Lateral Alae Research Articles

Redescription of Raphidascaris (Ichthyascaris) vicentei (Nematoda: Raphidascarididae) Parasitizing Lutjanid Fishes (Actinopterygii: Lutjanidae) from the Northeast Coast of Brazil, Including First Observation Using SEM.

In this study, 143 lutjanid fishes representing four different species from the Northeast coast off Brazil were analyzed for parasites. The aim of the present study is to provide a detailed redescription of R. (I.) vicentei, collected from lutjanid fishes in Brazil, including the first observation of the species using scanning electron microscopy (SEM). Nematodes found clarified in a crescent glycerin series, were photographed and measured (in mm), and some specimens destined for SEM. The Illustrations were made using an optical microscope with a drawing tube. Nematodes found were identified as Raphidascaris (Ichthyascaris) vicentei, infecting 6.29% of the examined fish. Detailed morphological analysis revealed the following characteristics observed for the first time in this species: labial papillae, narrow lateral alae and the detailed structure of male spicules. These contributions help filling the gaps in the literature and expand the knowledge of this parasite morphology. The presence of R. (I.) vicentei in four lutjanid species may indicates low host specificity, highlighting its adaptability to different hosts. Furthermore, new host records are given. This research provides the most comprehensive morphological description of R. (I.) vicentei to date, generating crucial insights for a better understanding of the parasitic biodiversity off the Brazilian Northeastern coast of Brazil, as well as establishing foundation for future investigations on the ecology and impacts of these parasites in fish populations from this region.

Morphological and molecular characterization of Desmicola ryukyuensis n. sp. (Nematoda: Oxyuridomorpha: Thelastomatidae) from the wood-feeding cockroach Panesthia angustipennis yayeyamensis Asahina, 1988 (Blattaria: Blaberidae) in the Ryukyu Archipelago, Japan.

Desmicola ryukyuensis n. sp. (Nematoda: Oxyuridomorpha: Thelastomatidae) is described from the wood-feeding cockroach Panesthia angustipennis yayeyamensis Asahina, 1988 (Blattaria: Blaberidae) in Iriomote Island, Japan. The males of D. ryukyuensis n. sp. are similar to D. lamdongensis Sokolova, 2019 but differ by the length of the spicule and the extension of the lateral alae. The females of D. ryukyuensis n. sp. resemble those of D. ornata Jex, Schneider, Rose & Cribb, 2005, but can be differentiated by the shape of the sensilla in the interlabial space and the presence of lateral alae in D. ryukyuensis n. sp. that are absent in D. ornata. The females of D. ryukyuensis n. sp. are similar to D. lamdongensis. However, they differ in the morphology of the lips and the size of the eggs. The phylogeny of D. ryukyuensis n. sp. is inferred by the D2-D3 domains of the 28S rDNA. The new species forms a clade with another sequence of an unidentified Desmicola species from a Vietnamese wood-feeding cockroach.

New species of Cosmocerca (Nematoda: Cosmocercidae), parasite of Leptodactylus melanonotus in Western Mexico, and new records for this species and Incilius marmoreus (Amphibia)

Specimens of the amphibian species Leptodactylus melanonotus and Incilius marmoreus were collected in several localities in Colima State, Mexico, from July to October 2021. An undescribed species of nematode of the genus Cosmocerca was found in the intestine of L. melanonotus. The new species differs from every other species assigned to this genus by the combination of the following characters: absence of lateral alae in males, 5 plectanes, spicules size, and gubernaculum size and shape. This is the 39th species included in the genus worldwide and it is the second described in Mexico. Six helminth species were collected during this study: Rauschiella poncedeleoni, Cosmocerca colimense n. sp., Oswaldocruzia subauricularis, and Rhabdias sp. of L. melanonotus; Aplectana incerta and Oswaldocruzia pipiens of I. marmoreus.

Cosmocerca goroensis n. sp. (Nematoda: Cosmocercidae) from South Africa and its phylogenetic relationships with other cosmocercids based on partial 28S sequences.

Nematodes of the genus Cosmocerca are commonly found in various amphibians in South Africa and in most cases are identified as C. ornata. However, after detailed morphological studies and molecular approaches, three new species of the genus were recently described from three different frogs in South Africa. In present study, we describe another new species - Cosmocerca goroensis parasitising the Northern Pygmy Toad Poyntonophrynus fenoulheti in Soutpansberg mountains, Limpopo province, South Africa. The new species is characterised by prominent sex dimorphism, wide lateral alae, numerous somatic papillae in both sexes, and wide triangularly shaped gubernaculum and simple prominent spicules in males. Cosmocerca goroensis n. sp. distinguished from congeners, previously reported in Southern Africa by the shape of the gubernaculum and arrangement of somatic papillae in males. Morphological differences were confirmed by molecular analysis based on fragments of the 28S gene. Phylogenetic analysis based on the 28S gene fragments, including C. goroensis n. sp. and newly obtained sequence of C. ornata from Pelophylax lessonae from Ukraine, supported previously known data of closer relationships between species of Cosmocerca and Aplectana and more distant with Cosmocercoides spp.

Morphological and molecular characterization of Travassosinema viatorum n. sp. (Nematoda: Oxyuridomorpha: Travassosinematidae) from the invasive millipede Chamberlinius hualienensis Wang, 1956 (Diplopoda: Polydesmida: Paradoxosomatidae) in Okinawa, Japan.

Travassosinema viatorum n. sp. (Nematoda: Oxyuridomorpha: Travassosinematidae) is described from the invasive millipede Chamberlinius hualienensis Wang, 1956 (Diplopoda: Polydesmida: Paradoxosomatidae) in Okinawa, Japan. Females of T. viatorum n. sp. resemble T. claudiae Morffe & Hasegawa, 2017; T. thyropygi Hunt, 1996 and T. travassosi Rao, 1958 by lacking both lateral alae and a contraction posterior to the vulva. The body length of T. viatorum n. sp. is shorter than the aforementioned species. It differs from T. claudiae and T. thyropygi by its comparatively longer oesophagus, more posterior vulva, lack of cuticular ribs in the alae of the umbraculum and in the position of the nerve ring and excretory pore. Travassosinema viatorum n. sp. can be differentiated from T. travassosi by the extension of the cephalic umbraculum and the smaller eggs. The phylogeny of T. viatorum n. sp. is inferred by the D2-D3 domains of the 28S rDNA. The new species is located in a monophyletic clade with other sequences of Travassosinema from millipedes. The comparison of the phylogenies of Travassosinema and their hosts points to host switching rather than coevolution as a mechanism to explain the host-nematode relationships. This constitutes the second species of the genus Travassosinema described from the Japanese archipelago and the first oxyuridomorph nematodes found in C. hualienensis.

Descriptions of Leptolaimus sinensis sp. nov. and Perspiria brevicaudata sp. nov. (Nematoda) from the Yellow Sea, China

Two new free-living marine nematodes which were collected at silt beach of Rizhao along the Yellow Sea are identified here as Leptolaimus sinensis sp. nov. and Perspiria brevicaudata sp. nov. Leptolaimus sinensis sp. nov. is characterized by annulated cuticle with lateral alae, 2 µm in width; buccal cavity cylindrical; cephalic setae 2 µm long; amphidial fovea unispiral, circular in outline; six to seven evenly spaced tubular precloacal supplements and 23-29 continuous alveolar supplements extending from cloaca to level of the base of buccal cavity; spicules slender, slightly arcuate; gubernaculum with dorso-caudal apophysis; tail conico-cylindrical, about 6 times cloacal body diameter in males and elongated in females, about 9 times anal body diameter in length. Perspiria brevicaudata sp. nov. is characterized by having four cephalic setae and four cervical setae; small buccal cavity with dorsal tooth and minute ventral tooth; amphidial fovea unispiral, looking like double circle in outline, surrounded partially by cuticle striations; spicules arcuate with ventral velum, handle-like proximally and tapered distally; gubernaculum plate-shaped, without apophysis; twelve winged precloacal supplements present. Updated identification keys for group of Leptolaimus species characterized by the presence of both alveolar and tubular precloacal supplements and for species of Perspiria are also given.

Morphological and molecular characterization of Cosmocercoides amapari n. sp. (Nematoda: Cosmocercidae), parasitic in hylid frogs from the Brazilian Amazon.

Cosmocercoides Wilkie, 1930 are gastrointestinal parasites commonly found in amphibians and reptiles, with 4 species reported from the Neotropical region. In the present study, a new species of Cosmocercoides, namely Cosmocercoides amapari n. sp. is described using integrated approaches such as light and scanning microscopy, and DNA sequencing of the mitochondrial cytochrome c oxidase subunit 1 gene. The specimens were collected from the large intestine of 3 species of hylid frogs in Amapá, Brazil. The new species can be distinguished from its congeners by morphological traits, including the pattern of caudal papillae, absence of the gubernaculum, 2 poorly sclerotized spicules, presence of lateral alae and somatic papillae along the body. In addition, our molecular analyses and phylogenetic reconstructions strongly support the status of the new taxon, which clustered poorly with a large clade of Cosmocerca spp. Cosmocercoides amapari n. sp. is the 29th species of the genus, the 5th from the Neotropical region, the third reported in Brazil, the second described from the Amazon region and the first belonging to the Neotropical region with molecular data.

A new species of Aplectana Railliet & Henry, 1916 (Nematoda: Cosmocercidae) in the Brazilian Amazon and the taxonomic status of Aplectana longa.

Nematodes of the genus Aplectana Railliet & Henry, 1916 are common parasites of the digestive tract of amphibians and reptiles in the Neotropical region. During a parasite survey on Boana boans (Linnaeus, 1758), we found specimens of nematodes with Aplectana characteristics. We observed a set of characteristics that differs the species of our study from its congeners, and the present study describes a new species of Aplectana parasite of B. boans using light microscopy and scanning electron microscopy. Aplectana pella n. sp. has lateral alae and somatic papillae in males and females; males have equal short spicules, and the gubernaculum is absent. The arrangement of pairs of caudal papillae also differs from other species (2 precloacal,1 adcloacal, and 5 postcloacal+1 unpaired). In females, the vulva is simple, with non-prominent lips, and equatorial. This is the first record of the genus Aplectana parasitizing B. boans and the 58th species described for this genus. Additionally, we added the precloacal papillae pattern of A. delirae, and based on morphological and morphometric characteristics, we propose the reallocation of Aplectana longa to the genus Oxyascaris.

A New Species of Free-Living Nematodes (Desmodorida, Desmodoridae) in the Romanian Black Sea Waters

The paper reports the record of Pseudochromadora gomoi sp.n. in circalittoral habitats (at depths of 47–59 m) of the Romanian Black Sea waters. The species is characterized by a unispiral amphidial fovea, the presence of lateral alae stretching from the posterior end of the cardia to the level of the cloacal opening, but also shows unique features found in other Desmodorida genera (i.e., the presence of a precloacal ventral ala in males similar to several Desmodora or Echinodesmodora species and eight subcephalic setae on the head capsule). The presence of a constrictor cuticle ring and orange elongated ducts in the anterior body part as in Pseudodesmodora lacrima, Leduc and Wharton, 2010, were also noted. The morphometric measurements of our species differ from most of the Pseudochromadora species reported in specialty literature. We extracted and counted all desmodorid individuals from 9 meiobenthic samples collected in June 2020, and performed a detailed morphological analysis of 12 individuals (5 females and 7 males) belonging to our species, also highlighting the dissimilarities with the related desmodorid species.

Leidynema bestium sp. n. (Oxyuridomorpha: Thelastomatidae) an intestinal parasite of blaberid cockroaches from Yaroslavl Zoo, Russia

A new species of thelastomatid Leidynema bestium sp. n. is described from the hind gut lumen of the cockroaches Diploptera punctata (Eschscholtz, 1922) and Elliptorhina chopardi (Lefeuvre, 1966). The new species is characterized by a combination of morphological features: presence of lateral alae in both sexes with posterior margin of alae in females not ending in the shape of a spike; longitudinal striation of the anteriormost annuli in males; four male genital papillae, equatorial position of vulva. In the cladogram inferred from analysis of D2-D3 segment of LSU rDNA L. bestium sp. n. demonstrates a position independent of the Leidynema species with known sequences of this taxonomic marker near the basal node for this genus.

Identification and characterization of epicuticular proteins of nematodes sharing motifs with cuticular proteins of arthropods.

Specific collagens and insoluble proteins called cuticlins are major constituents of the nematode cuticles. The epicuticle, which forms the outermost electron-dense layer of the cuticle, is composed of another category of insoluble proteins called epicuticlins. It is distinct from the insoluble cuticlins localized in the cortical layer and the fibrous ribbon underneath lateral alae. Our objective was to identify and characterize genes and their encoded proteins forming the epicuticle. The combination between previously obtained laboratory results and recently made available data through the whole-genome shotgun contigs (WGS) and the transcriptome Shotgun Assembly (TSA) sequencing projects of Ascaris suum allowed us to identify the first epicuticlin gene, Asu-epic-1, on the chromosome VI. This gene is formed of exon1 (55 bp) and exon2 (1067 bp), separated by an intron of 1593 bp. Exon 2 is formed of tandem repeats (TR) whose number varies in different cDNA and genomic clones of Asu-epic-1. These variations could be due to slippage of the polymerases during DNA replication and RNA transcription leading to insertions and deletions (Indels). The deduced protein, Asu-EPIC-1, consists of a signal peptide of 20 amino acids followed by 353 amino acids composed of seven TR of 49 or 51 amino acids each. Three highly conserved tyrosine motifs characterize each repeat. The GYR motif is the Pfam motif PF02756 present in several cuticular proteins of arthropods. Asu-EPIC-1 is an intrinsically disordered protein (IDP) containing seven predicted molecular recognition features (MoRFs). This type of protein undergoes a disorder-to-order transition upon binding protein partners. Three epicuticular sequences have been identified in A. suum, Ascaris lumbricoides, and Toxocara canis. Homologous epicuticular proteins were identified in over 50 other nematode species. The potential of this new category of proteins in forming the nematode cuticle through covalent interactions with other cuticular components, particularly with collagens, is discussed. Their localization in the outermost layer of the nematode body and their unique structure render them crucial candidates for biochemical and molecular interaction studies and targets for new biotechnological and biomedical applications.

A new species of nematode parasite, Cucullanus tunisiensis sp. nov. (Nematoda: Cucullanidae) from Epinephelus aeneus (Perciformes: Serranidae) off Tunisia.

Cucullanus tunisiensis sp. nov., (Nematoda: Cucullanidae), collected from the intestine of the white grouper Epinephelus aeneus from waters off the coast of Tunisia is described based on light and scanning electron microscopic observations. The new species is characterized by the presence of lateral alae, ventral sucker, long unequal spicules (left spicule 2474-2789 μm long, right spicule 2357-2518 μm long). This is the sixth nominal species of the genus Cucullanus Müller, 1777 and the first representative of this genus infecting fishes of Serranidae family reported from Tunisian waters.

A new species of Hystrignathus (Nematoda: Thelastomatoidea: Hystrignathidae) associated with the Bess Beetle Passalus Interruptus Linnaeus (Coleoptera: Passalidae) from The Peruvian Amazonia.

Bess beetles (Passalidae) are known to maintain biological interactions with a diverse gut symbiotic community, which is far from being well described since these communities from most of the species of Passalidae have not been studied. In order to improve our knowledge of these communities, we describe a new species of Nematoda of the genus Hystrignathus (Hystrignathidae) associated with Passalus interruptus, a bess beetle species of the tribe Passalini collected in Hunuco, Peru, in the Peruvian Amazonia. Hystrignathus nunashae n. sp. is characterized by the presence of cuticular spines beginning just after the end of the first cephalic annule, a posterior cephalic ring dilated and longer than the anterior ring, as well as ornamented eggs. The new species has a didelphic-amphidelphic reproductive system, lateral alae extending from the posterior end of procorpus almost reaching the anus, and a short subulate tail. The external and internal morphological traits of the new species are described, and additionally, based on nuclear ribosomal DNA, we investigated the phylogenetic relationships of the new species.

Redescription of Ransomnema bravoae Sánchez-Velázquez, 1981 (Ransomnematoidea: Ransomnematidae) from Anadenobolus putealis Loomis, 1969 (Diplopoda: Rhinocricidae) from Mexico

Summary Ransomnema bravoae from the intestine of the endemic rhinocricid, Anadenobolus putealis, from Mexico, is redescribed. This species was originally described from the spirobolid Hiltonius carpinus from Morelos State, Mexico. A redescription is presented and a neotype proposed due to the loss of the type material. Ransomnema bravoae can be distinguished from all other described species of Ransomnema by the presence of a cervical expansion extending from the base of the buccal cone to approximately the last one-third of the muscular pharynx and is offset by a slight constriction at the termination point, the presence of broad lateral alae beginning at the cervical expansion termination and terminating at the phasmids, the size and distribution of the male caudal papillae, and the size of the spicules, the right spicule being 3-4 times longer than the left. Ransomnema bravoae resembles R. alatum and R. bursatum in the presence of lateral alae but differs markedly in their distribution along the body. The right spicule is within the size range of that of R. longispiculum. Males of R. bravoae possess the usual papillal composition of the genus and are very similar to that of R. christiei in that the last pair of papillae is arranged in tandem. It is similar to species where males possess three precloacal papillae placed on lateral protuberances, showing morphological affinities to Caribbean species R. artigasi and R. habanense from Cuba.

Skrjabinodon castillensis n. sp. (Nematoda:Pharyngodonidae) from the Homonota horrida and H.darwinii (Squamata: Phyllodactylidae) from Argentina and key for the Neotropical species of the genus Skrjabinodon.

Skrjabinodon castillensis n. sp. is described and illustrated here, based on specimens found in the large intestines of Homonota horrida (province San Juan) and Homonota darwinii (province Neuquén) (Squamata: Phyllodactylidae) from Argentina. The new species is assigned to Skrjabinodon based lateral alae present in males, absent in females. Lateral alae beginning midway between lips and nerve ring and ending just posterior to first pair of caudal papillae. Females with vulva near esophageal bulb. In males, caudal alae absent, paired caudal papillae present. Skrjabinodon castillensis n. sp. represents the 9th species from the Neotropical realm. The new species differs from all other species assigned to Skrjabinodon by morphology of tail filament and number of tail filament spines. Skrjabinodon castillensis n. sp. is the only species of this genus known from Argentina. A key to the species of Skrjabinodon in the Neotropical realm is provided.

New species of Filaria (Nematoda: Filariidae) in the Lesser Grison Galictis cuja (Molina) (Carnivora: Mustelidae) from northern Patagonia, Argentina and comments about the South American species of the genus

Filaria lorenzo n. sp. is described in the Lesser Grison, Galictis cuja from northern Patagonia, Argentina. The new species can be differentiated from the eight species of Filaria from the Old World by the shape of the sclerotized preesophageal ring. The four remaining species of the genus parasitize American Mephitidae and/or Mustelidae. Filaria carvalhoi from Brazil and F. texensis from USA lack a preesophageal ring, whereas F. taxideae from USA and F. conepati from Argentina share with our specimens a preesophageal ring mostly mushroom shaped. Our specimens differ from F. taxideae by lacking lateral alae, by a different ornamentation of the female tail and by the male lacking adcloacal papillae. The new species also differs from F. conepati by the shape of the preesophageal ring and by the shape of the eggs. The indirect examination of the types of F. conepati and F. carvalhoi, corroborated the existence of differences between these two species, allowing us to refute their synonymy, as proposed by some authors. Our results extend the taxonomy of Filaria to 13 species and comprise the first report of a filarioid nematode for an Argentinean mustelid, and the first report for Patagonia.

Morphological and molecular characterizations for the developmental stages of Hysterothylacium species infecting Argyrops spinifer

Hysterothylacium species are perhaps the most abundant and diverse group of marine ascaridoids; however, their life cycle and specific identification in larval stages are difficult. In this study, three members of the genus Hysterothylacium (Ward and Magath, 1917) are morphologically described from the digestive tract of Argyrops spinifer, genetically characterized and their relationship with related taxa are compared and discussed. The former species (Hysterothylacium reliquens Norris and Overstreet, 1975) (p = 10%) is mainly characterized by its large body (male 30.89, females 34.15 mm long), the shape of lips, the presence of lateral alae, a short caecum, and a long ventricular appendix, length of spicules, number and distribution of genital papillae, and tail tip with numerous spines. The other species [fourth (L4) and third (L3) larval stages] (p = 46.66, 26.66%, respectively) are mainly characterized by body length (18.21 and 6.20 mm long, respectively), distinct three lips for L4 and poorly developed for L3, a shorter caecum than the ventricular appendix, tail tip lacks any distinct cuticular projections. Molecular tools were done via sequencing and analyzing target regions of ribosomal [internal transcribed spacer (ITS) and small ribosomal DNA (18S)] and mitochondrial [cytochrome c oxidase subunit 1 (COX1)]. These sequences demonstrate discrimination at the species level and confirm the validity of species determined by morphological identification. All sequenced parasite samples were identified as H. reliquens based on nucleotide sequence comparisons with other ascaridoids. In these analyses, Raphidascarididae formed a sister group to Anisakidae with strong nodal support. On MP trees, a genus-specific cluster with a well-support value was delineated in genera Raphidascaris, Contracaecum, and Hysterothylacium. This study demonstrated that selected gene regions of H. reliquens yielded unique sequences (gbl MZ148786.1, MZ148788.1, and MZ148789.1) that confirmed its taxonomic position in Raphidascarididae. Therefore, morphological and molecular tools are important for accurate diagnosis of genus and species of ascaridoids.

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.

Morphological and molecular characterization of Buzionema lutgardae n. sp. (Nematoda: Oxyuridomorpha: Thelastomatidae) from the cockroach Byrsotria sp. (Blattaria: Blaberidae) in Cuba.

Buzionema lutgardae n. sp. (Nematoda: Oxyuridomorpha: Thelastomatidae) is described from the cockroach Byrsotria sp. (Blattaria: Blaberidae), endemic to Cuba. Females of B. lutgardae n. sp. are shorter than those of B. validum Kloss, 1966 (16002150 µm vs. 31313378 µm), but the oesophagus is comparatively longer (b = 2.963.77 vs. 4.654.87). The lateral alae of the new species extend from ca. the midpoint of the cylindrical part of the procorpus to the level of the anus in contrast to the base of the basal bulb to the level of the anus in B. validum. The males of B. lutgardae n. sp. are shorter than those of B. validum (780940 µm vs. 11771423 µm) and their lateral alae end at some distance before the cloaca instead the level of the cloaca in B. validum. The phylogeny of B. lutgardae n. sp. is inferred by the D2-D3 domains of the 28S rDNA. B. lutgardae n. sp. and B. validum form a monophyletic clade with strong nodal support, as sister-group of the genus Leidynema Schwenck in Travassos, 1929.

Further data on Iranian marine nematode diversity, with description of three new Desmodoridae Filipjev, 1922 (Nematoda: Desmodorida) species from the Persian Gulf

Summary The Desmodoridae is a diverse and widespread family of free-living nematodes. Here, we provide the first record of the group in the Persian Gulf and describe three new species: Metachromadoroides sinuspersici sp. n., Zalonema iranicum sp. n. and Z. supplementorum sp. n. Metachromadoroides sinuspersici sp. n. is characterised by finely annulated cuticle, short and stout cephalic sensilla, amphidial fovea on cuticular thickening, pharyngeal bulb well developed and partitioned into three sections, absence of precloacal supplements, and presence of 6-8 pairs of rounded postcloacal papillae. Zalonema iranicum sp. n. is characterised by papilliform subcephalic sensilla (best observed with SEM), convex cephalic capsule, large multispiral amphidial fovea with 4-5 turns in both males and females, buccal cavity with one ventrosublateral and two dorsal teeth and posterior body of males with lateral alae extending from the last third of the body to the cloacal aperture and ventral alae extending 1395-2250 μm anterior to the cloacal aperture, and no precloacal supplements. Zalonema supplementorum sp. n. is characterised by four subcephalic sensilla 1-2 μm long, multispiral amphidial fovea with three turns in both males and females, buccal cavity with one dorsal and two ventrosublateral teeth, males with lateral alae present on each side of body from posterior half of body to cloacal aperture, ventral alae extending 942-1257 μm anterior to cloacal aperture, strongly cuticularised spicules 41-43 μm long, and 12-16 precloacal supplements. Near full length SSU and partial D2-D3 LSU sequences are provided for M. sinuspersici sp. n. and Z. iranicum sp. n., and the COI sequence is provided for Z. iranicum. The SSU phylogeny suggests a close relationship between M. sinuspersici sp. n. and Metachromadora and Metachromadoroides species and the monophyly of Zalonema (after currently available data). The LSU phylogeny suggests an affinity between Metachromadoroides and Zalonema with Spirinia and Acanthopharynx, respectively.