taxonID	type	description	language	source
0B86CB2052025EAF84E8A4709A0F5CB3.taxon	description	Figs 1, 2, 3, 4, 5, 6	en	Vu, Tam T. T., Abolafia, Joaquín, Nguyen, Anh D., Le, Thi Mai Linh, Peña-Santiago, Reyes (2025): Vastnema crassicutaneum gen. et sp. nov. (Nematoda, Dorylaimida, Dorylaimidae), an interesting new taxon from natural areas of Vietnam. Zoosystematics and Evolution 101 (2): 583-596, DOI: 10.3897/zse.101.144271
0B86CB2052025EAF84E8A4709A0F5CB3.taxon	materials_examined	Holotype. Female adult, Northern Vietnam, Bac Can province, Cho Don district, Nam Xuan Lac nature reserve, December 2021 (coordinates 22 ° 17 ' 30 " N, 105 ° 31 ' 06 " E, elevation 800 m), soil from a wild forest. Paratypes. Eleven females and seven males with the same collection details as the holotype.	en	Vu, Tam T. T., Abolafia, Joaquín, Nguyen, Anh D., Le, Thi Mai Linh, Peña-Santiago, Reyes (2025): Vastnema crassicutaneum gen. et sp. nov. (Nematoda, Dorylaimida, Dorylaimidae), an interesting new taxon from natural areas of Vietnam. Zoosystematics and Evolution 101 (2): 583-596, DOI: 10.3897/zse.101.144271
0B86CB2052025EAF84E8A4709A0F5CB3.taxon	description	Description. Adult. Moderately slender to slender (a = 25 – 34) nematodes of large to very large size, 4.79 – 6.35 mm long. Body cylindrical, clearly narrowing towards the anterior end, much less towards the posterior extremity, as the tail is short and rounded. Upon fixation, habitus almost straight. Cuticle smooth (but a very fine transverse striation is appreciable with SEM), three-layered, consisting of thin outer and inner layers and much thicker intermediate layer, especially conspicuous at level of anterior region and tail, 12.5 – 15.5 µm thick at anterior region, 9 – 15 µm in midbody, and 14 – 20 µm on tail. Lateral chord 12 – 29 µm wide, occupying up to one-sixth (8 – 16 %) of midbody diameter, lacking any differentiation. Body pores very small, the lateral ones arranged in a single row throughout the body length, a few dorsal and ventral pores are present at cervical region. Lip region rounded, occasionally slightly asymmetrical, visibly tapering, less than one-fourth (18 – 24 %) of body diameter at neck base, 2.2 – 2.5 times as wide as high, continuous with the adjoining body or hardly offset by a very shallow depression. SEM observations: lips totally amalgamated, oral field wide as inner and outer labial papillae are quite close, perioral area not differentiated, labial papillae button-like, cephalic papillae appearing as very small pores (Fig. 6 A – C). Amphidial fovea cup-like, its aperture 10.5 – 13.5 µm wide, occupying less than one-half (33 – 48 %) of lip region diameter, appearing as a wide transverse slit visibly occluded at its middle. Cheilostom almost cylindrical, 32 – 40 µm long, with moderately thick walls, but lacking any other specialization. Odontostyle strong, 1.7 – 2.0 times longer than lip region diameter, 8.3 – 11.8 times as long as wide, 0.89 – 1.13 % of body length, its aperture 19 – 27 µm long or less than one-half (36 – 48 %) of the total length. Guiding ring, double, but very delicate and difficult to visualize in some specimens. Odontophore simple, rod-like, 1.3 – 1.6 times the odontostyle. A mucro 2.5 – 8.5 × 1.5 – 3 µm is present in several specimens at level of odontophore base (Fig. 2 A, B, K). Pharynx comparatively very short (b = 6.3 – 8.7), strongly muscular, very gradually enlarging into the basal expansion that is 3.4 – 6.1 times as long as wide, 1.9 – 3.0 times longer than body diameter at neck base, and occupies up to one-half (46 – 49 %) of the total neck length; pharyngeal gland nuclei located as follows: DO = 52 – 56, DN = 53 – 58, S 1 N 1 = 67 – 69, S 1 N 2 = 74 – 79, S 2 N = 83 – 88. Nerve ring located at 228 – 308 µm or 33 – 36 % of the total neck length from the anterior end. Pharyngo-intestinal junction consisting of a conical to somewhat cylindroid cardia 41 – 84 × 17 – 32 µm almost entirely enveloped by intestinal tissue, and a weak, ring-like structure around the junction of cardia to pharyngeal base. Female. Genital system diovarian, with both branches equally and well-developed, the anterior 823 – 1250 µm long, or 16 – 24 % of body length, the posterior 835 – 1153 µm long, or 15 – 21 % of body length. Ovaries variable in length, 221 – 704 µm the anterior, 185 – 619 µm the posterior, often reaching and surpassing the sphincter level, with oocytes arranged first in several rows and then in a single one. Oviduct variably long too, 157 – 349 µm or 0.8 – 2.0 body diameters, consisting of two sections almost equal in length: distal part made of prismatic cells and proximal one an elongated pars dilatata always with wide lumen inside and containing abundant sperm cells, therefore functioning as spermatheca. A weak sphincter separates the oviduct from the uterus. Uterus 571 – 804 µm or 3.2 – 4.3 body diameters long, bipartite, consisting of distal, longer, and slender region with narrow lumen and a proximal, shorter, and wider region with broad lumen and often containing abundant sperm cells inside; distal region always bearing a very special differentiation, resembling the Z-like structure of some dorylaims, with a concentration of many small spindle-shaped elements visibly refringent that adopt a peculiar arrangement (Fig. 3 A, B, G, H), all together measuring 13 – 18 × 22 – 26 µm. Vagina 54 – 73 µm long, to ca one-third (31 – 36 %) of body diameter: pars proximalis 39 – 51 × 26 – 37 µm, with divergent walls surrounded by moderately developed circular musculature; pars refringens, consisting of (lateral view) two separated triangular pieces 12 – 16 × 6 – 10 µm and with a combined width of 26 – 32 µm; pars distalis 5 – 10 µm long. Vulva longitudinal, slightly elliptical, 8 – 11 µm long. Prerectum 2.2 – 3.3, rectum 0.8 – 1.3 body diameters long. Anus a weakly arched transverse slit ca 15 µm long. Tail short and rounded, inner core 17 – 22 µm long, occupying less than half (37 – 48 %) of tail length, caudal pores two pairs, at the middle of tail, one sublateral, another subdorsal. Male. Prerectum 3.4 – 5.5, cloaca 1.3 – 1.5 times longer than body diameter at level of the cloacal aperture. Genital system diorchic with opposite testes. Sperm cells elliptical, 8 × 4.5 µm. In addition to the pre-cloacal pair, situated at 16 – 24 µm from the cloacal aperture, there is a series of 47 – 58, shortly spaced (7 – 14, exceptionally reaching 19 µm in between), very low, ventromedian supplements, the most posterior of them located at 101 – 154 µm from the adcloacal pair, thus with a perceptible hiatus. As seen with SEM, the ventromedian supplements are not mammiform as so usual in dorylaims but appear as short longitudinal slits that resemble the stomata of plant leaves (Fig. 6 K – M). Spicules dorylaimid, relatively slender, 6.9 – 9.1 times longer than wide, 1.8 – 2.0 times longer than body diameter at level of the cloacal aperture: head 12 – 25 µm long, occupying up to one-sixth (8 – 16 %) of spicule length, 1.2 – 1.8 times as long as wide, with its dorsal side visibly longer than the ventral one; median piece 6.5 – 8.5 µm wide, occupying 32 – 44 % of spicule maximum width; posterior tip 5 – 9 µm wide; ventral hump and hollow little marked in general, the hump situated at 49 – 70 µm or 33 – 47 % of spicule length; curvature 118 – 135 °. Lateral guiding pieces 16 – 24 µm long, 4.0 – 4.8 times wider than long, almost cylindrical but visibly tapering at its posterior third. Tail similar to that of female, maybe slightly more conoid.	en	Vu, Tam T. T., Abolafia, Joaquín, Nguyen, Anh D., Le, Thi Mai Linh, Peña-Santiago, Reyes (2025): Vastnema crassicutaneum gen. et sp. nov. (Nematoda, Dorylaimida, Dorylaimidae), an interesting new taxon from natural areas of Vietnam. Zoosystematics and Evolution 101 (2): 583-596, DOI: 10.3897/zse.101.144271
0B86CB2052025EAF84E8A4709A0F5CB3.taxon	description	Molecular characterization. After sequencing and editing, six (three 18 S and three 28 S) rDNA sequences were obtained of type material for phylogenetic analyses. The three 28 S sequences were 798, 679, and 651 bp long, with 511 bp in common, and a Blast search showed that the longest of them was 96.9 % similar to that of Labronema porosum Vu, Elshishka, Nguyen, Le, Mladenov & Peneva, 2024 (acc. PP 060468), 96.3 % to that of L. bidoupense Vu, Elshishka, Nguyen, Le, Mladenov & Peneva, 2024 (acc. PP 060469), 92.0 % to that of Labronema vulvapapillatum (Meyl, 1954) Loof & Grootaert, 1981 (acc. AY 592997), 91.5 % to that of L. vulvapapillatum (acc. AY 592996), 91.3 % to that of Labronema sp., and 90.8 % to that of Nevadanema nevadense Álvarez-Ortega & Peña-Santiago, 2012 (acc. JN 242245), all of them rounded-tailed representatives of Dorylaimidae de Man, 1876, Labronematinae Peña-Santiago & Álvarez-Ortega, 2014. The three 18 S sequences were 1698, 1690, and 1689 bp long, with 1684 bp in common, and a Blast search showed that the longest of them was 97.2 % similar to that of Aporcelaimellus sp. (acc. JX 674034), 97.2 % to that of L. ferox Thorne, 1939 (acc. AY 552972), 97.2 % to that of Aporcelaimellus sp. (acc. PP 099686), 97.1 % to that of Prodorylaimus sp. (EF 207246), and 97.0 % to that of Mesodorylaimus sp. (acc. MG 921256).	en	Vu, Tam T. T., Abolafia, Joaquín, Nguyen, Anh D., Le, Thi Mai Linh, Peña-Santiago, Reyes (2025): Vastnema crassicutaneum gen. et sp. nov. (Nematoda, Dorylaimida, Dorylaimidae), an interesting new taxon from natural areas of Vietnam. Zoosystematics and Evolution 101 (2): 583-596, DOI: 10.3897/zse.101.144271
0B86CB2052025EAF84E8A4709A0F5CB3.taxon	diagnosis	Diagnosis. The new species is characterized by its 4.79 – 6.35 mm long body, cuticle three-layered and 12.5 – 15.5 µm thick at anterior region, lip region continuous with the adjoining body and 26 – 31 µm wide, odontostyle 49 – 60 µm long or 1.8 – 2.0 times the lip region diameter, neck 627 – 888 µm long, pharyngeal expansion occupying 46 – 49 % of the total neck length, female genital system diovarian, uterus complex and 571 – 804 µm or 3.2 – 4.3 body diameters long, pre-equatorial (V = 38 – 44) and longitudinal vulva, tail short and rounded in both sexes (39 – 56 µm, c = 98 – 140, c ’ = 0.5 – 0.7), spicules 138 – 160 µm long, and 45 – 58 small ventromedian supplements with hiatus.	en	Vu, Tam T. T., Abolafia, Joaquín, Nguyen, Anh D., Le, Thi Mai Linh, Peña-Santiago, Reyes (2025): Vastnema crassicutaneum gen. et sp. nov. (Nematoda, Dorylaimida, Dorylaimidae), an interesting new taxon from natural areas of Vietnam. Zoosystematics and Evolution 101 (2): 583-596, DOI: 10.3897/zse.101.144271
0B86CB2052025EAF84E8A4709A0F5CB3.taxon	etymology	Etymology. The species epithet derives from the Latin terms crassus = thick and cutaneum = skin, cuticle, and refers to this peculiar trait of the new taxon.	en	Vu, Tam T. T., Abolafia, Joaquín, Nguyen, Anh D., Le, Thi Mai Linh, Peña-Santiago, Reyes (2025): Vastnema crassicutaneum gen. et sp. nov. (Nematoda, Dorylaimida, Dorylaimidae), an interesting new taxon from natural areas of Vietnam. Zoosystematics and Evolution 101 (2): 583-596, DOI: 10.3897/zse.101.144271
0A55070680465C639544763A8C260446.taxon	type_taxon	Type and only species. Vastnema crassicutaneum sp. nov.	en	Vu, Tam T. T., Abolafia, Joaquín, Nguyen, Anh D., Le, Thi Mai Linh, Peña-Santiago, Reyes (2025): Vastnema crassicutaneum gen. et sp. nov. (Nematoda, Dorylaimida, Dorylaimidae), an interesting new taxon from natural areas of Vietnam. Zoosystematics and Evolution 101 (2): 583-596, DOI: 10.3897/zse.101.144271
0A55070680465C639544763A8C260446.taxon	etymology	Etymology. The genus name derives from VAST (Vietnam Academy of Science and Technology) and “ nema ”.	en	Vu, Tam T. T., Abolafia, Joaquín, Nguyen, Anh D., Le, Thi Mai Linh, Peña-Santiago, Reyes (2025): Vastnema crassicutaneum gen. et sp. nov. (Nematoda, Dorylaimida, Dorylaimidae), an interesting new taxon from natural areas of Vietnam. Zoosystematics and Evolution 101 (2): 583-596, DOI: 10.3897/zse.101.144271
0A55070680465C639544763A8C260446.taxon	diagnosis	Diagnosis. Dorylaimidae. Labronematinae. Large to very large-sized nematodes. Cuticle dorylaimid, very thick, three-layered. Lip region tapering, continuous with the adjoining body, with totally fused lips and very small cephalic papillae. Amphid aperture less than one-half of lip region diameter. Odontostyle strong, up to twice the lip region diameter, with wide aperture. Guiding ring, delicate, double. Odontophore rod-like, simple. Pharynx unusually short, entirely muscular, very gradually enlarging, with basal expansion occupying less than half of the total neck length. Female genital system di-ovarian with a peculiar uterine differentiation, well-developed pars refringens vaginae, and pre-equatorial longitudinal vulva. Tail similar in both sexes, short and rounded. Spicules dorylaimid, slender. Ventromedian supplements 45 – 58 in number, very shortly spaced, small, not typically mammiform, with hiatus.	en	Vu, Tam T. T., Abolafia, Joaquín, Nguyen, Anh D., Le, Thi Mai Linh, Peña-Santiago, Reyes (2025): Vastnema crassicutaneum gen. et sp. nov. (Nematoda, Dorylaimida, Dorylaimidae), an interesting new taxon from natural areas of Vietnam. Zoosystematics and Evolution 101 (2): 583-596, DOI: 10.3897/zse.101.144271
