Shape Of Spicules Research Articles

Paracapillaria (Ophidiocapillaria) siamensis sp. nov. (Nematoda: Trichuroidea): a new nematode in Naja kaouthia from Thailand.

A comprehensive investigation, incorporating both morphological and molecular analyses, has unveiled the existence of a hitherto unknown nematode species, Paracapillaria (Ophidiocapillaria) siamensis sp. nov., residing in the intestine of the monocled cobra, Naja kaouthia, in the central region of Thailand. This study integrates morphological characteristics, morphometric examination, scanning electron microscopy and molecular phylogenetic analysis (COI, 18S rRNA and ITS1 genes). The findings place the newly described species within the subgenus Ophidiocapillaria, elucidating its distinctive characteristics, including a frame-like proximal spicule shape, approximate lengths of 19 000 and 22 500 μm with approximate widths of 90 and 130 μm for males and females, 39‒45 stichocytes, elevated lips without protrusion, a dorsal bacillary band stripe with an irregular pattern of bacillary cells and evidence of intestinal infection. These features serve to differentiate it from other species within the same subgenus, notably Paracapillaria (Ophidiocapillaria) najae De, , a species coexisting P. siamensis sp. nov. in the monocled cobra from the same locality. This study addresses the co-infection of the novel species and P. najae within the same snake host, marking the second documented instance of a paracapillariid species in the monocled cobra within the family Elapidae. The genetic characterization supports the formal recognition of P. siamensis sp. nov. as a distinct species, thereby underscoring its taxonomic differentiation within the Capillariidae family. This research identifies and characterizes the new nematode species, contributing valuable insights into the taxonomy of this nematode.

First genetic characterisation and phylogenetic position of Aplectana hylambatis (Nematoda: Cosmocercidae), infecting Pithecopus azureus (Anura: Hylidae) in the Brazilian Pantanal.

Aplectana hylambatis (Baylis, 1927) is a widespread nematode in South America that infects different species of anurans from different families. Although the morphology of this species shows intraspecific variations and is well studied, A. hylambatis does not have genetic characterisation. Therefore, the present study aimed to provide the first genetic characterisation of this parasite, based on 18S and 28S rDNA sequences, as well as to evaluate its phylogenetic position in the family Cosmocercidae. The present specimens showed no major morphological variations and were assigned to A. hylambatis mainly based on the shape of spicules and the presence of mamelon-like structures slightly anterior to the vulva. The genetic characterisation confirmed the close relationship between A. hylambatis and other cosmocercids, and the 28S sequences were more informative for phylogenetic reconstruction, especially for those relationships at higher and intermediate levels. Aplectana hylmabatis was in a basal position within a clade formed by other congeners and species of Cosmocerca. The geographic origin may have influence in the divergence process of Aplectana spp. and genus was non-monophyletic and closely related to Cosmocerca, similar to previous findings. The present results will be useful for future studies on the phylogeny of Cosmocercidae, since several genera and species in this family still lack genetic characterisation. Furthermore, the 28S sequences can be useful in genetic studies of A. hylambatis populations, since this species appears to have phenotypic variations.

Integrated characterisation of Daubaylia burnupiae n. sp. (Nematoda: Daubayliidae) from a freshwater gastropod in South Africa, with comments on the biology of Daubaylia spp.

Gastropod-nematode associations are underreported worldwide. In the present study, juvenile and adult nematodes were found in the freshwater gastropod Burnupia stenochorias (Melvill & Ponsonby, 1903), from the Vaal River, South Africa. The nematodes were confirmed to belong to the genus Daubaylia chitwood & chitwood, 1934 (Daubayliidae). This is the first report of Daubaylia from a snail belonging to the family Burnupiidae, and the first report of this nematode taxon in southern Africa. Like D. pearsoni and D. malayanum from Australia and Malaysia respectively, adult females of the current species possess multiple well-developed eggs in the uteri, with larvae developing in utero. Morphological and molecular characteristics showed that the nematodes are distinct from all the described species of Daubaylia. Thus, they are considered a new species, Daubaylia burnupiae n. sp. The species differs from its congeners based on spicule shape, the short tail of the male, an anal cuticular knob-like protrusion on the female, and oesophagi with short isthmi and short glandular basal bulbs in both sexes. Three club-shaped pharyngeal lobes, extending slightly above the surface of the cephalic lips in both sexes and a pre-cloacal median papilla on the male were described using scanning electron microscopy, the first of such observations for the daubayliids. Genetic analyses showed that partial sequences of D. burnupiae n. sp. differed from species for which genetic data are available, by at least 26 and 9 base pair differences for 28S and 18S rDNA, respectively. Our results show that low prevalence and abundance of nematodes in the snails, corresponded with increased pollution in the river. We suspect that exposure to pollutants reduces the viability of the infective gravid female nematode during transmission. Therefore, the nematode is a potential bioindicator for aquatic pollution.

On stars and spikes: Resolving the skeletal morphology of planktonic Acantharia using synchrotron X-ray nanotomography and deep learning image segmentation.

Acantharia (Acantharea) are wide-spread marine protozoa, presenting one of the rare examples of strontium sulfate mineralization in the biosphere. Their endoskeletons consist of 20 spicules arranged according to a unique geometric pattern named Müller's principle. Given the diverse mineral architecture of the Acantharia class, we set out to examine the complex three-dimensional skeletal morphology at the nanometer scale using synchrotron X-ray nanotomography, followed by image segmentation based on deep learning methods. The present study focuses on how the spicules emanate from the robust central junction in the orders Symphyacanthida and Arthracanthida, the geometry of lateral spicule wings as well as pockets of interspicular space, which may be involved in cell compartmentalization. Through these morphometric studies, we observed subtle deviations from the previously described spatial arrangement of the spicules. According to our data, spicule shapes are adjusted in opposite spicules as to accommodate the overall spicule arrangement. In all types examined, previously unknown interspicular interstices were found in areas where radial spicules meet, which could have implications for the crystal growth mechanism and overall endoskeletal integrity. A deeper understanding of the spiculogenesis in Acantharia can provide biomimetic routes towards complex inorganic shapes. STATEMENT OF SIGNIFICANCE: Morphogenesis, the origin and control of shape, provides an avenue towards tailored inorganic materials. In this work, we explored the intricate skeletal organization of planktonic Acantharia, which are amongst the few strontium sulfate biomineralizing organisms in nature. By using nanoscale X-ray imaging and deep learning image segmentation, we found deviations from previously described geometric patterns and undiscovered skeletal features. The bio-inspired synthesis of inorganic materials with complex shape has important ramifications for solid-state chemistry and nanotechnology.

Two new species of Cyatholaimidae (Nematoda: Chromadorida) from the Southeastern Brazilian coast with emphasis on the pore complex and lateral pore-like structures.

Cyatholaimidae is a common and diverse family of mainly marine nematodes, potentially, with a large number of species to be discovered. The taxonomy of the group is marked by a lack of information about the evolutionary history of the characters and of detailed descriptions of morphological structures that may be taxonomically relevant. Two new species of the family are described from a sublittoral region in Southeastern Brazil, emphasizing the importance of the distribution and morphology of pore complex and pore-like structures present on the cuticle. The taxonomic importance of the cuticle ornamentation and spicule shape for the Biarmifer species, as well as the precloacal supplements structures of Pomponema species, are discussed. Biarmifer nesiotes sp. nov. differs from other species of the genus by the presence of eight longitudinal rows of pore complex on the cuticle and by the shape of the copulatory structure. Pomponema longispiculum sp. nov. differs from the most similar species, P. stomachor Wieser, 1954, by the smaller number of turns of the amphidial fovea, the shorter tail and the beginning of the cuticle lateral differentiation (3/4 of the pharynx length vs. end of the pharynx, respectively). We also obtained the SSU rDNA sequence from Pomponema longispiculum sp. nov., which is closely related to Pomponema sp. (MN250093) by about 91%. Updated tabular keys to species identification of each genus (Biarmifer and Pomponema) are included, containing morphometric data, characters related to cuticle ornamentation, and copulatory structures.

The Lysosome Origin of Biosilica Machinery in the Demospongiae Model Petrosia ficiformis (Poiret, 1789)

The silicification mechanism in sponges is a biologically controlled process where the complex and amazing shape of spicules is the result of the hierarchical assembly of silicon particles to form a composite structure with organic compounds, mainly constituted by proteins. In this work, using an integrated approach of transcriptomic and proteomic analysis, we describe the protein content of sponge spicules in the marine demosponge Petrosia ficiformis (Poiret, 1789). Proteins from spicules were obtained via an ammonium fluoride extraction procedure to remove the inorganic silica followed by SDS-PAGE electrophoresis. The resulting data of LC-MS/MS analysis of the extracted SDS-PAGE bands were then processed with the MASCOT software to search against a database consisting of transcripts and predicted proteins of P. ficiformis. The results revealed a very heterogeneous group of 21 proteins, including silicatein beta, different isoforms of cathepsins, proteins with strong homologies with enzymes like sulphatases, glycosidases, lipid-related proteins, phosphatases, and some others with unknown function. Most of the proteins found here have structures and domains attributable to lysosomes enzymes and for this reason it could be related to these cellular structures the evolutionary origin of the biosilica machinery in sponges.

Bursaphelenchus suri n. sp.: A second Bursaphelenchus syconial parasite of figs supports adaptive radiation among section Sycomorus figs

The nematode genus Bursaphelenchus is a highly divergent group. This genus mainly consists of mycophagous entomophilic species, but some species have specialized as obligate or facultative plant parasites, facultative insect parasites, or exhibit feeding dimorphism (phenotypic plasticity) leading to mycophagous and predatory forms. In the present study, a new Bursaphelenchus species, B. suri n. sp. was isolated from fresh syconia (figs) of Ficus sur and is described and illustrated based on its typological characters and molecular phylogenetic status. The new species is characterized by its highly derived feeding structures found in obligate plant parasites, lip possessing a labial disc and a long and thick stylet with a long conus and extremely well-developed basal swellings. In addition, slender body of both sexes is characteristic of the species. The new species is phylogenetically and typologically closely related to B. sycophilus, i.e., these two species share the characteristic feeding structures and form a well-supported clade within the B. fungivorus group in the genus. Biologically, these two species are both isolated from fresh figs of the section Sycomorus. However, the new species differs from B. sycophilus by the length of the female post-uterine sac and the shape of the male spicule, i.e., the new species has a long post-uterine sac and spicule condylus without dorsal recurvature. Thus, the new species is the second obligate fig parasite of the genus, and the evolutionary relationship between the B. suri n. sp. and B. sycophilus clade and section Sycomorus figs is hypothesized as an example of adaptive radiation with more species to be discovered.

Devibursaphelenchus alienae n. sp. isolated from the bark of dead Quercus aliena in Japan

Summary A new Devibursaphelenchus species isolated from the bark of a dead Quercus aliena, which had been infected and killed by Japanese oak wilt, was collected in Shiga, Japan. The new species is characterised by the relatively large body in males (661-768 μm) and females (893-1071 μm), conspicuous male bursal flap, male spicule with long condylus and wide blade, female post-vulval uterine sac (PUS) 39-54 μm or 1.6-2.3 times the vulval body diam. long, vestigial female anus, and female tail forming a strongly ventrally recurved elongate conoid with bluntly pointed or narrowly rounded terminus. The new species is typologically similar to D. lini, sharing a large body, conspicuous bursal flap, long PUS, and spicule shape, but can be distinguished from it by the absence of variation in the female tail shape, i.e., the tail of the new species is always long and strongly ventrally curved, while the tail shape varies more in D. lini. A previous molecular phylogenetic analysis suggested that the new species is fairly close to D. lini, but can be distinguished from it by the 1.0% (16 bp) difference within 1.6 kb of the 18S and 3.7% (26 bps) difference within 0.7 kb of the D2-D3 LSU ribosomal RNA genes. The newly found nematode is described and illustrated herein as D. alienae n. sp.

Two new insect-associated tylenchids, Sychnotylenchus hibisci n. sp. and Neoditylenchus xiphydriae n. sp. (Tylenchomorpha: Anguinidae), from Japan

Summary We isolated two tylenchid species belonging to the Sychnotylenchinae, Sychnotylenchus hibisci n. sp. and Neoditylenchus xiphydriae n. sp., from the bark beetle Ernoporus corpulentus and wood wasp Xiphydria ogasawarai, respectively. Sychnotylenchus hibisci n. sp. is characterised by its moderately stout body in both male and female, gubernaculum to spicule length ratio of one-third or less, crustaformeria structure composed of four columns with six large, rounded cells, and a broad female tail with a rounded terminus. The new species is closely related to S. ulmi, with which it shares body shape and gubernaculum to spicule length ratio, but is distinguished by the female tail shape and several morphometric values. Neoditylenchus xiphydriae n. sp. is characterised by its oval to leaf-shaped male bursa, male tail tip reaching the distal end of, and protruding beyond the bursa, a long post-vulval uterine sac (PUS), and a conical female tail with a narrowly rounded terminus. The species is typologically similar to N. pinophilus but is distinguished by its male spicule shape, gubernaculum to spicule length ratio, and longer PUS. Phylogenetically, the Sychnotylenchinae belongs under the Anguinidae (superfamily Sphaerularioidea) and is closely related to several Ditylenchus, Neotylenchus, Neomisticius, and Ficotylus species.

Liolophura species discrimination with geographical distribution patterns and their divergence and expansion history on the northwestern Pacific coast

The chiton Liolophura japonica (Lischke 1873) is distributed in intertidal areas of the northwestern Pacific. Using COI and 16S rRNA, we found three genetic lineages, suggesting separation into three different species. Population genetic analyses, the two distinct COI barcoding gaps albeit one barcoding gap in the 16S rRNA, and phylogenetic relationships with a congeneric species supported this finding. We described L. koreana, sp. nov. over ca. 33°24′ N (JJ), and L. sinensis, sp. nov. around ca. 27°02′–28°00′ N (ZJ). We confirmed that these can be morphologically distinguished by lateral and dorsal black spots on the tegmentum and the shape of spicules on the perinotum. We also discuss species divergence during the Plio-Pleistocene, demographic expansions following the last interglacial age in the Pleistocene, and augmentation of COI haplotype diversity during the Pleistocene. Our study sheds light on the potential for COI in examining marine invertebrate species discrimination and distribution in the northwestern Pacific.

Morphological variability of Oswaldocruzia filiformis (Nematoda: Molineidae) in amphibians from European Russia

The morphological and morphometric variability of the nematode Oswaldocruzia filiformis from ten amphibian species (Pelophylax ridibundus, Pelophylax lessonae, Pelophylax esculentus, Rana arvalis, Rana temporaria, Bufo bufo, Bufotes viridis, Pelobates vespertinus, Bombina bombina and Lissotriton vulgaris) was studied. The sampling was performed during the period of 2018–2020 in fifteen localities of European Russia. We examined the following morphological features: the number of crests in mid-body level, the shape of lateral alae, the shape of cephalic vesicle, shape and structure of spicules in males, the shape and structure of male caudal bursa, the shape and structure of the dorsal ray of bursa; and the measurements of nine morphometric characteristics in nematode females and seven characters in males, subjected to variability. Significant differences in the variability of morphometric characteristics of O. filiformis of both sexes in different amphibian species and amphibians from various regions were revealed. Likewise, significant differences were revealed for most of morphometric features of O. filiformis from amphibians of the same species from different regions of Russia. The type of male caudal bursa and the structure and shape of spicules were identical in all O. filiformis males studied. Likewise, we have not found variability in the structure of the reproductive system in O. filiformis females. Variability was noted in the shape and size of the cephalic vesicle and lateral alae, in the number at the mid-body level, in the shape and structure of the dorsal rib of male caudal bursa. Differences in morphometric characteristics of O. filiformis from amphibians of the same species from different regions of Russia can be explained by the phenotypic plasticity of the species. While variations in the nematode morphology from different amphibian species are caused by the host-induced morphological variability of the parasite. Differences in the size of nematodes and their morphology in different regions of Russia studied may be caused by changes in ecological conditions in amphibian habitats. The broad morphological variability of the nematode O. filiformis increases the adaptive capabilities of the helminth and allows it to parasitize a wide range of hosts.

Red Blood Cell (RBC) Echinocyte SEM Structure Directly Affected by Oxygen, Heat and F‐actin Destabilization

The RBC cytoskeleton is a spectrin-actin meshwork tethered to the integral membrane protein, band 3, through several proteins, including ankyrin. Their interactions affect membrane curvature, mechanics, microdomain formation, and may participate in oxygenation of hemoglobin (Hb) as deoxyHb displaces ankyrin to bind band 3. Our focus is to understand how hypoxia and elevated temperature cause RBC shape changes that may impact microvascular rouleaux formation and vessel blockage with thermal burn injury. We hypothesized that both oxygen and F-actin destabilization are required for shape change. Washed human RBCs (BioIVT) suspended in saline with 1% DMSO, 3.7μM Jasplakinolide (JASPA, polymerizes F-actin), 26.14μM Latrunculin A (LatA, depolymerizes F-actin), 0.5μM Cytochalasin D (CytoD, disrupts cytoskeleton), 2μM 4,4ʹ-diisothiocyano-2,2ʹ-stilbenedisulfonic acid (DIDS, binds band 3, untethers cytoskeleton from membrane) or control (platelet poor plasma, PPP). Each was tested at 2 temperatures (T: 37, 45°C) and 3 oxygen levels (O2: 0, 5, 10%). At T/O2, suspensions were fixed with 1.5% paraformaldehyde 1.5% glutaraldehyde, then with OsO4. Samples were serially dehydrated in ethanol, and coated with 12-15nm Au-Pd in Ar (6mA, Polaron E5100). SEM images (FEI Nova NanoSEM 450, high vacuum mode 4-5 mm working distance, beam 2kV, Everhart-Thornley Detector) were obtained and analyzed using ImageJ (NIH) for 44 samples and 656 RBC. RBC long and short diameters were obtained. For echinocytes (ECH), ‘edge’ spicule (seen on periphery), height, H, width at base (BW) and mid-height (MW) were measured; ‘face’ spicule (seen on presenting face) topology was measured (inter-node distances, nearest neighbors, angles). RBC were classified per the clinical standard as biconcave (discocyte), ECH-I (short broad spicules, flat cell), ECH-II (formed spicules, elliptical cell), ECH-III (well formed spicules, spherical). Independent of treatment, T or O2, we first confirmed that spicule shape progressed to taller with a narrower base, with closer packed conformation as ECH progressed from I to III. Independent of treatment or O2, spicules at 45°C for ECH-I were smaller in H and BW/MW, and more closely packed than at 37°C; ECH-II/III only displayed closer packing. In PPP ECH-I spicules at 0%/37°C were broader and further spaced, while spicules at 10%/45°C were significantly smaller in BW/MW and closer packed; ECH-II/III were not affected by oxygen. Concentrating on ECH-I, DIDS removed the effects on W and spacing at all oxygen/temps. Actin destabilization (CytoD) removed the effect of O2 and T on W, but not spacing; while depolymerization (LatA) had little effect on W or spacing. Actin polymerization (JASPA) had no effect on W, but removed the effect of O2 on spacing. Thus, decoupling the cytoskeleton from band 3 (0% oxygen or DIDS) resulted in fewer broad spicules; depolymerization only (LatA) had little effect, while destabilization (CytoD) reduced the W but not spacing of spicules, and polymerization (JASPA) affected spacing but not W.

Spiroxys ankarafantsika Roca et Garcia, 2008 (Nematoda: Gnathostomatidae) and Other Nematodes Parasitising Pelusios spp. (Testudines: Pelomedusidae) from South Africa and Mozambique.

The nematode Spiroxys ankarafantsika was described parasitising freshwater turtles Pelusios castanoides and Pelomedusa subrufra from Madagascar. During parasitological surveys at different localities in Mozambique and South Africa the species was recovered from the digestive tract of Pelusios sinuatus, P. subniger and P. castanoides. The species were identified based on the morphology of the anterior extremity (absence of additional teeth on pseudolabia) and the male caudal end (number and arrangement of caudal papillae, size and shape of spicules). Molecular data included a 720bp sequence fragment of 18S rDNA, the entire internal transcribed spacer 1 (ITS1), 5.8S rRNA, and internal transcribed spacer 2 (ITS), flanked by a 288bp 18S rDNA sequence and about 1000bp 28S rDNA sequence, and the mitochondrial cytochrome c oxidase subunit I (cox1) gene marker obtained in the present study. All specimen recovered were identical, based on morphological and molecular data, with the exception of two specimens showing an intraspecific divergence of 9% based on a 694bp sequence fragment of the cox1 gene. Additionally, a Contracaecum sp. third stage larva and an unidentified larva with mushroom-shaped anterior extremity were found. Descriptions of S. ankarafantsika and the two above-mentioned larval stages, supported by photomicrographs and molecular data 18S rDNA, ITS1-5.8S-ITS2-28S and cox1 gene fragments are presented herein.

Descriptions of Trichodorus lownsberyi sp. n., Nanidorus minor (Colbran, 1956) Siddiqi, 1974 (Nematoda: Trichodoridae) and Longidorus quercus sp. n. (Nematoda: Longidoridae) from Mexico

Summary A new species of stubby root nematode, Trichodorus lownsberyi sp. n., collected from soil around Buxus sempervirens at Montecillo Campus, Colegio de Postgraduados, Mexico, is described and illustrated. Trichodorus lownsberyi sp. n. is characterised by the abundant males with a characteristic spicule shape, the narrower part about mid-blade having visible bristles in most specimens, and the presence and position of the three ventromedian cervical papillae, which are all anterior to the secretory-excretory pore. Females possess a rhomboid-shaped vagina and oval to rounded triangular vaginal sclerotised pieces with a pore-like vulva. The phylogenetic relationships of T. lownsberyi sp. n. with related species were constructed using the ITS2 rRNA and the D2-D3 expansion segments of 28S rRNA gene sequences. Trichodorus lownsberyi sp. n. was a sister species to T. viruliferus in the phylogenetic trees. A Mexican population of Nanidorus minor from a peach orchard is also described and illustrated. The new needle nematode, Longidorus quercus sp. n., was recovered from soil around roots of oak, Quercus crassipes, from Cerro Jusda ‘El Diablo’ in Mexico State. Longidorus quercus sp. n. females are characterised by the C-shaped posterior end of the body after fixation, L = 4.9 (3.9-5.6) mm, a = 71 (60.8-93.2), lip region rounded, sometimes slightly flattened, marked by depression, odontostylet 170 (144-206) μm long, hemispherical to bluntly conoid tail and no males. The new species was characterised using the D2-D3 of 28S rRNA and COI gene sequences. The phylogenetic relationships of L. quercus sp. n. with other Longidorus species were reconstructed using the D2-D3 of 28S rRNA gene sequences.

A novel species Spinonema gracilispiculum sp. n. (Nematoda: Desmodoridae) from the oxygen minimum zone of Eastern Arabian Sea margin.

A new species of marine free living nematode Spinonema gracilispiculum sp. n. is described from the oxygen minimum zone of the eastern Arabian Sea (216m) margin. This new nematode species was found exclusively in the station with sandy texture and dissolved oxygen level 0.35 ml/l and are represented by only few individuals from a single location, despite analysing 288 core samples from an extensive survey along the eastern Arabian Sea OMZ region covering from 06°57'19″N to 21°30'639″N. Spinonema gracilispiculum sp. n. differs from other known species of the genus in the body length, position of the dorsal spine, contour and span of lateral alae, size and shape of spicules, number of pre cloacal setae and sexual dimorphism in presence of dorsal spine and amphideal fovea shape. This is the first record of the genus Spinonema from the Indian Ocean. A pictorial and dichotomous keys to the species of Spinonema are also provided, supplemented with comparative morphometric details of all valid species based on published information.

Molecular and morphological characterisation of Trichodorus species (Nematoda: Trichodoridae), with description of T. pseudoaequalis n. sp. from California and other states of the USA

Summary During surveys for stubby root nematodes in the natural vegetation of California, Oregon and Washington, USA, three known species, viz., Trichodorus californicus, T. intermedius and T. obscurus were recovered together with ten unidentified Trichodorus species. The three known and one new species were studied using an integrated approach. Trichodorus pseudoaequalis n. sp. is characterised by a medium-sized body about 800 μm long on average, male with two ventromedian cervical papillae anterior to secretory-excretory pore and three precloacal supplements all located anterior to the retracted spicules; spicules 39 μm long (average), slightly ventrally curved, more so in head region and blade with slight indentation mid-way and striation more pronounced in posterior half. Females possess a rather short (average 33% of corresponding body diam.) pear-shaped vagina with small vaginal sclerotised pieces (ca 1.5 μm long), rounded triangular in shape, obliquely orientated and close together; one pair of sublateral body pores anterior (about four vulval body diam.) to vulva and one pair of post-advulvar sublateral body pores. Trichodorus pseudoaequalis n. sp. differs from the most similar species, T. aequalis, in male characters like general spicule shape and ornamentation and in the position of the dorsal pharyngeal gland nucleus in both sexes (at same level of posterior ventrosublateral pair vs clearly separated). The phylogenetic relationships of the recovered species were reconstructed using the ITS2 rRNA and the D2-D3 expansion segments of 28S rRNA gene sequences.

New Genus and Two New Species of Free-Living Nematodes (Nematoda, Monhysterida) from Artificial Reservoirs in Vietnam

Descriptions and illustrations are presented for a new genus and two new species of free-living nematodes found in sediments of four artificial reservoirs for shrimp aquaculture. Paradaptonema gen. n. is morphologically close to Daptonema Cobb, 1920, but it has three glands around cardia that are absent in Daptonema, as well as a peculiar structure of the reproductive apparatus in males. Paradaptonema securum gen. n., sp. n. is characterized by a finely annulated cuticle, relatively long external labial setae, the presence of a postvulvar cell, and a peculiar shape of spicules and gubernacula. Thalassomonhystera longisoma sp. n. is morphologically close to Th. minor Gagarin, Nguyen Thi Thu, 2008 and Th. elegans Gagarin, Nguyen Vu Thanh, 2013, but differs from them in the length and slenderness of the body, as well as in the size of the external labial bristles and spicules.

Molecular and morphological characterization of Ektaphelenchoides maafiae n. sp. (Nematoda: Ektaphelenchinae) from northern forests of Iran

AbstractEktaphelenchoides maafiae n. sp. was isolated during a survey of nematodes associated with bark samples of an oak tree (Quercus castaneifolia) in Gorgan, Golestan Province, northern Iran. The new species has a body length of 480–546 μm (in females) and 431–480 μm (in males). The cuticle is weakly annulated, with three lateral lines. Lip region offset. The stylet is 13–15 μm long without basal swellings. The excretory pore is located at the level of the metacorpus base to slightly posterior, and hemizonid is at 15–17 μm posterior to the excretory pore. The post‐uterine sac is short, 6–8 μm long. Spicules having rounded condylus, rostrum short, conical with bluntly pointed tip, a cucullus (apophysis) presented on the dorsal distal end. Male tail bearing four (2 + 2) caudal papillae, conical, with sharply pointed terminus. The new species is close to four known species of the genus, including E. hunti, E. ruehmi, E. caspiensis and E. poinari, but differs from them by body size, shape of tail terminus, stylet length, shape and size of spicules, length of post‐vulval uterine sac and number of caudal papillae. Phylogenetic analysis based on small subunit (SSU) and partial large subunit (LSU) sequences of rDNA confirmed its status as a new species.

Serpinema cayennensis n. sp. (Nematoda: Camallanidae), a parasite of the freshwater turtle Rhinoclemmys punctularia Daudin (Reptilia: Testudines: Geoemydidae) from French Guiana: morphology and phylogenetic relationships with other turtle-parasitising camallanids.

The genus Serpinema was erected from the genus Camallanus to include species parasitising freshwater turtles. Following this, the taxonomic status of Serpinema was challenged by different authors considering it as a subgenus or junior synonym of Camallanus. Several specimens of these nematodes were retrieved from the spot-legged wood turtle Rhinoclemmys punctularia from Cayenne, French Guiana. These specimens clearly differed from previously reported Serpinema and Camallanus species parasitising turtles by the number of caudal papillae, shape of spicules and development of vulvar lips. Based on morphological characters the nematodes were assigned to the genus Serpinema and described as a new species S. cayennensis n. sp. The description followed by the molecular data analyses based on 28S, 18S rDNA and cytochrome oxidase subunit 1 (COI) gene sequences.

Recognizing the Causes of Parasite Morphological Variation to Resolve the Status of a Cryptogenic Pentastome

Exotic species can threaten biodiversity by introducing parasites to native hosts. Thus, it is critical to identify if the same parasite species infects both native and exotic hosts. However, developmental- or environmental-induced morphological variation may render species identification ambiguous. Our study reports a range expansion in the southern United States of the pentastome Raillietiella indica from the Mediterranean gecko, Hemidactylus turcicus, as well as a host expansion into the green anole, Anolis carolinensis, in the anole's native range. Species identification was based on sequence data and male spicule shape. In agreement with a study from Australia, we found that much of the morphological variation in hook measurements, the primary diagnostic traits of raillietiellid pentastomes, was due to development. Here, we explicitly link this developmental variation to instar stage by incorporating experimental infection data obtained from the literature. We also show that the various hook traits are themselves highly correlated and, thus, likely not independent. Taking instar stage and correlated hook variables into account, we directly controlled for development on a composite hook size measurement. Using a large sample size from H. turcicus, we did not find any consistent effects of potential factors (host sex, host snout-vent-length, or parasite intensity) that may result in environmental-induced variation in relative hook size (corrected for body length). However, relative male spicule size tended to be negatively correlated with parasite intensity. In contrast, both pentastome body length and relative hook size significantly varied among host species whereas relative male spicule size was not significantly different among host species. Our study independently supports the conclusions that developmental- and host-induced morphological variations need to be accounted for to accurately identify pentastome species.