taxonID	type	description	language	source
674787D8AE13FF95FDB4F8DD81C57755.taxon	diagnosis	Diagnosis (from Fonseca & Bezerra 2014) Body generally long and slender. Rounded anterior and posterior ends. Cuticle striated. Anterior sensilla variable: 6 + 6 + 4 in the Siphonolaiminae and 0 + 6 + 4 or 0 + 0 + 4 in the Astomonematinae. Amphids circular. One or two gonads may be present. Gubernaculum apophysis oriented dorsocaudally. Tail shortened by histolysis.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE12FF95FD81FE69850A744F.taxon	diagnosis	Diagnosis (from Fonseca & Bezerra 2014) Six + four cephalic setae situated at more or less same level. Outer labial setae always shorter than cephalic setae. Amphids circular. Buccal cavity may contain axial cuticularized spear-like structure (siphon). Pharynx narrow anteriorly and widening posteriorly. One anterior outstretched gonad.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE12FF95FDDBFD47851F72AB.taxon	type_taxon	Type species Siphonolaimus niger de Man, 1893.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE12FF95FDDBFD47851F72AB.taxon	diagnosis	Diagnosis (from Zograf et al. 2015) Cuticle striated. Buccal cavity containing an axial cuticularized spear-like structure (siphon). Six outer labial setae and four cephalic setae situated more or less at same level, the six always shorter than the four. Amphids circular. One anterior outstretched ovary. Single anterior testis. Gonad located to the left of intestine.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE12FF95FDDBFD47851F72AB.taxon	discussion	Remarks A key to males of all 21 valid species of Siphonolaimus was provided by Zograf et al. (2015).	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE12FF9EFDA3FB198160706D.taxon	description	urn: lsid: zoobank. org: act: CDE 73 FE 3 - 042 C- 4089 - B 4 B 2 - 3 FB 5 DE 579 F 4 A	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE12FF9EFDA3FB198160706D.taxon	description	Figs 1 – 3, Table 2	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE12FF9EFDA3FB198160706D.taxon	diagnosis	Diagnosis Siphonolaimus curtisensillus sp. nov. is characterized by body length 3.5 – 5.3 mm, papillose outer labial sensilla, short cephalic setae (3 µm or 0.21 – 0.27 cbd), 2 – 3 µm long subcephalic setae, amphids 36 – 41 % cbd wide, arcuate spicules 1.2 – 1.7 cloacal body diameters long, gubernaculum with sharply bent crurae and dorsocaudal apophyses, at least 30 inconspicuous precloacal supplements, vulva located at 68 – 76 % of body length from anterior extremity, uterus wall slightly cuticularized opposite vulva, and tail conical and gradually tapering. Differential diagnosis The new species is most similar to S. banyulensis Boucher, 1971 (known only from males), S. mejillinus Pastor de Ward, 1989 and S. japonicus Zograf, Trebukhova & Pavlyuk, 2015 in having papillose outer labial sensilla as well as short (<0.3 cbd) cephalic setae. Siphonolaimus curtisensillus sp. nov can be differentiated from S. banuylensis by the shorter body length (in males: 3.5 – 5.3 vs 7.8 – 8.3 mm in S. banyulensis), shorter spicules (1.2 – 1.7 vs 3.0 – 3.7 cloacal diameters in S. banyulensis), and longer tail (in males: 2.8 – 4.0 vs 1.5 – 1.8 cloacal body diameters in S. banyulensis), from S. mejillinus by the shorter body length (3.5 – 5.3 vs 7.0 – 8.3 mm in S. mejillinus), larger amphids (36 – 41 vs 18 – 19 % cbd in S. mejillinus), and tail shape (elongated conical vs short and rounded in S. mejillinus) and from S. japonicus by the higher a ratio (a = 63 – 76 vs 32 – 55 in S. japonicus), longer siphon (44 – 64 vs 32 – 41 µm in S. japonicus), longer tail (cʹ = 2.8 – 5.6 vs 2.0 – 2.3 in S. japonicus) and number of precloacal supplements (at least 30 vs 15 in S. japonicus).	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE12FF9EFDA3FB198160706D.taxon	etymology	Etymology The species name is derived from the Latin ʻ curtus ʼ meaning ʻshortʼ and diminutive of Latin ʻ sensus ʼ meaning ʻperceiveʼ, ʻfeelʼ, and refers to the short cephalic sensilla characteristic of the species.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE12FF9EFDA3FB198160706D.taxon	materials_examined	Material examined Holotype NEW ZEALAND • ♂; Hikurangi Margin, Mungaroa cold seep site; 41.9382 ° S, 175.3128 ° E; 2076 m water depth; collected on 7 Jul. 2019; sandy mud (96 % silt / clay, mean particle size 20 µm), voyage TAN 1904, station 21; NIWA 154903. Paratypes NEW ZEALAND • 1 ♂, 2 ♀ ♀; same collection data as for holotype; NIWA 154904 • 1 ♂, 2 ♀ ♀; Hikurangi Margin, Mungaroa cold seep site; 41.9378 ° S, 175.3112 ° E; 2075 m water depth; collected on 7 Jul. 2019; sandy mud (97 % silt / clay, mean particle size 15 µm), voyage TAN 1904, station 18; NIWA 154905.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE12FF9EFDA3FB198160706D.taxon	distribution	Type habitat and locality New Zealand continental slope, Hikurangi Margin, Mungaroa cold seep.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE12FF9EFDA3FB198160706D.taxon	description	Description Male Body colourless, long, cylindrical, tapering slightly towards both extremities. Cuticle with fine transverse striations without lateral differentiation. A few sparse, short somatic setae, ca 2 µm long, present in pharyngeal and posterior body regions. Cephalic region slightly rounded, no lip region visible. Inner labial papillae not observed; six short outer labial papillae, 1.5 – 2.0 µm long, at about same level as four slightly longer cephalic setae, 3 µm long (0.21 – 0.27 cbd). Ring of eight short subcephalic setae, 2 – 3 µm long, slightly anterior to amphid, and two subcephalic setae located ventrally and dorsally at level of amphid. Amphideal fovea circular with slightly cuticularized outline, situated 0.7 – 0.8 cbd from anterior end. Buccal cavity with spear-like siphon, 44 – 64 µm long or 26 – 33 % of pharynx length. Pharynx cylindrical, muscular, with elongated posterior bulb; pharyngeal lumen not cuticularised. Nerve ring at 60 – 65 % of pharynx length from anterior. Secretory-excretory system present; pore located at or immediately posterior to level of nerve ring, ampulla small, renette cell not observed. Cardia small, 11 – 13 µm long, partially surrounded by intestine. Intestine wall consists of numerous clear cells each with nucleus. Reproductive system monorchic with single anterior outstretched testis. Position of testis relative to intestine could not be determined. Sperm cells globular, 15 – 19 × 14 – 16 µm. Spicules paired, curved, tapering distally, 1.2 – 1.7 cloacal body diameters long. Gubernaculum with sharply bent lateral pieces (crurae) and almost straight dorso-caudal apophyses. Two rows of 10 – 13 ejaculatory glands located on either side of vas deferens. At least 30 inconspicuous papillose precloacal supplements present, located 18 – 22 µm apart. Tail conical, gradually tapering distally, 2.8 – 4.5 cloacal body diameters long; a few short and sparse somatic setae present subventrally and subdorsally. Caudal glands and spinneret not observed. Females Similar to males, but with slightly longer tail, 4.4 – 5.6 anal body diameters long. Reproductive system monodelphic with single anterior ovary located to the left of intestine; mature eggs ca 135 × 42 µm. Spermatheca present posterior to vulva. Vulva situated slightly posterior to two thirds of body length from anterior extremity. Proximal portion of vagina surrounded by constrictor muscle, vaginal glands not observed. Proximal portion of uterus opposite vulva slightly cuticularized over ca two corresponding body diameters.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE19FF9FFDA4F920840C7784.taxon	diagnosis	Diagnosis (from Fonseca & Bezerra 2014) Cuticle often striated and seldom smooth. Inner labial sensilla as papilla or not visible. Amphids circular in most cases; seldom curved into a round bow-like shape. Inner side of labial region often formed by an annular, soft skinned pad that narrows the buccal aperture. Cardia noticeably lengthened. Two outstretched gonads facing opposite directions, seldom single gonad. Anterior gonad to the left or right of intestine, and posterior gonad to opposite side.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE19FF9FFDA4F920840C7784.taxon	discussion	Remarks The Linhomoeidae comprises three subfamilies: the Linhomoeinae Filipjev, 1922, Desmolaiminae Schneider, 1926 and Eletherolaiminae Filipjev, 1922. These subfamilies are differentiated mainly based on the arrangement of cephalic sensilla and structure of the buccal cavity.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE18FF9FFDB0FE38818674C2.taxon	diagnosis	Diagnosis (modified from Fonseca & Bezerra 2014) Anterior sensilla in two circles (6 + 10) with or without additional setae. Amphids with circular or oval outline, usually cuticularized. Buccal cavity shallow, cup-shaped, seldom cylindrical, more or less cuticularized. Pharynx widening posteriorly, sometimes forming a distinct bulb. Tail conical or conicocylindrical.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE18FF9FFDCAFCF382B473CF.taxon	type_taxon	Type species Linhomoeus elongatus Bastian, 1865.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE18FF9FFDCAFCF382B473CF.taxon	diagnosis	Diagnosis (modified from Fonseca & Bezerra 2014) Cuticle finely striated. Six inner labial papillae; six outer labial setae and four cephalic setae in one circle with the cephalic setae longer than the outer labial setae; additional setae may be present. Amphids circular, cryptospiral or cryptocircular. Buccal cavity cup-shaped, more or less cuticularized, sometimes with teeth or plates, and sometimes divided by a cuticular ring. Pharynx posteriorly enlarged, without forming a distinct bulb. Cardia usually conspicuous and elongated. Two outstretched ovaries. Gubernaculum with dorsal apophyses. Tail conical or conicocylindrical.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE18FF9FFDCAFCF382B473CF.taxon	discussion	Remarks Linhomoeus was synonymised with Paralihomoeus De Man, 1907 by Fonseca & Bezerra (2014) because no clear diagnoses could be provided to distinguish these genera. According to the latter authors, a total of 59 species now belong to Linhomoeus.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE18FF99FDCBF9C5849F729A.taxon	description	urn: lsid: zoobank. org: act: 7 E 20 B 27 F-A 479 - 47 FF- 8 BCF-A 0640 FC 9656 D	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE18FF99FDCBF9C5849F729A.taxon	description	Figs 4 – 6, Table 3	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE18FF99FDCBF9C5849F729A.taxon	diagnosis	Diagnosis Linhomoeus pycnocricus sp. nov. is characterized by body length 3.8 – 5.6 mm, ratio of a = 40 – 50, 6 + 16 arrangement of cephalic sensilla with six outer labial setae 5 – 6 µm or 17 – 25 % cbd long, four slightly shorter cephalic setae 3 – 4 µm or 10 – 16 % cbd long, and six additional setae similar in length to outer labial setae; eight subcephalic setae present, 4 – 6 µm long; strongly cuticularized amphidial fovea 35 – 40 % cbd wide; buccal cavity cup-shaped with strongly cuticularized base and walls; secretory-excretory pore located at level of nerve ring or immediately posterior or anterior; spicules 0.9 – 1.1 cloacal body diameters long, gubernaculum with straight dorsocaudal apophyses, 25 – 27 papilliform precloacal supplements present; conicocylindrical tail, 5.5 – 9.8 cloacal / anal body diameters long. Differential diagnosis The new species is most similar to L. anteporus (Vitiello, 1969) Fonseca & Bezerra, 2014, L. bocki (Schuurmans Stekhoven, 1946) Fonseca & Bezerra, 2014, L. brevisetosus Schuurmans Stekhoven, 1946, L. caxinus (Vitiello, 1969) Fonseca & Bezerra, 2014, L. conicaudatus (Allgén, 1930) Fonseca & Bezerra, 2014, L. deconincki (Groza-Rojancovski, 1972) Fonseca & Bezerra, 2014, L. ordinarius (Wieser, 1956) Fonseca & Bezerra, 2014, and L. undulatus Wieser, 1959, 2014, and in having relatively short cephalic setae and outer labial setae (<40 % cbd). Linhomoeus pycnocricus sp. nov. differs from L. anteporus in longer body length (3.8 – 5.6 vs 1.7 – 1.9 mm in L. anteporus), higher ratio of a (40 – 50 vs 37 – 40 in L. anteporus) and b (16 – 17 vs 8 in L. anteporus), position of secretory-excretory pore (at or slightly anterior or posterior to nerve ring vs well anterior to nerve ring in L. anteporus), longer spicules (70 – 81 vs 33 µm) and shorter cephalic and outer labial setae (10 – 25 vs 35 µm in L. anteporus), from L. bocki in lower ratio of a (40 – 50 vs 75 – 88 in L. bocki), position of secretory-excretory pore (at or slightly anterior or posterior to nerve ring vs halfway between nerve ring and anterior body extremity in L. bocki), and presence of precloacal papillae and caudal setae (vs absent in L. bocki), from L. brevisetosus in shorter body length (3.8 – 5.6 vs 8.6 mm in L. brevisetosus), lower ratio of a (40 – 50 vs 119), b (16 – 17 vs 25 in L. brevisetosus), and c (8 – 11 vs 18 in L. breviseosus), and in tail shape having (elongated conicocylindrical vs short and conical in L. brevisetosus), from L. caxinus in longer body length (3.8 – 5.6 vs 1.5 – 2.1 mm in L. caxinus), lower ratio of a (40 – 50 vs 58 – 73 in L. caxinus), shorter cephalic and outer labial setae (10 – 25 vs 36 – 40 % cbd in L. caxinuss) and longer spicules (70 – 81 vs 16 – 20 µm in L. caxinus), from L. conicaudatus in lower ratio of a (40 – 50 vs 60 – 61 in L. conicaudatus), shorter cephalic and outer labial setae (10 – 25 vs 30 % cbd in L. conicaudatus) and tail shape (elongated conicocylindrical vs short and conical), from L. deconincki in the lower ratio of a (40 – 50 vs 64 – 82 in L. deconincki), position of vulva (49 – 55 vs 44 % of body length from anterior in L. deconincki), number of precloacal supplements (25 – 27 vs 10 in L. deconincki) and larger amphid (35 – 42 vs 28 % cbd in L. deconincki), from L. ordinarius in the lower ratio of a (40 – 50 vs 90 – 95 in L. ordinarius) and b (16 – 17 vs 13 – 14 in L. ordinarius), slightly shorter cephalic and outer labial setae (10 – 25 vs 27 – 30 % cbd in L. ordinarius), larger amphids (35 – 42 vs 30 – 33 % cbd in L. ordinarius), and buccal cavity armature (strongly cuticularized vs not cuticularized in L. ordinarius), and from L. undulatus in longer body longer length (3.8 – 5.6 vs 2.3 mm in L. undulatus), tail shape (conicocylindrical without subventral papillae vs conical with seven pairs of subventral papillae in L. undulatus), and larger amphid (35 – 42 vs 25 % cbd in L. undulatus).	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE18FF99FDCBF9C5849F729A.taxon	etymology	Etymology The species name is derived from the Greek ʻ pycnos ʼ (= dense, thick) and ʻ krikos ʼ (= ring), and refers to the thickly cuticularized amphideal fovea of the species.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE18FF99FDCBF9C5849F729A.taxon	materials_examined	Material examined Holotype NEW ZEALAND • ♂; Hikurangi Margin, Uruti South cold seep site; 41.4251 ° S, 176.3510 ° E; 1227 m water depth; collected on 13 Jul. 2019; sandy mud (96 % silt / clay, mean particle size 17 µm), voyage TAN 1904, station 61; NIWA 154906. Paratypes NEW ZEALAND – Uruti South cold seep site • 1 ♂; 41.4250 ° S, 176.3510 ° E; 1226 m depth, collected on 13 Jul. 2019; voyage TAN 1904, station 62; NIWA 154908 • 1 ♀; 41.4279 ° S, 176.3485 ° E; 1245 m depth, collected on 14 Jul. 2019; sandy mud (97 % silt / clay, mean grain size 14.2 µm), voyage TAN 1904, station 64; NIWA 154910 • 3 ♂ ♂; 41.4266 ° S, 176.3497 ° E; 1230 m depth, collected on 14 Jul. 2019; sandy mud (97 % silt / clay, mean grain size 19 µm); voyage TAN 1904, station 66; NIWA 154907 • 2 ♀ ♀; 41.4260 ° S, 176.3506 ° E; 1237 m depth, collected on 14 Jul. 2019; sandy mud (94 % silt / clay, mean grain size 18 µm); voyage TAN 1904, station 68; NIWA 154909.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE18FF99FDCBF9C5849F729A.taxon	distribution	Type habitat and locality New Zealand continental slope, Hikurangi Margin, Uruti South cold seep.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE18FF99FDCBF9C5849F729A.taxon	description	Description Male Body mostly colourless except for slight brown colouration in pharyngeal region and presence of brown granules in intestine wall, cylindrical, tapering slightly towards both extremities. Cuticle finely striated, no lateral differentiation. Somatic setae apparently absent. Blunt to rounded cephalic region, not set-off from rest of body. Narrow mouth opening surrounded by bulge of inner portion of lip region. Six minute inner labial papillae surrounding mouth opening. Six outer labial setae, 5 – 6 µm or 17 – 25 % cbd long, situated at same level as four slightly shorter cephalic setae; 3 – 4 µm or 10 – 16 % cbd. Six additional setae present at same level as cephalic and outer labial setae in most specimens; additional setae similar in length to outer labial setae or slightly shorter, situated laterally, lateroventrally and laterodorsally, resulting in a 6 + 16 arrangement of cephalic sensilla. Eight subcephalic setae present, 4 – 6 µm long; two subdorsal and two subventral setae situated at level of amphid, and two sublateral setae located slightly posterior to each amphid. Amphidial fovea circular; outline strongly cuticularized, usually with pitted appearance in centre, surrounded by cuticle striations, ca 0.3 – 0.4 cbd from anterior extremity. Buccal cavity cup-shaped, 10 – 15 µm deep, up to 15 µm wide, with strongly cuticularized base and walls; teeth-like projections not observed. Ducts of pharyngeal glands visible, emptying at base of buccal cavity. Pharynx muscular, anterior portion surrounding base of buccal cavity, not swollen; posterior portion of pharynx slightly swollen but not forming a true bulb. Nerve ring located near middle of pharynx or slightly anteriorly or posteriorly. Secretory-excretory system present, small ventral gland situated at level of cardia; excretory pore located at level of nerve ring or immediately posterior or anterior to it. Cardia well-developed, 43 – 93 µm long. Reproductive system with two opposed testes; outstretched anterior testis, posterior testis may be oustretched or reflexed. Anterior and posterior located either both to the right or both to the left of intestine. Sperm cells globular, 17 – 20 × 18 – 23 µm. Spicules short, arcuate, 0.9 – 1.1 cloacal body diameters long, strongly cuticularized, tapering distally. Gubernaculum with straight dorsocaudal apophyses. Twentyfive to twenty-seven papilliform precloacal supplements, beginning 15 – 30 µm anterior to cloaca and 9 – 28 µm apart. Tail conicocylindrical, with short subventral setae on anterior conical portion; terminal setae not observed. Caudal glands not well defined. Female Similar to males but with fewer caudal setae. Reproductive system with two opposed outstretched ovaries both located to the left of intestine. Spermatheca not observed. Vulva located near mid-body. Vaginal glands present. Pars proximalis vaginae surrounded by constrictor muscle.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE1EFF86FDCFFB2A851E72BD.taxon	description	urn: lsid: zoobank. org: act: E 4 C 34 AE 7 - 53 F 3 - 4 B 0 A- 9 C 5 F- 6 BF 6 A 7668 A 8 E	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE1EFF86FDCFFB2A851E72BD.taxon	type_taxon	Type species Aulostomonema abyssum gen. et sp. nov.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE1EFF86FDCFFB2A851E72BD.taxon	diagnosis	Diagnosis Cuticle finely striated. Six outer labial setae and four cephalic setae of similar length and located in one circle; additional setae and subcephalic setae absent. Amphids circular. Mouth opening narrow, followed by elongated constriction of the anteriormost portion of the pharyngostome separating the lip region from the cuticularized, cylindrical buccal cavity. Pharynx not surrounding buccal cavity anteriorly; posterior bulb present. Cardia well developed. Male reproductive system with single anterior outstretched testis. Gubernaculum with dorsal apophyses. Tail conical. Differential diagnosis The new genus is tentatively placed within the Linhomoeidae, as it matches almost all aspects of the diagnosis of the family, including the arrangement of the cephalic sensilla, amphid shape, elongated cardia, and copulatory apparatus. However, Aulostomonema gen. nov. is characterized by a unique feature not found in other genera of the family, i. e., a constriction in the anteriormost portion of the buccal region (pharyngostome) separating the cylindrical buccal cavity from the lip region. This feature should not be confused with the inner soft skinned pad of the lip region (cheilostome) narrowing the buccal aperture of many Linhomoeidae. The constriction in the anteriormost portion of the buccal region of Aulostomonema is similar to the constriction found in the Siphonolaiminae (family Siphonolaimidae), anteriorly to the spear-like siphon. The new genus, however, lacks the siphon which characterizes the Sipholaiminae and possesses six outer labial setae and four cephalic setae in one circle instead of two separate circles as in the Siphonolaiminae. The new genus is tentatively placed within the Linhomoeinae due to the arrangement of the cephalic sensilla (i. e., six outer labial setae and four cephalic setae in one circle) and the cuticularised buccal cavity. Aulostomonema gen. nov. differs from all genera within the Linhomoeinae in having an elongated cylindrical buccal cavity, compared to a cup-shaped buccal cavity in all other genera within the Linhomoeinae. Aulostomonema gen. nov. differs from the genera in the subfamily Desmolaiminae which are characterized by a minute or conical buccal cavity, and which never have setiform outer labial sensilla and cephalic setae in a single circle. Within the Desmolaiminae, Aulostomonema gen. nov. is most similar to the genus Terschellingoides Timm, 1967 (subfamily Desmolaiminae) in having an elongated cylindrical buccal cavity and a single anterior outstretched testis, but differs from the latter in the arrangement of the cephalic sensilla, i. e., a single circle of six outer labial setae and four cephalic setae vs four cephalic setae only in Terschellingoides. The new genus has some affinities with the closely-related Eleutherolaiminae Filipjev, 1922 due to the cylindrical buccal cavity. However, Aulostomonema gen. nov. differs from all genera in this subfamily in having an elongated buccal cavity (vs short buccal cavity in the other genera) and in the arrangement of the cephalic sensilla, which in Eletherolaiminae consists of a 4 + 2 + 4, 4 + 6 or 6 + 4 arrangement.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE1EFF86FDCFFB2A851E72BD.taxon	etymology	Etymology The genus name is derived from the Greek ʻ aulos ʼ meaning ʻfluteʼ, ʻpipeʼ, ʻtubeʼ, ʻ stoma ʼ for ʻmouthʼ and ʻ nema ʼ for ʻthreadʼ and refers to the shape of the buccal cavity in this genus of nematode.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE01FF83FDBEFB16830D75A5.taxon	description	urn: lsid: zoobank. org: act: 105 F 5 B 86 - DC 27 - 4689 - 8279 - 10549 DAC 2 C 21	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE01FF83FDBEFB16830D75A5.taxon	description	Figs 7 – 9, Table 4	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE01FF83FDBEFB16830D75A5.taxon	diagnosis	Diagnosis Aulostomonema abyssum gen. et sp. nov. is characterized by body length 7.1 – 8.8 mm; short, 3 µm long outer labial setae and cephalic setae in single circle; amphids ca 0.5 cbd from anterior extremity; narrow mouth opening followed by constriction expanding posteriorly into cuticularized, cylindrical buccal cavity 19 – 23 µm long and 3 µm in diameter; excretory pore located at level of nerve ring or slightly posterior; spicules 1.5 cloacal body diameters long, gubernaculum with dorsocaudal apophyses, at least 10 – 13 papilliform precloacal supplements present; short conical tail with rounded posterior extremity.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE01FF83FDBEFB16830D75A5.taxon	etymology	Etymology The species name is derived from the Latin ʻ abyssus ʼ meaning ʻa deep pit, the deep seaʼ, ʻhellʼ and refers to the deep type locality.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE01FF83FDBEFB16830D75A5.taxon	materials_examined	Material examined Holotype NEW ZEALAND • ♂; Hikurangi Margin, Mungaroa cold seep site; 41.9382 ° S, 175.3128 ° E; 2077 m water depth; collected on 7 Jul. 2019; sandy mud (96 % silt / clay, mean particle size 20 µm), voyage TAN 1904, station 21; NIWA 154911. Paratypes NEW ZEALAND – Hikurangi Margin, Mungaroa cold seep site • 1 ♂; 41.9403 ° S, 175.3157 ° E; 2091 m water depth; collected on 7 Jul. 2019; sandy mud (98 % silt / clay, mean particle size 16 µm), voyage TAN 1904, station 23; NIWA 154912 • 2 juveniles; 41.9354 ° S, 175.3076 ° E; 2070 m water depth; collected on 7 Jul. 2019; sandy mud (98 % silt / clay, mean particle size 16 µm), voyage TAN 1904, station 15; NIWA 154913.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE01FF83FDBEFB16830D75A5.taxon	distribution	Type habitat and locality New Zealand continental slope, Hikurangi Margin, Mungaroa cold seep.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE01FF83FDBEFB16830D75A5.taxon	description	Description Male Body cylindrical, colourless, tapering slightly towards both extremities. Cuticle finely striated, no lateral differentiation. Somatic setae short and sparse. Rounded cephalic region, not set-off from rest of body. Lip region poorly developed; inner labial papillae not observed. Six short outer labial setae, 3 µm or 13 – 14 % cbd long, situated at same level as four cephalic setae of same length. Additional and subcephalic setae absent. Amphidial fovea circular; outline cuticularized, surrounded by cuticle striations, ca 0.5 cbd from anterior extremity. Narrow mouth opening followed by constriction 20 – 22 µm in length, apparently surrounded by several small glands, expanding posteriorly into cuticularized, cylindrical buccal cavity, 19 – 23 µm long and 3 µm in diameter. Pharynx muscular, not surrounding cylindrical buccal cavity; posterior portion of pharynx swollen into pharyngeal bulb; ducts of pharyngeal glands not observed. Nerve ring located slightly posterior to middle of pharynx. Secretory-excretory system with large ventral gland situated at level of cardia; excretory pore located at level of nerve ring or slightly posterior. Cardia not surrounded by intestine, well-developed, 43 – 93 µm long. Multiple pseudocoelomocytes present in pharyngeal region. Intestine with amorphous brown content. Reproductive system with one anterior outstretched testis located to the left of intestine. Sperm cells globular 12 – 17 × 18 – 22 µm. Spicules short, arcuate, with velum, 1.5 cloacal body diameters long, strongly cuticularized, tapering distally. Gubernaculum with dorsocaudal apophyses tapering distally or with bifid tip. At least 10 – 13 papilliform precloacal supplements present, difficult to observe, beginning ca 30 µm anterior to cloaca and 30 – 80 µm apart. Several large rectal glands present; multiple ejaculatory glands present on either side of vas deferens extending 5 – 6 cloacal body diameters anterior to cloaca Tail short, conical with rounded posterior extremity. Caudal glands not observed. Juvenile Similar to males but with shorter body length, lower ratios of a, b and c, slightly smaller amphids, and longer conical tail with pointed posterior extremity.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE04FF83FDC9FBFA8444701C.taxon	diagnosis	Diagnosis (from Fonseca & Bezerra 2014) Cuticle striated. Six outer labial setae and four cephalic setae in one circle, with cephalic setae shorter than or at most equal to outer labial setae. Often additional setae and occasionally eight groups of subcephalic setae present. Buccal cavity usually funnel-shaped, completely or only at the base surrounded by pharyngeal tissue. Ventral gland mostly absent. Females with one anterior ovary to the left of intestine. Males usually with two testes, the anterior one to the left of intestine, the posterior one to the right of intestine (or absent).	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE04FF83FDC9FBFA8444701C.taxon	discussion	Remarks A list of valid genera and species of the family Xyalidae was provided by Venekey et al. (2014). The Xyalidae is a large and diverse family of nematodes currently comprising 50 valid genera (Venekey et al. 2014; Jiang & Huang 2015; Leduc 2015; Yu & Xu 2015; Gagarin 2020).	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE04FF80FDF7F9B0834F7222.taxon	description	urn: lsid: zoobank. org: act: BF 025843 - A 358 - 490 E- 8 C 22 - 0 CA 5 B 967 BF 79	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE04FF80FDF7F9B0834F7222.taxon	type_taxon	Type species Deraionema barbatum gen. et sp. nov.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE04FF80FDF7F9B0834F7222.taxon	diagnosis	Diagnosis Cuticle finely striated; sixteen longitudinal rows of subcephalic setae posterior to amphids; sexual dimorphism in amphid shape: in males, amphideal fovea and aperture form a single, narrow band (or ‘ collar’) around the entire circumference of the cephalic region, presumably resulting from the fusion of the left and right amphids, in females, amphids are transversely oval with faint outline; large conical buccal cavity; male reproductive system with two opposed testes; spicules slender and elongated; gubernaculum without apophyses; conicocylindrical tail with terminal setae. Differential diagnosis The new genus differs from all other genera within the Xyalidae, and indeed all genera within the entire phylum Nematoda, in having males with a single annular amphideal fovea and aperture surrounding the entire circumference of the cephalic region. Within the Xyalidae, amphids are most commonly rounded or oval-shaped, or can be spindle-shaped (Xenolaimus Cobb, 1920) or indistinct (e. g., Gnomoxyala Lorenzen, 1977). In some genera such as Pseudoechinotheristus Blome, 2002, the oval amphids are transversely elongated and may occupy close to 100 % of the corresponding body diameter, but the two amphids always remain distinct. In Deraionema gen. nov., it appears that the two amphids have become so wide as to become fused, thus forming a single structure. In some specimens, it is possible to discern the amphideal nerve extending posteriorly from the amphid, which allows to determine the position of the lateral sectors. Deraionema gen. nov. is most similar to Paramonohystera Steiner, 1916 in the conical buccal cavity, structure of the copulatory apparatus (i. e., elongated, slender spicules and gubernaculum without apophyses) and conicocylindrical tail with terminal setae. In addition to differences in male amphid shape, the two genera can be differentiated by the presence of 16 longitudinal rows of subcephalic setae in Deraionema gen. nov. (vs absent in Paramonohystera).	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE04FF80FDF7F9B0834F7222.taxon	etymology	Etymology The species name is derived from the Greek ʻ deraion ʼ meaning ʻnecklaceʼ, ʻcollarʼ and ʻ nema ʼ meaning ʻthreadʼ, and refers to the shape of the amphids in males.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE07FF8DFDAFFB9282997313.taxon	description	Figs 10 – 12, Table 5	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE07FF8DFDAFFB9282997313.taxon	diagnosis	Diagnosis Deraionema barbatum gen. et sp. nov. is characterized by body length 2.1 – 3.2 mm; outer labial setae 6 – 8 µm long and cephalic setae 4 – 5 µm long; short and sparse subcephalic setae present anterior to amphids; sixteen longitudinal rows of subcephalic setae present posterior to amphids, increasing in length posteriorly; pronounced sexual dimorphism in amphid shape: in males, amphideal fovea and aperture form a single, narrow band around the entire circumference of the cephalic region, presumably resulting from the fusion of the left and right amphids, in females, amphids are transversely oval with faint outline; large conical buccal cavity with cuticularized ring (cheilostome) and three transverse cuticularized pieces (pharyngostome); slender, elongated spicules 2.4 – 3.9 cloacal body diameters long with lateral extensions distally bearing minute spines; gubernaculum long and thin, without apophyses or crurae; conicocylindrical tail 3.3 – 4.8 cloacal / anal body diameters long.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE07FF8DFDAFFB9282997313.taxon	etymology	Etymology The species name is derived from the Latin ʻ barbatus ʼ meaning ʻbeardedʼ and refers to the longitudinal rows of subcephalic setae.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE07FF8DFDAFFB9282997313.taxon	materials_examined	Material examined Holotype NEW ZEALAND • ♂; Hikurangi Margin, Uruti South cold seep site; 41.4251 ° S, 176.3510 ° E; 1227 m water depth; collected on 13 Jul. 2019; voyage TAN 1904, station 61; NIWA 154914. Paratypes NEW ZEALAND • 2 ♂ ♂; same collection data as for holotype; NIWA 154915 • 1 ♂, 1 ♀; Hikurangi Margin, Uruti South cold seep site; 41.4250 ° S, 176.3510 ° E; 1226 m water depth; collected on 13 Jul. 2019; sandy mud (91 % silt / clay, mean particle size 24 µm); voyage TAN 1904, station 61; NIWA 154916 • 3 ♂ ♂; Mungaroa cold seep site; 41.9378 ° S, 175.3112 ° E; 2075 m water depth; collected on 7 Jul. 2019; sandy mud (96 % silt / clay, mean grain size 17 µm); voyage TAN 1904, station 19; NIWA 154917.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE07FF8DFDAFFB9282997313.taxon	distribution	Type habitat and locality New Zealand continental slope, Hikurangi Margin, Uruti South and Mungaroa cold seeps.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE07FF8DFDAFFB9282997313.taxon	description	Description Male Body cylindrical, colourless, tapering slightly towards both extremities. Cuticle finely striated, no lateral differentiation. Eight longitudinal rows of short and sparse somatic setae short and sparse. Rounded cephalic region, not set-off from rest of body. Lip region well developed with six inner labial papillae. Six outer labial setae, 20 – 22 % cbd long, situated at same level as four slightly shorter cephalic setae, 13 – 17 % cbd. Up to six additional setae present at same level as outer labial and cephalic setae, either adjacent to outer labial and cephalic setae or halfway between outer labial setae, 4 µm long. Variable number of subcephalic setae (up to 20) present at level of buccal cavity and anterior to amphids, 4 – 5 µm long. Sixteen longitudinal rows of 12 – 20 subcephalic setae present beginning immediately posterior to amphids, increasing in length posteriorly, 4 – 47 µm long. Amphidial fovea a single, continuous narrow band around entire circumference of cephalic region, 5 µm in height, located 0.8 – 0.9 cbd from anterior body extremity; amphideal aperture narrower than amphideal fovea, 2 µm in height, consisting of a single narrow opening surrounding entire circumference of cephalic region. Buccal cavity large, 26 – 38 µm deep and up to 19 µm wide, conical; cuticularized ring present at base of cheilostome; wall of pharyngostome lightly cuticularized and with three transverse cuticularized pieces arranged in a broken ring, one in each of the dorsal and ventrosublateral sectors. Pharynx muscular, surrounding most of buccal cavity, without posterior bulb; ducts of pharyngeal glands not observed. Nerve ring located at one third of pharynx length from anterior. Secretory-excretory system usually indistinct; pore located posterior to nerve ring near middle of pharynx, ventral gland not observed. Cardia surrounded by intestine, 18 – 30 µm long. Reproductive system diorchic with two opposed and outstretched testes; anterior testis located to the left of intestine and posterior testis to the right of intestine. Sperm cells globular, small, 4 – 5 × 5 – 7 µm. Spicules slender, 2.5 – 3.9 cloacal body diameters long, strongly cuticularised, with rounded lateral extensions distally bearing numerous minute spines. Gubernaculum elongated, thin proximally, without dorsocaudal apophyses or crurae. Precloacal supplements absent. Rectal glands and ejaculatory glands not observed. Tail conicocylindrical, with numerous subventral setae and sparse subdorsal setae, 6 – 14 µm long, three terminal setae 26 – 33 µm long. Three caudal glands present. Female Similar to males but additional setae absent, rows of subcephalic setae posterior to amphids with fewer (5 – 8) setae, oval amphids with faint contours, and tail with sparsely distributed setae. Reproductive system with single anterior outstretched ovary located to the left of intestine, mature egg 49 × 101 µm; spermatheca present posterior to vulva. Vulva located at two thirds of body length from anterior body extremity; single vaginal gland present.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE0AFF8AFE57FAA3811C77D1.taxon	diagnosis	Diagnosis (emended from Holovachov 2015) Cuticle smooth or finely annulated. Lateral alae absent. Epidermal glands absent. Somatic sensilla present. Labial region rounded, continuous with body contour. Inner labial sensilla indistinct. Outer labial sensilla pore-like or papilliform, located on outer surface of lips. Cephalic sensilla papilliform or setiform, located at base of labial region, anterior to amphid. Amphidial aperture circular. Subcephalic and cervical sensilla, deirid and ocelli absent. Secretory-excretory system present; renette cell located opposite to ventral side of pharynx, cardia or anterior part of intestine. Excretory ampulla present. Excretory duct very short, usually opens near level of nerve ring in males and further anteriorly in females. Stoma small, undifferentiated. Pharynx divided into anterior long tubular section with strongly cuticularised lumen and weakly developed tissue, and strongly muscularized oval basal bulb. Cardia cylindrical or conoid, partly enveloped by intestinal tissue in its posterior part. Female reproductive system didelphic, amphidelphic, ovary branches reflexed antidromously. Spermatheca present, axial. Vulva equatorial, transverse. Vagina thick; pars refringens vaginae absent. Male reproductive system diorchic, both testes outstretched. Spicules symmetrical, straight or arcuate; gubernaculum present or absent. Copulatory apparatus composed of a row of midventral precloacal sensilla (absent in some species). Postcloacal sensilla absent. Tail similar between sexes, conoid or subcylindrical with rounded terminus. Three caudal glands present, with common or multiple openings.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE0AFF8AFE57FAA3811C77D1.taxon	discussion	Remarks This family was placed within the order Plectida by De Ley & Blaxter (2004) but was later considered incertae sedis by Holovachov (2014) due to lack of molecular data and unclear phylogenetic affinities. The placement of this family remains uncertain despite recent molecular analyses (Leduc & Zhao 2021).	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE0DFF8AFDA7FDEC810475F5.taxon	type_taxon	Type species Aegialoalaimus elegans de Man, 1907.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE0DFF8AFDA7FDEC810475F5.taxon	diagnosis	Diagnosis (from Holovachov 2015) See family diagnosis.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE0DFF8AFDA7FDEC810475F5.taxon	discussion	Remarks The genus currently comprises five valid species (Leduc & Zhao 2021) and was revised by Holovachov (2015).	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE0DFFB7FDCDFBC983C072A2.taxon	description	urn: lsid: zoobank. org: act: 4 D 4 BD 1 F 6 - 70 E 8 - 4 E 2 B-BF 6 C- 530389 C 772 AA	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE0DFFB7FDCDFBC983C072A2.taxon	description	Figs 13 – 15, Table 6	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE0DFFB7FDCDFBC983C072A2.taxon	diagnosis	Diagnosis Aegialoalaimus magnus sp. nov. is characterized by body length 2.8 – 3.3 mm, papilliform cephalic sensilla, amphids with strongly cuticularized outline and central region with pitted appearance, radiating, cuticularized processes surrounding junction of pharyngostome and cheilostome, secretory-excretory pore located at or near level of nerve ring and ventral gland well posterior to cardia, spicules 1.4 – 1.6 cloacal body diameters long, well-developed gubernacular apophyses, 11 – 12 inconspicuous precloacal supplements, and conical tail 2.8 – 3.5 cloacal or anal body diameters long. Differential diagnosis The new species differs from all other species of the genus in the longer body (2.8 – 3.3 vs <2.0 mm in all other species), gubernaculum with conspicuous apophyses (vs apophyses absent in all other species) and greater number of precloacal supplements (11 – 12 vs 0 – 8 in all other species).	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE0DFFB7FDCDFBC983C072A2.taxon	etymology	Etymology The species name is derived from the Latin ʻ magnus ʼ meaning ʻlargeʼ, ʻgreatʼ and refers to the relatively large size of the species.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE0DFFB7FDCDFBC983C072A2.taxon	materials_examined	Material examined Holotype NEW ZEALAND • ♂; Hikurangi Margin, Mungaroa cold seep site; 41.9376 ° S, 175.3110 ° E; 2075 m water depth; collected on 7 Jul. 2019; sandy mud sediment (97 % silt / clay, mean particle size 19 µm), voyage TAN 1904, station 18; NIWA 154918. Paratypes NEW ZEALAND • 2 ♀ ♀; same collection data as for holotype; NIWA 154920 • 1 ♂; Glendhu cold seep site; 41.7695 ° S, 176.0882 ° E; 1993 m depth; collected 10 Jul. 2019; sandy mud sediment (88 % silt / clay, mean particle size 27 µm), voyage TAN 1904, station 40; NIWA 154919.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE0DFFB7FDCDFBC983C072A2.taxon	distribution	Type habitat and locality New Zealand continental slope, Hikurangi Margin, Mungaroa and Glendhu cold seeps.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE0DFFB7FDCDFBC983C072A2.taxon	description	Description Male Body colourless, cylindrical along most of its length, tapering slightly towards both extremities. Cuticle with fine transverse striations without lateral differentiation. Body pores and epidermal glands absent. A few sparse, short somatic papillae, 1 µm long, present in anterior pharyngeal region. Cephalic region slightly rounded; lip region poorly developed, continuous with body contour, lips fused. Inner labial papillae not observed; six short outer labial papillae, <1 µm long, located slightly anterior to four slightly longer cephalic papillae, 1 – 1.5 µm long. Subcephalic setae absent. Amphideal fovea circular with strongly cuticularized outline and central region with pitted appearance, situated well posterior to cephalic sensilla, 0.6 – 0.7 cbd from anterior end. Ocelli absent. Oral opening termina. Cheilostome is a narrow tube 7 – 8 µm long; pharyngostome 4 – 6 µm wide, indistinguishable from the cuticularised lumen of the pharynx. Six short and cuticularized radiating processes surrounding junction of pharyngostome and cheilostome, S-shaped. Pharynx divided into two sections: anterior tubular part and posterior (basal) bulb. Tubular part of the pharynx is 163 – 196 µm long, 4 – 8 µm wide, with irregular contour, surrounded by thin sheath of non-muscular tissue. Posterior bulb muscular, oval-shaped, surrounded by six elongated glands with ducts extending anteriorly, each comprised of multiple nucleated cells. Pharyngeal glands sometimes visible. Nerve ring located at 59 – 67 % of pharynx length from anterior. Secretoryexcretory system present; pore located at or immediately posterior to level of nerve ring, ampulla small, renette cell located 1.5 – 2.5 cbd posterior to pharyngeal bulb. Cardia ca 15 – 18 µm long, partially surrounded by intestine. Reproductive system diorchic with with two anteriorly-directed testes both located ventrally or to the left of intestine; anterior testis outstretched, posterior testis reflexed. Sperm cells globular, 13 – 17 × 9 – 13 µm, of similar shape and dimensions in both testes. Spicules paired, equal, strongly cuticularized, arcuate and 1.4 – 1.6 cloacal body diameters long; tapered distal end swollen proximal end (capitulum). Gubernaculum dorso-caudal apophyses slightly bent distally. Ejaculatory and rectal glands not observed. Eleven to twelve inconspicuous tubular precloacal supplements located 15 – 48 µm apart. Tail conical, with rounded tip, 2.8 – 3.3 cloacal body diameters long, without somatic setae. Three caudal glands and spinneret present. Female Similar to males, but with excretory pore located at or slightly anterior to level of nerve ring. Reproductive system didelphic with two opposed and reflexed ovaries both located ventrally or to the left of intestine; spermatheca absent. Vulva situated at mid-body. Proximal portion of vagina surrounded by constrictor muscle, small vaginal glands present. Uterus wall not cuticularized.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE30FFB7FDA7FAF883A273C3.taxon	diagnosis	Diagnosis (from Tchesunov 2014) Cuticle annulated, without dots, but spines, fringes or longitudinal ornamentation may be present. No specialised ambulatory setae at anterior and posterior body ends.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE30FFB7FDB3F9F281CB7100.taxon	diagnosis	Diagnosis (from Tchesunov 2014) Cuticle annulated except in cephalic region. Cephalic region with thickened cuticle except in lip region and set off as a conspicuous cephalic capsule. Amphideal fovea generally not surrounded by cuticle annulations; may be located on a cuticularized plate. Buccal cavity mostly with distinct teeth. Pharyngeal bulb round or elongated.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE30FFB4FDCDF8BE8184746B.taxon	type_taxon	Type species Desmodora communis (Bütschli, 1874).	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE30FFB4FDCDF8BE8184746B.taxon	diagnosis	Diagnosis (modified from Verschelde et al. 1998) Cuticle without ridges or spines. Cephalic capsule either smooth or partly to entirely ornamented with structures resembling pores or small vacuoles, which have been shown by scanning electron microscopy to not be visible on the cuticle surface (e. g., Fadeeva et al. 2016); cephalic setae located either in the lip region or on main part of head capsule. Subcephalic setae sometimes present, when present few in number and mainly located posteriorly to amphideal fovea. Amphideal fovea cryptospiral or multispiral, seldom loopshaped. Buccal cavity with large dorsal tooth and smaller subventral teeth. Pharynx with oval or circular posterior bulb. Spicules short, arcuate, with capitulum and velum. Precloacal supplements sometimes present, usually pore-like, seldom consisting of cuticular swellings or flaps. Tail usually conical, seldom conico-cylindrical.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE33FFBEFDFAFD5B82A570AB.taxon	description	urn: lsid: zoobank. org: act: 4 ED 46 F 36 - 0 AEA- 43 BA- 9 EF 5 - 0 A 2 D 799 E 7135	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE33FFBEFDFAFD5B82A570AB.taxon	description	Figs 16 – 18, Tables 7 – 8	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE33FFBEFDFAFD5B82A570AB.taxon	diagnosis	Diagnosis Desmodora parapilosa sp. nov. is characterized by body length 2.3 – 3.2 mm, jointed inner labial setae, outer labial setae and cephalic setae, main portion of cephalic capsule with numerous, irregularly distributed pores (or vacuoles), large amphideal fovea with 2.25 turns in males (smaller in females with 1.75 – 2.0 turns), buccal cavity with large cuticularised dorsal tooth, two smaller ventrosublateral teeth and two lateral, transverse rows of small denticles, arcuate spicules 1.3 – 1.5 cloacal body diameters long, short, plate-like gubernaculum, vulva at almost two thirds of body length from anterior and conical tail 2.6 – 3.5 cloacal or anal body diameters long. Differential diagnosis The new species is most similar to Desmodora pilosa Ditlevsen, 1926 in the shape of the amphids (spiral), presence of pores / vacuoles in the cephalic capsule, buccal cavity armature with rows of denticles and structure of the copulatory apparatus. Desmodora parapilosa sp. nov. can be differentiated from the latter by the jointed anterior sensilla (vs not jointed in D. pilosa), larger amphids (in males: 51 – 63 vs 37 % cbd in D. pilosa), number of amphid turns (2.25 in males and 1.75 – 2.0 in females vs 1.25 turns in males and females of D. pilosa), and shorter spicules (61 – 66 vs 72 – 96 µm in D. pilosa).	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE33FFBEFDFAFD5B82A570AB.taxon	etymology	Etymology The species name refers to the morphologically similar species Desmodora pilosa Ditlevsen, 1926.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE33FFBEFDFAFD5B82A570AB.taxon	materials_examined	Material examined Holotype NEW ZEALAND • ♂; Hikurangi Margin, Uruti South cold seep site; 41.4251 ° S, 176.3510 ° E; 1226 m water depth; collected on 13 Jul. 2019; sandy mud sediment (91 % silt / clay, mean particle size 23 µm), voyage TAN 1904, station 62; NIWA 154921. Paratypes NEW ZEALAND – Uruti South cold seep site • 3 ♂ ♂; same collection data as for holotype; NIWA 154922 • 1 ♀; 41.4260 ° S, 176.3506 ° E; 1237 m water depth; collected on 14 Jul. 2019; sandy mud sediment (94 % silt / clay, mean particle size 18 µm); voyage TAN 1904, station 68; NIWA 154923 • 1 ♀; Uruti South cold seep site; 41.4253 ° S, 176.3509 ° E; 1235 m water depth; collected on 14 Jul. 2019; voyage TAN 1904, station 70; NIWA 154924.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE33FFBEFDFAFD5B82A570AB.taxon	distribution	Type habitat and locality New Zealand continental slope, Hikurangi Margin, Uruti South cold seep.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE33FFBEFDFAFD5B82A570AB.taxon	description	Description Male Long cylindrical body, widest at level of pharynx, with slight golden-brown colouration throughout except for main portion of cephalic capsule and intestine wall which which may be strongly stained by Rose bengal; rounded anterior end and conical tail. Cuticle coarsely annulated with annulations ca 1.2 µm apart; minute cuticle spines present on surface of cuticle, difficult to observe using light microscopy. Several protists often attached throughout body length and some specimens with patches of dense rod-shaped bacteria on outer cuticle, 4 – 8 µm long. Eight longitudinal rows of somatic setae along entire body length, 4 – 6 µm long in pharyngeal and mid-body regions, and up to 10 µm long in precloacal region; subventral row of precloacal somatic setae associated with conspicuous epidermal glands. Welldeveloped cephalic capsule, 40 – 46 µm wide and 40 – 46 µm high, consisting of two parts separated by a sutura: a lip portion with relatively thin cuticle and extendable anterior portion and a main region with thickened cuticle (up to 7 µm thick) and comprising at least three quarters of cephalic capsule. Main portion of cephalic capsule with numerous, dense pores (or vacuoles) irregularly distributed except near base where pores may be arranged in transverse rows; sparse subcephalic setae present at base of cephalic capsule, 2 – 6 µm long. Six inner and six outer labial setae present on lip region; inner labial setae 2 – 4 µm long, outer labial setae 4 – 6 µm long. Four cephalic setae present at level of sutura, 3 – 5 µm long. Inner labial setae, outer labial setae and cephalic setae all with a single joint near tip where sensilla becomes markedly narrower. Amphideal fovea and aperture large, spiral with 2.25 turns and cuticularized outline, located on main portion of cephalic capsule; amphideal fovea slightly wider than amphideal aperture. Buccal cavity with large cuticularised dorsal tooth and two smaller ventrosublateral teeth; two lateral, transverse rows of small denticles also present. Cylindrical pharynx slightly swollen anteriorly and with oval posterior pharyngeal bulb. Secretory-excretory system not observed. Cardia 12 – 19 µm long, partially surrounded by intestine. Reproductive system monorchic with outstretched testis located to the right or left of intestine. Mature sperm cells globular or spherical, 8 × 8 – 10 µm. Short, arcuate spicules with well-developed capitulum, tapering shaft and distal end, 1.3 – 1.5 cloacal body diameters long; short, plate-like gubernaculum. Precloacal supplements and seta not observed. Conical tail with subventral and subdorsal rows of setae. Non-annulated tail tip without perforations. Caudal glands and spinneret present. Female Similar to males, but with smaller amphideal fovea with 1.75 – 2.0 turns and slightly longer tail. Reproductive system didelphic, amphidelphic with reflexed ovaries; position of ovaries relative to intestine not clear in one specimen, in other specimen, anterior ovary located to the left of intestine and posterior ovary to the right. Spermatheca not observed. Vulva located at almost two thirds of boody length from anterior. Proximal portion of vagina cuticularised; proximal portion of vagina surrounded by constrictor muscle. Vaginal glands present.	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
674787D8AE33FFBEFDFAFD5B82A570AB.taxon	discussion	Remarks The original description of D. pilosa by Ditlevsen (1926) based on Northwest Atlantic specimens did not include observations of male specimens or of buccal cavity armature. Ditlevsen (1926) did not describe pores in the cephalic capsule. Desmodora gorbunovi Filipjev, 1946 and Desmodora gorbunovi perforata Filipjev, 1946 were described based on Arctic Ocean specimens and later synonymized with D. pilosa by Gerlach (1963). The former lacks pores in the cephalic capsule whereas the latter is characterized by numerous pores in the cephalic capsule. Both of these are described by Filipjev (1946) as having a buccal cavity with a small dorsal tooth (although small ventrosublateral teeth may be present based on the drawings) without denticles. In his redescription of D. pilosa based on specimens from the Norwegian Sea, Jensen (1991) noted strong similarities between his specimens and Desmodora gorbunovi including the cephalic capsule with numerous pores, size and arrangement of anterior sensilla and somatic setae, structure of the amphideal fovea, and tail shape. Jensen’s specimens, however, have a buccal cavity with a band of numerous denticles, whereas Filipjev’s specimens do not have denticles. The descriptions of Filipjev (1946) and Jensen (1991) also show some inconsistencies in body dimensions and size of anterior sensilla and amphideal fovea (Table 8). Leduc (2021) recently described abyssal nematode specimens from the Southwest Pacific showing similarities to D. pilosa although inconsistencies in body size, dimensions, amphid size and cuticle ornamentation were noted. Despite the morphological differences between the Southwest Pacific specimens and the specimens described by Ditlevsen (1926), Filipjev (1946) and Jensen (1991), Leduc (2021) did not erect a new species because further data are required from the type locality of D. pilosa (upper continental slope of NW Atlantic) to determine the structure of the buccal cavity armature, presence or absence of pores in the cephalic capsule and male morphology of this species. A new species, Desmodora parapilosa sp. nov., is erected here because the Hikurangi margin specimens can be differentiated from the specimens described by Ditlevsen (1926), Filipjev (1946), Jensen (1991) and Leduc (2021) based on several key characters, i. e., the jointed anterior sensilla, larger amphids with greater number of turns, and shorter spicules. The new species also differs from the Southwest Pacific abyssal specimens in having a lower ratio of a, longer tail, longer gubernaculum, and smaller sperm (8 × 8 – 10 µm vs 10 – 11 × 16 – 19 µm) (Table 8).	en	Leduc, Daniel (2023): New nematode species and genera (Nematoda: Chromadorea) from cold seeps on Hikurangi Margin, New Zealand. European Journal of Taxonomy 856: 1-45, DOI: https://doi.org/10.5852/ejt.2023.856.2025, URL: http://dx.doi.org/10.5852/ejt.2023.856.2025
