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A new species of the genus Talanema , recovered from the northwest of Iran, was described based on morphological, morphometric, and molecular data. Talanema eshtiaghii sp. n. was characterized by its 1.45-1.68 mm long body, lip region offset by constriction and 13-15 μm wide, odontostyle 15-18 μm long, double guiding ring, neck 312-362 μm long, pharyngeal expansion occupying 41-43% of the total neck length, uterus tripartite, and 111-189 μm long or 2.1-3.2 body diameters, vulva transverse (V = 55-58), tail similar in both sexes, conical with a dorsal concavity (30-44 μm, c = 33-56, c' = 1.0-1.6), spicules 49-56 μm long, and 14-18 shortly spaced ventromedian supplements in front of the level of the anterior end of spicules, with distinct hiatus. It was compared to four closely similar species, with emphasis on the most relevant traits to distinguish them. Molecular phylogenetic studies using partial sequence of the 28S rDNA (D2-D3 segment) revealed that the new species forms a clade with other currently sequenced representatives of Talanema , tentatively supporting the monophyly of this genus., (© 2023 Nasir Vazifeh et al., published by Sciendo.)

Three Iranian populations of Discolaimium dubium are studied, including their morphological and morphometric characterization, molecular analysis (LSU-rDNA) and the description of the male for the first time. For comparative purposes, this species is distinguished by its 1.10 to 1.40 mm long body, lip region offset by constriction and 8 to 10 µm wide, odontostyle 7.5 to 10.5 µm long with aperture occupying 59 to 76% of total length, neck 300 to 362 µm, pharyngeal expansion 127 to 181 µm long or 44 to 46% of the total neck length, uterus simple and 38 to 53 µm or 1.2 to 1.5 times the body diameter long, V  = 52 to 58, tail conical (32-38 µm, c  = 32-43, c'  = 1.6-2.0) with rounded tip and a hyaline portion occupying 14 to 15% of tail length, spicules 30 to 32 µm long, and two or three widely space ventromedian supplements with hiatus. Both morphological and molecular data support its belonging to the genus Aporcella , whose monophyly is confirmed and to which the species is formally transferred as A. dubia (Das et al., 1969) comb. n., (© 2021 Authors.)

Epidorylaimus procerus sp. n., collected from a natural habitat in Vietnam, is described and illustrated. It is distinguishable by its 2.16 to 2.46-mm-long body, lip region offset by depression and 15 to 17-µm broad, odontostyle 32 to 35-µm long, neck 415 to 461-µm long, pharyngeal expansion occupying 47 to 52% of the total neck length, uterus 76 to 130-µm long or 1.0 to 1.5-body diameters, vulva transverse ( V  = 40-43), caudal region conical elongate (157-186 µm, c  =12.1-14.4, c'  = 4.4-5.5) with blister-like bodies, and hyaline portion occupying one-fourth its length, and males absent. Molecular analysis shows a close relationship of the new species and E. lugdunensis , supporting monophyly of the genus Epidorylaimus ., (© 2020 Authors.)

Two species of the genus Pungentus , one new and one known, collected in natural vegetation and cultivated soils in northwest of Iran, are studied. Pungentus sufiyanensis n. sp. is characterized by its 1.22 to 1.57 mm long body, offset lip region by a constriction and 7 to 9 μm broad, 18 to 21 μm long odontostyle, 304 to 348 μm long neck, 133 to 161 μm long esophageal expansion, mono - opisthodelphic female genital system without anterior uterine sac, slightly backward directed vagina, absence of pars refringens vaginae , V  = 47 - 54, rounded-conoid caudal region (17.5-23 μm, c  = 65-84, c ´ = 0.7-1) with saccate bodies, and the absence of male. Molecular analysis, based on D2-D3 expansion segments of the 28S rDNA (LSU), confirms the monophyly of the family Nordiidae and suggests the monophyly of the genus Pungentus , with the new species forming a clade with other Iranian species. New data are presented for six Iranian populations of P. engadinensis , and an updated key for the identification of Pungentus species is also provided., Two species of the genus Pungentus , one new and one known, collected in natural vegetation and cultivated soils in northwest of Iran, are studied. Pungentus sufiyanensis n. sp. is characterized by its 1.22 to 1.57 mm long body, offset lip region by a constriction and 7 to 9 μm broad, 18 to 21 μm long odontostyle, 304 to 348 μm long neck, 133 to 161 μm long esophageal expansion, mono - opisthodelphic female genital system without anterior uterine sac, slightly backward directed vagina, absence of pars refringens vaginae , V  = 47 − 54, rounded-conoid caudal region (17.5–23 μm, c  = 65–84, c ´ = 0.7–1) with saccate bodies, and the absence of male. Molecular analysis, based on D2-D3 expansion segments of the 28S rDNA (LSU), confirms the monophyly of the family Nordiidae and suggests the monophyly of the genus Pungentus , with the new species forming a clade with other Iranian species. New data are presented for six Iranian populations of P. engadinensis , and an updated key for the identification of Pungentus species is also provided.

The identity of Eucephalobus oxyuroides is discussed after studying two Iberian populations that fit the original description of the species. A new characterization is consequently provided as follows: 0.49 to 0.70 mm long body, lip region continuous with the adjoining body and bearing short probolae prongs, neck 132 to 158 µm long, spermatheca 23 to 47 µm long or 1.0 to 1.8 times the corresponding body diameter, post-vulval uterine sac 40 to 54 µm long or 2.0 to 2.5 times as long as the body diameter, V   =  58 to 64, female tail conical elongate with very acute terminus (60-79 µm, c  = 7.1-10.0, c ' = 4.9-5.8), male tail conical (36-49 µm, c  =10.9-14.3, c ' = 2.4-3.4) with an elongate acute mucro, and spicules 21 to 22 µm long. Previous records of the species are revised. An emended diagnosis of the genus is proposed, and its taxonomy is updated with a list of species, key to their identification and illustrations. The evolutionary relationships of Eucephalobus , as derived from the analyses of 18S and 28S rDNA fragments, reveals that it occupies a basal position within the subfamily Cephalobidae., The identity of Eucephalobus oxyuroides is discussed after studying two Iberian populations that fit the original description of the species. A new characterization is consequently provided as follows: 0.49 to 0.70 mm long body, lip region continuous with the adjoining body and bearing short probolae prongs, neck 132 to 158 µm long, spermatheca 23 to 47 µm long or 1.0 to 1.8 times the corresponding body diameter, post-vulval uterine sac 40 to 54 µm long or 2.0 to 2.5 times as long as the body diameter, V   =  58 to 64, female tail conical elongate with very acute terminus (60-79 µm, c  = 7.1-10.0, c ′ = 4.9-5.8), male tail conical (36-49 µm, c  =10.9-14.3, c ′ = 2.4-3.4) with an elongate acute mucro, and spicules 21 to 22 µm long. Previous records of the species are revised. An emended diagnosis of the genus is proposed, and its taxonomy is updated with a list of species, key to their identification and illustrations. The evolutionary relationships of Eucephalobus , as derived from the analyses of 18S and 28S rDNA fragments, reveals that it occupies a basal position within the subfamily Cephalobidae.

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., (© 2019 Authors.)

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 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.

The taxonomy and the systematics of the genus Makatinus are discussed by means of the characterization of its morphological pattern and the first molecular (D2-D3 expansion segments of 28S rDNA) analysis of a representative of this taxon, Makatinus crassiformis from Costa Rica. The presence of two or more pairs of male ad-cloacal genital papillae is the most characteristic autapomorphy of the genus, but the status of its species on this concern differ among them. Both morphological and molecular data support a relationship with Aporcelaimellus , which, however, might not be as close as usually assumed. An emended diagnosis of the genus, a key to species identification, and a compendium of their morphometrics are provided. Makatinus siddiqii is regarded as species inquirenda , Makatinus simus is retained under Eudorylaimus , and Makatinus tritici becomes a junior synonym of Aporcelaimellus tritici .

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.

A new species, the third one from Vietnam, of the genus Aporcelinus is described from natural areas. Aporcelinus falcicaudatus sp. n. is characterized by its 1.28 to 1.63 mm long body, lip region offset by weak constriction and 16 to 18 µm broad, odontostyle 18 to 21 µm at its ventral side, neck 354 to 406 µm long, uterus tripartite and 61 to 95 µm long, V = 50 to 55, tail strongly recurved dorsad and conical (23-31 µm, c = 43-58, c' = 0.7-0.9) with finely rounded tip, and male absent. Scanning electron microscope (SEM) study, the first of a representative of the genus, shows a lip region pattern significantly different from that observed in the typical aporcelaimid taxa.

Margollus bokanicus n. sp., collected from natural habitats in Khorasaneh district, Bokan, West Azarbaijan province, Iran, is described. Morphological and morphometric data are provided as well as drawings and light microscopy illustrations. The new species is characterized by a medium size body length (0.60 to 0.73 mm), labial and postlabial sclerotizations, lip region 7-μm wide, offset by constriction and long neck (167 to 207 μm), long pharyngeal basal bulb (27 to 36 μm) or 16% to 17% of total neck length, female genital system monodelphic-opisthodelphic, anterior branch reduced to a uterine sac (26-29 μm) or 1.1 to 1.3 times the body diameter, long posterior uterus (25-28 μm) or 1.1 to 1.3 times the body diameter, V = 40 to 47, cylindroid female tail (17 to 24 μm, c = 31 to 38, c' = 1.1 to 1.4), and males unknown. This taxon is easily distinguishable from other Margollus species by its smaller general size and more posterior vulva. A compendium of Margollus species is also presented.

A new species of the genus Protorhabditis is described from natural areas in the SE Iberian Peninsula. Protorhabditis spiculocrestata sp. n. is distinguished by its body length 387-707 mum in females and 375-546 mum in males, lip very low and flattened, stoma 14-22 mum long, female tail conical-elongate (48-100 mum, c = 6.4-8.3, c' = 4.8-7.5), phasmid near anus, male tail conical (20-27 mum, c = 18.3-22.3, c' = 1.4-1.5), bursa peloderan closed anteriorly and bears eight papillae (1+2+1+1+3), spicules 23-26 mum long, and gubernaculum 10-16 mum long. Diploscapter coronatus is also presented. Description, measurements and illustrations, including SEM photographs, are provided. A key to species of Protorhabditis is also given as well a compendium of their measurements.

The identity and taxonomy of the genus Crassolabium are discussed based on examination of material of C. australe, its type species and its comparison with Iberian species of close genera. The existence of refractive masses (thickenings) at the inner core of lateral lips, the most distinctive diagnostic feature of Crassolabium, is considered to be of minor taxonomical significance because of its interspecific and even intraspecific variability. It is concluded that Crassolabium and Thonus are identical, and a reversal of precedence among both genera is suggested. Crassolabium australe is re-described, and some comments are provided on C. robustum, the second species in the genus.

A new species of the genus Stegelletina is described from caves of Andalucía Oriental (SE Iberian Peninsula). Stegelletina coprophila sp. n. is characterized by its body 386 to 536 mum long in females and 391 and 521 mum in males, lateral field with three incisures, lips bearing four tines, labial probolae 4 to 6 mum long and bifurcate, pharyngeal corpus 1.5 to 2.9 times isthmus length, spermatheca 18 to 43 mum long, postvulvar sac 0.5 to 1.6 times the corresponding body diameter long, female tail conical (24-34 mum, c = 14.2-17.2, c' = 1.7-2.3), male tail conical (26-35 mum, c = 12.1-17.1, c' = 1.4-1.8), spicules 20 to 25 mum long, and gubernaculum 10 to 13 mum long. Descriptions, measurements and illustrations, including SEM photographs, are provided for the species.

The aim of this study was to determine the incidence of 18 environmental variables in the spatial distribution of 30 chorotypes (species groups with significantly similar distribution patterns) of dorylaimid and mononchid nematodes by means of logistic regression in a natural area in the southeastern Iberian Peninsula. Six variables (elevation, color chroma, clay content, nitrogen content, CaCO, and plant community associated) were the most important environmental factors that helped explain the distribution of chorotypes. The distribution of most chorotypes was characterized by some (one to three) environmental variables; only two chorotypes were characterized by five or more variables, and four have not been characterized.

A new species of the genus Nothacrobeles is described from natural areas (a salt lake) in the Southeast Iberian Peninsula. Nothacrobeles lanceolatus sp. n. is characterized by its body length, two rows of cuticular punctations per annulus, labial probolae bifurcate with divergent prongs, pharyngeal corpus 2.4 to 3.5 times isthmus length, spermatheca length, postuterine sac 0.5 to 1.1 times the corresponding body diameter ratio, female tail conical and bearing a spindle-shaped or conical mucro with acute terminus, phasmid at 8 to 17 microm posterior to the anus, male tail conical with acute mucro, spicules length, and gubernaculum length. In addition, Nothacrobeles cf. lunensis and Zeldia punctata are studied. Cervidellus capricornis is transferred to genus Nothacrobeles. A key to species of Nothacrobeles is also provided.

The spatial distribution of 138 Dorylaimid and Mononchid species collected in a natural area from the Southeast Iberian Peninsula was studied. A chorological classification was used to examine distribution patterns shared by groups of species. Eighty species were classified into 14 collective and 16 individual chorotypes. The geographical projections of several collective chorotypes are illustrated along with their corresponding distribution maps. The importance of this analysis to nematological study is briefly discussed.