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A new species of the genus Labronema, collected in a natural mountain habitat of the southern Iberian Peninsula, in Spain, is studied, including its morphological and morphometric characterization, SEM observations, and D2-D3 28S-rRNA sequences. Labronema montanum sp. n. is distinguishable by its 1.56 to 2.08 mm long body, with lip region being offset by constriction and 19 to 24 µm broad, odontostyle 21 to 29 µm long, neck 417 to 551 µm long, pharyngeal expansion 205 to 272 µm long, the presence of three cardiac lobes at the pharyngo-intestinal junction, a long and tripartite uterus, longitudinal vulva (V = 57-60), a short and rounded caudal region (19–35 µm, c = 56-86, c = 0.5-0.8), spicules 65 to 76 µm long, and 20 to 25 nearly contiguous ventromedian supplements with hiatus.

A new species of the genus Metaxonchium is described from a natural habitat in Iran. Metaxonchium magnum sp. n. is characterized by its 3.62–4.65 mm long body, lip region cap-like and offset by constriction and 13–16 μm wide, odontostyle fusiform and 14–17 μm long, neck 1016–1359 μm long, both parts of the pharynx separated by a short isthmus-like narrowing, pharyngeal expansion occupying 74.2 (73–77)% of total neck length in females and 70.4 (66–72)% in males, female genital system mono-opistho-ovarian, didelphic, anterior genital branch a large uterine sac with a small terminal mass occupying 7–14% of body length, posterior uterus long and tripartite with a Z-like differentiation, V = 50–52, caudal region short and rounded (24–41 μm, c = 99–161, c′ = 0.5–0.7), spicules 90–105 μm long and 10–13 spaced ventromedian supplements with hiatus. Analysis of D2–D3 28S rDNA sequences of the new species suggests that Metaxonchium might not be a monophyletic taxon, a matter that should be confirmed after future research. [ABSTRACT FROM AUTHOR]

The type species of the genus Epacrolaimus, Epacrolaimus declinatoaculeatus, is studied from the re-examination of type material of Aporcelaimus vorax, its junior synonym, and the observation of several Iberian populations and a few Iranian specimens. Morphologically, it displays a recognizable morphological pattern characterized by, among other features, the incurved nature of its odontostyle aperture, presence of perioral liplets or lobes, lip region 24–31 μm wide, odontostyle 21–25 μm long and comparatively anterior location of S2N pharyngeal gland nuclei. Nevertheless, variations in some morphological traits (vagina shape and tail shape) and in several morphometrics (body length, uterus length, vulva position, tail length and spicule length) are also noted. Sequences of D2–D3 domains of the 28S rDNA, 18S rDNA and COI mtDNA were obtained from several Iberian populations. Their analyses, in particular those from D2–D3 sequences, revealed the existence of a highly supported clade ((Epacrolaimus + Sectonema) + Metaporcelaimus), with a closer relationship between Epacrolaimus and Palaearctic populations of Sectonema, whereas the remaining aporcelaimid genera occupied placements in other clades. These results are discussed, with especial emphasis on the intricate separation of Epacrolaimus and Sectonema, which display significantly different protruding stomatal structure in spite of their close evolutionary relationship as derived from molecular trees. [ABSTRACT FROM AUTHOR]

A new species of dorylaimid nematode, Aporcelinus abeokutaensis sp. n., collected from a watermelon field in Nigeria, is described, illustrated and molecularly (D2–D3 28S ribosomal DNA) studied. It is characterized by its 1.18–1.52-mm-long body, lip region offset by weak constriction, 15.5–17.5 μm broad with perioral liplets, odontostyle 18–21.5 μm long at its dorsal side or 1.1–1.3 times the lip region diameter, neck 333–401 μm long, pharyngeal expansion occupying 45–51% of total neck length, uterus simple and 0.7–1.5 times the corresponding body diameter long, V = 48–53, tail conical with finely rounded tip (33–52 μm long, c = 26–41, c′ = 1.3–1.9) and a variably distinct dorsal concavity, and male unknown. Molecular analysis reveals that the new species grouped with other species of Aporcelinus in a highly supported clade, confirming the monophyly of the genus. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The new species Lenonchium zanjanense sp. n. is described from a natural habitat of Zanjan province, Iran, including line, light microscopy and scanning electron microscopy illustrations and a molecular (18S, 28S) study. It is characterized by its 3.50–4.51 mm long body, rounded lip region, continuous and 13.5–15.5 µm broad, odontostyle 21–24 µm long, neck 362–490 µm long, double guiding ring, pharyngeal expansion 190–285 µm long, female genital system didelphic–amphidelphic, uterus simple and 185–320 µm long or 3.4–5.9 times the corresponding body diameter, vulva nearly equatorial (V = 45–53), tail conical-elongated to filiform (90–165 µm, c = 23–43, c ′ = 2.4–5.3) with three or four mucro-like projections at the tip, spicules 58–64 µm long and 16–21 contiguous ventromedian supplements ending at the level of the anterior end of the spicules. The taxonomy of the genus is updated, with an emended diagnosis, list of species, key to their identification and a compendium of their main morphometrics. Lenonchium asterocaudatum is regarded as identical and a junior synonym of L. denticaudatum. New insights into the phylogeny of the group are also provided, and the classification of Lenonchium within Nordiidae is seriously questioned. [ABSTRACT FROM AUTHOR]

Two new species of the genus Aporcelinus from the USA are described and illustrated. Aporcelinus floridensis sp. n. is characterized by its 1.12–1.52 mm long body, lip region offset by marked constriction and 14.5–17.0 μm broad with perioral liplets, odontostyle 16.5–20.0 μm at its ventral side and 1.1–1.2 times the lip region diameter, neck 316–395 μm long, pharyngeal expansion occupying 43–48% of total neck length, uterus simple and 33–56 μm long or 0.8–1.2 times the corresponding body diameter, V = 48–54, female tail conical (36–49 μm long, c = 27–41, c' = 1.2–2.0) with finely rounded terminus and no hyaline portion, and male absent. Aporcelinus paolae sp. n. is characterized by its 1.29–1.80 mm long body, lip region offset by marked constriction and 14–16 μm broad, odontostyle 15–17 μm at its ventral side and 1.0–1.1 times the lip region diameter, neck 314–397 μm long, pharyngeal expansion occupying 43–53% of total neck length, uterus tripartite and 128–164 μm long or 2.6–3.6 times the corresponding body diameter, V = 53–57, female tail conical (30–39 μm long, c = 40–51, c' = 1.1–1.3) with finely rounded terminus and variably re-curved dorsad, male tail conical (27–36 μm, c = 39–59, c' = 0.9–1.2), ventrally straight and dorsally convex, spicules 48–54 μm long, and 7–9 irregularly spaced ventromedian supplements lacking hiatus. The analyses of the D2-D3 expansion segments of 28S rRNA (LSU) gene sequences of the two new species confirmed the monophyly of the genus, based upon currently available data, showing a close relationship between the genera Aporcelinus and Makatinus , and justified the placement of Aporcelaimellus , Makatinus and Aporcelinus under the subfamily Aporcelaimellinae. [ABSTRACT FROM AUTHOR]

Abstract Two new species of the genus Metaxonchium are described from natural habitats in Costa Rica. Metaxonchium parvisaccatum sp. n. is characterized by its 1.62–1.71 mm long body, lip region offset by constriction and 8.5–10 μm broad, odontostyle 10–11 μm long, neck 632–674 μm long, pharyngeal expansion occupying 68–71% of neck length, anterior genital branch reduced to a short uterine sac, 22–27 μm long or 1–2% of body length, posterior uterus long and tripartite without apophyses, vulva transverse (V = 54–55), caudal region short and rounded (23–26 μm, c = 62–76, c' = 0.7–0.8), and male absent. Metaxonchium stenospiculum sp. n. is characterized by its 2.15–2.85 mm long body, lip region offset by constriction and 12.5–16 μm broad, odontostyle 13.5–16 μm long, neck 756–1011 μm long, pharyngeal expansion occupying 64–74% of neck length, anterior genital branch 8–13% of body length and consisting of a long uterine sac plus a terminal mass, posterior uterus long and tripartite without apophyses, vulva transverse (V = 53–59), caudal region short and rounded, nearly hemispheroid (20–28 μm, c = 91–126, c' = 0.4–0.6) in females, and more conoid (29–41 μm, c = 80–88, c' = 0.6–0.8) in males, spicules 96–102 μm long, and 11–14 spaced ventromedian supplements without hiatus. Molecular analysis of M. stenospiculum sp. n. D2-D3 LSU provides new insights in the phylogeny of Belondiridae as its rounded-tailed genera might constitute a monophyletic group. [ABSTRACT FROM AUTHOR]

A new species of the genus Oscheius, O. saproxylicus sp. n., collected in decaying wood obtained from an orchard in Southern Iberian Peninsula, is reported. A detailed description, including morphometrics, LM and SEM images, and molecular (18S and 28S rDNA genes) information is provided. The female is characterized by a moderately long body, lateral field with three longitudinal ridges, midbody vulva, and conical tail with acute tip. It was distinguished from its closest relative, O. dolichura, by a shorter tail and longer rectum. The male was not found. Morphological and molecular data support its belonging to Dolichura-group. Molecular analyses show that both Insectivorus and Dolichura groups are related to each other, being proposed as subgenera of the genus Oscheius as Oscheius and Dolichorhabditis. Finally, an updated taxonomy of the genus is presented, with generic and subgeneric diagnoses, list of species and a key to their identification.

Two new species of the genus Crassolabium are described from natural areas in Vietnam. Crassolabium aenigmaticum sp. nov. is characterized by its body 1.23-1.58 mm long, lip region continuous, odontostyle 17.0-19.0 μm long, neck 320.0-397.0 μm long, uterus tripartite, pars refringens vaginae with two triangular pieces separated by an intermediate sclerotized area, V = 54-59, vulva longitudinal, tail short and rounded in both sexes, spicules 43.0-48.0 μm long, and seven to eight spaced ventromedian supplements. C. vietnamense sp. nov. can be distinguished in having body 1.55-1.88 mm long, lip region offset by constriction, odontostyle 19.5-22.0 μm long, neck 370.0-448.0 μm long, uterus very long and tripartite, pars refringens vaginae with two close together pieces, V = 55-59, vulva transverse and usually covered with a plug, tail short and rounded in both sexes, spicules 53.0-55.0 μm long, and eight to nine spaced ventromedian supplements, two of them within the range of spicules. [ABSTRACT FROM AUTHOR]