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Genus Syringolaimus de Man, 1888 Halirhabdolaimus Siddiqi, 2012: 65 syn. nov. Diagnosis (after Tchesunov 2017) Cuticle visually smooth or transversely striated. Lateral alae absent. Somatic sensilla undescribed. Labial region truncated. Inner labial sensilla indistinct. Morphology of inner and outer labial sensilla unclear. Four cephalic small papilliform sensilla. Amphid stirrup-shaped with transverse slit-like opening. Stoma cylindrical, with cuticularised walls and three protrusible bifid teeth located at same level at anterior edge of stegostom. Pharynx cylindrical anteriorly, with distinct basal bulb; valves absent. Cardia large, ovoid, partially embedded into intestinal tissue. Secretory-excretory system present. Female reproductive system didelphic, amphidelphic, ovary branches reflexed antidromously. Morphology of vulva and vagina unknown. Male reproductive system monorchic, testis outstretched. Spicules arcuate, symmetrical. Gubernaculum present. Precloacal supplements papilliform, in single midventral row. Caudal alae absent. Tail elongate. Caudal glands and spinneret present or absent. Type and only species Syringolaimus striatocaudatus de Man, 1888. syn. Syringolaimus striatocaudatus aberrans Micoletzky, 1924. syn. Syringolaimus striatocaudatus steineri Micoletzky, 1924. syn. Dolicholaimus propinquus Allg��n, 1933. syn. Dolicholaimus tenuicaudatus Allg��n, 1932. Included species Syringolaimus annae Lima, Lins, Da Silva & Esteves, 2009. Syringolaimus elegans Tchesunov, 2017. Syringolaimus filicaudatus Vitiello, 1970. Syringolaimus loofi Gourbault & Vincx, 1985. syn. Halirhabdolaimus loofi (Gourbault & Vincx, 1985). Syringolaimus renaudae Gourbault & Vincx, 1985. Syringolaimus smolae Lima, Lins, Da Silva & Esteves, 2009. Syringolaimus striatocaudatus de Man, 1888. Syringolaimus taniae Lima, Lins, Da Silva & Esteves, 2009. Species inquirenda Syringolaimus brevicaudatus Micoletzky, 1922. Syringolaimus caspersi Gerlach, 1951. Syringolaimus lichenii (Nasira & Turpeenniemi, 2002). syn. Trissonchulus lichenii Nasira & Turpeenniemi, 2002. Syringolaimus marisalbi Platonova & Mokievsky, 1994. Syringolaimus smarigdus Cobb, 1928. Nomina nuda Syringolaimus gladiatus Bussau, 1993. Syringolaimus ingens Bussau, 1993. Syringolaimus nitidus Bussau, 1993. Syringolaimus venustus Bussau, 1993. Remarks See Tchesunov (2017) for the most recent and comprehensive revision of the genus. The genus Halirhabdolaimus was proposed by Siddiqi (2012) for a single species, Syringolaimus loofi, and was only compared with the genus Rhabdolaimus. However, the author did not compare Halirhabdolaimus with Syringolamus. The differential diagnoses of both genera match perfectly and thus the proposal of the new genus was entirely unjustified., Published as part of Holovachov, Oleksandr, 2019, Campydoroides manautei gen. et sp. nov. from New Caledonia and a reappraisal of the suborder Campydorina (Nematoda), pp. 1-23 in European Journal of Taxonomy 518 on pages 17-18, DOI: 10.5852/ejt.2019.518, http://zenodo.org/record/2649833, {"references":["Siddiqi M. R. 2012. Ten new species of Rhabdolaimus de Man, 1880, with the proposal for Halirhabdolaimus gen. n. (Nematoda: Haliplectidae). International Journal of Nematology 22: 47 - 66.","Tchesunov A. V. 2017. Free-living nematodes of the genus Syringolaimus de Man, 1888 (Nematoda, Enoplida, Ironidae) from the Angola Basin, South-East Atlantic Abyss. Zootaxa 4306: 478 - 500. https: // doi. org / 10.11646 / zootaxa. 4306.4.2"]}

Syringolaimus magdae Lima, Lins, Da Silva & Esteves, 2009. Lima et al., 2009: p. 125-127, figs 3���4 (South���West Atlantic, off coast of Brazil, Campos Basin, 1050 m, siltclay), one male. Cuticle smooth along the entire body or striations not easily observed. Ventral pore situated at 35.2% of pharynx length from anterior end; ventral gland cell body present. Caudal glands and spinneret present. Monorchic. No supplementary organs mentioned. Syringolaimus marisalbi Platonova & Mokievsky, 1994 sp. inq. Platonova & Mokievsky, 1994: p. 9���10, figs 9���14 (White Sea, upper intertidal zone, fine sand with clay), males, females and juveniles. Body cuticle largely smooth but striated on tail. Spinneret present. Ovaries are described as straight (erroneously?). Amphids, ventral pore and ventral gland, male gonads, supplementary organs and caudal glands not mentioned. Apparently, close or may be identical to S. striatocaudatus. Syringolaimus nitidus Bussau, 1993 nom. nud. Bussau, 1993: p. 501���505, Abb. 216, 217. (South���East Pacific / Peru Basin/, 4100���4200 m, dark brown ooze with manganese nodules), males and females. Body cuticle with extremely fine annulations. Metanemes not observed. Ventral pore at a distance of 60 ��m from anterior end (in a male), a bit anterior to the nerve ring. Spinneret evident but no caudal glands found. Monorchic. No supplementary organs mentioned., Published as part of Tchesunov, Alexei V., 2017, Free-living nematodes of the genus Syringolaimus de Man, 1888 (Nematoda, Enoplida, Ironidae) from the Angola Basin, South-East Atlantic Abyss, pp. 478-500 in Zootaxa 4306 (4) on pages 481-482, DOI: 10.11646/zootaxa.4306.4.2, http://zenodo.org/record/845097, {"references":["Lima, R. C. C., Lins, L., Da Silva M. R., & Esteves, A. M. (2009) Four new species of Syringolaimus De Man, 1888 (Nematoda: Ironidae) from the Southeast Atlantic (Brazil), with redefinition of valid species and the proposal of a new key. Zootaxa, 2096, 119 - 136.","Platonova, T. A. & Mokievsky, V. O. (1994) Revision of the marine nematodes of the family Ironidae (Nematoda: Enoplida). Zoosystematica Rossica, 3 (1), 5 - 17.","Bussau, Ch. (1993) Taxonomische und okologische Untersuchungen an Nematoden des Peru-Beckens. Dissertation zur Erlangen des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultat der Christian-Albrechts-Universitat zu Kiel, Kiel, 621 pp."]}

Syringolaimus renaudae Gourbault & Vincx, 1985. Gourbault & Vincx, 1985: p. 109���114, fig. 1���2 (SW Atlantic, Cape Basin, 3694���4180 m, deep-sea ooze), males and females. Cuticle finely annulated close to both extremities. Anterior end demarcated by a distinct collar. Amphidial fovea 40% of the corresponding body width in male. Ventral pore at the level of posterior end of the buccal cavity. Monorchic. No supplementary organs mentioned. Spinneret and caudal glands present. Syringolaimus smarigdus Cobb, 1928 sp. inq. Cobb, 1928: p. 249���253, fig. 1 (USA east coast, Massachusetts, from shells of gastropod molluscs Alectrion obsoleta feeding on algae Ralfsia). De Coninck & Schuurmans Stekhoven, 1933: p. 58 (junior synonym of S. striaticaudatus). Chitwood, 1951: p. 646, fig. 9 I ���K (Texas, from Sargassum algae). Description and brief redescriptions of this species are poorly detailed. Since neither measured values nor structural features contradict characteristics of S. striatocaudatus, I follow the opinion of De Coninck & Schuurmans Stekhoven (1933) and adopt synonymy of the species., Published as part of Tchesunov, Alexei V., 2017, Free-living nematodes of the genus Syringolaimus de Man, 1888 (Nematoda, Enoplida, Ironidae) from the Angola Basin, South-East Atlantic Abyss, pp. 478-500 in Zootaxa 4306 (4) on page 482, DOI: 10.11646/zootaxa.4306.4.2, http://zenodo.org/record/845097, {"references":["Gourbault, N. & Vincx, M. (1985) Deux especes nouvelles d'Ironidae marins; observations sur les spermatozoides \" flagelles \" des Nematodes. Bulletin du Museum national d'Histoire naturelle, Paris, 4 e Serie, 7, Section A, n o 1, 109 - 118.","Cobb, N. A. (1928) A new species of the nemic genus Syringolaimus with a note on the fossorium of nemas. Journal of the Washington Academy of Sciences, 18, 249 - 263.","De Coninck, L. A. & Schuurmans Stekhoven, J. H. (1933) The free-living marine nemas of the Belgian coast II. Memoires du Musee royal d'Histoire naturelle de Belgique, 58, 1 - 163.","Chitwood, B. G. (1951) North American marine nematodes. Texas Journal of Science, 3, 617 - 672."]}

Syringolaimus taniae Lima, Lins, Da Silva & Esteves, 2009. Lima et al., 2009: p. 130���133, figs 7���8 (South���West Atlantic, off coast of Brazil, Campos Basin, 1050���1350 m, silt-clay), males and female. Body cuticle with faint striation not easily detected. Ventral pore just posterior to the buccal cavity, ventral gland cell body at the level of cardia. Tail with anterior portion rounded and clearly set apart from distal filliform cylindrical part. Caudal glands present, spinneret long, representing 12.9% of tail length. Monorchic. No precloacal papilla present. Syringolaimus venustus Bussau, 1993 nom. n., sp. inq. Bussau, 1993: p. 505���507, Abb. 218 (South���East Pacific, Peru Basin, 4100���4200 m, dark brown ooze with manganese nodules), female and juveniles. Body cuticle extremely finely annulated. Metanemes not found. Amphidial fovea 25% of the corresponding body width in female. Neither ventral pore nor ventral gland cell body found. Spinneret evident but no caudal glands found., Published as part of Tchesunov, Alexei V., 2017, Free-living nematodes of the genus Syringolaimus de Man, 1888 (Nematoda, Enoplida, Ironidae) from the Angola Basin, South-East Atlantic Abyss, pp. 478-500 in Zootaxa 4306 (4) on page 482, DOI: 10.11646/zootaxa.4306.4.2, http://zenodo.org/record/845097, {"references":["Lima, R. C. C., Lins, L., Da Silva M. R., & Esteves, A. M. (2009) Four new species of Syringolaimus De Man, 1888 (Nematoda: Ironidae) from the Southeast Atlantic (Brazil), with redefinition of valid species and the proposal of a new key. Zootaxa, 2096, 119 - 136.","Bussau, Ch. (1993) Taxonomische und okologische Untersuchungen an Nematoden des Peru-Beckens. Dissertation zur Erlangen des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultat der Christian-Albrechts-Universitat zu Kiel, Kiel, 621 pp."]}

Identification of Syringolaimus species Species of Syringolaimus are pretty similar, but differ from one another in morphometrics and especially in relative length and shape of the tail. Other characters such as length of the buccal cavity and position of the amphidial aperture are also important for species discrimination and hence they are included in tables 1 and 2. Position of the ventral pore and presence/absence of preanal supplementary papilla, caudal glands and spinneret should also have significance for species identification but unfortunately they are very unevenly characterized in all species and hence it is impossible to present these traits for every species as icons in a pictorial key. Lima et al. (2009) provided a dichotomous key for fourteen Syringolaimus species designated by them as valid. Since some changes in the list of valid species are made and one new species is here described, I complement the key with morphometric characteristics (tables 1 and 2) and schematic icons of the tails (Fig. 1)., Published as part of Tchesunov, Alexei V., 2017, Free-living nematodes of the genus Syringolaimus de Man, 1888 (Nematoda, Enoplida, Ironidae) from the Angola Basin, South-East Atlantic Abyss, pp. 478-500 in Zootaxa 4306 (4) on page 483, DOI: 10.11646/zootaxa.4306.4.2, http://zenodo.org/record/845097, {"references":["Lima, R. C. C., Lins, L., Da Silva M. R., & Esteves, A. M. (2009) Four new species of Syringolaimus De Man, 1888 (Nematoda: Ironidae) from the Southeast Atlantic (Brazil), with redefinition of valid species and the proposal of a new key. Zootaxa, 2096, 119 - 136."]}

Syringolaimus filicaudatus Vitiello, 1970 Vitiello, 1970: p. 206���207, figs 51 a���j (Mediterranean, Gulf of Lion, 310���580 m). Body cuticle finely striated only in anterior and caudal regions. Ventral pore at 37% of pharynx length from anterior length. Caudal glands and spinneret present. Male gonads not described. No preanal supplementary papilla. Gubernaculum vestigial. Among other things, the species is distinguished from other species by fine striations of anterior cuticle and distinctly narrow arcuate spicules. Syringolaimus gladiatus Bussau, 1993 nom. nud. Bussau, 1993: p. 492���497, Abb. 211, 212, 213 (South-East Pacific, Peru Basin, 4100���4200 m, dark brown ooze with manganese nodules), males and females. Body cuticle with fine annulations. Metanemes present. Ventral pore situated between buccal cavity base and nerve ring, in male at a distance 87 ��m posterior to the anterior end; ventral gland cell body not found. Caudal glands and spinneret absent. Monorchic. No supplementary organs mentioned. Syringolaimus ingens Bussau, 1993 nom. nud. Bussau, 1993: p. 498���501, Abb. 214, 215 (South���East Pacific, Peru Basin, 4100���4200 m, dark brown ooze with manganese nodules), male and females. The largest (by body length) species of the genus. Body cuticle with extremely fine annulations. Metanemes present. Neither ventral pore nor ventral gland cell body found. Spinneret evident but no caudal glands found. Monorchic. No supplementary organs mentioned. Syringolaimus lichenii (Nasira & Turpeenniemi, 2002) Tahseen & Mehdi, 2009 sp. inq. Nasira & Turpeenniemi, 2002: p. 2���4, fig. 1 A���I, table 1 (Trissonchulus lichenii) (Pakistan, Karachi, beach, lichens), males and females. Unusual elongate cardia. Diorchic. Original diagnosis is very brief, anterior sensilla (besides amphid), supplementary papillae, caudal gland and spinneret are not mentioned. Tahseen & Mehdi (2009) noted that the species is inadequately described and better fits within the genus Syringolaimus on account of nonoffset lip region, presence of pharyngeal bulb and conical tail with caudal glands and terminal spinneret. However, presence of two testes does not correspond to the genus Syringolaimus., Published as part of Tchesunov, Alexei V., 2017, Free-living nematodes of the genus Syringolaimus de Man, 1888 (Nematoda, Enoplida, Ironidae) from the Angola Basin, South-East Atlantic Abyss, pp. 478-500 in Zootaxa 4306 (4) on page 481, DOI: 10.11646/zootaxa.4306.4.2, http://zenodo.org/record/845097, {"references":["Vitiello, P. (1970) Nematodes libres marins des vases profondes du Golfe du Lion. I. Enoplida. Tethys, 2, 139 - 210.","Bussau, Ch. (1993) Taxonomische und okologische Untersuchungen an Nematoden des Peru-Beckens. Dissertation zur Erlangen des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultat der Christian-Albrechts-Universitat zu Kiel, Kiel, 621 pp.","Nasira, K. & Turpeenniemi, T. A. (2002) Description of Trissonchulus licheniii n. sp. and Halalaimus gidanensis n. sp., with observations on three known species (Nematoda: Enoplida) from northern Arabian Sea. Pakistan Journal of Nematology, 20 (2), 1 - 16.","Tahseen, Q. & Mehdi, S. J. (2009) Taxonomy and relationships of a new and first continental species of Trissonchulus Cobb, 1920 along with two species of Ironus (Nematoda: Ironidae) collected from coal mines. Nematologia Mediterranea, 37, 117 - 132."]}

Syringolaimus annae Lima, Lins, Da Silva & Esteves, 2009 (Figures 2���3) Labels. Male: DIVA 1, M 48/1, st 346/2, Muc 3; female: DIVA 1, M 48/1, st 346/1, Muc 3. Material and conditions. One male, one female and two juveniles. All specimens are slightly compressed and have broken tail tips; the slightly shortened tails reduce tail lengths and body lengths, and raise body indices to a certain extent. Description. Body nearly cylindrical, but tapered to the anterior end. Male: L=1553 �� m, a=31.1, b=6.19, c=6.47, c'=5.71; body diameter at the level of: labial region 15 �� m, nerve ring 33 �� m, cardia 53 �� m, midbody 50 �� m, cloaca 39 �� m. Female: L=1236 �� m, a=35.7, b=5.57, c=8.83, c'=5.83, V=58.7%; body diameter at the level of: labial region 13 �� m, nerve ring 26 �� m, cardia 28 �� m, midbody 35 �� m, anus 24 �� m. Cuticle smooth along the entire body. Metanemes not visible. Head apex truncate. Anterior sensilla (besides amphids) not seen. Amphid as a rather broad transverse slit, amphidial fovea shallow and hardly discernible. In male, width of the amphidial aperture 6 �� m or 33% of the corresponding body diameter, distance from the head apex to the aperture 12 �� m. The same measurements in female are 4 �� m, 22%, 13 �� m, respectively. No somatic sensilla visible along the body. Three double teeth of the anterior stoma everted. Each tooth consists of two slightly unequal claws. Teeth length is 5 �� m in male and 3 �� m in female. Pharyngostom long, cylindroid, its length is 72 �� m in male and 32 �� m in female. In juveniles, replacing teeth are present just below the functioning teeth. Replacing teeth are distinctly double, consisting of two separate claws. Pharyngostom surrounded by narrow cuff with nonevident muscular striation. Pharynx nearly cylindrical up to terminal swelling, with transverse muscular striation and thick internal cuticular lining. There is a rounded terminal swelling with stronger muscular striation at posterior pharynx. Internal lining of the swelling not modified. In male, terminal bulb is 47 �� m long and 44 �� m wide; the same in female���31 �� m and 26 �� m, respectively. Cardia muscular, small, 12 �� m long, its posterior half surrounded by intestinal tissue. Ventral gland not found. In male, a poorly discernible structure resembling ventral pore situated at half distance between pharyngostom base and nerve ring. Tail consists of two distinct portions, anterior conical and posterior slim cylindrical parts; tail tip broken. No evident caudal glands. Since tail tip is broken in both specimens, spinneret can not be described. Females didelphic, amphidelphic; ovaries antidromously reflexed. Anterior ovary ventral and slightly to the right of the intestine, posterior ovary ventral to the intestine. Males monorchic, anterior testis outstretched and situated ventral to the intestine. Spicules half drawn out from the cloacal opening, short, arcuate, broad and weakly cuticularized, 49 �� m long. Gubernaculum as a pair of weakly cuticularized bars perpendicular to the body axis, with curved distal ends, 15 �� m long. There is a midventral precloacal supplementary papillum just anterior to the cloacal opening; there is also one more or less prominent anterior midventral elevation devoid of an internal canal, likely a cuticular fold. A pair of conical lateroventral papillae at the end of conical portion of the tail. Diagnosis. Body length 1236���1553 ��m, a=31���36. Tubular pharyngostom 32���72 ��m long. Terminal pharyngeal bulb 31���47 ��m long and 17���34 ��m wide. Spicules 49 ��m, weakly cuticularized. Precloacal supplementary papillum present. Tail cylindro-conical, with posterior cylindrical portion comprising 72���85% of entire tail; no terminal tube or spinneret. TABLE]. Morphometry of Syringolaimus species, males (valiđ species in bolđ, values rounđeđ). Species Characters Source Bođy a b c c' Distal Buccal Amphiđ wiđth as Distance from Length of Length of length, �� m slenđer tail cavity % of heađ apex to terminal spicules part as % of length, �� m corresponđing amphiđ, �� m pharyngeal along arc, entire tail bođy điameter bulb, �� m �� m length morphometric value calculateđ from đrawings of publisheđ species đescriptions. sex not specifieđ in the source citeđ. Species Characters Source Bođy a b c c' Distal slenđer Buccal Amphiđ wiđth as Distance Length of length, �� m tail part as % cavity % of from heađ terminal of entire tail length, corresponđing apex to pharyngeal length �� m bođy điameter amphiđ, �� m bulb, �� m morp hometric value calculateđ from đrawings of publisheđ species đescriptions. sex not specifieđ in the source citeđ. Discussion. This species fits well with the description of S. annae except for index a in males (31 vs. 41���73, likely because of compression of the body) and greater length of spicules (49 �� m vs. 17���34 �� m, spicules can be inaccurately measured because of their weakness and indistinctness), indices c and c' in females (c 8.8 vs. 4.8���7.4, c' 5.8 vs. 7.3���10.8, because of broken tail tip). Length of the buccal cavity differs notably in male and femalehowever, these values vary considerably in type specimens as well (28���55 �� m in males and 27���57 �� m in females, Lima et al., 2009). According to the original diagnosis of Lima et al. (2009), a spinneret is absent in this species (tail tips of our specimens are broken). Postcloacal lateroventral papillae are not indicated in the original diagnosis (Lima et al., 2009), probably because these small structures are poorly visible and hence could be overlooked., Published as part of Tchesunov, Alexei V., 2017, Free-living nematodes of the genus Syringolaimus de Man, 1888 (Nematoda, Enoplida, Ironidae) from the Angola Basin, South-East Atlantic Abyss, pp. 478-500 in Zootaxa 4306 (4) on pages 483-489, DOI: 10.11646/zootaxa.4306.4.2, http://zenodo.org/record/845097, {"references":["Lima, R. C. C., Lins, L., Da Silva M. R., & Esteves, A. M. (2009) Four new species of Syringolaimus De Man, 1888 (Nematoda: Ironidae) from the Southeast Atlantic (Brazil), with redefinition of valid species and the proposal of a new key. Zootaxa, 2096, 119 - 136."]}

Syringolaimus striatocaudatus de Man, 1888 De Man, 1888: p. 35���36, pl. III, IV, figs 16���16c (North Sea, the Netherlands, Walcheren, male and female). De Coninck, 1932: p. 17���20, figs 7���9 (North Sea, West Flanders, males and females). De Coninck & Schuurmans Stekhoven, 1933: p. 58, fig. 28���29 (Belgian coast, on Enteromorpha, one male and one juvenile). Hopper, 1969: p. 673���674, figs 7���10. Nova Scotia, East Canada, marsh grass). Ventral gland cell present but ventral pore is not always observed. Spinneret and caudal glands are evident. Midventral precloacal papilla is indicated in some descriptions. Hopper (1969) found a small lateral pore (���phasma���) at posterior end of conoid portion of the tail. Body size varies considerably in different descriptions. A complete set of morphometric data is provided only by Hopper (1969). The most obvious distinguishing character is prominent annulation of the tail cuticle while other body cuticle looks smooth. Synonymy: see Gerlach & Riemann, 1973. The most common and widespread species of Syringolaimus., Published as part of Tchesunov, Alexei V., 2017, Free-living nematodes of the genus Syringolaimus de Man, 1888 (Nematoda, Enoplida, Ironidae) from the Angola Basin, South-East Atlantic Abyss, pp. 478-500 in Zootaxa 4306 (4) on page 482, DOI: 10.11646/zootaxa.4306.4.2, http://zenodo.org/record/845097, {"references":["de Man, J. G. (1888) Sur quelques Nematodes libres de la mer du Nord nouveaux ou peu connu. Memoires de la Societe Zoologique de France, 1, 1 - 51.","De Coninck, L. A. (1932) Nieuwe bijdrage tot de kennis der vrijlevende nematoden van Belgie. Bulletin du Musee Royal d'Histoire Naturelle de Belgique, 8, 1 - 30.","De Coninck, L. A. & Schuurmans Stekhoven, J. H. (1933) The free-living marine nemas of the Belgian coast II. Memoires du Musee royal d'Histoire naturelle de Belgique, 58, 1 - 163.","Hopper, B. E. (1969) Marine nematodes of Canada. II. Marine nematodes from the Minas Basin-Scots Bay area of the Bay of Fundy, Nova Scotia. Canadian Journal of Zoology, 47, 671 - 690. https: // doi. org / 10.1139 / z 69 - 114","Gerlach, S. A. & Riemann, F. (1973) The Bremerhaven checklist of aquatic nematodes. A catalogue of Nematoda Adenophorea excluding the Dorylaimida. Part 1. Veroffentlichungen des Instituts fur Meeresforschung in Bremerhaven, 4 (Supplement), Heft 1, 1 - 404."]}

List of Syringolaimus species (valid species in bold) Most Syringolaimus species are small-sized and morphologically similar without many structural characters to distinguish related species. A few species are excluded here from the list of valid species because of the absence of males and/or incomplete diagnoses impeding recognition of specimens from outside of type localities (see also Platonova & Mokievsky, 1994 and Lima et al., 2009). These species are designated as species inquirendae meaning their validity can be restored after a proper redescription of specimens from type locality. A special case is presented by species described by Bussau (1993) in his PhD thesis, which can be treated as having a status of unpublished work. Furthermore, his paper does not indicate a repository institution where type specimens are be kept. On the other hand, many experts evaluate the work of Bussau as careful and very important, and actually treat species of Bussau (1993) as valid, although they were never formally described (e.g. Lima et al., 2009; Miljutin et al., 2010). Here, the Syringolaimus species of Bussau (1993) are qualified as nomina nuda since they do not conform to the Article 13 of ICZN (1999). Though these names are thus unavailable, the species of Bussau are described in details. Hence, their availability can be restored later even for the same names (ICZN, 1999). Since the species gladiatus, ingens and nitidus are fairly recognizable despite their unavailable names, I keep their dimensions here in the tables of species characters and their tail images on Fig. 1., Published as part of Tchesunov, Alexei V., 2017, Free-living nematodes of the genus Syringolaimus de Man, 1888 (Nematoda, Enoplida, Ironidae) from the Angola Basin, South-East Atlantic Abyss, pp. 478-500 in Zootaxa 4306 (4) on page 480, DOI: 10.11646/zootaxa.4306.4.2, http://zenodo.org/record/845097, {"references":["Platonova, T. A. & Mokievsky, V. O. (1994) Revision of the marine nematodes of the family Ironidae (Nematoda: Enoplida). Zoosystematica Rossica, 3 (1), 5 - 17.","Lima, R. C. C., Lins, L., Da Silva M. R., & Esteves, A. M. (2009) Four new species of Syringolaimus De Man, 1888 (Nematoda: Ironidae) from the Southeast Atlantic (Brazil), with redefinition of valid species and the proposal of a new key. Zootaxa, 2096, 119 - 136.","Bussau, Ch. (1993) Taxonomische und okologische Untersuchungen an Nematoden des Peru-Beckens. Dissertation zur Erlangen des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultat der Christian-Albrechts-Universitat zu Kiel, Kiel, 621 pp.","Miljutin, D. M., Gad, G., Miljutina, M. A., Mokievsky, V. O., Fonseca-Genevois, V. & Esteves, A. M. (2010) The state of knowledge on deep-sea nematode taxonomy: how many valid species are known down there? Marine Biodiversity, 40, 143 - 159."]}

Syringolaimus smolae Lima, Lins, Da Silva & Esteves, 2009 (Figures 4���6, Table 3) Material. Ten males and four females from both stations 325 (st. 325/4 Muc 8, 325/7 Muc8) and 346 (st. 346/1 Muc 3, 346/2 Muc 3). Description. Body slim and graceful. Cuticle smooth and moderately thick, fine cross striations visible only on ventral side of cylindrical part of the tail. Anterior cuticle between apex and amphidial fovea forming a circular thickening. There are three equal cheilostomatal teeth just out from the mouth opening. All the teeth are double (split from base) and thus consist of two claw-like parts. The claws of each tooth are slightly unequal; in most specimens, dorsal tooth composed of larger left and smaller right claws, smaller and bigger claws in ventrosublateral pairs more variable in position. Length of teeth is 2.3���3.5 ��m in males and 2.3���3.6 ��m in females. Sensilla around the mouth opening not visible. Amphidial aperture a large transverse slit posterior to the cheilostomal teeth. Amphidial fovea as a pocket with a wisp of ciliary processes within. In males, width of the amphidial aperture is 4.2 ��m or 29���45% of the corresponding body diameter, distance from the cephalic apex to the aperture is 13���18.4 ��m; same figures in a female with discernible aperture are 4.2 ��m, 35% and 16.6 ��m, respectively. There are scarce and hardly visible tiny papillae along the body. Metanemes not visible. Pharyngostom a rather long tube, with sclerotized lumen but flexible. Pharynx slender and muscular throughout its length, with thick internal cuticular lining. Pharyngostom surrounded with narrow, non-muscular tissue. Posterior part of the pharynx enlarged in an oval bulb; its internal cuticular lining not modified but distinctly set off from the lining of the major part of the pharynx. Cardia external, shaped as a truncate cone. Anteriormost intestinal cells with homogeneous content different from other intestinal cells that make them similar to progaster of Monhysteridae. Intestine with internal glycocalyx layer partly detached. Tail consists of anterior conical and posterior cylindrical parts not sharply differentiated from one another. Tail curved dorsally in all male and female specimens. Tail end rounded, no indication of spinneret; however, one or more caudal gland cell bodies discernible in some specimens (Fig. 6 A). Female reproductive system didelphic, amphidelphic; anterior ovary to the left, posterior ovary to the left of the intestine. Males monorchic, outstretched testis situated to the right or to the left and ventral of the intestine. Spermatozoa tadpole-like or drop-shaped, situated with knob-like nuclear part turned towards anterior end and tail-like part towards posterior end of the body, 13���16 ��m long, transparent, with dense nucleus in the thick end. Vas deferens with granular walls, its anterior part narrowed, posterior part enlarged. Spicules weak and arcuate, broad, with truncate anterior end and knobbed posterior end. Gubernaculum small (8���12 ��m), in a shape of a slightly curved bar. A small midventral supplementary organ is visible as a small mound with an internal canal situated just anterior (3.4���9.2 ��m) to the cloacal opening. In some males, structures similar to sublateral precloacal and a postcloacal papillae are visible. Diagnosis. Body length 900���1190 ��m, a=30���62. Tubular pharyngostom 39���60 ��m long. Terminal pharyngeal bulb 28���40 ��m long and 16���31 ��m wide. Spicules 17���30 ��m, weak and flexible. Precloacal supplementary papillum present. Tail cylindro-conical, with posterior cylindrical portion (47���80% of entire tail) always curved dorsally in both sexes; no terminal tube or spinneret. Discussion. The species fits well the description of S. smolae Lima et al., 2009 in dimensions and shape of the tail but differs by: absence of visible secretory-excretory pore at the level of the nerve ring, absence of a terminal spinneret on the tail tip, rather broad and weak spicules versus ���setiform��� spicules mentioned for S. smolae. Character Males (n=10) Females (n=4) Despite verbal statements about presence of the spinneret and setiform spicules in the text of the original diagnosis, the figures correspond well to respective organs of our specimens. Gut content. Intestine may be empty or contain a sausage of medium-coarse-granular material with sparse light-refractive particles as well as spherical homogeneous and slightly heterogeneous drops., Published as part of Tchesunov, Alexei V., 2017, Free-living nematodes of the genus Syringolaimus de Man, 1888 (Nematoda, Enoplida, Ironidae) from the Angola Basin, South-East Atlantic Abyss, pp. 478-500 in Zootaxa 4306 (4) on pages 489-494, DOI: 10.11646/zootaxa.4306.4.2, http://zenodo.org/record/845097, {"references":["Lima, R. C. C., Lins, L., Da Silva M. R., & Esteves, A. M. (2009) Four new species of Syringolaimus De Man, 1888 (Nematoda: Ironidae) from the Southeast Atlantic (Brazil), with redefinition of valid species and the proposal of a new key. Zootaxa, 2096, 119 - 136."]}

Syringolaimus elegans sp. n. (Figures 7���9) Material: DIVA 1, M 48/1, st 325/4, Muc 8. Holotype male and paratype juvenile with vestigial ovaries. The slides are deposited in Senckenberg Museum (Frankfurt am Main, Germany) under the inventory numbers SMF 17055 (holotype) and SMF 17056 (paratype). Male. Body slender, filiform. Body length 2718 �� m, a=98.8, b=8.47, c=11.8, c���=8.41. Body diameter at the level of: anterior sensilla 17 �� m, nerve ring 34.5 �� m, cardia 35.8 �� m, midbody 27.5 �� m, cloaca 24.1 �� m. Cuticle smooth along the entire body except numerous irregular transversal fissures or chaps like in cervical region. No metanemes found. Anterior sensilla hardly discernible as six papillae or pores. Amphidial aperture a transverse slit; fovea poorly visible. Width of the amphidial aperture 5.9 �� m or 31% of the corresponding body diameter, distance from anterior apex to aperture 11.5 �� m. No somatic sensilla along the body. Apical cuticle around the mouth opening widened and its internal sublayer sclerotized. There are three equal doubled cheilostomatal teeth about 4.6 �� m long. The teeth joined movably to the sclerotization of the internal layer of the apical cuticle. Each tooth consists of two parts (subteeth) fused basally; both parts isomorphic claw-like, one part somewhat bigger than another. Dorsal tooth consists of left bigger and right smaller parts. Pharyngostom 79 �� m long and 3.4 �� m wide, tubular, with sclerotized walls, but flexible. Pharyngostom enveloped by a cuff (manchette) with obliquely directed muscular striation. Pharynx evenly muscular throughout its length, with distinct thick internal cuticular lining. Posterior part of the pharynx slightly enlarged into an elongate ovoid bulb 70 �� m long and 32 �� m wide; however, its internal cuticular lining not modified. Cardia conical, with radial striation. Intestine with glycocalyx layer detached. Nerve ring distinct, at the middle of the pharynx. No clear indication of a ventral gland; however, a ventral pore and a thin intracuticular canal present at a distance of 36 �� m anterior to the nerve ring. Male monorchic, male genital branch 1156 �� m long, situated to the right of the intestine. Spermatozoa (or spermatids?) fiber-like. Vas deferens consists of anterior slender and posterior thicker portions. Spicules slender, arcuate, 32 �� m long, weakly sclerotized, their anterior (proximal) knobs not pronounced (underdeveloped?). Gubernaculum vestigial, hardly visible. There is one midventral precloacal supplementary papillum with a thin internal canal located at a distance of 8 �� m anterior to the cloacal opening; two other supplements situated a bit closer to the cloaca, are questionable and may actually represent cuticular folds. No other sensilla in pericloacal region. Tail long, its proximal conical part gradually transforms to thin whip-like part constituting about 67% of the total tail length. No indication of spinneret and caudal glands. IV juvenile stage (slightly compressed). Body length 2786 �� m, a=68.0, b=8.55, c=11.9, c'=8.1. Body diameter at the level of: anterior sensilla 12 �� m, nerve ring 38 �� m, cardia 51 �� m, midbody 48 �� m, cloaca 30 �� m. Width of the amphidial aperture 3.5 �� m or 24% of the corresponding body diameter, distance from anterior apex to aperture 9.3 �� m. Buccal cavity 61 �� m long. Replacing teeth present just posterior to the functional teeth. Terminal bulb 60 �� m. Vestigial female branches present but no vagina could be found. Posterior cylindrical portion of the tail 69% of the total tail length. Diagnosis. Body length of male 2718 �� m, a=98.8, b=8.5, c=11.8, c'=8.4. Distance from head apex to the amphidial aperture 11.5 �� m. Buccal cavity 79 �� m. Basal pharyngeal bulb 70 �� m long and 32 �� m wide. No ventral gland. Monorchic with single anterior outstretched testis. Spicules arcuate, very weak, 32 �� m. A single evident midventral precloacal supplementary organ as a papillum with an axial canal. Tail with cylindrical posterior portion constituting 67% of the entire tail. No evident spinneret and caudal glands. Differential diagnosis. Syringolaimus elegans sp. n. differs from all other species of Syringolaimus by slimmer body (a 99 vs. 30���73) and from all species except S. ingens by its greater body length (2718 �� m vs. 760��� 1750 �� m), longer buccal cavity (79 �� m vs. 28���58 �� m), and longer terminal pharyngeal bulb (70 �� m vs. 29���53 �� m). S. elegans sp. n. differs from S. ingens nom. nud., the largest species within the genus, by smaller and slimmer body (L=2718 �� m versus 3735 �� m, a=99 vs. 43), relatively longer tail (c'=8.4 vs. 4.0), smaller spicules (32 �� m vs. 70 �� m) and by presence of a precloacal supplementary papillum (not mentioned for S. ingens)., Published as part of Tchesunov, Alexei V., 2017, Free-living nematodes of the genus Syringolaimus de Man, 1888 (Nematoda, Enoplida, Ironidae) from the Angola Basin, South-East Atlantic Abyss, pp. 478-500 in Zootaxa 4306 (4) on page 494, DOI: 10.11646/zootaxa.4306.4.2, http://zenodo.org/record/845097

Identification of Syringolaimus species Species of Syringolaimus are pretty similar, but differ from one another in morphometrics and especially in relative length and shape of the tail. Other characters such as length of the buccal cavity and position of the amphidial aperture are also important for species discrimination and hence they are included in tables 1 and 2. Position of the ventral pore and presence/absence of preanal supplementary papilla, caudal glands and spinneret should also have significance for species identification but unfortunately they are very unevenly characterized in all species and hence it is impossible to present these traits for every species as icons in a pictorial key. Lima et al. (2009) provided a dichotomous key for fourteen Syringolaimus species designated by them as valid. Since some changes in the list of valid species are made and one new species is here described, I complement the key with morphometric characteristics (tables 1 and 2) and schematic icons of the tails (Fig. 1).

Syringolaimus renaudae Gourbault & Vincx, 1985. Gourbault & Vincx, 1985: p. 109–114, fig. 1–2 (SW Atlantic, Cape Basin, 3694–4180 m, deep-sea ooze), males and females. Cuticle finely annulated close to both extremities. Anterior end demarcated by a distinct collar. Amphidial fovea 40% of the corresponding body width in male. Ventral pore at the level of posterior end of the buccal cavity. Monorchic. No supplementary organs mentioned. Spinneret and caudal glands present. Syringolaimus smarigdus Cobb, 1928 sp. inq. Cobb, 1928: p. 249–253, fig. 1 (USA east coast, Massachusetts, from shells of gastropod molluscs Alectrion obsoleta feeding on algae Ralfsia). De Coninck & Schuurmans Stekhoven, 1933: p. 58 (junior synonym of S. striaticaudatus). Chitwood, 1951: p. 646, fig. 9 I –K (Texas, from Sargassum algae). Description and brief redescriptions of this species are poorly detailed. Since neither measured values nor structural features contradict characteristics of S. striatocaudatus, I follow the opinion of De Coninck & Schuurmans Stekhoven (1933) and adopt synonymy of the species.

Syringolaimus loofi Gourbault & Vincx, 1985 Gourbault & Vincx, 1985: p. 114���17, fig. 3 (coast of the Netherlands, in sponge Halichondria), males and females. Cuticle finely striated. Ventral pore at the posterior end of buccal cavity. Tail elongate, conical. Caudal glands present, spinneret short, conical. Monorchic. Preanal midventral papilla distinct., Published as part of Tchesunov, Alexei V., 2017, Free-living nematodes of the genus Syringolaimus de Man, 1888 (Nematoda, Enoplida, Ironidae) from the Angola Basin, South-East Atlantic Abyss, pp. 478-500 in Zootaxa 4306 (4) on page 481, DOI: 10.11646/zootaxa.4306.4.2, http://zenodo.org/record/845097, {"references":["Gourbault, N. & Vincx, M. (1985) Deux especes nouvelles d'Ironidae marins; observations sur les spermatozoides \" flagelles \" des Nematodes. Bulletin du Museum national d'Histoire naturelle, Paris, 4 e Serie, 7, Section A, n o 1, 109 - 118."]}

Syringolaimus de Man, 1888 Diagnosis (after Lorenzen, 1981, 1994; Platonova & Mokievsky, 1994; Lima et al., 2009; Smol et al., 2014, emended). Ironidae, Thalassironinae. Cuticle smooth or with transverse striations most obviously visible on the tail and elsewhere. Anterior sensilla papilliform or hardly visible. Amphidial fovea pocket-like, amphidial aperture a transverse slit. Metanemes evident or not. Buccal cavity anteriorly with three solid teeth each split deeply into two. Pharynx with distinct oval to rounded posterior bulb with thickened internal cuticle. Ventral gland and ventral pore present or not mentioned. Males monorchic. Spicules short, weak or strongly sclerotized, often with vela. Midventral precloacal papilla usually present. Females didelphic, amphidelphic, ovaries antidromously reflected. Tail conico-cylindrical, often, but not always, with long terminal tube. Caudal glands and spinneret present or not evident. Type species: Syringolaimus striatocaudatus De Man, 1888.

List of Syringolaimus species (valid species in bold) Most Syringolaimus species are small-sized and morphologically similar without many structural characters to distinguish related species. A few species are excluded here from the list of valid species because of the absence of males and/or incomplete diagnoses impeding recognition of specimens from outside of type localities (see also Platonova & Mokievsky, 1994 and Lima et al., 2009). These species are designated as species inquirendae meaning their validity can be restored after a proper redescription of specimens from type locality. A special case is presented by species described by Bussau (1993) in his PhD thesis, which can be treated as having a status of unpublished work. Furthermore, his paper does not indicate a repository institution where type specimens are be kept. On the other hand, many experts evaluate the work of Bussau as careful and very important, and actually treat species of Bussau (1993) as valid, although they were never formally described (e.g. Lima et al., 2009; Miljutin et al., 2010). Here, the Syringolaimus species of Bussau (1993) are qualified as nomina nuda since they do not conform to the Article 13 of ICZN (1999). Though these names are thus unavailable, the species of Bussau are described in details. Hence, their availability can be restored later even for the same names (ICZN, 1999). Since the species gladiatus, ingens and nitidus are fairly recognizable despite their unavailable names, I keep their dimensions here in the tables of species characters and their tail images on Fig. 1.

Syringolaimus is the most abundant and diverse genus of the family Ironidae (Nematoda) found in the Campos Basin, off Rio de Janeiro, Brazil. In this article, four new species of this genus are described. S. annae sp. n. is characterized by a conical-cylindrical tail without a spinneret. S. magdae sp. n. possesses a pair of ejaculatory glands located in the precloacal region, and a spinneret, which comprises 21.2% of the total tail length. In S. smolae sp. n. the spicule is setiform. S. taniae sp. n. has the anterior region of the tail rounded, with its terminal portion cylindrical-filiform.

Three nematode species of the genus Syringolaimus (Enoplida, Ironidae) were found in the Angola Basin (south-east Atlantic Ocean) at depths of almost 5500 m. One of them is described as new for science and the other two were initially recorded from the deep sea off the Brazilian coast and are redescribed here. Syringolaimus elegans sp. n. differs from all other species of Syringolaimus by a slimmer body (a=99 vs. 30–73) and from all species except S. ingens (nom. nud.) by its greater body length (2718 μ m vs. 760–1750 μ m), longer buccal cavity (79 μ m vs. 28–58 μ m), and longer terminal pharyngeal bulb (70 μ m vs. 53 μ m). All the Syringolaimus species together make up from 0.75 to 2.82% of all nematode individuals from all samples. Diagnoses of Syringolaimus annae Lima et al ., 2009 and S. smolae Lima et al ., 2009 are updated. An annotated list of Syringolaimus species is provided; the species annae , elegans , filicaudatus , loofi , magdae , renaudae , smolae , striatocaudatus and taniae are considered as valid, while brevicaudatus , caspersi , lichenii , marisalbi , smarigdus and venustus as species inquirendae, and gladiatus , ingens, nitidus and venustus as nomina nuda . Diagnostic characters and problems of species identification are discussed.

The highest numbers of nematodes with a percentage ranging from 76.4% in Cung Hau to 77% in Ham Luong estuaries. There were 92 genera (71 genera in Ham Luong and 62 genera in Cung Hau) of nematodes recorded in both estuaries. The mean nematode densities varied between 90 ± 31 - 1524 ± 269 ind.10 cm² and 105 ± 79 - 1120 ± 534 ind.10 cm² in Ham Luong and Cung Hau estuary, respectively. The nematode communities were mainly composed of Dichromadora, Daptonema, Oncholaimellus, Syringolaimus, Tripyloides, Parodontophora, Theristus and Halalaimus belonging to several dominant families, such as, Oncholaimidae, Xyalidae, Chromadoridae, Oxystominidae, Axonolaimidae and Sphaerolaimidae. In both estuaries, nematode density decreased from inland towards the mouth before they increased again at the mouth stations.

Key to species of Syringolaimus 1 Tail end filiform............................................................................................................................................................ 2 - Tail end not filiform.................................................................................................................................................... 10 2 Spicules narrow....................................................................................................................................... S. filicaudatus - Spicules wide................................................................................................................................................................ 3 3 Tail with setae.................................................................................................................................................. S. ingens - Tail without setae.......................................................................................................................................................... 4 4 Odontia divided............................................................................................................................................................. 5 - Odontia entire................................................................................................................................... S. striatocaudatus 5 Labial sensilla absent.................................................................................................................................. S. marisalbi - Labial sensilla present................................................................................................................................................... 6 6 Cephalic sensilla absent......................................................................................................................... S. taniae sp. n. - Cephalic sensilla present............................................................................................................................................... 7 7 Cephalic sensilla setaceous........................................................................................................................ S. renaudae - Cephalic sensilla papilla shaped................................................................................................................................... 8 8 Cuticule striations difficult to resolve..................................................................................................... S. annae sp. n. - Cuticule striations well defined along the body............................................................................................................ 9 9 Tail long “c” S. gladiatus - Tail short “c”> 6, with spinneret.................................................................................................................... S. nitidus 10 Labial sensilla absent................................................................................................................................ S. smarigdus - Labial sensilla present................................................................................................................................................. 11 11 Cephalic sensilla absent....................................................................................................................... S. magdae sp. n. - Cephalic sensilla present............................................................................................................................................. 12 12 Tail conical.......................................................................................................................................................... S. loofi - Tail conical-cylindrical............................................................................................................................................... 13 13 Tail without setae.................................................................................................................................. S. smolae sp. n. - Tail with setae.............................................................................................................................................. S. venustus, Published as part of Lima, Rita De Cássia Coelho, Lins, Lidia, Silva, Maria Cristina Da & Esteves, André Morgado, 2009, Four new species of Syringolaimus De Man, 1888 (Nematoda: Ironidae) from the Southeast Atlantic (Brazil), with redefinition of valid species and the proposal of a new key *, pp. 119-136 in Zootaxa 2096 on pages 134-135

Syringolaimus smolae sp. n. (Figs. 5 and 6) Type material: One male and one female collected from Stations 74 and 85 (Appendix). Holotype ♂ 1: slide number MNRJ 333 station 74; allotype ♀ 1 slide number MNRJ 334 station 85. Type locality: Campos Basin (Rio de Janeiro, Brazil). Holotype ♂ 1 found at 750 m depth in silt-clay sediments, layer between 0–2 centimeters. Allotype ♀ 1: found at 1350 m depth in silt-clay sediments, vertical profile: between 2–5 centimeters. Etymology. The specific epithet honors Nicole Smol, Coordinator of the Nematology course at Ghent University, Belgium. Description. Measurements: Holotype ♂ 1: L: 1036.5; hd: 7.8; amph wid: 3.6; cbd: 13.2; amph (%): 27.3; amph dist: 7.2; buc cav l: 37.2; ph: 175.5; buc cav 1/ph (%): 21.2; nr/ph (%): 51.3; ex pore/ph (%): 51.3; bulb l: 35.4; bulb l/ph (%): 20.2; bulb d: 18.6; cbd: 24; bulb(%): 77.5; mbd: 22.8; abd: 21; t: 112.2; con/t (%): 44.9; cil/t%: 55.1; spin: 6; spin/t (%): 5.3; spic: 28.2; gub: 13.8; a: 45.4; b: 5.9; c: 9.9; c’: 5.3. Allotype ♀ 1: L: 992; hd: 9.0; amph wid: 3.6; cbd: 10.8; amph %: 33.3; amph dist: 7.8; buc cav l: 33; ph: 158.4; buc cav 1/ph (%): 20.8; nr/ph (%): not visible; ex pore/ph (%): 41.7; bulb l: 30.6; bulb l/ph/ (%): 19.6; bulb d: 13.2; cbd: 17.1; bulb (%): 77.2; mbd: 17.4; abd: 13.8; t: 115.8; con/t (%): 42; cil/t (%): 58; spin: 6.0; spin/t (%): 5.1; a: 57; b: 6.3; c: 8.6; c’: 8.4. Male Holotype: Body 1036.5 µm long, maximum body diameter 22.8 µm. Cuticle faintly striated. Six outer labial papillae and four cephalic papillae. Amphideal phovea occupying 27.3% of corresponding body diameter. Head diameter 7.8 µm. Cylindrical, sclerotized, buccal cavity, weakly involved by pharynx muscles, 37.2 µm long, 21.2% of pharynx length. Three bifid teeth of equal size, one dorsal and two subventral. Delicate pharynx with an oval basal bulb, 35.4 µm long and 18.6 µm wide, corresponding to 77.5% of body diameter and 20.2% of total pharynx length. Secretory-excretory pore and nerve ring at same level, situated 51.3% from anterior end. Rounded cardia. Single testis lying on right side of intestine, with glandular part splitting duct into regions of cells of varying degrees of maturity. Short deferent duct with sperm cells in beginning of duct. One precloacal papilla present. Spicule setiform, vellum present. Gubernaculum triangular. Conical-cylindrical tail with spinneret (6 µm), corresponding to 5.3% of tail length. Cylindrical region corresponding to 55.1% of tail length. Three caudal glands present. Female Allotype: Body slender, amphidelphic-didelphic, with reflexed ovaries located ventrally to intestine. Vulva situated at 57% of total body length, with two glands on each side of vulva. Diagnosis. Syringolaimus smolae sp. n. is characterized by the setiform spicule, the triangular gubernaculum, the position of the secretory-excretory pore at the same level of the nerve ring, and the presence of two glands located posterior and anterior to the vulva. Relationships. S. smolae sp. n. resembles S. loofi Gourbault & Vincx, 1985; both species share the presence of inner labial papillae, bifid teeth, and precloacal papillae; the equal value of De Man ratios b and c; and the proportion of the small spinneret in relation to the total tail length. However, the secretory-excretory pore in S. smolae sp. n. is situated in the middle region of the pharynx, whereas in S. loofi the pore is situated at the base of the buccal cavity. Other differences observed are the spicule, gubernaculum, and the tail shapes (conical in S. loofi and conical-cylindrical in S. smolae sp. n.). The female of the new species possesses two glands, one on each side of the vulva. The presence of a glandular portion in the testis is not observed in S. loofi., Published as part of Lima, Rita De Cássia Coelho, Lins, Lidia, Silva, Maria Cristina Da & Esteves, André Morgado, 2009, Four new species of Syringolaimus De Man, 1888 (Nematoda: Ironidae) from the Southeast Atlantic (Brazil), with redefinition of valid species and the proposal of a new key *, pp. 119-136 in Zootaxa 2096 on pages 128-130, {"references":["Gourbault, N., & Vincx, M. (1985) Deux especes nouvelles d'Ironidae marins; observations sur les spermatozoides flagelles des Nematodes. Bulletin Musee National Histoire Natural, section A, 1, 109 - 118."]}

Syringolaimus smolae sp. n. (Figs. 5 and 6) Type material: One male and one female collected from Stations 74 and 85 (Appendix). Holotype ♂ 1: slide number MNRJ 333 station 74; allotype ♀ 1 slide number MNRJ 334 station 85. Type locality: Campos Basin (Rio de Janeiro, Brazil). Holotype ♂ 1 found at 750 m depth in silt-clay sediments, layer between 0–2 centimeters. Allotype ♀ 1: found at 1350 m depth in silt-clay sediments, vertical profile: between 2–5 centimeters. Etymology. The specific epithet honors Nicole Smol, Coordinator of the Nematology course at Ghent University, Belgium. Description. Measurements: Holotype ♂ 1: L: 1036.5; hd: 7.8; amph wid: 3.6; cbd: 13.2; amph (%): 27.3; amph dist: 7.2; buc cav l: 37.2; ph: 175.5; buc cav 1/ph (%): 21.2; nr/ph (%): 51.3; ex pore/ph (%): 51.3; bulb l: 35.4; bulb l/ph (%): 20.2; bulb d: 18.6; cbd: 24; bulb(%): 77.5; mbd: 22.8; abd: 21; t: 112.2; con/t (%): 44.9; cil/t%: 55.1; spin: 6; spin/t (%): 5.3; spic: 28.2; gub: 13.8; a: 45.4; b: 5.9; c: 9.9; c’: 5.3. Allotype ♀ 1: L: 992; hd: 9.0; amph wid: 3.6; cbd: 10.8; amph %: 33.3; amph dist: 7.8; buc cav l: 33; ph: 158.4; buc cav 1/ph (%): 20.8; nr/ph (%): not visible; ex pore/ph (%): 41.7; bulb l: 30.6; bulb l/ph/ (%): 19.6; bulb d: 13.2; cbd: 17.1; bulb (%): 77.2; mbd: 17.4; abd: 13.8; t: 115.8; con/t (%): 42; cil/t (%): 58; spin: 6.0; spin/t (%): 5.1; a: 57; b: 6.3; c: 8.6; c’: 8.4. Male Holotype: Body 1036.5 µm long, maximum body diameter 22.8 µm. Cuticle faintly striated. Six outer labial papillae and four cephalic papillae. Amphideal phovea occupying 27.3% of corresponding body diameter. Head diameter 7.8 µm. Cylindrical, sclerotized, buccal cavity, weakly involved by pharynx muscles, 37.2 µm long, 21.2% of pharynx length. Three bifid teeth of equal size, one dorsal and two subventral. Delicate pharynx with an oval basal bulb, 35.4 µm long and 18.6 µm wide, corresponding to 77.5% of body diameter and 20.2% of total pharynx length. Secretory-excretory pore and nerve ring at same level, situated 51.3% from anterior end. Rounded cardia. Single testis lying on right side of intestine, with glandular part splitting duct into regions of cells of varying degrees of maturity. Short deferent duct with sperm cells in beginning of duct. One precloacal papilla present. Spicule setiform, vellum present. Gubernaculum triangular. Conical-cylindrical tail with spinneret (6 µm), corresponding to 5.3% of tail length. Cylindrical region corresponding to 55.1% of tail length. Three caudal glands present. Female Allotype: Body slender, amphidelphic-didelphic, with reflexed ovaries located ventrally to intestine. Vulva situated at 57% of total body length, with two glands on each side of vulva. Diagnosis. Syringolaimus smolae sp. n. is characterized by the setiform spicule, the triangular gubernaculum, the position of the secretory-excretory pore at the same level of the nerve ring, and the presence of two glands located posterior and anterior to the vulva. Relationships. S. smolae sp. n. resembles S. loofi Gourbault & Vincx, 1985; both species share the presence of inner labial papillae, bifid teeth, and precloacal papillae; the equal value of De Man ratios b and c; and the proportion of the small spinneret in relation to the total tail length. However, the secretory-excretory pore in S. smolae sp. n. is situated in the middle region of the pharynx, whereas in S. loofi the pore is situated at the base of the buccal cavity. Other differences observed are the spicule, gubernaculum, and the tail shapes (conical in S. loofi and conical-cylindrical in S. smolae sp. n.). The female of the new species possesses two glands, one on each side of the vulva. The presence of a glandular portion in the testis is not observed in S. loofi.

Key to species of Syringolaimus 1 Tail end filiform............................................................................................................................................................ 2 - Tail end not filiform.................................................................................................................................................... 10 2 Spicules narrow....................................................................................................................................... S. filicaudatus - Spicules wide................................................................................................................................................................ 3 3 Tail with setae.................................................................................................................................................. S. ingens - Tail without setae.......................................................................................................................................................... 4 4 Odontia divided............................................................................................................................................................. 5 - Odontia entire................................................................................................................................... S. striatocaudatus 5 Labial sensilla absent.................................................................................................................................. S. marisalbi - Labial sensilla present................................................................................................................................................... 6 6 Cephalic sensilla absent......................................................................................................................... S. taniae sp. n. - Cephalic sensilla present............................................................................................................................................... 7 7 Cephalic sensilla setaceous........................................................................................................................ S. renaudae - Cephalic sensilla papilla shaped................................................................................................................................... 8 8 Cuticule striations difficult to resolve..................................................................................................... S. annae sp. n. - Cuticule striations well defined along the body............................................................................................................ 9 9 Tail long “c” S. gladiatus - Tail short “c”> 6, with spinneret.................................................................................................................... S. nitidus 10 Labial sensilla absent................................................................................................................................ S. smarigdus - Labial sensilla present................................................................................................................................................. 11 11 Cephalic sensilla absent....................................................................................................................... S. magdae sp. n. - Cephalic sensilla present............................................................................................................................................. 12 12 Tail conical.......................................................................................................................................................... S. loofi - Tail conical-cylindrical............................................................................................................................................... 13 13 Tail without setae.................................................................................................................................. S. smolae sp. n. - Tail with setae.............................................................................................................................................. S. venustus