Search

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 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]

A new Iranian population of Lindseyus costatus is characterized, including morphometrics, microphotographs, and molecular (18S, 28S rDNA) studies. It is compared with previously known populations. The results derived from molecular analyses failed to find close evolutionary relationships with other traditional genera of Belondiridae and Swangeriinae, adding more uncertainties about the internal phylogeny of the family. The taxonomy of Lindseyus is revised, with a new diagnosis, list of species, key to their identification, and a compilation of their main morphometrics.

Two new species of the genus Sectonema found in northern Iran are characterized, including morphological descriptions and molecular (18S-, 28S-rDNA) analyses. Sectonema tehranense sp. nov. is distinguished by its 7.22 - 8.53 mm long body, lip region offset by constriction and 24 - 31 μm wide with perioral lobes and abundant setae- or cilia-like projections covering the oral field, mural tooth 15.5 - 17 μm long at its ventral side, neck 1091 - 1478 μm long, pharyngeal expansion occupying 61 - 71% of the total neck length, female genital system diovarian, uterus simple and 3.9 - 4.2 times the corresponding body diameter long, transverse vulva ( V = 49 - 59), tail short and rounded (44 - 65 μm, c = 99 - 162, c' = 0.6 - 0.8), spicules 111 - 127 μm long, and 7 - 10 spaced ventromedian supplements with hiatus. Sectonema noshahrense sp. nov. displays a 4.07 - 4.73 mm long body, lip region offset by constriction and 23 - 25 μm wide with perioral lobes and abundant setae- or cilia-like projections covering the oral field, odontostyle 14 - 14.5 μm long, neck 722 - 822 μm long, pharyngeal expansion occupying 66 - 68% of the total neck length, female genital system diovarian, uterus simple and 2.4 - 2.7 times the corresponding body diameter long, transverse vulva ( V = 54 - 55), tail convex conoid (39 - 47 μm, c = 91 - 111, c' = 0.8 - 0.9), spicules 82 μm long, and seven spaced ventromedian supplements with hiatus. Molecular analyses confirm a maximally supported ( Epacrolaimus + Metaporcelaimus + Sectonema ) clade and a tentative biogeographical pattern, with sequences of Indolamayan taxa forming a clade separated from those of Palearctic ones. Parallel or convergent evolution processes might be involved in the phylogeny of the species currently classified under Sectonema. This genus is certainly more heterogeneous than previously assumed.

A new species of the free-living nematode genus Trachactinolaimus , collected in natural habitats of northern Iran, is described, including morphological and molecular (28S-rDNA) data. Trachactinolaimus persicus sp. n. is characterized by its 1.95-2.44 mm long body, lip region weakly offset by depression and 18-20 μm wide, odontostyle 25-27 μm long, neck 540-636 μm long, pharyngeal expansion occupying one-half of the total neck length, bipartite uterus 2.6-3.9 body diameters long, vulva ( V = 49-53) pore-like, tail long and filiform in both sexes (174-223 μm, c = 10.0-13.4, c' = 5.9-7.0 in females, 165-196 μm, c = 10.7-13.8, c' = 4.6-5.8 in males), spicules 68-75 μm long, and 12-14 almost contiguous ventromedian supplements with hiatus. Molecular data supports the monophyly of the genus and the hypothesis that Dorylaimidae are the sister group of actinolaims. The taxonomy of Trachactinolaimus is updated, including diagnosis, list of species, key to their identification, and a compendium of their main morphometrics. Dominiactinolaimus is regarded as its junior synonym.

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 S 2 N 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.

Two species of the genus Aporcella, one new and one previously known, collected from cultivated fields in Iran are studied. Description, morphometrics, illustrations (both line and microphotographs) and D2-D3 sequences are provided for Aporcella talebii sp. n., which is characterized by its 1.66-2.02-mm-long body, lip region offset by constriction and 15-17 μm broad, odontostyle 14-17.5 μm long, neck 412-484 μm long, pharyngeal expansion occupying 46-50% of total neck length, uterus simple and 1.6-2.0 times the corresponding body diameter long, V = 52-59, tail conical (40-50 μm, c = 37-47, c' = 1.1-1.4) with a weak but perceptible dorsal concavity at the end and male absent. Morphometrics, microphotographs and D2-D3 sequences of Aporcella simplex are also presented, this being its first Asian record. Molecular analyses confirm the monophyly of the genus, its close relationship with other taxa lacking pars refringens vaginae and the polyphyly of Aporcelaimidae.

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.

A new species of the genus Tylencholaimus, collected in natural areas of Iran, is described and illustrated, including SEM observations. Tylencholaimus discus sp. n. is characterized by its 0.65-0.76 mm long body, lip region offset by weak constriction and 7-7.5 µm broad with a conspicuous perioral disc, odontostyle 6-7 µm long, odontophore 9-10.5 µm long and visibly flanged rather than knobbed, neck 230-259 µm long with anterior region weakly muscular and basal expansion 98-125 µm long or occupying 42-49% of total neck length, female genital system mono-prodelphic, posterior branch reduced to a uterine sac 2-20 µm long or much shorter (0.1-0.6 times) than body diameter but very occasionally consisting of uterus, sphincter and a small terminal mass all together measuring 35-40 µm long, V = 65-74, tail short and rounded (13-17 µm, c = 41-57, c' = 0.6-0.8), and male unknown.

A new species of the genus Metaxonchium is described from natural habitats in Iran. The new species is characterized by having body length of 2.46-3.12 mm, lip region offset by constriction and 8-11 µm wide, odontostyle fusiform and 10-12 µm long, neck 773-1150 µm long, anterior portion of pharynx bearing a spindle-shaped thickening with valve-like structures inside, both parts of the pharynx separated by a short isthmus-like narrowing, pharyngeal expansion 531-825 µm long and occupying up to three-fourths of total neck length, female genital system monodelphic-opisthodelphic, anterior genital branch reduced to a large uterine sac and a small terminal mass, posterior uterus long and tripartite with an intermediate region bearing apophyses, V = 53-57, caudal region conoid with broadly rounded terminus (24-35 µm, c = 79-105, c' = 0.6-0.9), spicules 92-103 µm long and 7-10 spaced ventromedian supplements, at least two of them within the range of spicules. The taxonomy of the genus Metaxonchium is updated, including a list of its species, a key to their identification and a compendium of their morphometrics. Four species are transferred from Axonchium to Metaxonchium: M. coxi, M. japonicum, M. mizukuboi and M. zealandicum.