Deep Constriction Research Articles

Morphological and Molecular Characterization of Discolaimus haridwarensis sp. n. (Nematoda: Dorylaimida: Qudsianematidae) from India

Discolaimus haridwarensis sp. n. is described from agricultural fields of sugarcane in the Haridwar district, India. It is characterized by its 2.11–2.32 mm long body, lip region offset by deep constriction and 27–30 μm wide, odontostyle 20–23 μm long with aperture occupying 50–54% of its length, 436–487 μm long neck, pharyngeal expansion 57–59% of total neck length, uterus a simple tube-like structure 22–31 μm long or 0.3–0.5 times the corresponding body diameter, pars refringens vaginae absent, transverse vulva (V = 48–55), female tail conoid (34–40 µm, c = 53–68, c′ = 1.0–1.3) with rounded terminus, and males absent. The phylogenetic analysis inferred from the D2-D3 expansion segments of 28S rRNA gene and 18S rRNA gene sequences showed that Discolaimus haridwarensis sp. n. clustered with other dorylaimid species from the genus Discolaimus and the subfamily Discolaiminae.

Humidophila manipurensis sp. nov. and the first record of Humidophila bigibba (Hustedt) Lowe, Kociolek, Johansen, Van de Vijver, Lange-Bertalot et Kopalová from Northeast India

A new aerophilic diatom species, Humidophila manipurensis sp. nov., is described from the Sadu Chiru waterfalls, Manipur, India, a part of the Indo-Burma hotspot region. This species is characterized by having its valve shape slightly inflated at middle, terminal raphe ends that are slightly deflected, round areolae and a central depression. Further, we also recorded Humidophila bigibba from Meghalaya State, Northeast India, and this population is compared with the type population from Indonesia and Chinese populations. Fine structural details of both taxa were examined using light and scanning electron microscopy and compared with morphologically similar taxa in this genus. Addition of new species from this region will further add to the biodiversity richness of the Indo-Burma biodiversity hotspot. Further, this study confirms the presence of H. bigibba for the first time in India. This species has a deep constriction in the middle of the valve which is not found in the populations from the Indonesia and China.

A new species of Xiphinema americanum group (Nematoda: Longidoridae) from Iran, with additional data on three known species.

One new and three known species of the genus Xiphinema from the rhizosphere of fruit trees and rose shrubs in East Azarbaijan province, Iran, are presented based on the morphological, morphometric and molecular characters. The new species is distinguished by its 2.0-2.1 mm long body, relatively flattened lip region with 8.7-10.0 µm width, set off from body contour by a deep constriction, odontostyle 82.5-88.0 µm long, V = 52-54, reproductive system didelphic-amphidelphic with symbiotic bacteria in the reflexed ovaries, tail conoid, dorsally convex with rounded to slightly subdigitate tip (42.0-43.5 µm long, c = 61-65, c' = 1.6-1.8), and males unknown. The new species, X. babaii sp. n., looks very close to X. californicum, and is regarded as its cryptic species, being separated from it using some morphological differences. Their separation was further corroborated using molecular data. Three known species belonging to the Xiphinema americanum group namely X. primum, X. pachtaicum and X. simile were also collected during present study, and new data were provided for them. Xiphinema simile is a new record for the Iran's nematode fauna. Molecular phylogenetic studies using partial sequences of 28S rRNA gene D2-D3 fragments were performed, and the phylogenetic relationships of the new species were discussed.

Developmental characteristics of sporogenous hyphae: a new observation between Brassica juncea var. tumida and Albugo candida

Brassica juncea var. tumida (tumorous stem mustard) is widely cultivated as a feature vegetable in Ningbo, Zhejiang Province, and is used as a raw material for pickles in China. White blister rust, caused by Albugo candida, has severe negative effects on tumorous stem mustard, resulting in significant economic losses. In this study, hypha colonization and extension, haustorial formation, and the development process of sporogenous hyphae and sporangia in A. candida-infected tissues were studied using light and transmission electron microscopy. Additionally, the complex and unique sporogenous hypha developmental process was revealed. During A. candida infection, cytological and ultrastructural characteristics were similar to those of cruciferous plants. During sporogenous hyphae development, an initially cylindrical sporogenous hypha with a thin inner wall at the apex developed from a cell with a thick inner wall. At the apical end of the sporogenous hypha, an electron-dense complex gathered, causing the disintegration of the inner and outer walls and the formation of new inner and outer walls. With the formation of a clavate sporogenous hypha, a deep constriction of the cell wall occurred at its subapex, in which a septum was produced and a primary sporangium was separated from the sporogenous hypha. Both layers of the sporogenous hypha wall took part in the formation of the sporangial wall but were not related the formation of the sporangial outer wall in a septum, providing direct evidence of the holoblastic formation of sporangia. Furthermore, ultrastructural observation demonstrated that the development of the primary sporangial walls within a septum occurred later than that of their lateral walls, including the degradation of constricted outer walls around the septum, formation of the inner wall and subsequent outer walls of a sporangium in the upper septum layers, confirming the earlier observation. Therefore, this study provided the model of sporogenous hyphae development and sporangial formation in chain.

Morphological and molecular characterization of Aporcella femina sp. n. (Dorylaimida, Aporcelaimidae) from Nigeria.

A new species of the genus Aporcella collected from a watermelon field in Nigeria is described, including its morphological and molecular (small subunit (SSU) and large subunit (LSU) ribosomal DNA (rDNA)) characterization. Aporcella femina sp. n. is distinguished by its 3.21-3.64 mm-long body, inner cuticle layer with fine but distinct transverse striation, lip region offset by deep constriction, 22-25 μm broad, odontostyle 20-26 μm, neck 661-811 μm long, pharyngeal expansion occupying 52-56% of the total neck length, female genital system didelphic-amphidelphic, uterus 191-350 μm or 1.9-3.3 mid-body diameters long, V = 52-57, tail short and convex conoid (35-48 μm, c = 72-98, c' = 0.7-0.9) and males absent. Phylogenetic analyses based on the partial sequence of SSU and LSU (D2-D3) rDNA revealed a close relationship of A. femina sp. n. with other Aporcella species, confirming the monophyly of the genus as well as its association to a clade made of several taxa characterized by the absence of pars refringens vaginae.

New angarosphecid wasp (Hymenoptera: Apoidea, Angarosphecidae) from the mid-Cretaceous Burmese amber

A new genus and species of the family Angarosphecidae, Decasphex cretacicus gen. et sp. nov., from the mid-Cretaceous Burmese amber is described and illustrated. The new genus and species is most similar to Burmasphex Melo et Rosa, 2018 and can be easily distinguished in having female antenna 10-segmented (vs. 12-segmented), mesosoma more elongate, forewing with cell 2cua lower, and metasomal segments 1–3 not separated with deep constrictions. Ten-segmented female antenna is a novel morphotype example of the morphological diversity of Apoidea. A key to genera of the Angarosphecidae is provided.

Morphological and molecular characterisation of Aporcelaimellus nigeriensis sp. n. (Dorylaimida: Aporcelaimidae), a remarkable dorylaim from Nigeria

Summary A new species of Aporcelaimellus, collected in a watermelon field in Nigeria, is described, including its morphological and molecular (D2-D3 28S-rDNA, 18r-DNA) characterisation. Aporcelaimellus nigeriensis sp. n. is distinguishable by its 2.76-3.55 mm length, very coarse ventral body pores, lip region offset by deep constriction and 24-27 μm broad odontostyle 30-36 μm long at its dorsal and 28-31 μm at its ventral side, neck 648-779 μm long, pharyngeal expansion occupying 54-60% of total neck length, uterus 300-473 μm or 2.1-3.2 body diam. long and tripartite, V = 49-54, tail short and convex conoid (27-41 μm, c = 72-115, c′ = 0.5-0.7), spicules 108-137 μm long, and 9-10 spaced ventromedian supplements with hiatus. LSU analysis revealed a close relationship of A. nigeriensis sp. n. with other Aporcelaimellus species and questioned, once more, the monophyly of Aporcelaimidae. SSU phylogenetic tree was not able to resolve the relationship between the new species and other closely related species.

Displasia de streeter (síndrome de bridas amnióticas) a propósito de un caso

Introducción: La Displasia de Streeter o Síndrome de Bandas Amnióticas (SBA) es un grupo de defectos al nacimiento, que ocurre cuando algunas partes del feto en desarrollo (generalmente brazos, piernas o dedos) se “enredan” en bandas amnióticas de tipo fibrinoso dentro del útero, las cuales restringen el flujo sanguíneo y linfático, afectando el desarrollo del bebé.
 Objetivo: Describir un caso clínico de bandas amnióticas como causa de malformacion en las extremidades.
 Material y métodos: Estudio descriptivo retrospectivo, presentación de caso clínico.
 Resultados: En este trabajo se presenta el caso de un recién nacido varón que al nacimiento presenta sindactilia en mano izquierda, pie derecho y en tercio distal de pierna, banda de constricción profunda que provoca, edema y linfangitis así como hipertrofia de tercio distal de pierna y pie izquierdos.
 Conclusiones: Es importante la revisión de este caso puesto que la intervención debe ser multidisciplinaria (cirugía plástica, cirugía vascular, ortopedia y traumatología, pediatría, psicología) y precoz con la finalidad de evitar complicación vascular, funcional y estética.
 Resultados: En este trabajo se presenta el caso de un recién nacido varón que al nacimiento presenta sindactilia en mano izquierda, pie derecho y en tercio distal de pierna, banda de constricción profunda que provoca, edema y linfangitis así como hipertrofia de tercio distal de pierna y pie izquierdos.
 Conclusiones: Es importante la revisión de este caso puesto que la intervención debe ser multidisciplinaria (cirugía plástica, cirugía vascular, ortopedia y traumatología, pediatría, psicología) y precoz con la finalidad de evitar complicación vascular, funcional y estética

Morphological and molecular characterisation of Aporcelinus zapotitlanensis sp. n. (Dorylaimida: Aporcelaimidae) from central Mexico

Summary A new species of Aporcelinus, collected in a natural habitat of central Mexico, is described and illustrated, including molecular (D2-D3 28S-rRNA) data. Aporcelinus zapotitlanensis sp. n. is characterised by its 1.19-1.43 mm long body, lip region offset by a deep constriction and 16.5-18.5 μm broad, odontostyle 19.5-22 long, neck 325-368 μm long, pharyngeal expansion 150-201 μm long or 46-55% of the total neck length, uterus 130-167 μm long and tripartite, V = 54-56, tail conical with finely rounded tip (30-37 μm, c = 34-43, c′ = 1.2-1.4) lacking a distinct dorsal concavity, spicules 48-51 μm long, and 11-12 spaced ventromedian supplements with one or two of them located within the range of the spicules. Molecular analyses confirm the monophyly of Aporcelinus and places the new species within a clade shared with A. infundibulicaudatus and A. amazonicus.

The genus Metaporcelaimus Lordello, 1965 (Nematoda, Dorylaimida, Aporcelaimidae) in Ukraine. Description of one new and one known species with granulate egg shell.

Two Metaporcelaimus species, one new and one known, are described from Ukraine. Metaporcelaimus petrophilus sp. n. is characterized by its 1.30-1.58 mm long body, lip region offset by deep constriction and 16-18 µm broad, odontostyle 15-17 µm long, neck 360-413 µm long, pharyngeal expansion occupying 47-54% of total neck length, uterus simple and 83-125 µm long or 1.6-2.7 times the corresponding body diameter, uterine eggs with granulate shell, V = 51-55%, tail conical (35-40 µm, c = 33-42, c' = 1.4-1.8 in females), spicules 43-50 µm long, and 9-13 spaced ventromedian supplements with hiatus. New data, including the first description of male specimens and SEM study, are provided for M. ovogranulosus, the Ukrainian populations of which are nearly identical to the type population from California.

Morphological and molecular characterisation of Chitwoodius coffeae sp. n. (Dorylaimida: Tylencholaimidae) from Vietnam, with a revised taxonomy of the genus

Summary Chitwoodius coffeae sp. n. is described, including SEM observations and molecular (D2-D3 expansion segment of the rDNA 28S) analysis, from a coffee plantation in the Central Highlands of Vietnam. The new species is characterised by its 1.69-2.01 mm long body in females and 1.29-1.51 mm in males, lip region offset by deep constriction and 15-17 μm broad, odontostyle 27-30 μm long, neck 340-473 μm long, pharyngeal expansion occupying 52-54% of total neck length, uterus a simple tube-like structure 68-106 μm long, vulva longitudinal (V = 54-59), tail short and rounded conoid (20-28 μm, c = 54-88, c′ = 0.6-0.8) with a nearly terminal projection of inner cuticle layer, spicules 60-64 μm long, and 7-10 spaced ventromedian supplements without hiatus. SEM pictures, available for the first time for a representative of the genus, show a hexagonal (nearly hexastellate) oral field divided into six sectors by the existence of six deep incisures. Molecular analyses, also presented for the first time for a representative of the genus, results in a narrow evolutionary relationship among Chitwoodius and Tylencholaimus, and supports the monophyly of the Tylencholaimidae. This is the first record of Chitwoodius in Asian Far East territories. Chitwoodius ahmadi sp. n. is proposed for a misattributed population of C. seshadrii.

Taxonomy of the genus Labronema Thorne, 1939 (Nematoda: Dorylaimida: Dorylaimidae) with redescription of its type species, L. ferox Thorne, 1939

Summary Labronema ferox is redescribed on the basis of two females and four males from the USA. It is characterised by its 2.90-4.45 mm long body, lip region offset by deep constriction, 31-39 μm broad and slightly sucker-like with distinctly protruding perioral liplets, odontostyle 34-37 μm long with aperture occupying 37-42% its length, neck 673-883 μm long, pharyngeal expansion occupying 48-52% of total neck length, female genital system didelphic-amphidelphic, uterus long and complex, including an intermediate pars musculosa, vulva longitudinal (V = 51-54), caudal region short and rounded (27-39 μm, c = 93-135, ), spicules 76-89 μm long, and 20-25 nearly contiguous ventromedian supplements with an hiatus. Previous information about the species is analysed and discussed in the light of the present redescription. A new name, Labronemella zullinii sp. n., is proposed for the two females from Nepal described by Zullini in 1973. This new characterisation of L. ferox lays the foundations to study the taxonomy of the genus in more detail.

Morphological and molecular characterisation of Tylencholaimellus zeinabadensis sp. n. (Dorylaimida: Tylencholaimellidae) from Iran, with additional data on five known species of the genus

Summary Six species of the genus Tylencholaimellus, one new and five known, collected in virgin and cultivated soils of East Azarbaijan province, Iran, are studied. Tylencholaimellus zeinabadensis sp. n. is morphologically characterised by its 1.2-1.7 mm long body, lip region 10-13 μm wide and offset by deep and broad constriction, odontostyle 16-20 μm long, stylet 22-30 μm long, neck 186-234 μm long, pharyngeal bulb 30-43 μm long, anterior uterine sac 55-103 μm long or 0.9-1.7 corresponding body diam. long, V = 34-41, tail short and rounded to conoid (20-30 μm, c = 45-83, c′ = 0.5-1.0), spicules 39-50 μm long, and one or two ventromedian supplements with hiatus. Molecular analyses using the D2-D3 expansion regions of the 28S rRNA gene sequences of the new species confirmed the monophyly of this genus based upon currently available data. A population of T. affinis is described and illustrated, and new data (morphometrics, pictures and distribution) are provided for T. loofi, T. paracinctus, T. polonicus and T. striatus.

Multigene analysis of the catfish genus Trichomycterus and description of a new South American trichomycterine genus (Siluriformes, Trichomycteridae)

Trichomycterus comprises about 170 valid species, but its monophyly has been challenged in the last decades. Bayesian Inference and Maximum Likelihood analyses comprehending mitochondrial genes COI and CYTB and nuclear genes GLYT, MYH6 and RAG2 from 71 Trichomycterinae terminal taxa and eight outgroups were performed. The analyses highly supports a clade containing Trichomycterusnigricans, the type species of the genus, and several other congeners endemic to eastern and northeastern Brazil, herein considered as the genus Trichomycterus, the sister clade the southern Brazil and adjacent areas clade; the latter clade comprises two subclades, one comprising species of the genus Scleronema and another comprising species previously placed in Trichomycterus, herein described as a new genus. Cambevagen. n. is distinguished from all other trichomycterines by the presence of a bony flap on the channel of the maxillo-dentary ligament, the interopercle shorter than the opercle, a deep constriction on the basal portion of the antero-dorsal arm of the quadrate, absence of teeth in the coronoid process of the dentary, the maxilla shorter than the premaxilla, the cranial fontanel extending from the the medial posterior of frontal to the medial region of supraoccipital, and absence of the postorbital process of the sphenotic-prootic-pterosphenoid.

Ultra Structural Studies of the Septate Gregarine Phleobum elliptica Modak et al., 2011

Genus Phleobum Haldar and Chakraborty, 1974 is one of the important genera of septate gregarine (Apicomplexa: Eugregarinida: Hirmocystidae), observed in the gut of grasshoppers. So far nine species of the genus Phleobum has been described but there is no report of ultrastructural study. The present study records the ultrastructural details of Phleobum elliptica inhabiting the gut lumen of the grasshopper Atractomorpha crenulata (Insecta: Orthoptera: Pyrgomorphidae). Under SEM, both the protomerite and deutomerite are found to be entirely covered with longitudinal, parallel pellicular folds, which are either straight or undulating in nature. A deep constriction is present at the junction of protomerite and deutomerite. Folds of the gamont are not continuous from the tip to bottom, rather interrupted at the region of septum. Protomerite bears protuberance like apical uplifted area, delimited by a deep groove. Association are caudo-frontal. Anterior end of satellite bears sucker like structure which receive the pointed end of the primate’s deutomerite.

Morphological and molecular characterisation of Paralongidorus francolambertii sp. n. (Nematoda: Longidoridae) from Serbia

Paralongidorus francolambertii sp. n., a bisexual species found in the rhizosphere of silver lime (Tilia tomentosa) and common juniper (Juniperus communis), is described. The species is characterised by its medium to large size (L = 5.86-8.29 mm) and slender body (a = 143-197), a lip region flattened with rounded profile, clearly offset from the body by a deep constriction, a narrow neck between the head and body, a shoulder-like body posterior to the neck, a stirrup-shaped amphidial fovea, with conspicuous slit-like aperture, lying on the lateral cuticular collar, a moderately long odontostyle ca 140 μm long, a guide ring located at ca 28 μm from anterior end, a tail terminus with thickened outer cuticular layer in both sexes, and males with spicules ca 52 μm long. The D2-D3 expansion domains of the 28S rRNA gene and the ITS-containing region of P. francolambertii sp. n. were amplified and sequenced. Phylogenetic analyses by using the Maximum Likelihood method showed that P. francolambertii sp. n. had a sister relationship with P. rex and that all Paralongidorus species formed a well-supported group.

Morphology of Labronemella major n. sp. (Nematoda: Dorylaimida), a soil-dwelling nematode from China, including a revised key to species of the genus.

One new species from Qinghai Province, China, Labronemella major n. sp., is described. The new species is characterized by a body length of 3.03-3.34mm; lip region wide, offset by a distinct depression, disc-like with six separated inner liplets; amphid fovea funnel-shaped, distinctly bulged on body surface in scanning electron micrographs; odontostyle long (35-39μm) with distinct lumen, aperture about 39-47% of its length; odontophore rod-like and long; guiding ring double; pharyngeal basal expansion about half of the total neck length; uterus relatively long and tripartite; vulva transverse and sclerotized; spicules 81-90μm long; ventromedial supplements 19-23; tail short, rounded to conoid. It can be differentiated from all other species of the genus by its relatively longer body, odontostyle and spicules, and wider lip region. Due to the lip region being offset by a deep constriction, and the long (three or more times the body diameter at mid-body) tripartite uterus, the new species is close to Labronemella czernowitzensis (Micoletzky, 1922) Andrássy, 2002 and Labronemella labiata Andrássy, 1985. An improved key to the genus including the new species is provided.

Sectonema caobangense sp. n. from Vietnam (Nematoda, Dorylaimida, Aporcelaimidae).

Sectonema caobangense sp. n. from evergreen forest soil in Vietnam is described, including scanning electron micrograph (SEM) observations and D2-D3 LSU rDNA analysis. The new species is characterized by its 3.12 to 5.80 mm long body, lip region offset by deep constriction and 21 to 23 μm broad, mural tooth 13 to 14 μm long at its ventral side, 940 to 1,112 μm long neck, pharyngeal expansion occupying 61% to 69% of total neck length, uterus a long simple tube-like structure 292 to 363 μm long or 2.7 to 2.9 times the corresponding body diameter, pars refringens vaginae well developed, V = 48 to 56, short (36-51 μm, c = 77-132, c' = 0.5-0.8) and rounded tail, 87 to 99 μm long spicules, and four or five irregularly spaced ventromedian supplements bearing hiatus. Sectonema caobangense sp. n. differs from the typical pattern of Sectonema in the nature of the stomatal protrusible structure, bearing a mural tooth attached to the ventral side of the stoma. Molecular data obtained and the derived evolutionary trees support a close phylogenetic relationship with other Sectonema species.

Three new species of Sectonema Thorne, 1930 (Dorylaimida: Aporcelaimidae) from Vietnam

Three new species of the genus Sectonema collected from natural habitats in Vietnam are studied, described and illustrated, including line drawings, LM and/or SEM pictures. Sectonema birrucephalum sp. n. is characterised by its 2.73-4.35 mm long body, lip region 18-20 μm broad and offset by deep constriction, odontostyle 10.0-11.5 μm long on its ventral side, 659-989 μm long neck, pharyngeal expansion occupying 63-68% of total neck length, uterus a simple tube, 221-277 μm long, pars refringens vaginae present, V = 54-56, tail short (31-43 μm, c = 85-111, c′ = 0.6-0.8) and rounded, spicules 72-75 μm long, and four or five irregularly spaced ventromedian supplements beyond the range of the spicules. Sectonema buccociliatum sp. n. is distinguished by its 2.00-2.46 mm long body, lip region offset by constriction, 19-20 μm broad and bearing perioral cilia-like structures, odontostyle 13-14 μm long at its ventral side, 530-625 μm long neck, pharyngeal expansion occupying 62-69% of total neck length, uterus a simple tube, 116-152 μm long, pars refringens vaginae present, V = 56-62, tail short (23-31 μm, c = 72-104, c′ = 0.6-0.8) and rounded, spicules 56-68 μm long, and 3-5 spaced and weakly developed ventromedian supplements beyond the range of the spicules. Sectonema ciliatum sp. n. is characterised by its 2.79-3.13 mm long body, lip region offset by constriction, 21-22 μm broad and bearing perioral cilia-like structures, odontostyle 14-15 μm long at its ventral side, 699-722 μm long neck, pharyngeal expansion occupying 60% of total neck length, uterus a simple tube, 201-244 μm long, pars refringens vaginae present, V = 52-53, tail short (33-35 μm, c = 82-92, c′ = 0.6-0.7) and rounded, spicules 70-72 μm long, and three or four spaced and weakly developed ventromedian supplements beyond the range of the spicules. Molecular data obtained for S. ciliatum sp. n. and the derived evolutionary tree show a close phylogenetic relationship with other species of the genus.

Three new species of the genus Aporcelaimoides Heyns, 1965 from Vietnam (Nematoda, Dorylaimida, Aporcelaimidae), with an updated taxonomy of the genus.

Three new species of Aporcelaimoides from natural habitats in Vietnam are studied, described and illustrated, including line drawings, LM and/or SEM pictures. Aporcelaimoides brevistylum sp. n. is characterized by its body 1.95–2.90 mm long, lip region offset by deep constriction and 17–18 µm broad, ventral side of mural odontostyle 11–14 µm long with aperture occupying 62–71% of its length, neck 663–767 µm long, pharyngeal expansion occupying 58–66% of total neck length, uterus a simple tube 85–182 µm long, pars refringens vaginae absent, V = 55–63, tail short and rounded (34–46 µm, c = 49–76, c’ = 0.6–0.8), spicules 67–86 µm long, and one ventromedian supplement out the range of spicules. Aporcelaimoides minor sp. n. is distinguished in having body 2.09–2.61 mm long, lip region offset by deep constriction and 19–20 µm broad, mural odontostyle 14–16 µm long at its ventral side with aperture occupying 73–84% of its length, neck 579–649 µm long, pharyngeal expansion occupying 57–66% of total neck length, uterus a simple tube 44–69 µm long, pars refringens vaginae well developed, V = 48–56, female tail very short, rounded conoid or truncate (14–26 µm, c = 90–146, c’ = 0.3–0.6), and male unknown. Aporcelaimoides silvaticum sp. n. is characterized by its body 2.09–2.60 mm long, lip region offset by depression and 17–18 µm broad, mural odontostyle 11–12 µm long at its ventral side with aperture occupying 60–66% of its length, neck 597–720 µm long, pharyngeal expansion occupying 58–64% of total neck length, uterus a simple tube 128–243 µm long, pars refringens vaginae well developed, V = 58–60, tail short and rounded (27–37 µm, c = 67–94, c’ = 0.6–0.7), spicules 64–75 µm long, and two or three widely spaced ventromedian supplements bearing hiatus. The genus Aporcelaimoides is restored, its diagnosis emended, and three species of Sectonema, namely Sectonema amazonicum, Sectonema haguei and Sectonema moderatum, transferred to it. An updated list of its species, a key to their identification and a tabular compendium with the most important morphometric features are also presented.