriculatus, T. cephalatus, T. nimius, T. lo... more Summary. Descriptions of populations of Tylocephalus auriculatus, T. cephalatus, T. nimius, T. longicornis sp. n. and T. primitivus sp. n. are given on the basis of studies with light and scanning electron microscopy. T. longicornis sp. 11. is characterised by a body length of 540-560 pm, cervical cuticular expa~isions bearing 20-25 annules and extending well posterior to the level of "subcephalic" setae, cornua 13 pm long with filiform terminus, tail 43-45 pln long, 49-57 somatic and 7 caudal setae. T. primitivus sp. 11. is characterised by a body length of 300-450 ym, weakly developed cervical cuticular expansions bearing 7-1 1 annules and extending halfway to the level of "subcephalic" setae, cornua cylindrical and 3-5 pm long, tail 28-46 pm long, 10-16 somatic and 3-5 caudal setae. An emended diagnosis and a revised classification of the genus Tylocephalus, and a key for identification of species in the subfamily Wilsonematinae are given.

Polar Biology - POLAR BIOL, 1996

In a previous paper the occurrence of nematodes, rotifers and tardigrades in 29 samples from nuna... more In a previous paper the occurrence of nematodes, rotifers and tardigrades in 29 samples from nunataks in Dronning Maud Land, East Antarctica taken 1991/1992 was recorded. In this study, a more thorough description of animal distribution is possible by adding 64 new samples (1993/1994), thus increasing the total number from these studies to 93 soil samples from 11 nunataks. The number of species recorded from the area has now increased from 27 to 34. The populations were patchily distributed and the species composition differed between nunatak areas in Vestfjella and Heimefrontfjella. In most samples only one or a few species of nematodes or tardigrades were found. The number of rotifer species in a particular sample varied from nought to seven. Rotifers occurred in most of the samples (76%) with a maximum density of 750 specimens/gram dry weight. The nematode distribution was more restricted. Nematodes were found in high abundance on only four of the nunataks and occurred in 35% of ...