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Graph representation learning is an effective tool for facilitating graph analysis with machine learning methods. Most GNNs, including Graph Convolutional Networks (GCN), Graph Recurrent Neural Networks (GRNN), and Graph Auto-Encoders (GAE), employ vectors to represent nodes in a deterministic way without exploiting the uncertainty in hidden variables. Deep generative models are combined with GAE in the Variational Graph Auto-Encoder (VGAE) framework to address this issue. While traditional VGAE-based methods can capture hidden and hierarchical dependencies in latent spaces, they are limited by the data’s multimodality. Here, we propose the Gaussian Mixture Model (GMM) to model the prior distribution in VGAE. Furthermore, an adversarial regularization is incorporated into the proposed approach to ensure the fruitful impact of the latent representations on the results. We demonstrate the performance of the proposed method on clustering and link prediction tasks. Our experimental results on real datasets show remarkable performance compared to state-of-the-art methods.

Eudorylaimus kahaqensis sp. n. (Figs 1–6) Material examined: Twenty females, twelve males and several juveniles, in acceptable (mostly good) condition. Measurements: See Table 1. Description. Adult: Slender nematodes (a = 29–39) of medium size, 1.40–1.75 mm long. Body cylindrical, tapering towards both ends as the tail is conical. Habitus regularly curved ventrad, an open ‘C’ or ‘J’ shape in females, ‘J’ or ‘G’ shaped in males. Cuticle 2.0–2.5 µm thick in the anterior region, 2.0–3.5 µm at mid-body and 3.0–4.0 µm on tail; outer layer with fine transverse striation throughout the body, perceptible even under LM; inner layer thicker than the outer one, especially visible at caudal region. Lip region anteriorly truncate, nearly continuous with the adjacent body, 2.8–3.2 times as wide as high, and ca one half (45–50%) of body diameter at neck base; anterior margin visibly corrugated or wrinkled. SEM observations: lips totally amalgamated; labial and cephalic papillae distinct but weakly protruding, button-like; oral field broad, with coarse radial striation—visibly stronger than the transverse striation of the adjacent body, and responsible for the corrugated anterior marginrunning from the oral aperture to the posterior margin of lip region; oral aperture apparently small. A moderately sclerotized but perceptible cephalic framework is present. Amphidial fovea stirrup-shaped, aperture a transverse slit 9–11 µm wide and occupying ca one-half (50–56%) of lip region diameter. Cheilostom wider than usual, with convex walls. Odontostyle equal to lip region diameter long, comparatively slender (9–12 times as long as wide), 1.1–1.3% of total body length, and with aperture 6–8 µm long or occupying less than one-half (33–44%) of total length. Guiding ring simple, somewhat plicate, and located at 8–11 µm or 0.4–0.5 times the lip region diameter from the anterior end. Odontophore rod-like, 1.7–2.0 times the odontostyle in length, its junction with the pharyngeal lining rather inconspicuous. Anterior portion of pharynx slender but muscular, enlarging very gradually into the basal expansion that is 7.4–9.0 times as long as wide, 4.0–4.6 times as long as the body diameter at neck base and occupies 45–53% of total neck length; gland nuclei located as follows: DO = 60–66, DN = 66–70, S1N1 = 78–83, S1N2 = 82–88, S2N = 90–94, S2O = 94; DN remarkably posterior in position, far from pharyngeal enlargement, S1N1 conspicuously longer than wide, with its nucleolus much larger than that of S1N2 and even slightly larger than those of S2N, and S2O visibly behind S 2N. Nerve ring at 128–145 µm or 35–37% of the neck length from the anterior end. One coelomocyte 7.5– 13 x 5.5–10.0 µm is present in dorsal position in all the specimens examined a short distance behind the nerve ring, at 145–162 µm from the anterior end. Cardia cylindroid, 13.5–19.0 x 7.0–8.5 µm. A dorsal cell mass is always present at the pharyngo-intestinal junction. Intestine without any special differentiation. Female: Genital system didelphic-amphidelphic, with both branches of similar morphology and length, the anterior 192–264 µm or 11–14% of total body length, the posterior 182–273 µm or 12–14% of total body length. Ovaries reflexed, 77–101 µm long, not reaching the oviduct-uterus junction; oocytes in several rows in the germinative zone, then in one row. Oviduct 84–120 µm or 2.0–2.8 times the corresponding body diameter long, consisting of a slender portion made of prismatic cells and an appreciably longer than wide pars dilatata with visible lumen and often containing sperm cells. A marked narrowing surrounded by a weak muscular ring is present separating oviduct and uterus. Uterus a simple tube-like structure 62–125 µm or 1.5–2.3 times the corresponding body diameter long, often containing sperm cells as well. Vagina 26–33 µm long, extending to 63– 70% of body diameter: pars proximalis 18–24 x 16 –22 µm, with somewhat sigmoid walls and surrounded by moderately developed musculature; pars refringens consisting of two trapezoidal pieces 3.0–3.5 x 7.0–7.5 µm and a combined width of 15–18 µm; pars distalis 5.5–6.5 µm long. One gland cell (granular in appearance) is present close the vagina both anteriorly and posteriorly. Vulva a transverse slit. Intestine-prerectum junction especially granular and colored in all the specimens examined. Prerectum 1.4–1.6, rectum 1.1–1.2 times the anal body diameter in length. Caudal region regularly curved ventrad and conical (somewhat) elongate with finely rounded tip; hyaline portion well developed, 17–30 µm or 28–45% of the total tail length. Male: Genital system diorchic, with opposite testes. In addition to the ad-cloacal pair situated at 11–15 µm from the cloacal aperture, there is a series of 7–9 irregularly spaced (12–15 µm apart), ventromedian supplements, the most posterior of which is located at 22–28 µm from the ad-cloacal pair, at the level of or a short distance behind the anterior end of spicules. A distinct pre-cloacal space (hiatus) is therefore not present. Spicules dorylaimid, 1.7–1.9 times longer than the body diameter at level of cloacal aperture, 3.9–4.2 times longer than wide, and curved ventrad 124–130º; head 12–16 µm long, occupying 23–30% of total spicule length, 2.0–2.3 times as long as wide, with its dorsal side distinctly longer than the ventral one and slightly curved; median piece 35–41 µm long, 6.4–7.6 times longer than wide, occupying 37–46% of spicule width, and reaching the spicule posterior tip. Lateral guiding piece 13–17 µm long, 5.2–6.8 times longer than wide, with slightly bifid end. Prerectum 1.8– 2.5, cloaca 1.4–1.7 times the body diameter at level of cloacal aperture. Caudal region similar to that of female, its hyaline portion 22–25 (11.5 in one specimen, probably aberrant) µm long, occupying 39–40 (26)% of total tail length. Diagnosis. The new species is characterized by its 1.40–1.75 mm long body, lip region nearly continuous and 17–21 µm wide and bearing a weakly sclerotized but distinct cephalic framework, cheilostom broad and with convex walls, odontostyle 21–23 µm long with aperture occupying 33–44% of its length, presence of a dorsal coelomocyte a short distance behind the nerve ring, neck 347–397 µm long, DN rather posterior (66–70%), pharyngeal expansion 162–205 µm or occupying 45–53% of total neck length, presence a dorsal cell mass at level of pharyngo-intestinal junction, V = 48–52, caudal region conical (somewhat) elongate (50–73 µm, c = 24–30, c’ = 1.9–2.6 in females, 45–68 µm, c = 22–32, c’ = 1.7–2.3 in males) and regularly curved ventrad with large hyaline portion, spicules 48–55 µm long and 7–9 irregularly spaced ventromedian supplements lacking hiatus. Relationships. Eudorylaimus kahaqensis sp. n. is easily recognizable by an unusual combination of features, but its conical, somewhat elongate, caudal region in both sexes and the position of its most posterior ventromedian supplement at the level of the anterior end of the spicules and not too far anterior to the pre-cloacal pair (i. e., lacking a distinct hiatus) raise doubts about its true generic identity (see further discussion below), since it possesses characteristics of the genera Eudorylaimus Andrássy, 1959, Allodorylaimus Andrássy, 1986 and Epidorylaimus Andrássy, 1986. Within Eudorylaimus, it resembles several species (some without known males), in particular E. altherri Tjepkema et al., (1971), E. nudicaudatus Heyns, 1993 and E. unicus Khan & Araki, 2000. It differs from E. altherri in its nearly continuous (vs offset by constriction and visibly wider than the adjacent body) lip region, longer odontostyle (21–23 vs 19.3 ± 1.2 µm), shorter female prerectum (43–50 vs 90 ± 22 µm), pars refringens vaginae with trapezoidal (vs triangular) pieces, and male as frequent as female (vs male absent). From E. nudicaudatus, it differs in its nearly continuous (vs offset by constriction) lip region, longer odontostyle (21–23 vs 13–15 µm, equal to vs distinctly shorter than lip region diameter), more posterior vulva (V = 48–52 vs V = 43–48), comparatively longer female tail (c = 24–30 vs c = 32–46) with long (vs very short) hyaline portion, and male lacking (vs having) hiatus. It can be distinguished from E. unicus by its nearly continuous (vs offset by constriction) lip region, more posterior DN (vs close the pharyngeal expansion), longer vagina (extending to 63–70% vs up to one-half of body diameter), longer female tail (c’ = 1.9–2.6 vs c’ = 1.6–1.8) with different morphology (ending in a finely rounded vs relatively coarse tip), and male present (vs absent). The new species also resembles E. rugosus (Andrássy, 1957) Andrássy, 1959 in several aspects (general morphology and morphometry, lip region nearly truncate and visibly slender odontostyle) but differs in its longer tail (c = 24–30, c’ = 1.9–2.6 vs c = 30–33, c’ = 1.5–1.6). It can also be compared to E. pseudobokori Zell, 1986 in its general morphology and morphometry as well its comparatively long caudal region, but can be distinguished by the morphology of lip region (truncate and continuous vs angular and offset) and odontostyle (slender vs more robust), and the number (7–9 vs 5) and arrangement of ventromedian supplements (most posterior of them at level of or slightly posterior to vs visibly anterior to the end of spicules). In lacking a distinct precloacal space in males, the new species also resembles members of Allodorylaimus, especially A. aljabaranus Quijano et al., (1991) and A. digiturus (Thorne, 1939) Andrássy, 1986. It differs from A. aljabaranus in its broader (17.0–21 vs 14–16 µm) and amalgamated (vs lips separated and angular) lip region, and fewer ventromedian supplements (7–9 vs 10–15) with different arrangement (only the most posterior ventromedian supplement located at the level of the anterior end of the spicules or a short distance posterior vs two or three ventromedian supplements well within the range of the spicules). From A. digiturus, a poorly known species described on the basis of only one male, it differs in its larger general size (body length 1.40–1.75 vs 1.30 mm), broader lip region (17.0–21 vs ca 12 µm), longer (21–23 vs ca 12 µm) and more slender (9–12 vs ca 6 times as long as wide) odontostyle, and fewer ventromedian supplements (7–9 vs 11) with different arrangement (only the most posterior ventromedian supplement located at the level of the anterior end of the spicules or a short distance behind it vs two ventromedian supplements well within the range of the spicules). In its general morphology, and in particular in its comparatively long tail in both females and males, and males lacking hiatus, the new species resembles some Epidorylaimus representatives (see the updated diagnosis and compendium by Ahmad et al., 2016), especially E. consobrinus (de Man, 1880) Andrássy, 1986 and E. filicaudatus (Tjepkema et al., 1971) Andrássy, 1986. The new species differs from E. consobrinus, a poorly characterized species, in its weakly (vs distinctly) angular lip region, and shorter caudal region (c’ = 1.9–2.6 vs c’ = 2.7–4.3 in females) with different morphology (with finely rounded vs acute tip, large vs no hyaline portion). It can be distinguished from E. filicaudatus by having weakly (vs distinctly) angular lip region, more attenuated odontostyle (9–12 vs up to 7 times as long as wide), shorter caudal region (50–73 vs 81–123 µm), and frequent males (vs male unknown). Finally, some traits (continuous lip region, broad cheilostom) of the new species resemble those found in species of the genus Chrysonema Thorne, 1929, but it does not fit at all the very peculiar morphological pattern of this taxon (see Andrássy, 2009), which is characterized by, among other diagnostic features, a very slender body (a - ratio very usually over 50), comparatively small and attenuate odontostyle, absence of pars refringens vaginae, tail conical elongate (c’ > 4), tapering very gradually, and male bearing subventral caudal papillae. Type locality and habitat. The new species has been collected from Iran, East Azarbaijan province, north of Maragheh, Kahaq region (GPS coordinate 47º13´35.7´´E, 37º28´12.1´´ N), where it was found in the rhizosphere soil of walnut, spruce and willow. Type material. Female holotype, 10 female and eight male paratypes deposited in the Nematode Collection of Nematology Laboratory, Department of Plant Protection, Faculty of Agriculture, University of Tabriz, Tabriz, Iran. Two female and two male paratypes with the Nematode Collection, University of Jaén, Spain. Etymology. The specific epithet refers to the geographical origin of the new species in Kahaq region, Iran. Remarks. The new species herein described is an excellent example of the problematic taxonomy of the conical-tailed species of the family Qudsianematidae. It is characterized by a combination of features that allows its relatively easy identification but that, at the same time, raises doubt about its generic identity. Its conical, somewhat elongate caudal region is intermediate between those observed in species of Eudorylaimus, which tend to be shorter, and those of Epidorylaimus species, which tend to be longer, but there is no distinct borderline between the two genera. The location of the posteriormost ventromedian supplement is also notable: situated at approximately the level of the anterior end of the spicules, it is not too much farther from the adcloacal pair than from the penultimate ventromedian supplement of the series, so that a pre-cloacal space (hiatus) is not distinctly perceptible, again representing an intermediate condition between Eudorylaimus (males with distinct hiatus) and Allodorylaimus and Epidorylaimus (both with males lacking hiatus, i.e. with one or more ventromedian supplements within the range of the spicules). With due caution, the new species has been provisionally classified under Eudorylaimus because its general morphology fits better the pattern of that genus. Nevertheless, leaving aside the tail length and the presence/absence of a hiatus, it should be emphasized that the new species displays other features (nearly truncate and continuous lip region with corrugated anterior margin, broad cheilostom, weakly sclerotized but perceptible cephalic framework, presence of a coelomocyte shortly behind the nerve ring, dorsal gland pharyngeal nucleus in rather posterior position, etc.) that conform a peculiar pattern that might deserve separate generic status if other species are found that share it.

Metaxonchium persicum sp. n. (Figs 1���4) Morphometrics. See Table 1. Description. Type population from Azarbaijan rangelands (6 ♀♀ + 3 ♂♂). Adult: Slender to very slender nematodes of medium to large size, 2.46���3.12 mm long. Body cylindrical, visibly tapering towards the anterior end, less so towards the posterior end since the caudal region is short and conoid. Habitus curved ventrad upon fixation, C- or G-shaped. Cuticle three-layered, consisting of inner layer thicker than the others, especially obvious at caudal region where it bears distinct radial striation, an intermediate and more transparent layer, and a thinner outer layer nearly smooth under LM but bearing very fine transverse striation under SEM; cuticle thickness 2���3 ��m in anterior region, 4���6 ��m at mid-body and 8���15 ��m on dorsal side of tail. Cervical lacunae often clearly visible. Lateral chord comparatively narrow, 5���7 ��m wide or up to one-tenth (7���10 %) of mid-body diameter, of granular nature and lacking any other differentiation. Lip region rounded to slightly truncate anteriorly, offset by constriction, 2.2���2.8 times as broad as high or less than one-sixth (11���15 %) of body diameter at neck base; lips separate, under SEM appearing conoid, tapering toward the oral aperture, and with deep radial incisures in between; labial and cephalic papillae very low, not interfering the labial contour. Amphid fovea cup-like, its aperture 7���9 ��m wide or occupying about four-fifths (75���82 %) of lip region diameter. Cheilostom a truncate cone, lacking any differentiation. Odontostyle small, somewhat fusiform, as thick as the cuticle at its level, equal to or hardly longer (1.0��� 1.2 times) than lip region diameter, 5.8���6.8 times as long as wide and 0.36���0.40 % of body length; aperture 3.0��� 3.5 ��m long, occupying one-fourth to one-third (25���35 %) of total length. Guiding ring thin, simple but visibly refractive, at 11���14 ��m or 0.8���0.9 times the lip region diameter from the anterior end. Odontophore rod-like, 1.8���2.2 times the odontostyle length, bearing a very slight thickening at its approximate midpoint. Pharynx consisting of a slender and weakly muscular anterior portion, which is separated from the basal expansion by a short isthmus-like narrowing, and bearing a well developed, spindle-shaped thickening with valvelike structures, situated at 117���155 ��m from anterior end; basal expansion 13���20 times as long as broad, 7.5���9.9 times longer than body diameter at neck base, and occupying up to three-fourths (68���73 %) of total neck length; a very distinct spiral muscular sheath, with nearly straight muscular bands, envelops the whole basal expansion. Cardia tongue-like, 22���25 ��m long x 13���14 ��m wide, surrounded by intestinal tissue. Caudal region conoid with broadly rounded terminus, ventrally straighter, dorsally more convex; caudal pores two pairs at the posterior half of tail, one lateral, another subdorsal. Female: Genital system monodelphic-opisthodelphic. Anterior branch 117���324 ��m long or 6���11 % of body length, and consisting of a long uterine sac often devoid of sperm cells, and a small solid terminal mass probably representing oviduct and/or ovary remnants. Posterior branch very long and impossible to measure as its tract always appears strongly convoluted: reflexed ovary large, 170���370 ��m long, with oocytes arranged first in several rows and then in a single row; oviduct joining the ovary subterminally, 135���142 ��m long or 1.4���2.1 body diameters, and consisting of a tubular part made of prismatic cells and a well developed pars dilatata with distinct lumen and occasionally containing sperm cells. A strong sphincter separates oviduct and uterus. Uterus very long and tripartite, i.e., provided with a proximal region with very wide lumen, a convoluted long intermediate region with narrow lumen and containing numerous refractive, irregular elements (apophyses), and a large spherical distal pars dilatata. One female bearing a uterine egg, 145 x 52 ��m. Vagina 32���42 ��m long, extending inwards about one-half (43���55 %) of the corresponding body diameter; pars proximalis longer than wide, 21���24 x 15 ���20 ��m, with convergent walls and surrounded by moderately developed, circular musculature; pars refringens (in lateral view) consisting of two trapezoidal pieces measuring 4��� 5 x 7���8 ��m and with a combined width of 9���11 ��m; pars distalis 3���7 ��m long. Vulva a somewhat posterior transverse slit, about 10 ��m long. Prerectum 4���10, rectum 1.0��� 1.4 anal body diameters long. Anus a straight transverse slit about 8 ��m long. Male: Genital system diorchic, with opposite testes. In addition to the adcloacal pair, situated at 15���17 ��m from cloacal aperture, there is a series of 7���10 ventromedian supplements 17���34 ��m apart, the posteriormost of which is situated at 38���50 ��m from the adcloacal pair; hiatus lacking as at least two ventromedian supplements lie within the range of spicules. Spicules dorylaimoid, curved ventrad, relatively slender (7.8���8.3 times as long as wide) and long (1.8���2.2 times the cloacal body diameter), and with a rather narrow anterior part. Lateral guiding pieces 19���20 ��m long, 9���10 six times as long as wide. Other material examined (9 ♀♀ from three locations). These nine females are nearly identical to those of type population. They have slightly smaller general size, but largely overlap in their morphometric ranges. In many of these females the pars refringens vaginae is variably developed, often with weaker sclerotization than usual. It is also remarkable that no male has been collected together with the females and that these do not contain sperm cells. Diagnosis. The new species is characterized by its body length of 2.46���3.12 mm, lip region offset by constriction and 8���11 ��m wide, odontostyle fusiform and 10���12 ��m long, neck 773���1150 ��m 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 ��m long and occupying up to threefourths 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 a intermediate region bearing apophyses, V = 53���57, caudal region conoid with broadly rounded terminus (24���35 ��m, c = 79���105, c��� = 0.6���0.9), spicules 93���102 ��m long and 7���10 spaced ventromedian supplements, at least two of them within the range of spicules. Relationships. In having comparatively large general size (body length more than 2 mm), echinophorous uterus (i.e., bearing abundant, refractive, spine-like elements or apophyses) and posterior vulva position (V more than 50), the new species is very similar to M. bihariense (Popovici, 1990) Andr��ssy, 1996, M. giennense Pe��a- Santiago & Coomans, 1990 and M. paravalvulatum Pe��a-Santiago & Coomans, 1990. It differs from M. bihariense in its wider lip region (8���11 vs 7���8 ��m, n= 14 in Romanian material), longer neck (773���1000 vs 600���775 ��m; b = 2.8���3.4 vs b = 3.2 ���4.0), presence of a valvate swelling at the anterior section of pharynx (vs absent or overlooked), an isthmus-like narrowing separating both pharyngeal sections (vs apparently no special differentiation marking this separation), pars refringens vaginae readily perceptible (vs weakly sclerotized if present), and male known (vs unknown). From M. giennense in the presence (vs absence) of valves at the spindle-shaped swelling in the anterior slender portion of pharynx, larger spicules (93���102 vs 71���87 ��m long, n= 9), and lower number of ventromedian supplements (7���10 vs 10���14) with different arrangement (two vs at least three of them within the spicules range, with the last two somewhat shifted from the midventral position, one on the left, the other on the right in M. giennense). And from M. paravalvulatum in its longer male tail (37���43 vs 30 ��m), larger spicules (93���102 vs 71 ��m long) with different shape (more slender and having a long slender anterior part vs more robust and lacking an especially narrow anterior part), and lower number of ventromedian supplements (7���10 vs 11) with different arrangement (two vs only one distinctly lying within the range of spicules). Type locality and habitat. The new species was collected from northwest Iran, Mahmood Abad region, East Azarbaijan province (GPS coordinates: N 38 �� 48 ��� 43.5 E 46 �� 51 59.6 ���), in Arasbaran rangelands, during 2012. Other localities and habitats. Dolat Abad district, Marand, in an orchard with fruit trees; Ass district, Arasbaran, in a natural pasture; and Hervi district, around Tabriz, in an orchard with fruit trees. Type material. Female holotype, two female and two male paratypes deposited in the Collection of Nematology Lab., University of Tabriz, Tabriz, Iran. Two female and one male paratypes deposited in the Nematode Collection of the University of Ja��n, Spain. Etymology. The specific epithet refers to the geographical origin of this species in Persia, the former name of Iran. Remarks. Metaxonchium persicum sp. n. is morphometrically very similar to M. giennense and M. paravalvulatum, making the identification of their respective females especially problematic. Nevertheless, the morphology of the spicules and the number and arrangement of the ventromedian supplements seem to be sufficiently different to support a provisionally separate status for these three species. Holotype Paratypes Character n ♀ 5 ♀♀ 3 ♂♂ 4 ♀♀ 4 ♀♀ ♀ 15 ♀&female, Published as part of Pe��a-Santiago, R., Niknam, G., ��lvarez-Ortega, S. & Jabbari, H., 2014, Metaxonchium persicum sp. n. from Iran (Nematoda, Dorylaimida, Belondiridae), with an updated taxonomy of the genus, pp. 501-517 in Zootaxa 3785 (4) on pages 502-504, DOI: 10.11646/zootaxa.3785.4.1, http://zenodo.org/record/229458, {"references":["Popovici, I. (1990) New and known nematode species (Nematoda: Dorylaimida) from Romania. Nematologica, 35 (1989), 438 - 454. http: // dx. doi. org / 10.1163 / 002825989 x 00188","Andrassy, I. (1996) Free-living nematodes in the Bukk mountains, Hungary. The fauna of the Bukk National Park, 33 - 63.","Pena-Santiago, R. & Coomans, A. (1990) Nematodes of the order Dorylaimida from Andalucia Oriental, Spain. Tylencholaimellus hispanicus sp. n. and two new species of Axonchium Cobb, 1920. Nematologica, 36, 144 - 160. http: // dx. doi. org / 10.1163 / 002925990 x 00121"]}

Peña-Santiago, R., Niknam, G., Álvarez-Ortega, S., Jabbari, H. (2014): Metaxonchium persicum sp. n. from Iran (Nematoda, Dorylaimida, Belondiridae), with an updated taxonomy of the genus. Zootaxa 3785 (4): 501-517, DOI: http://dx.doi.org/10.11646/zootaxa.3785.4.1

Taxonomy of Metaxonchium Coomans & Nair, 1975 = Axonchium (Metaxonchium) Cobb, 1920 (Coomans & Nair, 1975) = Axonchium (Discaxonchium) Cobb, 1920 (Coomans & Nair, 1975) = Axonchium (Epaxonchium) Cobb, 1920 (Coomans & Nair, 1975) = Axonchium (Spiculaxonchium) Cobb, 1920 (Ahmad & Jairajpuri, 1982; but see below) Brief historical outline. In the last paper of their excellent revision of the genus Axonchium Cobb, 1920, Coomans and Nair (1975; see also Jairajpuri & Ahmad, 1992) proposed its division into nine ���groups or subgenera��� (p. 325), one of them Metaxonchium, with three species, namely Axonchium (Metaxonchium) coronatum (de Man, 1907) Thorne & Swanger, 1936, which was proposed as type species, A. (M.) leptocephalum Altherr, 1953 and A. (M.) vaginatum Jairajpuri, 1965. The subgenus Metaxonchium was characterized and separated from its relatives by having, among other features, lip region offset, fusiform odontostyle, anterior portion of pharynx quite muscular and lacking a spindle-shaped portion, pars refringens vaginae present (= ���vagina sclerotized���), and males rare with small spicules. In describing two new Axonchium species from the Iberian Peninsula, Pe��a-Santiago and Coomans (1990) were aware that the differences between Metaxonchium and the subgenus Epaxonchium, also proposed by Coomans and Nair (op. cit.), were not significant and regarded the latter as a junior synonym of the former. Andr��ssy (1991) raised the rank of Metaxonchium to generic level and stated (see also Andr��ssy, 2009) that the subgenera Discaxonchium Coomans & Nair, 1975, Epaxonchium and Spiculaxonchium Ahmad & Jairajpuri, 1982 may be also classified under it. In 1996, the same author described the new species M. echinulatum from Hungary and provided an updated list of 19 valid species. Morphological characterization. Metaxonchium is a relatively homogeneous taxon, mainly characterized by its lip region with separate lips and offset by constriction, odontostyle short and fusiform, both pharyngeal sections separated by an isthmus-like narrowing, pars refringens vaginae well developed, caudal region short and rounded to convex conoid in both sexes, and spaced ventromedian supplements without hiatus. A few species, however, do not totally fit this general pattern and introduce some heterogeneity to the group: M. bihariense lacks a perceptible isthmus-like narrowing between both pharyngeal regions; M. choristum (Thorne, 1939) Andr��ssy, 1996 and M. serpens (Thorne, 1939) Andr��ssy, 1996 bear a series of 19���26 and 22���30 contiguous ventromedian supplements with and without hiatus, respectively; M. spiculum shows a peculiar combination of characters (deep constriction rather than an isthmus-like narrowing between both pharyngeal sections, which are abutting, spicules with very atypical morphology (bearing a very short median piece), and weakly developed ventromedian supplements arranged in two separate groups), which raises serious doubt about its belonging to Metaxonchium; M. tacitum (Ahmad & Jairajpuri, 1982) Andr��ssy, 1996 has abutting pharyngeal sections as well; and M. thornei (Hechler, 1969) Andr��ssy, 1996 bears 13���15 contiguous ventromedian supplements with hiatus. A few other morphological features display significant variation: presence/absence of valve-like elements in a swelling of the anterior pharyngeal section, presence/absence of apophyses in the uterus, and shape of pars refringens vaginae. Accordingly, the separation of most species is principally based on morphometrics. Diagnosis (emended). Medium to large-sized nematodes, body 1.6���4.2 mm long. Cuticle bi- or tri-layered, with fine transverse striation and especially thick at caudal region. Lip region offset by constriction, with separate lips. Amphid openings encircling most the lip region base. Odontostyle fusiform, 8���23 ��m long or about equal to lip region diameter. Guiding ring simple, visibly refractive. Odontophore rod-like, lacking any significant differentiation. Both pharyngeal sections typically separated by a isthmus-like narrowing, very occasionally by a constriction or without differentiation; basal expansion large, occupying up to three-fourths of total neck length. Cardia tongue-like, well developed. Female genital system mono-opisthodelphic, with anterior branch reduced to a more or less (but usually well-) developed uterine sac plus a vestigial terminal cell mass, posterior uterus long and often tripartite with apophyses (echinophorous uterus, cf. Andr��ssy, 1991) in several species; pars refringens vaginae well (very occasionally less) developed; vulva a transverse slit. Tail similar in both sexes, short and rounded to convex conoid. Males often frequent, with variably sized (39���107 ��m long) and shaped spicules, and 7��� 17 spaced ventromedian supplements (but 19���30 contiguous in two species), with or without hiatus. Relationships. Within the subfamily Axonchiinae Thorne, 1964, which contains eight genera (cf. Andr��ssy, 2009), Metaxonchium resembles the genera Axonchium, Dactyluraxonchium Coomans & Nair, 1975 and Syncheilaxonchium Coomans & Nair, 1975, but it can easily separated from all of them in the presence of well developed pars refringens vaginae (vs totally absent). Besides, it differs from Dactyluraxonchium in vaginal morphology (vs lumen first very wide and elliptical) and caudal region (vs conical subdigitate, distinctly longer than anal body diameter); and from Syncheilaxonchium in the morphology of lip region (vs non-offset, with amalgamated lips)., Published as part of Pe��a-Santiago, R., Niknam, G., ��lvarez-Ortega, S. & Jabbari, H., 2014, Metaxonchium persicum sp. n. from Iran (Nematoda, Dorylaimida, Belondiridae), with an updated taxonomy of the genus, pp. 501-517 in Zootaxa 3785 (4) on page 508, DOI: 10.11646/zootaxa.3785.4.1, http://zenodo.org/record/229458, {"references":["Coomans, A. & Nair, P. (1975) The genus Axonchium (Nematoda: Belondiridae). VI. Atypical species, keys, subgenera and conclusions. Nematologica, 21, 296 - 332. http: // dx. doi. org / 10.1163 / 187529275 x 00059","Cobb, N. A. (1920) One hundred new nemas. (Type species of 100 new genera). Contributions to a Science of Nematology, 9, 217 - 243.","Ahmad, W. & Jairajpuri, M. S. (1982) Studies on the genus Axonchium Cobb, 1920 from India. Nematologica, 28, 21 - 33. http: // dx. doi. org / 10.1163 / 187529282 x 00484","Jairajpuri, M. S. & Ahmad, W. (1992) Dorylaimida. Free-living, Predaceous and Plant-parasitic Nematodes. Oxford & IBH Publishing Co. Pvt. Ltd. New Delhi, India, 458 pp.","de Man, J. G. (1907) Observations sur quelques especes de nematodes terrestres libres de l'Ile de Walcheren. Annales de la Societe Royale de Zoologie et Malacologie de Belgique, 41 (1906), 161 - 174.","Thorne, G. & Swanger, H. H. (1936) A monograph of the nematode genera Dorylaimus Dujardin, Aporcelaimus n. gen., Dorylaimoides n. gen., and Pungentus n. gen. Capita Zoologica, 6, 1 - 223.","Altherr, E. (1953) Nematodes du sol du Jura vaudois et francais. I. Bulletin de la Societe Vaudoise des Sciences Naturelles, 65, 429 - 460.","Jairajpuri, M. S. (1965) A new species of the genus Axonchium Cobb with notes on the occurrence of A. caudatum Williams in India, and the taxonomic status of Discolaimus pakistanicus Timm and Bhuiyan. Proceedings of the Zoological Society of Calcutta, 18, 155 - 158.","Pena-Santiago, R. & Coomans, A. (1990) Nematodes of the order Dorylaimida from Andalucia Oriental, Spain. Tylencholaimellus hispanicus sp. n. and two new species of Axonchium Cobb, 1920. Nematologica, 36, 144 - 160. http: // dx. doi. org / 10.1163 / 002925990 x 00121","Andrassy, I. (1991) The free-living nematode fauna of the Batorliget Nature Reserves. The Batorliget Nature Reserve-after forty years, 129 - 197.","Andrassy, I. (2009) Free-living nematodes of Hungary. III. Pedozoologica Hungarica nº 5. Hungarian Natural History Museum. Budapest, Hungary, 608 pp.","Thorne, G. (1939) A monograph of the nematodes of the superfamily Dorylaimoidea. Capita Zoologica, 8, 1 - 261.","Andrassy, I. (1996) Free-living nematodes in the Bukk mountains, Hungary. The fauna of the Bukk National Park, 33 - 63.","Hechler, H. C. (1969) Taxonomy and morphology of Axonchium (Nematoda: Belondiroidea), and a description of A. thornei n. sp. Journal of Nematology, 1, 321 - 348.","Thorne, G. (1964) Nematodes of Puerto Rico: Belondiroidea, new superfamily, Leptonchidae Thorne, 1935, and Belonenchinae new family (Nematoda: Adenophorea, Dorylaimida). University of Puerto Rico Agriculture Experimental Station Technical Paper, No. 39, 1 - 51."]}

Metaxonchium persicum sp. n. (Figs 1–4) Morphometrics. See Table 1. Description. Type population from Azarbaijan rangelands (6 ♀♀ + 3 ♂♂). Adult: Slender to very slender nematodes of medium to large size, 2.46–3.12 mm long. Body cylindrical, visibly tapering towards the anterior end, less so towards the posterior end since the caudal region is short and conoid. Habitus curved ventrad upon fixation, C- or G-shaped. Cuticle three-layered, consisting of inner layer thicker than the others, especially obvious at caudal region where it bears distinct radial striation, an intermediate and more transparent layer, and a thinner outer layer nearly smooth under LM but bearing very fine transverse striation under SEM; cuticle thickness 2–3 Μm in anterior region, 4–6 Μm at mid-body and 8–15 Μm on dorsal side of tail. Cervical lacunae often clearly visible. Lateral chord comparatively narrow, 5–7 Μm wide or up to one-tenth (7–10 %) of mid-body diameter, of granular nature and lacking any other differentiation. Lip region rounded to slightly truncate anteriorly, offset by constriction, 2.2–2.8 times as broad as high or less than one-sixth (11–15 %) of body diameter at neck base; lips separate, under SEM appearing conoid, tapering toward the oral aperture, and with deep radial incisures in between; labial and cephalic papillae very low, not interfering the labial contour. Amphid fovea cup-like, its aperture 7–9 µm wide or occupying about four-fifths (75–82 %) of lip region diameter. Cheilostom a truncate cone, lacking any differentiation. Odontostyle small, somewhat fusiform, as thick as the cuticle at its level, equal to or hardly longer (1.0– 1.2 times) than lip region diameter, 5.8–6.8 times as long as wide and 0.36–0.40 % of body length; aperture 3.0– 3.5 µm long, occupying one-fourth to one-third (25–35 %) of total length. Guiding ring thin, simple but visibly refractive, at 11–14 µm or 0.8–0.9 times the lip region diameter from the anterior end. Odontophore rod-like, 1.8–2.2 times the odontostyle length, bearing a very slight thickening at its approximate midpoint. Pharynx consisting of a slender and weakly muscular anterior portion, which is separated from the basal expansion by a short isthmus-like narrowing, and bearing a well developed, spindle-shaped thickening with valvelike structures, situated at 117–155 Μm from anterior end; basal expansion 13–20 times as long as broad, 7.5–9.9 times longer than body diameter at neck base, and occupying up to three-fourths (68–73 %) of total neck length; a very distinct spiral muscular sheath, with nearly straight muscular bands, envelops the whole basal expansion. Cardia tongue-like, 22–25 Μm long x 13–14 Μm wide, surrounded by intestinal tissue. Caudal region conoid with broadly rounded terminus, ventrally straighter, dorsally more convex; caudal pores two pairs at the posterior half of tail, one lateral, another subdorsal. Female: Genital system monodelphic-opisthodelphic. Anterior branch 117–324 Μm long or 6–11 % of body length, and consisting of a long uterine sac often devoid of sperm cells, and a small solid terminal mass probably representing oviduct and/or ovary remnants. Posterior branch very long and impossible to measure as its tract always appears strongly convoluted: reflexed ovary large, 170–370 µm long, with oocytes arranged first in several rows and then in a single row; oviduct joining the ovary subterminally, 135–142 Μm long or 1.4–2.1 body diameters, and consisting of a tubular part made of prismatic cells and a well developed pars dilatata with distinct lumen and occasionally containing sperm cells. A strong sphincter separates oviduct and uterus. Uterus very long and tripartite, i.e., provided with a proximal region with very wide lumen, a convoluted long intermediate region with narrow lumen and containing numerous refractive, irregular elements (apophyses), and a large spherical distal pars dilatata. One female bearing a uterine egg, 145 x 52 µm. Vagina 32–42 µm long, extending inwards about one-half (43–55 %) of the corresponding body diameter; pars proximalis longer than wide, 21–24 x 15 –20 Μm, with convergent walls and surrounded by moderately developed, circular musculature; pars refringens (in lateral view) consisting of two trapezoidal pieces measuring 4– 5 x 7–8 µm and with a combined width of 9–11 µm; pars distalis 3–7 Μm long. Vulva a somewhat posterior transverse slit, about 10 µm long. Prerectum 4–10, rectum 1.0– 1.4 anal body diameters long. Anus a straight transverse slit about 8 µm long. Male: Genital system diorchic, with opposite testes. In addition to the adcloacal pair, situated at 15–17 Μm from cloacal aperture, there is a series of 7–10 ventromedian supplements 17–34 Μm apart, the posteriormost of which is situated at 38–50 Μm from the adcloacal pair; hiatus lacking as at least two ventromedian supplements lie within the range of spicules. Spicules dorylaimoid, curved ventrad, relatively slender (7.8–8.3 times as long as wide) and long (1.8–2.2 times the cloacal body diameter), and with a rather narrow anterior part. Lateral guiding pieces 19–20 Μm long, 9–10 six times as long as wide. Other material examined (9 ♀♀ from three locations). These nine females are nearly identical to those of type population. They have slightly smaller general size, but largely overlap in their morphometric ranges. In many of these females the pars refringens vaginae is variably developed, often with weaker sclerotization than usual. It is also remarkable that no male has been collected together with the females and that these do not contain sperm cells. Diagnosis. The new species is characterized by its 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 threefourths 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 a 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 93–102 µm long and 7–10 spaced ventromedian supplements, at least two of them within the range of spicules. Relationships. In having comparatively large general size (body length more than 2 mm), echinophorous uterus (i.e., bearing abundant, refractive, spine-like elements or apophyses) and posterior vulva position (V more than 50), the new species is very similar to M. bihariense (Popovici, 1990) Andrássy, 1996, M. giennense Peña- Santiago & Coomans, 1990 and M. paravalvulatum Peña-Santiago & Coomans, 1990. It differs from M. bihariense in its wider lip region (8–11 vs 7–8 µm, n= 14 in Romanian material), longer neck (773–1000 vs 600–775 µm; b = 2.8–3.4 vs b = 3.2 –4.0), presence of a valvate swelling at the anterior section of pharynx (vs absent or overlooked), an isthmus-like narrowing separating both pharyngeal sections (vs apparently no special differentiation marking this separation), pars refringens vaginae readily perceptible (vs weakly sclerotized if present), and male known (vs unknown). From M. giennense in the presence (vs absence) of valves at the spindle-shaped swelling in the anterior slender portion of pharynx, larger spicules (93–102 vs 71–87 µm long, n= 9), and lower number of ventromedian supplements (7–10 vs 10–14) with different arrangement (two vs at least three of them within the spicules range, with the last two somewhat shifted from the midventral position, one on the left, the other on the right in M. giennense). And from M. paravalvulatum in its longer male tail (37–43 vs 30 µm), larger spicules (93–102 vs 71 µm long) with different shape (more slender and having a long slender anterior part vs more robust and lacking an especially narrow anterior part), and lower number of ventromedian supplements (7–10 vs 11) with different arrangement (two vs only one distinctly lying within the range of spicules). Type locality and habitat. The new species was collected from northwest Iran, Mahmood Abad region, East Azarbaijan province (GPS coordinates: N 38 ° 48 ′ 43.5 E 46 ° 51 59.6 ″), in Arasbaran rangelands, during 2012. Other localities and habitats. Dolat Abad district, Marand, in an orchard with fruit trees; Ass district, Arasbaran, in a natural pasture; and Hervi district, around Tabriz, in an orchard with fruit trees. Type material. Female holotype, two female and two male paratypes deposited in the Collection of Nematology Lab., University of Tabriz, Tabriz, Iran. Two female and one male paratypes deposited in the Nematode Collection of the University of Jaén, Spain. Etymology. The specific epithet refers to the geographical origin of this species in Persia, the former name of Iran. Remarks. Metaxonchium persicum sp. n. is morphometrically very similar to M. giennense and M. paravalvulatum, making the identification of their respective females especially problematic. Nevertheless, the morphology of the spicules and the number and arrangement of the ventromedian supplements seem to be sufficiently different to support a provisionally separate status for these three species. Holotype Paratypes Character n ♀ 5 ♀♀ 3 ♂♂ 4 ♀♀ 4 ♀♀ ♀ 15 ♀&female

Entomopathogenic nematodes (EPNs) are lethal pathogens of agricultural insect pests. Little is known about their sublethal effects on the insect hosts. The lethal effects of Steinernema carpocapsae on fourth instar larvae of Colorado potato beetle (CPB), Leptinotarsa decemlineata were detected using soil infection and direct injection of the nematode into the hemocel. LC20 and LC80 values of 7.8 (3.0 - 13.4) infective juveniles (IJs) and 126.7 (91-206.7) IJs were obtained for the soil application method and 10.2 (8.7 - 11.4) IJs and 22.7 (19.73 - 28.0) IJs for direct injection, respecitvely. Sublethal effects of S. carpocapsae on last instar larvae and subsequent surviving adults and phenoloxidase (PO) activity in hemolymph of nematode-injected last instar larvae were investigated. Sublethal effects included adult cuticular discoloration, deformation of the wings, legs and antenna and decreased fertilized egg production in females. Considering cuticular discoloration in most treated insects, it is hypothesized that production of PO in the insect larvae infected with an entomopathogenic nematode, S. carpocapsae might have costs for surviving adult insects. PO specific activity in CPB against S. carpocapsae generally increased up to 48 h post injection. Here in, the sublethal effects are discussed as a potential tread-offs of PO production in nematode-injected insects.