New data on two remarkable Antarctic species Amblydorylaimus isokaryon (Loof, 1975) Andrássy, 1998 and Pararhyssocolpus paradoxus (Loof, 1975), gen. n., comb. n. (Nematoda, Dorylaimida)

Abstract The taxonomic position of two antarctic dorylaimid species Amblydorylaimus isokaryon (Loof, 1975) Andrássy, 1998 and Pararhyssocolpus paradoxus (Loof, 1975), gen. n., comb. n. are discussed on the basis of morphological, including SEM study, morphometric, postembryonic and sequence data of 18S rDNA and the D2-D3 expansion fragments of large subunit rDNA. The evolutionary trees inferred from 18S sequences show insufficient resolution to determine the assignment of the two species to particular families, moreover Pararhyssocolpus paradoxus gen. n., comb. n. (=Rhyssocolpus paradoxus) previously regarded as a member of Nordiidae or Qudsianematidae, showed distant relationship both to Rhyssocolpus vinciguerrae and Eudorylaimus spp. The phylogram inferred from 28S sequences revealed that Amblydorylaimus isokaryon is a member of a well-supported group comprised of several Aporcelaimellus spp., while, no close relationships could be revealed for the Pararhyssocolpus paradoxus gen. n., comb. n. to any nematode genus. On the basis of molecular data and morphological characteristics, some taxonomic changes are proposed. Amblydorylaimus isokaryon is transferred from family Qudsianematidae to family Aporcelaimidae, and a new monotypic genus Pararhyssocolpus gen. n. is proposed, attributed to Pararhyssocolpidae fam. n. The diagnosis of the new family is provided together with emended diagnosis of the genera Amblydorylaimus and Pararhyssocolpus gen. n. Data concerning distribution of these endemic genera in the Antarctic region are also given.


Introduction
Taxonomic studies on Antarctic nematodes are sparse and current knowledge about species distribution, biogeography and their relationship to the global fauna is still poor (Velasco-Castrillón and Stevens 2014). Almost all Antarctic nematode species have been recorded only from this region (Andrássy 1998a;Maslen and Convey 2006;Convey et al. 2008). This high degree of endemism is probably caused by the longterm isolation and harsh climate of the region (Convey et al. 2008;Nielsen et al. 2011), and indicates that they are glacial survivors rather than post-glacial colonists (Andrássy 1998a;Maslen and Convey 2006;Chown and Convey 2006).
Nineteen species of order Dorylaimida Pearse, 1942 have been recorded from this region which is approximately 0.7% of the known dorylaimid species; all of them being endemic. Regarding the genera distribution a single genus, namely Amblydorylaimus Andrássy, 1998 inhabiting Maritime Antarctic is considered endemic.
Molecular studies of free-living Dorylaimida members are increasing (Mullin et al. 2005;Holterman et al. 2006;Pedram et al. 2009;Álvarez-Ortega et al. 2013a, b, c;Nedelchev et al. 2014;Peña-Santiago et al. 2015). Nevertheless, Antarctic dorylaimids have received little attention in this respect with only one study of this widespread order in Antarctic. Velasco-Castrillón and Stevens (2014) analysed the morphological and molecular diversity of Antarctic nematodes using the mitochondrial cytochrome c oxidase subunit I (COI) gene.
Here we present data on the morphology, molecular taxonomy and distribution of two dorylaimid species with unclear taxonomic position occurring in the Maritime Antarctic.
For light-microscopy, specimens were processed in anhydrous glycerine by a Seinhorst method (1959) and mounted on permanent slides. Drawings were prepared using an Olympus BX 51 compound microscope with DIC and a drawing tube. Photographs were taken using an Axio Imager.M2 -Carl Zeiss compound microscope with a digital camera (ProgRes C7) and specialised software (CapturePro Software 2.8).
Measurements were made using an Olympus BX 41 light microscope with a drawing tube and digitizing tablet (CalComp Drawing Board III, GTCO CalCom Peripherals, Scottsdale, AZ, USA) and Digitrak 1.0f computer program (Philip Smith, John Hutton Institute, Dundee, UK).
Specimens used for SEM observations were rinsed in 0.1 M cacodylate buffer (twice for 10 min), post-fixed in 1% OsO 4 for 2 h, washed twice for 10 min in 0.1 M cacodylate buffer and dehydrated in an ethanol series (Mutafchiev et al. 2013), immersed in hexamethyldisilazane for 30 min and air dried. They were coated with gold in fine coater JEOL JFS 1200 and examined using a JEOL JSM 5510 microscope at 10 kV.
The location of pharyngeal gland nuclei is presented following Loof and Coomans (1970) and Andrássy (1998b).

DNA extraction, amplification and sequencing
Genomic DNA was extracted from one male and one female specimen of both species using a standard nematode digestion protocol (Holterman et al. 2006). The specimens used for DNA extraction, amplification and sequencing are from Nelson (Amblydorylaimus isokaryon (Loof, 1975) Andrássy, 1998) and King George (Pararhyssocolpus paradoxus gen. n., comb. n.) Islands. For further details, see Nedelchev et al. (2014). Identical sequences were obtained from both individuals of the same species. The sequences of both Antarctic species have been deposited in GenBank with the following accession numbers: for the 18S rDNA KM092519 (A. isokaryon) and KM092521 (P. paradoxus gen. n., comb. n.) and for the D2-D3 rDNA KM092520 (A. isokaryon) and KM092522 (P. paradoxus gen. n., comb. n.).

Sequence and phylogenetic analysis
A BLAST (Basic Local Alignment Search Tool) search at NCBI (National Center for Biotechnology Information) was performed using the obtained sequences as queries to confirm their nematode origin and to identify the most closely related nematode sequences. The sequences revealing highest similarity to newly obtained sequences were included in the phylogenetic analyses of both ribosomal gene regions (Griffiths et al. 2006;Holterman et al. 2006;Meldal et al. 2007;Lesaulnier et al. 2008;Pedram et al. 2010;Álvarez-Ortega and Peña-Santiago 2012a;2012b;Donn et al. 2012;Álvarez-Ortega et al. 2013;Nedelchev et al. 2014).
The Multiple Sequence Alignments (MSA) of both gene regions were performed using the Clustal Omega tool (Sievers et al. 2011) via the EBI webserver: http://www. ebi.ac.uk/Tools/msa/clustalw2/. Two datasets (big and small, consisting of 61 and 17 sequences, respectively) were analysed for 18S rDNA. Subsequently, the MSAs were manually optimised and trimmed using MEGA 6 (Tamura et al. 2013). Newly acquired sequence from another Antarctic species Coomansus gerlachei (de Man, 1904) Jairajpuri & Khan, 1977 from Nelson Island (accession number KM092523) was used as outgroup species for the big 18S dataset. Otherwise, midpoint rooting was applied for other sequence datasets due to the uncertainties in species identification and nonmonophyly of the families Aporcelaimidae Heyns, 1965, Qudsianematidae Jairajpuri, 1965and Nordiidae Jairajpuri & Siddiqi, 1964, observed in other studies . The best-fitting model (General Time Reversible model plus Gamma distribution rates (GTR + G)) of nucleotide substitution for both datasets was estimated using the Bayesian (BIC) and Aikaike Information Criteria (AIC) in MetaPIGA v3.1 (Helaers and Milinkovitch 2010). Subsequently, the phylogenetic reconstructions were performed using the Bayesian Inference (BI) algorithm implemented in MrBayes 3.2.2. (Huelsenbeck and Ronquist 2001;Ronquist et al. 2012). A total of 759 and 1616 positions in the final datasets were used for D2-D3 and 18S rDNA dataset, respectively. The Bayesian MCMC tree searches were run using default heating parameters for 2 000 000 generations with a sample frequency of 1000 generations. The first 25% of the chains discarded as burning and the remaining 75% trees kept to summarise the tree topology, branch lengths, and posterior probabilities (PP) of branch support. Convergence diagnostic values were calculated every 1000 generations with a predefined stop value equal to 0.01. A single strict consensus tree was visualised using FigTree v1.4.0 graphical viewer (http://tree.bio.ed.ac.uk/software/figtree/). Posterior probabilities values of ³0.80 were considered as credible support values for nodes.

Locality
Juveniles. Morphometrics obtained from juvenile specimens, and the relationship between the lengths of their functional and replacement odontostyles and body lengths, identified four juvenile stages ( Figure 13). Tail in J1-J3 elongated conoid, ventrally arcuate with rounded terminus, in J4 as in females, c' decreasing during successive stages to female (Table 4, Figs 6, 10).
Discussion. The main morphological characters of the studied populations are very similar, only the specimen from King George Island differs by its shorter body, pharynx, pharyngeal expansion, anterior and posterior female genital branches, prerectum and tail (Table 2). Our materials generally agree well with the type specimens (Loof, 1975), although some differences occurred: the present specimens have broader lip region (length of odontostyle 1.2-1.3 vs 1.5 times longer than lip region diam., longer uterine eggs (123-135 vs 117-122 µm), and somewhat longer distance adcloa-cal pair of papillae -cloaca (29-37.5 vs 26-29 µm) (Andrássy 1998a). Loof (1975) described the vulva as longitudinal but according to Andrássy (1998a) it is more or less a roundish pore, although he may not have observed females in ventral position. Our SEM studies confirm Loof's observations. Andrássy (1998a) reported that spermatozoids have an atypical shape for dorylaimids being rounded or potato-like, however our observations showed that their shape is spindle-like, similar to the drawings by Loof (1975). Further, the presence of a tongue-like projection between the intestine and prerectum not mentioned in the original description was observed. None of the above mentioned authors reported the cuticular irregularities around the vulva documented here both by LM and SEM.
This species was originally described as Eudorylaimus isokaryon by Loof (1975); later Andrássy (1998a) established a new genus, Amblydorylaimus to accommodate it on the basis of several morphological characters (amphidial fovea and odontostyle shape, equally sized mid-pharyngeal nuclei, atypical sperm shape, nipper-like adspicular pieces and unusual location of adcloacal pair of supplements). He described and illustrated A. isokaryon having a specific shape of odontostyle -resembling garden shears; the aperture appeared small. He suggested that this unusual shape was not caused by fixation artefacts as "other organellum of cuticular origin is clearly visible, without any deformation" and "all other Eudorylaimus species collected by Spaull (Loof, 1975) in his study trip do possess normally shaped, well preserved dorylaimid spear". Andrássy (1998a) suggested that it would be necessary to know if living specimens possessed this shape of odontostyle. We examined living specimens of this species, and did not find the peculiarities of the odontostyle shape observed by this author. In the original description, Loof (1975) did not mention this special feature of odontostyle and noted that the odontostyle aperture occupied one-third of its length. In our specimens the odontostyle is weakly sclerotised, regular with usual dorylaimid shape; the length of aperture longer, occupying 1/3-1/2 of the odontostyle. In earlier prepared slides, the odontostyle showed some irregularities similar to those described by Andrássy (1998a). The same author (1998a, 2009a) considered this genus as a member of family Qudsianematidae, but noted that it significantly differs from every genus of this family with its characteristic morphology. Molecular data based on 28S rDNA, however showed that this genus is a member of family Aporcelaimidae and not family Qudsianematidae. This conclusion is supported by our morphological evidences: large aperture of odontostyle (reaching almost ½ of odontostyle length), oral opening a dorso-ventral slit, cuticle thick with refractive layer, not fixed guiding ring etc. which confirm Amblydorylaimus fits better to the family Aporcelaimidae. Based on morphology and molecular data (28S) Amblydorylaimus is closely related to genus Aporcelaimellus Heyns, 1965 from which it can be differentiated by its longer and not robust odontostyle with shorter aperture (av. 2/5 vs more than 1/2 of odontostyle length), and not overlapping vs overlapping edges, lip region with radial vs bilateral symmetry (Álvarez-Ortega and Peña-Santiago 2013), vulva longitudinal vs transverse (except A. macropunctatus (Heyns, 1967) Jimenez-Guirado, 1994 distinguished by its longitudinal vulva), position of adcloacal pair of papillae in males (more distant from cloacal opening vs very close) and lateral guiding pieces bifurcate vs simple. Recently, Andrássy (2009b) proposed a new genus close to Aporcelaimellus and Amblydorylaimus, the genus Aporcelinus Andrássy, 2009. The latter genus differs from the genus Amblydorylaimus by the structure of cardia (with a small dorsal lobe), transverse vulva, eggshell wrinkled, ventromedian supplements small, irregularly spaced, without precloacal space, location of adcloacal pair and shape of tail (conoid tail with sharply pointed terminus). Vinciguerra et al. (2014) believed that the taxonomic position of Aporcelinus is ambiguous; they noted that this genus could also be assigned to family Qudsianematidae on the basis of its morphological features (odontostyle aperture length, simple guiding ring and thickness of cuticle, composed of two layers). Related to the cuticle structure, it should be mentioned that genus Aporcelinus has three layered cuticle with inner refractive layer, well visible on several photomicrographs (Figs 4E, 8A-C) presented by Vinciguerra et al. (2014). Further, the location of ad-cloacal pair of male ventromedian papillae (comparatively far from cloaca opening) in A. isokaryon shows some similarity to Crassolabium persicum Jabbari, Niknam, Vinciguerra, Moslehi, Abolafia & Peña-Santiago, 2012, but the latter species differs from it by the odontostyle structure (weakly sclerotised vs quite robust), not differentiated vs bipartite uterus, structure of pars distalis (without differentiation vs with two small sclerotisations close to the pars refringens in C. persicum) (Jabbari et al. 2012).
On the basis of morphological and molecular data, we propose the genus Amblydorylaimus to be transferred from family Qudsianematidae to the family Aporcelaimidae. It is worth mentioning that the latter family obviously is non monophyletic and we propose this taxonomic change on the base of the close relationships with the genus Aporcelaimellus now regarded as a member of family Aporcelaimidae.
Diagnosis (emended). Amblydorylaimus. Aporcelaimidae. Aporcelaiminae. Body large, about 3 mm. Cuticle three-layered, outer layer thin with fine but distinct transverse striation. Lip region angular, offset from adjacent body by a constriction. Oral aperture dorso-ventral, hexagonal. Amphidial fovea caliciform with small posterior pouches. Odontostyle long, weakly sclerotised. Guiding sheath distinct, anterior and posterior edges moderately cuticularised. Odontophore rod like. Pharynx expanded in its posterior half. Nuclei distinct, dorsal nucleus fairly posterior in position, first subventral pair large and equal in size, posterior pair rather far from the end of pharyngeal expansion. Prerectum sharply separated from mid-intestine. Female genital system didelphic amphidelphic. Ovaries very short, uterus long without differentiation. Vulva longitudinal, cuticular irregularities present around it. Pars refringens vaginae well developed. The posterior end of the intestine with tongue-like structure. Sperm spindle shaped. Spicula dorylaimid, lateral guiding piece distally bifurcate. Ventromedian supplements numerous, regularly spaced, preceded by one adcloacal pair of papillae comparatively far from cloacal aperture. Tail similar in both sexes, short conoid, ventrally arcuate, with bluntly rounded tip. Tail in J1-J3 conoid elongated, in J4 as in female.

Description.
Female. Habitus curved ventrad after fixation, more so in posterior body end. Cuticle smooth, when viewed under light microscope, 3-4 µm thick in postlabial region, 5-7 µm at mid-body and 4-7 µm on tail; consisting of three layers the inner one much ticker and refractive, not reaching the end of tail. Under SEM it is finely transversally striated (annules ca 0.6 µm wide). Lip region appears rounded, slightly offset by a depression, 2.3-3.4 times as broad as high, lips amalgamated, outer labial and cephalic papillae protruding above lip region contour. Under SEM inner labial papillae not elevated, close to each other and to oral aperture, outer labial and cephalic papillae below the margin of oral field. Oral aperture seems round hexagonal. Lateral pores well visible (13-14 in the pharyngeal region), the first four as two pairs at the anterior end, next more or less equally spaced. Cheilostom a truncate cone. Amphidial fovea funnel-shaped, opening at level of labial depression, its aperture about half of lip region diam. Odontostyle slender, with clear lumen, aperture subterminal, narrow (Figure 22 B) and indistinct as observed by LM in adults (Figures 18A-C, 19B, 21F); 8-12 times longer than wide, 0.9-1.0 lip region diam. long. Odontophore simple, 1.9-2.3 times odontostyle length long. Guiding ring double, situated at 0.7-0.8 times lip region diam. from anterior end. Nerve ring located at 151-178 µm from anterior end or 32-38% of total neck length. Pharynx consisting of slender but muscular anterior section enlarging gradually and "bibulbar" (Andrássy, 1986), basal expansion with somewhat narrower middle part, 206-231 µm long or 44-52% of total neck length (Figs 14A, 18D). Dorsal nucleus (DN) lying very close to anterior edge of pharyngeal expansion. One nucleus of anterior ventrosublateral pair of pharyngeal glands well visible, large, posterior pair of ventrosublateral nuclei slightly larger, nuclei located almost at one and the same level (pharyngeal characters presented in Table 6). Cardia conoid, measuring 28-39 × 14-19 µm, cell mass near cardia present in some specimens. The posterior end of the intestine with tongue-like projection. Prerectum short, 2-4 times, rectum 1.3-1.8 anal body diam. long. Distinct sphincter at prerectum and rectum junction. Genital system didelphic-amphidelphic, with both branches equally and well developed, anterior 450.5±21.3 (422-478) µm, posterior 463.8±37.9 (404-531) µm long, respectively. Ovaries usually large, oviduct consisting of a tubular part and well developed pars dilatata. Sphincter between oviduct and uterus moderately developed. Uterus long (anterior 220-307 µm, posterior 222.5-356 µm long, respectively), bipartite, consists of a wider proximal part followed by narrower distal part surrounded by large hyaline cells. Uteri contain sperm. Vagina extending inwards for 55-74% of body diameter, pars proximalis 35-50 × 22-30 µm, with straight walls, pars refringens (in lateral view) consisting of two massive trapezoidal separate sclerotised pieces with a combined width of 18-21 µm, pars distalis 8.5-12 µm long. Vulva a transverse slit; under SEM vulval lips spindle shaped, irregularities and ruptures of body cuticle present on both sides of vulva. Lateral vulval flaps absent. In two females uterine eggs observed, measuring 133-148 × 68.5-77 µm. Tail conical, ventrally arcuate, distal part offset, tip finger-like, sharply pointed. Three pairs of caudal pores.

Locality
Sequence and phylogenetic analyses. The BLAST search using D2-D3 region sequence of P. paradoxus gen. n., comb. n. showed highest similarity (93%) to the sequences of several Opisthodorylaimus sylphoides (Williams, 1959) Carbonell & Coomans, 1985clones and Prodorylaimus sp. (AY593008-10, EF207241, Holterman et al. 2008. The 18S rDNA sequence showed 99% similarity to several dorylaimid   (Loof, 1975), comb. n. Scatter plot of the functional (•) and replacement odontostyle (▲) in relation to the body length of the juvenile stages and adults: females (▲) and males (▲). species belonging to different families including A. isokaryon, and various Aporcelaimellus spp. The hypothesis testing using closely and more distantly related 18S rDNA sequences ( Figure 24) revealed distant relationship of P. paradoxus gen. n., comb. n. to the only available sequences of Rhyssocolpus Andrássy, 1971(R. vinciguerrae Pedram, Pourjam, Robbins, Ye, Peña-Santiago, 2011 Figure 4) (fam. Nordiidae) and Eudorylaimus Andrássy, 1959 (two Eudorylaimus spp.) (fam. Qudsianematidae). The ambiguous position of both P. paradoxus gen. n., comb. n. and A. isokaryon could be a result of the low resolution of the SSU rDNA, non-monophyly of these four families and/ or probably incorrect species identifications. The majority of the nematode sequences belonging to the superfamily Dorylaimoidea de Man, 1876 available at the GenBank have no morphological and metrical data and their identification is questionable.
In an additional analysis using the most closely related sequences performed in order to clarify the possible evolutionary relationships of P. paradoxus gen. n., comb. n. (Figure 25): it clustered into the same clade with A. isokaryon and some other species of the families Qudsianematidae, Dorylaimidae and Aporcelaimidae. Further, in the 28S rDNA-based phylogenetic tree P. paradoxus gen. n., comb. n. grouped with species belonging to different families ( Figure 26) and no close relationships to any of them were revealed.
Discussion. The specimens examined generally agree well with data reported for this species, although some differences occurred: lip region offset by slight depression vs deep depression; vulva transverse vs "probably pore-like rather than transverse", smaller DN-DO distance (0.5-1 vs 1.6-3.4%) (Loof 1975). Further, the distinct sphincter at prerectum/rectum junction, tongue-like structure at the posterior end of intestine and subventral papillae in male were not mentioned in the original description. Figure 24. Hypothesis of the phylogenetic relationships of Amblydorylaimus isokaryon (Loof, 1975) and Pararhyssocolpus paradoxus (Loof, 1975), gen. n. comb. n. based on 18S rDNA (61 sequences) inferred from a Bayesian analysis using GTR+G model and Coomansus gerlachei (de Man, 1904) for rooting the tree. Posterior probabilities higher than 0.8 are presented.
Originally this species was attributed to family Qudsianematidae. Loof (1975) placed it in Eudorylaimus, because of widened near the middle pharynx and numerous ventromedian supplements. Nevertheless, he reported that it showed several characters close to Rhyssocolpus (shape of lip region, short odontostyle, and wrinkled cuticle near vulva, although he regarded the last one a not generic rank character). Subsequently Andrássy (1986) included it in family Nordiidae (genus Rhyssocolpus) ignoring the characters in which this species differs from the other members of genus Rhyssocolpus e.g. the greater number of contiguous ventromedian supplements and specific shape of pharyngeal expansion. Again, Loof (1988) reported that many features of this species (numerous and contiguous supplements, pharyngeal expansion at about half pharynx length, DN lying at about 60% of pharynx, distinct first pair of ventrosublateral pharyngeal glands) conflicted with the diagnosis of Rhyssocolpus and continued to regard this Antarctic species as a member of Eudorylaimus (Qudsianematidae). Very recently, Peña-Santiago et al. (2015) provided a revised taxonomy of the genus Rhyssocolpus and proposed R. paradoxus be retained under Eudorylaimus. However, it differs from the latter genus by the arrangement of ventromedian supplements in males (contiguous vs Figure 25. Hypothesis of the phylogenetic relationships of Amblydorylaimus isokaryon (Loof, 1975) and Pararhyssocolpus paradoxus (Loof, 1975), gen. n. comb. n. based on 18S rDNA of closest species (17 sequences) inferred from a Bayesian analysis using GTR+G model and midpoint rooting of the tree. Posterior probabilities higher than 0.8 are presented. Species coloured according the classification of Andrássy (2009a) and Peña-Santiago and Álvarez-Ortega (2014): dark blue -fam. Aporcelaimidae, light blue -fam. Actinolaimidae, green -fam. Dorylaimidae, red -fam. Qudsianematidae. spaced), double vs single guiding ring, slender vs wider odontostyle and specific shape of pharyngeal expansion.
Recent molecular studies Peña-Santiago et al. 2015) as well as our molecular data inferred from the analysis of 18S and D2-D3 expansion segments of the 28S rDNA, showed that this genus could not be assigned to any known Dorylaimoidea family.  (Loof, 1975) and Pararhyssocolpus paradoxus (Loof, 1975), gen. n. comb. n. based on 28S rDNA D2-D3 inferred from a Bayesian analysis using GTR+G model and midpoint rooting of the tree. Posterior probabilities higher than 0.8 are presented. Species coloured according the classification of Andrássy (2009a) and Peña-Santiago and Álvarez-Ortega (2014): dark blue -fam. Aporcelaimidae, light blue -fam. Actinolaimidae, dark green -fam. Dorylaimidae, light green -fam. Thornenematidae, red -fam. Qudsianematidae, yellow -fam. Swangeriidae, violet -fam. Belondiridae. *For abbreviations of localities see Table 1 With considering the differences discussed above, as well as molecular data, the herein studied species cannot be regarded either as a member of the genus Rhyssocolpus or the genus Eudorylaimus and their attributed families, consequently a new genus Pararhyssocolpus gen. n., and a new family Pararhyssocolpidae fam. n. are proposed to accommodate this species.
Relationships. On the basis of main characters, this genus/family appears close to family Nordiidae, Qudsianematidae (subfamily Qudsianematinae Jairajpuri, 1965) and Dorylaimidae. The new family differs from the first family in pharynx widening at the middle of neck vs pharynx widening behind the middle of the neck, the pharyngeal expansion shape (somewhat "bibulbar", with narrower middle part vs cylindrical), ventromedian supplements contiguous vs mostly spaced (except Lenonchium Siddiqi, 1965, it differs from the new family by its longer and filiform tail). From subfamily Qudsianematinae, Pararhyssocolpidae fam. n. can be differentiated by its double vs single guiding ring and labial papillae arrangement (small vs larger distance between inner labial papillae), indistinct vs distinct aperture of odontostyle. Also, the new family differs from fam. Dorylaimidae in odontostyle aperture (indistinct vs distinct) and especially in its characteristic postembryonic development pattern -J1 with long tail, c' decreasing in successive stages and adults caused by the increasing of anal diameter rather than shortening of tail, adults with similar tail shape -conical with distal third much narrower, finger-like vs one or more juvenile stages bearing long (filiform or conical elongated) caudal region, adults with similar (either long or short and rounded, never conical) or dissimilar (long in females, short and rounded, ex-