@article {Qing2017b, title = {3D printing in zoological systematics: Integrative taxonomy of Labrys chinensis gen. nov., sp. nov. (Nematoda: Tylenchomorpha)}, journal = {Journal of Zoological Systematics and Evolutionary Research}, number = {July}, year = {2017}, keywords = {3d modeling, NEMATODE, new genus, new species, phylogeny, Tylenchidae}, issn = {09475745}, doi = {10.1111/jzs.12191}, url = {http://doi.wiley.com/10.1111/jzs.12191}, author = {Qing, Xue and Bert, Wim} } @book {Kolombia2017, title = {Morphological and molecular characterisation of Scutellonema species from yam (Dioscorea spp.) and a key to the species of~the~genus}, series = {Nematology}, volume = {19}, number = {7}, year = {2017}, pages = {751{\textendash}787}, keywords = {asiedu, clathricaudatum, coi, crop, cultivated for its edible, d2-d3, DIAGNOSTICS, dioscorea spp, ghana, IDENTIFICATION, is an important staple, KEY, nigeria, phylogeny, scutellonema, scutellonema cavenessi, scutellonema paralabiatum, species delimitation, tubers in west africa, west africa, yam}, isbn = {1568541100003}, issn = {1388-5545}, doi = {10.1163/15685411-00003084}, url = {http://booksandjournals.brillonline.com/content/journals/10.1163/15685411-00003084}, author = {Kolombia, Yao A. and Karssen, Gerrit and Viaene, Nicole and Kumar, P. Lava and Joos, Lisa and Coyne, Danny L. and Bert, Wim} } @article {Slos2017, title = {Caenorhabditis monodelphis sp. n.: defining the stem morphology and genomics of the genus Caenorhabditis}, journal = {BMC Zoology}, volume = {2}, number = {1}, year = {2017}, pages = {4}, publisher = {BMC Zoology}, keywords = {De, description, Evolution, Genome, phylogeny, systematics, taxonomy}, issn = {2056-3132}, doi = {10.1186/s40850-017-0013-2}, url = {http:///bmczool.biomedcentral.com/articles/10.1186/s40850-017-0013-2}, author = {Slos, Dieter and Sudhaus, Walter and Stevens, Lewis and Bert, Wim and Blaxter, Mark} } @article {Janssen2017b, title = {Molecular characterization and species delimiting of plant-parasitic nematodes of the genus Pratylenchus from the penetrans group (Nematoda: Pratylenchidae)}, journal = {Molecular Phylogenetics and Evolution}, year = {2017}, abstract = {Root-lesion nematodes of the genus Pratylenchus are an important pest parasitizing a wide range of vascular plants including several economically important crops. However, morphological diagnosis of the more than 100 species is problematic due to the low number of diagnostic features, high morphological plasticity and incomplete taxonomic descriptions. In order to employ barcoding based diagnostics, a link between morphology and species specific sequences has to be established. In this study, we reconstructed a multi-gene phylogeny of the Penetrans group using nuclear ribosomal and mitochondrial gene sequences. A combination of this phylogenetic framework with molecular species delineation analysis, population genetics, morphometric information and sequences from type location material allowed us to establish the species boundaries within the Penetrans group and as such clarify long-standing controversies about the taxonomic status of P. penetrans, P. fallax and P. convallariae. Our study also reveals a remarkable amount of cryptic biodiversity within the genus Pratylenchus confirming that identification on morphology alone can be inconclusive in this taxonomically confusing genus.}, keywords = {Cryptic species complex, DNA Barcoding, phylogeny, Pratylenchus arlingtoni, Root-lesion nematodes, species delimitation}, issn = {10959513}, doi = {10.1016/j.ympev.2017.07.027}, url = {http://dx.doi.org/10.1016/j.ympev.2017.07.027}, author = {Janssen, Toon and Karssen, Gerrit and Orlando, Valeria and Subbotin, Sergei A. and Bert, Wim} } @article {Godjo2018, title = {Steinernema kandii n. sp. (Rhabditida: Steinernematidae), a~new~entomopathogenic nematode from northern Benin}, journal = {Nematology}, year = {2018}, pages = {1{\textendash}22}, keywords = {1934, bicornutum -group, d2-d3, description, entomopathogenic nematodes, epn, have been, its, molecular, morphology, Morphometrics, new species, of the family, phylogeny, RHABDITIDA, steinernematidae filipjev, taxonomy, xenorhabdus indica}, isbn = {1568541100003}, issn = {1388-5545}, doi = {10.1163/15685411-00003201}, url = {http://booksandjournals.brillonline.com/content/journals/10.1163/15685411-00003201}, author = {Godjo, Anique and Afouda, Leonard and Baimey, Hugues and Couvreur, Marjolein and Zadji, Lionel and Houssou, Gladys and Bert, Wim and Willems, Anne and Decraemer, Wilfrida} } @article {ISI:000449120200008, title = {Hidden diversity in mushrooms explored: A new nematode species, Neodiplogaster unguispiculata sp n. (Rhabditida, Diplogastridae), with a key to the species of Neodiplogaster}, journal = {Zoologischer Anzeiger}, volume = {276}, year = {2018}, month = {sep}, pages = {71{\textendash}85}, publisher = {ELSEVIER GMBH, URBAN \& FISCHER VERLAG}, type = {Article}, address = {OFFICE JENA, P O BOX 100537, 07705 JENA, GERMANY}, abstract = {Neodiplogaster unguispiculata n. sp. is based on morphological and molecular data. N. unguispiculata sp. n. was isolated from Chondrostereum purpureum in Lappersheide, Tessenderlo, Belgium and cultured on potato dextrose agar seeded with fungi. N. unguispiculata sp. n. is characterised by a unique combination of the following traits: the morphology of the spicules that are distally claw-like bending ventrally, the shape of the gubernaculum that envelope the spicules, the well-developed peloderan bursa with a notched tip, a bursa spanning from anterior the cloaca to tail tip, and by the long, filiform female tail. N. unguispiculata sp. n. shows stomatal dimorphism. Phylogenetic analyses shows that monophyly of Neodiplogaster is maximally supported by both maximum likelihood and Bayesian interference methods. Various species delimitation methods appear to produce a variety of different species hypotheses in Neodiplogaster. Our study shows that molecular can support different species hypotheses. Finally, a key to the species of Neodiplogaster is provided. (C) 2018 Elsevier GmbH. All rights reserved.}, keywords = {Evolution, Neodi, phylogeny, systematics, taxonomy}, issn = {0044-5231}, doi = {10.1016/j.jcz.2018.07.004}, author = {Slos, Dieter and Couvreur, Marjolein and Bert, Wim} } @article {Slos2018, title = {Description of Myolaimus mycophilus Slos \& Bert sp. n. (Rhabditida: Myolaimidae)}, journal = {Nematology}, volume = {20}, number = {2}, year = {2018}, pages = {175{\textendash}186}, abstract = {Copyright {\textcopyright} 2018 by Koninklijke Brill NV, Leiden, The Netherlands. Myolaimus mycophilus Slos \& Bert sp. n. was isolated from mushrooms from different locations in Belgium and cultured on nutrient agar seeded with Escherichia coli OP50. Myolaimus mycophilus sp. n. is characterised by a unique combination of the following characters: adults with lateral fields not differentiated, buccal cavity triangular, cheilostom anisomorphic, female with a post-vulval uterine sac as long as the corresponding body diam., wrinkled eggshell, male with seven pairs of genital papillae, cloacal aperture covered by a trapezoidal cloacal flap and with a single ventral papilla at its base. The new species and M. goodeyorum Andr{\'a}ssy, 1984 were molecularly characterised by sequencing the 18S and D2-D3 28S expansion segments of rDNA. Phylogenetic relationships were reconstructed based on concatenated analyses and the phylogenetic placement of Myolaimus, an intriguing genus within the Rhabditida, is discussed.}, keywords = {Belgium, fungi, Ganoderma applanatum, Laetiporus sulphureus, molecular, morphology, Morphometrics, Myolaimus goodeyorum, new species, phylogeny, taxonomy, Trametes}, isbn = {1568541100003}, issn = {15685411}, doi = {10.1163/15685411-00003134}, author = {Slos, Dieter and Couvreur, Marjolein and Bert, Wim} } @article {Nguyen2019a, title = {Description of Rotylenchus rhomboides n. sp. and a Belgian population of Rotylenchus buxophilus (Tylenchomorpha: Hoplolaimidae)}, journal = {Journal of Nematology}, volume = {51}, number = {1}, year = {2019}, pages = {1{\textendash}20}, abstract = {During a survey in the Botanical garden of Ghent University, a new species Rotylenchus rhomboides n. sp. and a population of Rotylenchus buxophilus were found. Rotylenchus rhomboides n. sp. is characterized by the presence of a rhomboid-like widening of the mid-ridge of lateral field at the level of vulva, a feature previously unknown within the genus. The population of the new species, composed only by females, has a rounded labial region with 4 to 5 annuli, robust stylet (31{\textendash}37μm long), short dorsal esophageal gland (9{\textendash}19μm) overlap of the intestine, vulva located slightly posterior to mid-body, and hemispherical or rounded tail shape with large phasmids located 3 to 5 annuli anterior to the level of anus. The hierarchical cluster analysis based on morphological features indicated that the new species closely resembles R. corsicus, R. gracilidens, and R. rugatocuticulatus. The DNA analyses of the D2-D3 of 28S rDNA, ITS rDNA, and COI mtDNA sequences of Rotylenchus rhomboides n. sp. show a close relationship with R. buxophilus, R. goodeyi, R. laurentinus, R. pumilus, and R. incultus, all of which can also be differentiated from the new species by morphological features. The combination of morphological, morphometric, and molecular characteristics confirmed the new species and the first report of R. buxophilus on yam (Dioscorea tokoro) in Belgium.}, keywords = {28S{\textendash}D2D3, coi, Dioscorea tokoro, Hierarchical cluster, its, morphology, Musa basjoo, phylogeny, Plant-parasitic, Rotylenchus, Systematic, taxonomy}, issn = {0022300X}, doi = {10.21307/jofnem-2019-023}, author = {Nguyen, Huu Tien and Trinh, Quang Phap and Couvreur, Marjolein and Singh, Phougeishangbam Rolish and Decraemer, Wilfrida and Bert, Wim} } @article {Wang2019, title = {Aphelenchoides medicagus n. sp. (Tylenchina: Aphelenchoididae) found in Medicago sativa imported into China from the USA}, journal = {Nematology}, volume = {21}, year = {2019}, pages = {709{\textendash}723}, abstract = {Aphelenchoides medicagus n. sp. isolated in Ningbo Port, P.R. China, from dried leaves and shoots of Medicago sativa imported from the USA, is described. It is characterised by a lateral field with four lines (three bands), stylet 9.0-12.0 μ m long, excretory pore situated at same level as, or slightly posterior, to the nerve ring, vagina sclerotised, female vulval flap absent, post-uterine sac short, spicules 9.2-14.2 μ m long (median curved line), rosethorn-shaped, apex and rostrum rounded, poorly developed, female and male tail conical with terminus bearing star-like processes. The new species belongs to the Group 3 category of Aphelenchoides species sensu Shahina. Phylogenetic analyses based on 18S, ITS and 28S D2-D3 of rDNA and mtCOI sequences confirmed its status as a new species and closely related to A. besseyi and A. fujianensis .}, keywords = {alfalfa, description, lucerne, molecular, morphology, Morphometrics, new species, phylogeny, plant-parasitic nematode, quarantine, SEM, taxonomy}, isbn = {1568541100003}, issn = {15685411}, doi = {10.1163/15685411-00003247}, author = {Wang, Zhen and Bert, Wim and Gu, Jianfeng and Couvreur, Marjolein and Li, Hongmei} } @article {188, title = {Baujardia mirabilis gen. n., sp n. from pitcher plants and its phylogenetic position within Panagrolaimidae (Nematoda : Rhabditida)}, journal = {NematologyNematology}, volume = {5}, year = {2003}, note = {Times Cited: 0 Article English Bert, W State Univ Ghent, Dept Biol, Ledeganckstr 35, B-9000 Ghent, Belgium Cited References Count: 26 731KR BRILL ACADEMIC PUBLISHERS PLANTIJNSTRAAT 2, P O BOX 9000, 2300 PA LEIDEN, NETHERLANDS LEIDEN Part 3}, pages = {405-420}, abstract = {Measurements. line drawings and scanning electromicrographs are provided of Baujardia mirabilis gen. n., sp. n., isolated from pitcher fluid of Nepenthes mirabilis from Thailand. The new genus differs from all known nematodes in having two opposing and offset spermatheca-like pouches at the junction of oviduct and uterus. It also differs from most known Rhabditida in having four cephalic setae instead of papillae. Phylogenetic analysis of small subunit rDNA sequence data robustly places the new genus within Panagrolaimidae as a sister taxon to Panagrellus. These unusual nematodes resemble Panagrellus in body size (1.8-2.7 mill in females, 1.3-1.9 mm in males) and in the monodelphic, prodelphic female reproductive system with thickened vaginal walls and prominent postvulval sac. However. they differ from Panagrellus in the characters mentioned above, in their comparatively longer stegostom and in the shape of the male spicules. Because of its aberrant characters, inclusion of this new genus in Panagrolaimidae requires changes to the family diagnosis}, keywords = {analysis, CEPHALOBIDAE, Evolution, FAMILY, freshwater, GENUS, MODEL, Nematoda, NEMATODE, nematodes, Nepenthes, new genus, new species, Panagrellus, phylogeny, REPRODUCTIVE-SYSTEM, RHABDITIDA, SEQUENCE, taxonomy, Thailand, TOOL}, isbn = {1388-5545}, author = {Bert, W. and De Ley, I. T. and Van Driessche, R. and Segers, H. and De Ley, P.} } @proceedings {157, title = {Tylenchina (Nematoda) phylogeny: Evidence from molecules and gonoduct morphology}, volume = {38}, number = {2}, year = {2006}, note = {Times Cited: 0 Meeting Abstract English Cited References Count: 0 086KM SOC NEMATOLOGISTS}, pages = {262-263}, keywords = {gonoduct, morphology, Nematoda, PHYLOGENIES, phylogeny}, isbn = {0022-300X}, author = {Bert, W. and Weekers, P. and Borgonie, G.} } @article {139, title = {Molecular phylogeny of the Tylenchina and evolution of the female gonoduct (Nematoda : Rhabditida)}, journal = {Molecular Phylogenetics and EvolutionMolecular Phylogenetics and Evolution}, volume = {48}, number = {2}, year = {2008}, note = {Times Cited: 1 Article English Bert, W Univ Ghent, Dept Biol, Nematol Sect, Ledeganckstr 35, B-9000 Ghent, Belgium Cited References Count: 82 339CQ ACADEMIC PRESS INC ELSEVIER SCIENCE 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SAN DIEGO}, pages = {728-744}, abstract = {Tylenchina are a morphologically and functionally diverse group of nematode species that range from free-living bacteriovores, over transitory grazing root-hair feeders to highly specialized plant-parasites with complex host associations. We performed phylogenetic analyses of small subunit rDNA sequences from 97 species including an analysis that account for the RNA secondary structure in the models of evolution. The present study confirms the sister relationship of the bacteriovore Cephalobiclae with the predominantly plant-parasitic Tylenchomorpha. All analyses appoint the fungal-feeding Aphelenchidae and Aphelenchoididae as being polyphyletic but the morphology based hypothesis of their monophyly could not be significantly rejected. Within the Tylenchomorpha, the families that exclusively parasitize higher plants are joined in a single clade. However, only the monophyletic position of the (super)families Hoplolaimidae and Criconematoidea were supported; Anguinidae, Tylenchidae, Belonolaimidae and Pratylenchidae appeared to be paraphyletic or polyphyletic. Parsimony and likelihood ancestral state reconstruction revealed that burrowing endoparasitism and sedentary encloparasitism each evolved, respectively, at least six and at least three times independently, mostly from migratory ectoparasitic ancestors. Only root-knot nematodes have evolved from burrowing endoparasitic nematodes. Traditional classifications are partially misled by this convergent evolution of feeding type and associated morphology. Contrastingly, mapping attributes of the gonoduct cellular architecture, including newly obtained data of 18 species belonging to the Aphelenchoidea, Criconematoidea, Anguinidae and Panagrolaimidae, revealed a broad congruence of the gonoduct characters and the molecular phylogenetic hypothesis. Yet, the presence of an offset spermatheca and proliferation of uterus cells has evolved multiple times, the latter associated with derived endoparasitic feeding specialization and resulting reproduction mode. Ancestral state reconstruction further revealed that the gonoduct of the morphologically and ecologically dissimilar tylenchid and cephalobid nematodes evolved from a common ancestor. (C) 2008 Elsevier Inc. All rights reserved}, keywords = {analysis, ANCESTRAL CHARACTER STATES, ancestral state reconstruction, Bayesian inference, Belgium, Belonolaimidae, caenorhabditis-elegans, CELLS, CEPHALOBINA NEMATODA, CLASSIFICATION, D2-D3 EXPANSION SEGMENTS, DEVELOPMENTAL BIOLOGY, doublet model, EMBRYONIC CELL LINEAGES, Evolution, FAMILY, feeding type, gonad, gonoduct, Hoplolaimidae, long branch attraction, MODEL, MOLECULAR PHYLOGENY, morphology, Nematoda, NEMATODE, nematodes, parsimony, PHYLOGENIES, phylogeny, plant-parasitic nematodes, RHABDITIDA, ribosomal DNA, RIBOSOMAL-RNA, secondary structure model, SEQUENCE, SEQUENCES, SPERMATHECA, TYLENCHIDA, Tylenchidae, TYLENCHOIDEA NEMATODA}, isbn = {1055-7903}, author = {Bert, W. and Leliaert, F. and Vierstraete, A. R. and Vanfleteren, J. R. and Borgonie, G.} } @article {141, title = {An improved molecular phylogeny of the Nematoda with special emphasis on marine taxa}, journal = {Molecular Phylogenetics and EvolutionMolecular Phylogenetics and Evolution}, volume = {42}, number = {3}, year = {2007}, note = {Times Cited: 2 Review English Meldal, B. H. M Univ Cambridge, Hutchison MRC Res Ctr, Dept Oncol, Addenbrookes Hosp, Hills Rd, Cambridge CB2 0XZ, England Cited References Count: 102 157KB ACADEMIC PRESS INC ELSEVIER SCIENCE 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SAN DIEGO}, pages = {622-636}, abstract = {Phylogenetic reconstructions of relations within the phylum Nematoda are inherently difficult but have been advanced with the introduction of large-scale molecular-based techniques. However, the most recent revisions were heavily biased towards terrestrial and parasitic species and greater representation of clades containing marine species (e.g. Araeolaimida, Chromadorida, Desmodorida, Desmoscolecida, Enoplida, and Monhysterida) is needed for accurate coverage of known taxonomic diversity. We now add small subunit ribosomal DNA (SSU rDNA) sequences for 100 previously un-sequenced species of nematodes, including 46 marine taxa. SSU rDNA sequences for > 200 taxa have been analysed based on Bayesian inference and LogDet-transformed distances. The resulting phylogenies provide support for (i) the re-classification of the Secernentea as the order Rhabditida that derived from a common ancestor of chromadorean orders Araeolaimida, Chromadorida, Desmodorida, Desmoscolecida, and Monhysterida and (ii) the position of Bunonema close to the Diplogasteroidea in the Rhabditina. Other, previously controversial relationships can now be resolved more clearly: (a) Alaimus, Campydora, and Trischistoma belong in the Enoplida, (b) Isolaimium is placed basally to a big clade containing the Axonolaimidae, Plectidae, and Rhabditida, (c) Xyzzors belongs in the Desmodoridae, (d) Comesomatidae and Cyartonema belongs in the Monhysterida, (e) Globodera belongs in the Hoplolaimidae and (0 Paratylenchus dianeae belongs in the Criconematoidea. However, the SSU gene did not provide significant support for the class Chromadoria or clear evidence for the relationship between the three classes, Enoplia, Dorylaimia, and Chromadoria. Furthermore, across the whole phylum, the phylogenetically informative characters of the SSU gene are not informative in a parsimony analysis, highlighting the short-comings of the parsimony method for large-scale phylogenetic modelling. (c) 2006 Elsevier Inc. All rights reserved}, keywords = {Adenophorea, analysis, Bayesian inference, BAYESIAN-INFERENCE, Chromadorea, CLASSIFICATION, DNA, DORYLAIMIDA, Enoplea, Evolution, FOSSIL EVIDENCE, Globodera, Hoplolaimidae, LogDet transformation, marine nematodes, MITOCHONDRIAL-DNA, N-SP, Nematoda, NEMATODE, nematodes, parsimony, phylogenetic reconstruction, PHYLOGENIES, phylogeny, PHYLUM NEMATODA, RHABDITIDA, RIBOSOMAL-RNA GENE, Secernentea, SEQUENCES, SSU rDNA, systematics, taxonomy}, isbn = {1055-7903}, author = {Meldal, B. H. M. and Debenham, N. J. and De Ley, P. and De Ley, I. T. and Vanfleteren, J. R. and Vierstraete, A. R. and Bert, W. and Borgonie, G. and Moens, T. and Tyler, P. A. and Austen, M. C. and Blaxter, M. L. and Rogers, A. D. and Lambshead, P. J. D.} } @article {132, title = {Assessment of the configuration of the posterior cells of the nematode embryo as potential phylogenetic marker}, journal = {Russian Journal of NematologyRussian Journal of Nematology}, volume = {16}, number = {2}, year = {2008}, note = {Times Cited: 0 Article English Vangestel, S Univ Ghent, Dept Biol, Nematol Sect, KL Ledeganckstr 35, B-9000 Ghent, Belgium Cited References Count: 55 383BP MYLNEFIELD RESEARCH SERVICES INVERGOWRIE, DUNDEE DD2 5DA, SCOTLAND DUNDEE}, pages = {107-120}, abstract = {We have reconstructed the evolutionary history of an early developmental character by mapping the configuration of the posterior cells in the early embryo onto the SSU-based molecular phylogeny of Holterman (2006). We have analyzed the early embryonic development of 19 species, complemented with 20 species from the literature, covering representatives in each clade. We show that the Caenorhabditis elegans configuration, found in most species in clade III-X, is the ancestral state for these clades. alternative configurations arose inependently in clade IX, (Diploscapter coronatus), X (Halicephalobus gingivalis), XI (all investigated species) and XII (Meloidogyne incognita). A variable configuration of the posterior cells arose at least twice independently during nematode evolution, once in clade IX (D. coronatus) and once in an ancestor, shared by clade XI and XII and thus can be used as a phylogenetic marker to delineate these clades. Statistical tests based on our data-set show that the presence of a variable configuration is related to developmental tempo and egg shape}, keywords = {Belgium, C-ELEGANS EMBRYOS, Caenorhabditis, Caenorhabditis elegans, caenorhabditis-elegans, CELLS, CLEAVAGE, EARLY EMBRYOGENESIS, embryology, ENOPLIDA, Evolution, GUT, LINEAGE, MELOIDOGYNE, MOLECULAR PHYLOGENY, Nematoda, NEMATODE, phylogenetic marker, PHYLOGENIES, phylogeny, spatial configuration, SPECIFICATION}, isbn = {0869-6918}, author = {Vangestel, S. and Houthoofd, W. and Bert, W. and Vanholme, B. and Calderon-Urrea, A. and Willems, M. and Artois, T. and Borgonie, G.} } @article {72, title = {Mature spermatozoa of Brevibucca sp (Nematoda: Rhabditida: Brevibuccidae)}, journal = {Russian Journal of NematologyRussian Journal of NematologyRussian Journal of Nematology}, volume = {19}, number = {2}, year = {2011}, note = {ISI Document Delivery No.: 895YZTimes Cited: 0Cited Reference Count: 30Yushin, Vladimir V. Claeys, Myriam Houthoofd, WouterEUMAINE [RFBR 11-04-00368, RFBR 11-04-98555, FEB RAS 09-III-A-06-216]; RF government [2010-220-01-180]This research was supported in part by EUMAINE; RFBR 11-04-00368; RFBR 11-04-98555; FEB RAS 09-III-A-06-216 and RF government grant 2010-220-01-180. The authors are grateful to D.V. Fomin (Institute of Marine Biology, Vladivostok) for technical assistance.Russian acad sci, inst parasitologyMoscow}, pages = {131-138}, type = {Article}, abstract = {Mature spermatozoa found in the female gonoduct of the nematode Brevibucca sp. (Brevibuccidae, Rhabditida) were studied with transmission electron microscopy. As in other nematodes, the spermatozoa in Brevibucca sp. represent an aberrant type of male gametes characterised by the absence of an axoneme and an acrosome. Mature spermatozoa of Brevibucca sp. are amoeboid bipolar cells Ca 4-4.5 mu m diam.; each cell is subdivided into a main cell body and a pseudopod devoid of organelles. The main cell body includes a condensed nucleus, many mitochondria and so-called {\textquoteright}membranous organelles{\textquoteright} (MO). These unique organelles are characteristic of developing, as well as of mature, spermatozoa of many nematodes. The MO in Brevibucca sp. sperm resemble large (ca 0.5 diam.) vesicles with transparent content and a system of internal finger-like projections of the outer membrane. Each MO is joined to the plasmalemma of the main cell body and is open to the intercellular exterior via a pore. Each spermatozoon has a prominent pseudopod filled with the filamentous components of the cytoskeleton. The structure and development of the rhabditid (order Rhabditida apud De Ley \& Blaxter, 2002) sperm is somewhat conserved throughout the order. That is, the general pattern of spermatozoon recognized as "rhabditid" in Brevibucca sp. is similarly expressed in Spiruromorpha, Ascaridomorpha, Panagrolaimomorpha, Tylenchomorpha and Rhabditomorpha. Thus, such conservation lacks phylogenetic pointers at the scale of order. The spermatozoa of the rhabditid pattern observed also in Brevibucca sp. may be considered as an ancestral or symplesiomorphic character for several clades of the order Rhabditida.}, keywords = {caenorhabditis-elegans, dimorphism, female gonoduct, fibrous bodies, filarioidea, membranous organelles, mitochondria, phylogenetic-relationships, phylogeny, pseudopod, sperm development, spermatogenesis, sphaerularioidea, steinernematidae, tylenchomorpha, ultrastructure}, isbn = {0869-6918}, author = {Yushin, V. V. and Claeys, M. and Houthoofd, W.} }