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Summary Members of the family Leptolaimidae are reported for the first time from Iran with description of two new species of Leptolaimus from the Persian Gulf in the south of the country. Leptolaimus hormozganensis sp. n. is described based upon three populations. It differs from other Leptolaimus species in the position of the pharyngeal supplement and the number of precloacal tubular supplements and has a single sickle-shaped tubular pharyngeal supplement at mid-pharynx level in both sexes, 9-12 male precloacal supplements and one female preanal supplement. Leptolaimus dimorphus sp. n. is characterised by the presence of a pharyngeal tubular supplement only in some adults, one female preanal supplement and four male precloacal supplements. It differs from other species in that the pharyngeal supplement is only present in some specimens, presence of four male precloacal supplements, tail 50-59 μm long and ventrosublateral position of vulva on either the right or left side of the body. Near full length SSU rDNA sequences are provided for L. hormozganensis sp. n. and two different males (one with, and one without, a pharyngeal supplement) of L. dimorphus sp. n. COI sequences for three populations of L. hormozganensis sp. n. from different regions of the Persian Gulf are also obtained. New sequences of two Leptolaimus species formed a clade with other sequenced Leptolaimus spp. and representatives of two genera of Leptolaimidae, i.e., Aphanolaimus and Paraplectonema in a phylogeny based on SSU rDNA gene with 1.00/81 Bayesian posterior probability/maximum likelihood bootstrap (BPP/BS) values. Molecular phylogeny confirmed the synonymy of Leptolaimus and Halaphanolaimus that was formerly proposed based only on morphology. Based on SSU sequences and morphological characters, the presence of a pharyngeal supplement may not be a species-specific character and should not be used to differentiate genera.

Two new free-living marine nematode species of the genus Antomicron Cobb, 1920 belonging to the family Leptolaimidae are described from the seabed sediment of Jiaozhou Bay of the Yellow Sea. Antomi...

Genus Leptolaimus de Man 1876 Diagnosis (Holovachov 2014) Cuticle annulated. Lateral alae present. Cephalic sensilla papilliform or setiform. Amphideal fovea ventrally unispiral (circular in outline). Buccal cavity elongate and tubular. Male reproductive system diorchic, usually having both tubular and alveolar precloacal supplements. The number of supplements varies from zero to 40 for alveolar and zero to 11 for tubular. Female has two opposed and reflexed ovaries, may also have tubular supplements in some species.

Leptolaimus boucheri sp. nov. (Figures 1���3 and Table 1) Type material Three males and four females were collected from the Bohai Sea, China. Holotype male on slide DST151-98. Paratypes on slides DST2-7, DST151-99, DST151-86, DST151-81, DST151- 92 and DST151-87. Type locality and habitat All specimens were found in muddy sediments of the 0���2 cm and 2���5 cm layers, intertidal zone of Tianjin Bay along the Bohai Sea, China (39.209��N, 117.955��E). Etymology The species is named in honour of Dr Guy Boucher, in recognition of his contributions to nematode taxonomy. Measurements All measurement data are given in Table 1. Description Males. Body slender, 545���602 ��m long, tapering towards anterior and posterior ends, greatest body diameter at middle of body. Cuticle distinctly annulated along the body; annuli 2���3 ��m wide, without ornamentation. Lateral alae present, 2 ��m wide at mid-body, originating in the middle of the pharynx and extending along the body to almost half of tail length. Numerous body pores present in sublateral position at both sides of lateral field. Anteriormost body pore located at lateral field and level of buccal cavity base, about 30 ��m from the cephalic apex. Somatic setae not observed. Labial region truncate, slightly offset from body contour. Inner labial sensilla and outer labial sensilla not visible. Cephalic sensilla papilliform. Amphideal fovea circular, 62.5% of corresponding body diameter, situated 9���10 ��m from the cephalic apex. Buccal cavity long, cylindrical, 35���38 ��m deep, 40���44% of pharyngeal length. Pharynx slender, posterior region swollen and forming oval basal bulb. Cardia cylindrical, with posterior part embedded in intestine. Nerve ring surrounding pharynx at 66 ��m from the anterior end. Secretory-excretory system indistinct. Tail conico-cylindrical, 3.8���4.5 cloacal body diameter in length, anterior conical portions gradually transforming to posterior slender cylindrical portions, posteriorly swollen. Caudal glands indistinct. Spinneret present. Caudal setae sparse, and usually six to eight caudal setae distributing subventral and subdorsal sides of tail. Reproductive system with two opposed testes. Anterior testis outstretched, posterior one reflexed. Spicules slender, slightly arcuate, proximally cephalated and distally pointed. Gubernaculum plate-like, curved to spicules, without apophyses. Accessory apparatus composed of a papilla, four evenly spaced tubular supplements and 15���21 successive alveolar supplements. A papillary supplement just anterior to the cloaca. Tubular precloacal supplements almost straight, with tapered tip, 11 ��m long. Winged alveolar supplements with cuticularised wall. The most anterior alveolar supplement located at level of posterior portion of pharynx, 102���112 ��m from the anterior end. The posteriormost one situated about 20 ��m anterior to the anteriormost tubular supplement, 371���417 ��m from the anterior end. Four evenly spaced tubular supplements extending for 82���87 ��m from cloaca forward. The posteriormost tubular supplements 23���25 ��m in front of cloaca. Females. Similar to males in most aspects except body slightly thicker (24���27 ��m vs 18���19 ��m), amphideal fovea slightly smaller (3 ��m vs 5 ��m wide in males) and having a single ventral pre-anal supplements. Supplement tubular, 6���8 ��m long, situated 36��� 50 ��m anterior to anus. Reproductive system didelphic, with two opposed, reflexed ovaries, located to the left side of intestine. Mature eggs large, oval-shaped. Spermathecae not observed. Vagina straight, 0.25 times vulval body diameter long. Vulva midventral, slightly raised, located at mid-body length, 51���53% of total body length from the anterior end., Published as part of Geng, C. X., Hao, Y. D. & Huang, Y., 2022, Description of Leptolaimus boucheri sp. nov. (Nematoda: Leptolaimidae) from the Bohai Sea, China, pp. 2951-2960 in Journal of Natural History 55 (47 - 48) on pages 2953-2954, DOI: 10.1080/00222933.2022.2033868, http://zenodo.org/record/6351778

Antomicron holovachovi sp. nov. (Figures 1–3 and Table 1) Type material One male and two females were obtained. Holotype: male, on slide number JZW(17–8). Paratypes: ♀ 1 and ♀ 2, on slides numbered JZW(17–7) and JZW(47–31), respectively. (The holotype specimen is deposited in the Marine Biological Museum of Chinese Academy of Sciences, Qingdao, and the paratype specimens are deposited in the biodiversity laboratory of Liaocheng University.) Type locality and habitat Specimens were collected from the surface 0–2 cm sublittoral silt sediment in Jiaozhou Bay (JZW-17: 36.119°N, 120.217°E). Water depth of 11 m. Etymology The species is named in honour of Dr Oleksandr Holovachov, Swedish Museum of Natural History, for his contributions to nematode taxonomy. Measurements All measurement data are given in Table 1. Description Male. Body cylindrical, tapering anteriorly in cervical region and posteriorly on tail. Cuticle with widely spaced transverse striation, 2.2 µm apart, without ornamentation. Lateral field present, consists of single ala (two incisures), 2 µm wide at mid-body; originating at base of amphideal fovea and extending posteriorly to anterior part of tail. Some body pores situated at both sides of lateral field in pharyngeal region. Labial region bluntly rounded, continuous with body contour, lips fused. Cephalic capsule obvious. Anteriormost body annule, which demarcates labial region, located at level of middle of amphid. Inner and outer labial sensilla indistinct. Cephalic sensilla setiform, 1.5 µm long. Amphidial fovea elongate, loop-shaped, 11 µm long and 4.5 µm wide (2.4 times as long as it is wide), 8 µm from the anterior end. Nerve ring surrounding pharynx at level of anterior to excretory pore. Secretory-excretory system present; ventral gland cell large, located anterior part of intestine (230 µm from the anterior end), extends anteriorly along ventral side of pharynx and forms an excretory ampulla just anterior to pharyngeal bulb, and opens to the exterior via a pore just posterior to nerve ring. Buccal cavity uniformly tubular. Pharynx cylindrical anteriorly, with distinct oval basal bulb with strong cuticular internal lining. Cardia cylindrical, its posterior part embedded in intestine. Tail conicocylindrical, gradually narrowing to posterior cylindrical part. Unstriated tail tip swollen. Caudal setae scattered. Three caudal glands present. Spinneret distinct. Reproductive system diorchic; anterior testis outstretched; posterior one reflexed. Spicules slender, slightly ventral curved, with cephalated proximal end and tapered distal end. Gubernaculum rectangular, with a dorsal caudal apophysis, 5 µm long. Accessory apparatus composed of five 11–11.5 µm midventral straight tubular supplements extending for 122 µm from cloaca towards anterior end, and 41 evenly spaced alveolar supplements extending anteriorly. Anteriormost alveolar supplement located at level of cardia, 124 µm from anterior end,posteriormost alveolar supplement 21 µm from the anteriormost tubular supplement (i.e. 143 µm anterior to cloaca). Posteriormost tubular supplement 18 µm anterior to cloaca, anterior to spicules. One pair of subventral precloacal setae and one pair of postcloacal setae present, 2–3 µm long. Female. Similar to male in most respects except slightly shorter body length. Reproductive system didelphic, with two opposed and reflexed ovaries. Oviduct a narrow tube. Two oval, saclike spermathecae located on each side (anterior and posterior) of vulva. Spermathecae filled with oval spermatozoa. Uterus a wide tube. Vagina straight, 0.3 times vulval body diameter in length. Vulva located just before middle of body. Three females of Antomicron were found in sublittoral sediment of Jiaozhou Bay. One of them was found with a male of Antomicron holovachovi sp. nov. in the same locality, and its main measurement data match with the male of Antomicron holovachovi sp. nov. Therefore, the female was identified as Antomicron holovachovi sp. The other female, which was from the locality where the male of another new species was found, and which had a thicker body and slightly longer amphideal fovea, was identified as Antomicron chinensis sp. nov. The third female, which matches the first female, was identified as Antomicron holovachovi sp. nov. The female of Antomicron holovachovi sp. nov. differs from the female of Antomicron chinensis sp. nov. by a slender body (maximum body diameter 23–26 µm vs 33 µm), slightly shorter amphideal fovea (10–12 µm vs 14 µm) and anterior position of vulva (40–45% vs 51%). Differential diagnosis and discussion Antomicron holovachovi sp. nov. is characterised by loop-shaped amphideal fovea, central elevation ridge-like; male with five straight tubular and 41 alveolar supplements; short cephalic setae; one pair of precloacal subventral setae; slightly curved slender spicules with cephalated proximal end and tapered distal end; rectangular gubernaculum with a short dorsal caudal apophysis. The new species belongs to a group of species the males of which have both tubular and alveolar supplements. The new species is morphologically close to Antomicron intermedius Gagarin and Nguyen Vu Thanh, 2005 in most aspects, but differs from the latter species in having elongated loop-shaped amphideal fovea (vs doughnut-shaped amphideal fovea; 2.4 vs 1.6 times as long as its width), central elevation ridge-like (vs oval), many more alveolar supplements (41 vs 29–36) and the shape of tubular supplements. The new species differs from the similar species A. profundum Vitiello, 1971 by longer body length (747–813 vs 512–575 µm), longer spicules (20 vs 17.5 µm) and many more alveolar supplements (41 vs 0–14). Further differences between Antomicron holovachovi sp. nov. and other congeners are specified in Table 2 and the key below.

Zhai, H. X., Wang, C. M., Huang, Y. (2020): Two new species of Antomicron Cobb, 1920 (Nematoda: Leptolaimidae) from Jiaozhou Bay, China. Journal of Natural History 54 (19-20): 1199-1212, DOI: 10.1080/00222933.2020.1781948, URL: http://dx.doi.org/10.1080/00222933.2020.1781948

One new nematode species is described and two new species records are provided from the edge (6,080 m depth) and axis (7,132 m) of Kermadec Trench, Southwest Pacific. Leptolaimus hadalis sp. nov. is characterised by medium body 587–741 μm long, labial region not offset from body contour, inconspicuous labial sensilla, amphid located 12–19 μm from anterior end, female without supplements, male with four tubular precloacal supplements (alveolar supplements absent), tubular supplements almost straight with dentate tip, arcuate spicules and weakly cuticularized dorsal gubernacular apophyses strongly bent distally. In a previously published ecological survey of Kermadec Trench, L. hadalis sp. nov. was the most abundant species in a core obtained at 8,079 m water depth and third most abundant species in a core obtained at 7,132 m, while only one individual was found at 6,096 m depth, and none at 9,175 m depth (Leduc & Rowden, 2018). Alaimella aff. cincta and Desmodora aff. pilosa are recorded for the first time from the Southwest Pacific region. Prior to the present study, Alaimella had only been recorded from coastal locations and from the Weddell sea to a depth of 2,000 m. The record of Desmodora aff. pilosa at 6,080 m depth is the deepest record of a Desmodora species to date, although unidentified Desmodora specimens have been found as deep as 6,300 m in the South Sandwich Trench. The morphology of the Kermadec Trench Alaimella aff. cincta and Desmodora aff. pilosa specimens bear a strong resemblance to their respective type populations from the Northern Hemisphere, but further morphological and molecular data are required to ascertain whether they in fact represent distinct species.

Chronogaster africana Heyns & Coomans, 1980 Figures 9 & 10 Measurements: Table 4 ......continued on the next page The female specimen was identified as Chronogaster africana based on morphometrics and morphology, especially the morphology of the tail terminus displaying a mucro with six short spines, and the absence of no crystalloids in the body cavity. The female specimen found in Telperion Nature Reserve (no males found) matches that of the original description by Heyns & Coomans (1980) with only difference being the length of the post-uterine branch (12.5 µm vs 6–9.5 µm). First time SEM observations on this species revealed the following: Lip region three annules long with four cephalic setae and amphid openings on second annule with their posterior margins protruding slightly. Amphid aperture with two protrusions towards inside. Cuticle shows distinct annules, no lateral field. Excretory pore located 140 µm from anterior end its opening one body annule wide. Lateral caudal pore on tail 30 µm posterior from anus on lateral side of body. This pore indicates two openings, one in the anterior and one in the posterior margin (Figure 10 B). Tail terminus consists of six small projections on the base of one larger mucro. In some instances, an extra projection noticed on larger mucro (Figure 10 C–F). Annules at the base of the tail tip showed some anastomoses / breaks in striations on lateral sides (Figure 10 F). Discussion. Chronogaster africana was first described in South Africa in 1980 from water sediment samples in Boskop Dam and The Kloof (North West Province), Natalspruit (Gauteng Province), and Krom River (Western Cape Province). It was then again reported in South Africa in 1992 from sand near the weir in the Sabie River near Lower Sabie (Mpumalanga Province) (Botha & Heyns 1992). As this species has been reported in this country only, it is considered endemic to South Africa. Locality and material examined: In the Telperion Nature Reserve a female specimen of C. africana was collected at the Wetland site (Table 1) with locality number MP00043 and deposited in the National Collection of Nematodes (ARC—Plant Health and Protection, Biosystematics, Pretoria) on slide number 50567., Published as part of Girgan, Chantelle, Marais, Mariette, Fourie, Hendrika, Tiedt, Lourens & Swart, Antoinette, 2019, Description of two new species, Aphanolaimus strilliae n. sp. (Nematoda: Aphanolaimidae) and Makatinus africanus n. sp. (Nematoda: Aporcelaimidae), and SEM observations on three known species from freshwater sources in the Telperion Nature Reserve (Mpumalanga, South Africa), pp. 201-234 in Zootaxa 4651 (2) on pages 216-217, DOI: 10.11646/zootaxa.4651.2.1, http://zenodo.org/record/3363080, {"references":["Heyns, J. & Coomans, A. (1980) Freshwater nematodes from South Africa 5. Chronogaster Cobb, 1913. Nematologica, 26 (2), 187 - 208. https: // doi. org / 10.1163 / 187529280 X 00080","Botha, A. & Heyns, J. (1992) Further records and descriptions of nematodes from rivers in the Kruger National Park (orders Enoplida, Chromadorida, Monhysterida, Mononchida and Araeolaimida). Koedoe, 35 (2), 11 - 25."]}

Two new species of the order Plectida are described from Chatham Rise, New Zealand. Leptolaimus dififtinus sp. nov. is characterised by the short body 319–420 microns long, truncate labial region slightly offset from body contour and bearing conspicuous outer labial papillae, cephalic setae 1.3–1.4 microns long, amphid located 4–9 microns from anterior end, lateral alae originating from middle of buccal cavity length, female without supplements, male with precloacal and postcloacal pairs of subventral setae, nine tubular supplements (alveolar supplements absent), tubular supplements weakly S-shaped with pointed tip, spicules arcuate 24 microns or 1.4 cloacal body diameters long and dorsal gubernacular apophyses. Lavareda iramscotti sp. nov. is characterised by adult body length 3,023–3,121 microns long, eight longitudinal rows of body pores each with short papilla, cephalic setae 4–5 microns long, tail 146–165 microns long, male with spicules 54 microns long, gubernaculum with triangular apophyses, 20 precloacal supplements with bifid distal tips arranged in 9 + 1 + 10 pattern, female with vulva at 55% of body length from anterior and cuticularisation perpendicular to vagina at level of vulva. The present study provides the first record of a Leptolaimus species from the New Zealand region and the first description of a female specimen of the genus Lavareda.

Aphanolaimus strilliae n. sp. and Makatinus africanus n. sp. are described from freshwater sources in the Telperion Nature Reserve, Mpumalanga, South Africa. Aphanolaimus strilliae n. sp. is characterised by a body length of 1240–1613 μm, more than 800 body annules, lateral field originating between the first and second lateral body pore at the 34th–46th annule, first lateral body pore located at the 25th–35th annule, vagina V-shaped and bent anteriorly, 142–195 µm long uterus and 165–207 µm long tail with spinneret offset. This species is ovoviviparous and no males were found. Makatinus africanus n. sp. is characterised by a large, thick body (3228–4128 μm long, a = 30–39 wide), slightly set off lip region with amalgamated lips; 31–34 μm long odontostyle; long tongue-shaped cardia, and stout, short tail (30–43 μm long) with a small peg / digitate extension and male absent. Populations of three known species, Chronogaster africana, Eutobrilus annetteae and Neotobrilus ampiei, from fresh water at the Telperion Nature Reserve are described and scanning electron microscope graphs of these species published for the first time.

Deontolaimus cangioensis sp. n. (Table 2, Figure 3, 4) Description. Males: (mainly referring to holotype). Body length 607 µm, maximum diameter 20 µm. Cuticle finely annulated with a lateral field visible from just behind the base of the pharynx to its terminus in the tail region. Head with four small cephalic setae (R3) 2 µm long (0.25 hd), sensillae of R1, and R2 minute papilliform and difficult to detect. Amphids one-turn spiral, 2 µm wide (0.25 hd), and located at the level of the cephalic setae (R3) from anterior end. Dorsal buccal tooth 14µm long (2 hd), strongly cuticularised at the tip. Pharynx cylindrical, only weakly enlarged at posterior end. Ventral gland or its exit pore not seen. Testes two, outstretched and directed forward, located on the left side of intestine. Spicules 26 µm (1.5 abd) measured on the chord, slender, regularly bent with proximal half swollen. Gubernaculum small with curved dorso-caudal apophysis. 31 simple, cup-shaped precloacal supplements beginning posterior to the end of the dorsal tooth and extending to middle body position (60% of body length from anterior end). Tail conical 62 µm long (3.7 abd). Tail tip very strongly cuticularised and unstriated. There are two minute post cloacal setae, the first located 26 µm (1.5 abd) posterior to cloaca, and the second 0.5 cbd from the first. Three caudal glands. Females: (paratypes) . Similar to males in general appearance. Body length averaging 654 µm (505-774µm) Cuticle annulated with 3 weak lateral lines, visible at the middle of the body. The maximum diameter averages 20 µm (14-23 µm). Dorsal tooth averaging 11 µm (9-14 µm) in length, a little smaller than in male. Amphids located at nearly the same position as in male. Ovaries opposed and reflexed antidromously, with the anterior ovary on the right side of the intestine and the posterior ovary on the left side. Vulva at 50-52% of body length. Tail conical with tail tip pointed. Tubular structures (supplements) never seen in females. Remarks. The new species resembles D. papillatus de Man, 1880 in body shape, especially in the tail region and tail terminus. It differs from D. papillatus in the shape of gubernaculum: simple plate-like in D. papillatus vs complicated plate-like with dorsally curved apophyses in D.cangioensis. Type material. Holotype (1♂), slide VNMN.0057. Paratypes: 2 ♂, VNMN. 0058 - 59, 4♂, VNMN.0065 – 68, deposited at the Vietnam National Museum of Nature, Vietnam. Etymology. The species name refers to the type locality: the Can Gio mangrove forest. Characteristic holotype ♂ 1 Paratypes Paratypes ♂ 2 ♂ 3 ♀ 1 ♀ 2 ♀ 3 ♀ 4 L 607 598 468 737 774 600 505 a 30.3 48.2 37.8 31.4 35.4 30.3 37.3 b 4.2? 4.2 4.9 5.3 4.4 4.7 c 9.7 9.5 10.0 11.6 10.3 8.7 10.1 c’ 3.7 6.3 4.4 4.6 5.1 5.1 5.3 spic. 26 not clear not clear sup. 31 32 35 V% 52 51 51 50 Key to the species of the genus Deontolaimus (Based on Holovachov & Bostrom, 2015) 1. Anterior ovary reduced, posterior ovary functional................................................ D. monhystera - Both ovaries equally developed, functional (if known)........................................................2 2. Males with caudal alae at level with cloaca....................................................... D. prytherchi - Males without caudal alae at level with cloaca.............................................................. 3 3. Cephalic setae located anterior to amphid according to illustration................................. D. pontollittoralis - Cephalic setae located at level with or posterior to amphid.................................................... 4 4. Excretory pore located at level with onchiostyle or anterior-most part of intestine.................................. 5 - Excretory pore located at level with nerve ring............................................................. 6 5. Body 1.2–1.7 mm long, excretory pore located 9–17 µm posterior to cephalic setae........................ D. catalinae - Body 0.7–0.8 mm long, excretory pore located at level with cephalic setae bases........................... D. parvus 6. Amphid multispiral...................................................................................7 - Amphid unispiral.....................................................................................9 7. Cephalic setae located at level with amphid base; tail very long (c' = 9–12).............................. D. praedator - Cephalic setae located far posterior to amphid base; tail short (c' = 2.5–5.5).......................................8 8. Cephalic setae short (6.5–8.5 µm); tail longer (c' = 3.3–5.4).......................................... D. uniformis - Cephalic setae long (18 µm); tail shorter (c' = 2.5–3.4).................................................. D. exilis 9. Cephalic setae located far posterior to amphid base.........................................................10 - Cephalic setae located at level with amphid base........................................................... 11 10. Spicules 24–30 µm long..................................................................... D. longicauda - Spicules 20–21 µm long.................................................................. D. trituberculatus 11. Body over 2.5 mm long (2.7–3.2 mm); spicules over 60 µm long (63–65 µm).............................. D. guillei - Body less than 2.5 mm long (0.5–2.4 mm); spicules less than 60 µm long (20–59 µm)..............................12 12. Cephalic setae relatively long (=5–8 µm, measured from illustrations)..........................................13 - Cephalic setae relatively short (=1–2 µm).................................................................14 13. Tail relatively long (c' = 6), spinneret broad conoid, not offset from............................... D. cylindricaudatus - Tail relatively short (c' = 3.8–4.6), spinneret narrow and curved dorsad, sharply offset from tail....... D. lorenzeni nom. n. 14. Alveolar supplements extend along entire body almost to cloaca............................................... 15 - Alveolar supplements present in pharyngeal region only.....................................................17 15. Gubernaculum simple plate-like without apophyses, body over 1.0 mm long; spicules over 40 µm long....... D. paraguillei - Gubernaculum complicated with dorsal curve apophyses, body less than 1.0 mm long; spicules less than 40 µm long......16 16. Spicules 20 µm long; 47 (47- 49 supplements); c’ = 7.3......................................... D. mangrovi sp. n. - Spicules 26 µm long; 31 (32- 359 supplements); c’ = 3.7...................................... D. cangioensis sp. n. 17. Body over 1.5 mm long (1.6–2.4 mm); spicules over 50 µm long (53–59 µm).............................. D. tardus - Body less than 1.5 mm long (0.5–1.1 mm); spicules less than 40 µm long (20–35 µm)..............................18 18. Alveolar supplements very distinct along the pharyngeal region...................................... D. papillatus - Alveolar supplements small and difficult to discern.................................................... D. timmi

1. Deontolaimus mangrovi sp. n. (Table 1, Figure 1,2) Description. Male. Body length 650 ��m (478-766��m). Maximum diameter 15��m (14-16 ��m). Cuticle finely annulated with longitudinal unstriated band extending from just posterior to the amphids and visible to the end of the conical region of the tail. Four cephalic setae very minute and difficult to detect, six anterior sensilla not visible. Amphids a simple spiral of one turn situated well forward between the cephalic setae, 2-3 ��m width (0.5-0.6 hd). Buccal cavity with a long stylet-like tooth, 19 ��m (3.3 hd) in length. Pharynx cylindrical, enlarged in the posterior one-third into an elongate bulb. Testes paired, outstretched and located on the left side of intestine. Spicules ventrally curved, 22 ��m in length, measured along the chord. Gubernaculum with caudal apophysis. 32-49 simple, cup-shaped precloacal supplements. The number and arragement of supplements variesin different individuals. In specimens with 32-34 supplements, 26-27 supplements are frequently located from the anterior pharyngeal region to the middle of the body, with 6-8 remaining supplements located in the precloacal region, of which 4 supplements form a subgroup present anterior of the cloaca. In other specimens with 47-49 supplements, 42-44 supplements make up the anterior group, with only 5 supplements in the precloacal region and 3 supplements in the subgroup nearest the cloaca. However, the number of supplements in the region from the anterior part of the pharynx to the cardia is a constant 17-19 supplements. Tail 93 ��m long (7.7 abd), conical for 25-30% of its length, then narrowing and elongated. Female. Similar to male in most features. Body length 869 ��m (752-920��m), much longer then in male. Maximum diameter 21 ��m, a little wider than male. Ovaries pair, opposed and reflexed. Vulva at 46% (43-52%) of body length. Remark. The new species differs from D. papillatus de Man, 1880 in tail shape: conical then elongated and end without pointed tip in D. papillatus vs with conical with pointed tip strongly cuticularised in D. cangioensis. Type material. Holotype (1♂) adult male, slide VNMN.0048. Paratypes. 9♂♂, slides: VNMN. 0049 - 55, 6♀, slides VNMN.0059 ��� 64, deposited at the Vietnam National Museum of Nature, Vietnam. Etymology. The species epithet refers to the mangrove forest where this species was found., Published as part of Tu, Nguyen Dinh, Thanh, Nguyen Vu, Hoang, Lai Phu & Saint-Paul, Ulrich, 2016, Two new species of the genus Deontolaimus de Man, 1880 (Nematoda: Leptolaimidae) from mangrove ecosystems of Vietnam, pp. 73-80 in Zootaxa 4205 (1) on page 74, DOI: 10.11646/zootaxa.4205.1.6, http://zenodo.org/record/192554, {"references":["de Man, J. G. (1880) Die einheimischen, frei in der reinen Erde und im sußen wasser lebenden Nematoden. Vorlaufige Bericht und descriptiv-systematischer Theil. Tijdschrift Nederlandsche dierkundige Uereeniging, 5, 1 - 104."]}

Two new species of the free-living marine nematode genus Deontolaimus (Leptolaimidae) are described from mangrove forests of the Can Gio Biosphere Reserve and Tien Yen, Quang Ninh, Vietnam. D. mangrovi sp. nov. is distinguished from D. papillatus de Man, 1880 and D. cangioensis sp. nov. by tail shape: conical and then elongated, without pointed tip. Deontolaimus cangioensis sp. nov. resembles D. papillatus in body shape, especially in the pointed tail terminus. D. cangioensis differs from D. papillatus in having a complicated gubernaculum with dorsally curved apophyses.

This paper focuses on Antomicron, Leptolaimus and Procamacolaimus, three genera inhabiting coastal water systems of the Patagonian, Chubut and Santa Cruz provinces of Argentina, providing a review of their taxonomy for a new identification key. One new species belonging to the genus Antomicron and one new species belonging to the genus Leptolaimus of the family Leptolaimidae are described from Puerto San Julián, Santa Cruz province: Antomicron alveolatum sp. nov. has 35 alveoli and three precloacal supplements and Leptolaimus gabinoi sp. nov. is characterized by the structure and number of precloacal supplements (three) with hamate distal end with two hooks. Another species belonging to the genus Procamacolaimus of the family Camacolaimidae is described and recorded from Puerto Madryn, Chubut province of Argentina: Procamacolaimus dorylaimus.

Alaimella cincta Cobb 1920 and Alaimella macramphis sp. n. are described and illustrated. Both the species were first recorded for the White Sea in northern Russia. A. cincta occurs in the shells of the agglutinated foraminiferan Reophax curtus, as well as freely in bottom sediments. A. macramphis sp. n. is described from a single male sampled from bottom sediments. A. macramphis sp. n. is distinguished from two previously known species of Alaimella (A. cincta Cobb 1920 and A. truncate Cobb 1920) by having a longer body, longer cephalic setae, and a wide amphid equal to the respective body diameter. The new species also differs from A. truncate by the distinct striation of the cuticular annulations. The Alaimella species are additionally characterized by having a posterior glandular widening of the esophagus. An emended diagnosis of the genus Alaimella Cobb 1920 and a key for species identification are provided.

Camacolaimus norwegicus Allg��n, 1933 (Fig. 17) Type material. Lectotype male (slide # Type- 3555) deposited in the invertebrate type collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Specimen is in relatively good condition with larger structures recognizable, except for the damaged anterior end. Male. Body long, slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation. Cuticle smooth. Lateral field, body pores, epidermal glands and subcephalic, cervical and somatic sensilla cannot be observed. Anterior body end damaged. Nerve ring, hemizonid and secretory-excretory system cannot be observed. Pharynx cylindrical anteriorly, expanding posteriorly into a weak basal bulb. Reproductive system diorchic, both testes outstretched. Spicules paired, symmetrical, with arcuate subcylindrical shaft and small manubrium. Gubernaculum plate-like, with small dorsal apophysis. Tail elongate-conoid. Caudal glands indistinct. Spinneret present. Discussion. Since the anterior end of this specimen cannot be studied in detail, it is impossible to identify this species with confidence. The species is considered species inquirenda et incerta sedis within Nematoda., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on pages 31-32, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["Allgen, C. (1933) Freilebende Nematoden aus dem Trondhjemsfjord. Capita Zoologica, 4 (2), 1 - 162."]}

Onchium ocellatum Cobb, 1920 (Figs 1���2; Table 1) Material examined. Four males and eight females (slides # 139311 ���139316, 139318, 139320, 139322, 139329) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Habitat and locality. Sand and shells from 15���22 m deep, Bonden island in Skagerrak off the west coast of Sweden (N 58 12 ' 37 '', E 11 18 ' 53 ''), 0 9 August 2011, legit O. Holovachov (one male); gravel, mud and algae from 30���70 m deep, Skagerrak off the west coast of Sweden (N 58 �� 22 ' 14 '', E 11 �� 05' 00''), 0 9 August 2011, legit O. Holovachov (one male and two females); coarse gravel from 30���50 m deep, Skagerrak off the west coast of Sweden (N 58 �� 17 ' 58 '', E 11 �� 10 ' 05''), 0 9 August 2011, legit O. Holovachov (two males and two females); algae from 15���55 m deep, Skagerrak off the west coast of Sweden (N 58 �� 17 ' 24 '', E 11 �� 10 ' 48 ''), 0 9 August 2011, legit O. Holovachov (one female); coarse sediment with algae from 45���55 m deep, Skagerrak off the west coast of Sweden (N 58 �� 17 ' 32 '', E 11 �� 11 ' 24 ''), 0 9 August 2011, legit O. Holovachov (three females). Description. Male. Body slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation, especially so in posterior part. Cuticle finely annulated; annules without ornamentation. Lateral field absent. Crystalloids absent. Body pores and epidermal glands absent. Somatic sensilla present, most prominent along pharyngeal region and on tail; anteriormost somatic sensilla are located posterior to ocelli. Labial region rounded, continuous with body contour; lips fused. Annulation along anteriormost part of body very weak; cuticle encircling labial region does not form "cephalic capsule". Inner and outer labial sensilla indistinct. Cephalic sensilla setiform. Subcephalic and cervical sensilla absent. Amphidial fovea ventrally-unispiral, located anterior to cephalic sensilla bases. Ocelli present, each ocellum consists of one to three oval pigment bodies of different size; "lens"-like structure absent; number of pigment bodies is different between different individuals and can even be different on opposite body sides in the same specimen; in some specimens ocelli not visible. Nerve ring surrounding pharynx at anterior third of its length. Hemizonid not seen. Secretory-excretory system present; renette cell located on left-hand side of body along anterior part of intestine; it extends anteriorly along ventral side of pharynx and forms excretory ampulla just posterior to nerve ring level. Excretory canal weakly cuticularised, extends from excretory ampulla for a short distance and opens to exterior on ventral side, at level with or just anterior to nerve ring. Oral opening terminal. Buccal cavity uniformly tubular: cheilostom barrel���shaped; stegostom tubular, with large dorsal onchiostyle. Onchiostyle with acute tip and subcylindrical body. Pharynx glandular, cylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Dorsal pharyngeal sector strongly developed over entire pharynx length, more so in its posterior part. Subventral pharyngeal sectors weakly developed along anterior part (anterior to nerve ring) and completely reduced (indistinct) posterior to nerve ring level. Dorsal pharyngeal gland orifice opens at base of onchiostyle; orifices of subventral pharyngeal glands indistinct. Cardia short, embedded in intestine. Several large coelomocytes are present on each body side along posterior part of pharynx and anterior part of intestine, their cell bodies extend anteriorly into narrow ducts that are located laterally. Reproductive system diorchic, both testes outstretched. Spicules paired, symmetrical, with arcuate subcylindrical shaft and small manubrium; manubrium is ventrally inclined. Gubernaculum present, small, platelike. Alveolar supplements present along pharyngeal region but visible only when specimen is in subventral position, they are very small and located at the bottom of a narrow ventral grove. Tubular supplements absent. Midventral precloacal sensilla absent. Tail usually with four pairs of papilliform sensilla: first and third pair (counting from cloaca) are subventral, second and fourth pair are sublateral. Tail elongate-conoid, ventrally curved. Three caudal glands present, their nuclei are incaudal. Spinneret conoid, functional. Female. Body slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation, especially so along tail. Cuticle finely annulated; annules without ornamentation. Lateral field absent. Crystalloids absent. Body pores and epidermal glands absent. Somatic sensilla present, most prominent along pharyngeal region; anteriormost somatic sensilla are located posterior to ocelli. Labial region rounded, continuous with body contour; lips fused. Annulation along anteriormost part of body very weak; cuticle encircling labial region does not form "cephalic capsule". Inner and outer labial sensilla indistinct. Cephalic sensilla setiform. Subcephalic and cervical sensilla absent. Amphidial fovea ventrally-unispiral, located anterior to cephalic sensilla bases. Ocelli present, each ocellum consists of one to three oval pigment bodies of different size; "lens"-like structure absent; number of pigment bodies is different between different individuals and can even be different on different body sides in same specimen. Nerve ring surrounding pharynx at anterior third of its length. Hemizonid not seen. Secretory-excretory system present; renette cell located on left-hand side of body along anterior part of intestine; it extends anteriorly along ventral side of pharynx and forms excretory ampulla just posterior to nerve ring level. Excretory canal weakly cuticularised, extends from excretory ampulla for a short distance and opens to exterior on ventral side, at level with or just anterior to nerve ring. Oral opening terminal. Buccal cavity uniformly tubular: cheilostom barrel-shaped; stegostom tubular, with large dorsal onchiostyle. Onchiostyle with acute tip and subcylindrical body. Pharynx glandular, cylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Dorsal pharyngeal sector strongly developed over entire pharynx length, more so in its posterior part. Subventral pharyngeal sectors weakly developed along anterior part (anterior to nerve ring) and completely reduced (indistinct) posterior to nerve ring level. Dorsal pharyngeal gland orifice opens at the base of onchiostyle; orifices of subventral pharyngeal glands indistinct. Cardia short, embedded in intestine. Several large coelomocytes are present on each body side along posterior part of pharynx and anterior part of intestine, their cell bodies extend anteriorly into narrow ducts that are located laterally. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 83���197 ��m long (equal to 4.7���8.8 % of total body length), located on right-hand side of intestine (n = 6), posterior genital branch 90���231 ��m long (equal to 6.2���10.4 % of total body length), located on left-hand side of intestine (n = 6). Oviduct short. Spermathecae filled with sperm. Uterus voluminous. Vagina straight, 0.2���0.4 times vulval body diameters long. Epiptygmata, pars refringens vaginae and sensory structures around vulva absent. Rectum 0.8���1.4 anal body diameters long. Tail elongate-conoid, ventrally curved. Three caudal glands present, their nuclei are incaudal. Spinneret conoid, functional. Diagnosis. Onchium ocellatum is particularly characterised by 1.44���2.23 mm long body; anterior end without cephalic capsule; anteriormost somatic sensilla located posterior to ocelli; ocelli with one to three oval pigment bodies of different size; excretory pore located just anterior to nerve ring level; onchiostyle uniformly cylindrical; male with alveolar supplements along pharyngeal region, tubular supplements absent; spicules arcuate and 34���42 ��m long. Remarks. This species was originally described based on a single juvenile specimen, presumably a female. Most of the characters mentioned in the original description of Onchium ocellatum are characteristic for the genus Onchium in general and can not be used for species identification. Present specimens agree with the original description of O. ocellatum in the position of excretory pore, which was clearly described and illustrated to be located just in front of nerve ring. Most of the other presently considered valid species of Onchium have the excretory pore located close to the anterior end, while its position is unknown in O. minutum Kito, 1981. Therefore, we consider our population identical with O. ocellatum as described by Cobb (1920). For the same reasons (position of excretory pore) both the populations of Onchium ocellatum as described by Blome (1982) and Onchium parocellatum as described by Luc & De Coninck (1959) are considered conspecific with recent specimens. The identity of specimens described as (or synonymised with) O. ocellatum by Allg��n (1933, 1935, 1938), Bresslau & Stekhoven (1940), Gerlach (1962), Timm (1952) and Wieser (1956 a, b) is impossible to verify without being able to study actual specimens. Their respective descriptions are rather incomplete and do not include all the important morphological data. At present, we will consider all these specimens to represent O. ocellatum for the sake of taxonomic stability., Published as part of Holovachov, Oleksandr, 2015, Swedish Plectida (Nematoda). Part 8. The genus Onchium Cobb, 1920, pp. 521-546 in Zootaxa 3911 (4) on pages 522-527, DOI: 10.11646/zootaxa.3911.4.3, http://zenodo.org/record/242601, {"references":["Cobb, N. A. (1920) One hundred new nemas (type species of 100 new genera). Contribution to a science of Nematology, 9, 217 - 343.","Kito, K. (1981) Studies on the Free - Living Marine Nematodes from Hokkaido, IV. Journal of the Faculty of Science Hokkaido University, Series VI (Zoology), 22, 250 - 278.","Blome, D. (1982) Systematik der Nematoda eines Sandstrandes der Nordseeinsel Sylt. Mikrofauna des Meeresbodens, 86, 1 - 194.","Luc, M. & De Coninck, L. A. P. (1959) Nematodes libres marins de la region de Roscoff. Archives de Zoologie Experimentale et Generale, 98, 103 - 166.","Allgen, C. (1933) Freilebende Nematoden aus dem Trondhjemsfjord. Capita Zoologica, 4, 1 - 162.","Allgen, C. (1935) Die freilebenden Nematoden des Oresunds. Capita Zoologica, 6, 5 - 192.","Allgen, C. (1938) Uber einige im reinen Schalensand der Westkuste Norwegens freilebende Nematoden. Volume 5. Festschrift fur Prof. Dr. Embrik Strand, 22 pp. [pp. 404 - 425]","Bresslau, E. & Schuurmans Stekhoven, J. H. (1940) Marine Freilebende Nematoda aus der Nordsee. Musee royal d'histoire naturelle de Belgique, 74 pp.","Gerlach, S. (1962) Freilebende Meeresnematoden von den Malediven. Kieler Meeresforschungen, 18, 81 - 108.","Timm, R. W. (1952) A Survey of the Marine Nematodes of Chesapeake Bay, Maryland. Chesapeake Biological Laboratory, 95, 1 - 70.","Wieser, W (1956 a) Eine Sammlung mariner Nematoden aus Piraeus (Griechenland). Osterreichische Zoologische Zeitschrift, 6, 597 - 630.","Wieser, W. (1956 b) Free - living marine nematodes III. Axonolaimoidea and Mohysteroidea. Acta Universitatis Lundensis, 52, 1 - 115."]}

Camacolaimus glauxicola Allg��n, 1951 a (Fig. 15) Female. Body slender, weakly fusiform; ventrally curved upon fixation, especially so along tail. Cuticle finely annulated. Lateral field, body pores, epidermal glands and subcephalic, cervical and somatic sensilla cannot be observed. Labial region rounded, continuous with body contour. Inner and outer labial sensilla indistinct. Cephalic sensilla setiform. Amphidial fovea ventrally-unispiral, located just anterior to cephalic sensilla bases. Ocelli absent. Nerve ring and hemizonid indistinct. Secretory-excretory system present, but only excretory pore recognizable���it opens to exterior on ventral side, at around midpharynx. Oral opening terminal. Buccal cavity uniformly tubular: cheilostom barrel-shaped; stegostom tubular, with large dorsal onchiostyle. Onchiostyle with acute tip and subcylindrical body. Pharynx muscular, cylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Pharyngeal glands and cardia indistinct. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Vagina straight. Epiptygmata, pars refringens vaginae and sensitive structures around vulva indistinct. Rectum short. Tail elongate-conoid, ventrally curved. Caudal glands and spinneret present. Discussion. Description and illustrations of this species match superficially the diagnosis of the family Camacolaimidae, in particular the genera Deontolaimus and Procamacolaimus in presence of single dorsal onchiostyle and paired female reproductive system (Allg��n 1951 a: 356, Fig. 2). This species was described from the same exact sample as Camacolaimus papillosus Allg��n, 1950 (see below). Besides primary sexual dimorphism, no other differences can be found between the two. Since Camacolaimus papillosus is considered a junior synonym of Deontolaimus papillatus (see below), Camacolaimus glauxicola is also synonimized with D. papillatus., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on pages 30-31, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["Allgen, C. (1951 a) Uber einige westschwedische terrestrisch lebende Nematoden. Zoologscher Anzeiger, 146, 354 - 357","Allgen, C. A. (1950) Westschwedische marine litorale und terrestrische Nematoden. Arkiv for Zoologi (Serie 2), 1, 301 - 344."]}

Holovachov, Oleksandr (2015): Swedish Plectida (Nematoda). Part 8. The genus Onchium Cobb, 1920. Zootaxa 3911 (4): 521-546, DOI: http://dx.doi.org/10.11646/zootaxa.3911.4.3

Camacolaimus tenuicaudatus Allg��n, 1933 Type material. Not found. Comments. Description and illustrations of this species do not provide sufficient information to be able to assign this species to any nematode genus or family (Allg��n, 1933: 42, Fig. 21 a���b). Slides from this locality include large numbers of specimens from the genus Syringolaimus, the tail and spinneret of which strongly resemble the drawing of the tail of C. tenuicaudatus. However, since the exact specimen used by Allg��n for the original description and illustrations was not found, we cannot be sure that it is identical with Syringolaimus. It is considered species inquirenda et incerta sedis within Nematoda., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on page 37, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["Allgen, C. (1933) Freilebende Nematoden aus dem Trondhjemsfjord. Capita Zoologica, 4 (2), 1 - 162."]}

Deontolaimus paraguillei sp. n. (Fig. 9; Table 5) Type material examined. Holotype male (slide # Type- 8776) deposited in the invertebrate type collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Type locality. Soft bottom 352���374 m deep, Skagerrak off the west coast of Sweden (N 58 �� 19 ' 15.6 '' ��� 20.9 '', E 10 �� 29 ' 33.5 '' ���34.0''), 10 September 2012, legit "Inventering Bratten" (one male). Additional material examined. Three males and two females (slides # 148131���148135) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Habitat and locality. Coarse sediment with algae from 45���55 m deep, Skagerrak off the west coast of Sweden (N 58 �� 17 ' 32 '', E 11 �� 11 ' 24 ''), 0 9 August 2011, legit O. Holovachov (two females); soft bottom 221���260 m deep, Skagerrak off the west coast of Sweden (N 58 �� 28 ' 28.0'' ��� 31.1 '', E 10 �� 33 ' 19.1 '' ��� 23.8 ''), 11 September 2012, legit "Inventering Bratten" (one male); soft bottom 139���153 m deep, Skagerrak off the west coast of Sweden (N 58 �� 34 ' 21.3 '' ��� 16.6 '', E 10 �� 38 ' 11.2 '' ��� 29.4 ''), 12 September 2012, legit "Inventering Bratten" (one female). Description. Adult. Body slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; usually strongly ventrally curved upon fixation, especially so in posterior part. Cuticle annulated; annules without ornamentation. Lateral field present, single cuticular ridge weakly demarcated by two lines extending from intestinal region to posterior part of tail, in some specimens discernible only along posterior body end. Crystalloids absent. Body pores and epidermal glands absent. Somatic sensilla present, equally distributed along entire body; anterior-most somatic sensilla are located short distance posterior to amphid, at level with onchiostyle base. Labial region rounded, continuous with body contour; lips fused. Annulation along anterior-most part of body very weak; anterior-most annule appearing posterior to amphid and cephalic sensilla bases. One circle of labial sensilla visible on the anterior surface of labial region, they are small papilliform. Cephalic sensilla setiform, equal to 0.2���0.3 labial region diameter in length, their bases are located at level with middle or posterior edge of amphid. Subcephalic and cervical sensilla absent. Amphidial fovea ventrally-unispiral, making one turn, located at level with cephalic sensilla bases. Ocelli absent. Nerve ring surrounding pharynx at anterior two-fifth of its length. Hemizonid not seen. Secretory-excretory system present; renette cell located on left-hand side of body along anterior part of intestine; it extends anteriorly along ventral side of pharynx and forms excretory ampulla just posterior to nerve ring level. Excretory canal weakly cuticularised, extends from excretory ampulla for a short distance and opens to exterior on ventral side, at level with or just posterior to nerve ring. Oral opening terminal. Buccal cavity uniformly tubular: cheilostom barrel-shaped; stegostom tubular, with large dorsal onchiostyle. Onchiostyle with bluntly rounded tip and subcylindrical body. Pharynx muscular in its anterior part and glandular in its posterior part, cylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Dorsal pharyngeal gland orifice opens at base of onchiostyle; orifices of subventral pharyngeal glands indistinct. Cardia short, embedded in intestine. Tail similar in shape in both sexes (more curved ventrad in male) elongate-conoid, ventrally curved. Three caudal glands present, their nuclei are incaudal. Spinneret long conoid, slightly curved dorsad, functional. Male. Reproductive system diorchic, both testes outstretched. Spicules paired, symmetrical, with arcuate subcylindrical shaft and small manubrium; manubrium is ventrally inclined. Gubernaculum present, plate-like, with paired dorsocaudal apophysis. Alveolar supplements present along entire body, very small, extending from anterior body end to about three body diameters in front of cloaca. Tubular supplements absent. Midventral precloacal sensilla absent. Two small postcloacal sensilla present, located subventrally at level of middle of tail length, discernible only by their nerve endings; sclerotized lamina absent. Tail with three pairs of papilliform sensilla: first (counting from cloaca) subventral pair located short distance posterior to cloacal opening, second subventral pair located at middle of tail length, and third sublateral pair located at posterior one-fourth of tail length. Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 107���145 ��m long (equal to 5.9���7.7 % of total body length), located on right-hand side of intestine (n = 2), posterior genital branch 193���207 ��m long (equal to 10.7���11 % of total body length), located on left-hand side of intestine (n = 2). Oviduct short. Spermathecae filled with sperm. Uterus voluminous. Vagina straight, 0.3 times vulval body diameter long. Weak epiptygmata-like structure seen in one female but not in the other. Pars refringens vaginae and sensitive structures around vulva absent. Rectum 1.0��� 1.2 anal body diameters long. Diagnosis. Deontolaimus paraguillei sp. n. is characterized by 1.4���1.8 mm long body; anterior-most somatic sensilla located at level with onchiostyle; cephalic sensilla equal to 0.2���0.3 labial region diameter in length; amphidial fovea ventrally-unispiral with one turn, located at level with cephalic sensilla bases; excretory pore located just posterior to nerve ring level; onchiostyle with bluntly rounded tip and subcylindrical body; male with alveolar supplements extending from anterior end to to about three body diameters in front of cloaca, tubular supplements absent; spicules 42���46 ��m long; and didelphic female reproductive system. Remarks. The current specimens are similar to Deontolaimus guillei (de Bovee, 1977) comb. n. in the morphology of the labial region (unispiral amphid, cephalic sensilla bases located at level with posterior edge of amphid) and relatively long acute spinneret. The two species can be separated by the following characters: body length (1.37���1.87 mm in D. paraguillei sp. n. vs 2.72���3.17 mm in D. guillei) and other body measurements, cephalic setae length (2 ��m in D. paraguillei sp. n. vs 6 ��m in D. guillei), tail length (c' = 4.3���5.4 in D. paraguillei sp. n. vs c' = 2.4���3.2 in D. guillei), spicule length (42���46 ��m in D. paraguillei sp. n. vs 63���65 ��m in D. guillei), and gubernaculum length (6���8.5 ��m in D. paraguillei sp. n. vs. 12���13 ��m in D. guillei). Deontolaimus paraguillei sp. n. is close to D. tardus in body size, length and position of cephalic setae, and shape of the amphid. These two species can be separated by the tail length (c'= 4.3���5.4 in D. paraguillei sp. n. vs c'= 2.5���3.1 in C. tardus), length of spicules (42���46 ��m in D. paraguillei sp. n. vs 58���59 ��m in C. tardus), and distribution of alveolar supplements in males (along most of the body length in D. paraguillei sp. n. vs along the pharyngeal region and anterior-most part of intestine in C. tardus). Type material. Holotype male (slide # Type- 8777), and one male and three female paratypes (slide # Type- 8778) deposited in the invertebrate type collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Type locality. Coarse sediment with algae from 45���55 m deep, Skagerrak off the west coast of Sweden (N 58 �� 17 ' 32 '', E 11 �� 11 ' 24 ''), 0 9 August 2011, legit O. Holovachov (two males and three females). Description. Adult. Body slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; usually strongly ventrally curved upon fixation, especially so in posterior part. Cuticle annulated; annules without ornamentation. Lateral field present, single cuticular ridge demarcated by two lines extending from anterior part of intestinal region to middle of tail. Crystalloids absent. Body pores and epidermal glands absent. Somatic sensilla present, equally distributed along entire body; anterior-most somatic sensilla are located short distance posterior to amphid, at level with onchiostyle shaft. Labial region rounded, continuous with body contour; lips fused. Annulation along anterior-most part of body very weak; anterior-most annule appearing posterior to amphid and cephalic sensilla bases. One circle of labial sensilla visible on the anterior surface of labial region, they are small papilliform. Cephalic sensilla setiform, equal to 0.2���0.3 labial region diameter in length, their bases are located at level with posterior edge of amphid. Subcephalic and cervical sensilla absent. Amphidial fovea ventrally-unispiral, making one turn, located just in front of cephalic sensilla bases. Ocelli absent. Nerve ring surrounding pharynx at anterior two-fifth of its length. Hemizonid not seen. Secretory-excretory system present; renette cell located on left-hand side of body along anterior part of intestine; it extends anteriorly along ventral side of pharynx and forms excretory ampulla just posterior to nerve ring level. Excretory canal weakly cuticularised, extends from excretory ampulla for a short distance and opens to exterior on ventral side, at level with or just posterior to nerve ring. Oral opening terminal. Buccal cavity uniformly tubular: cheilostom barrel-shaped; stegostom tubular, with large dorsal onchiostyle. Onchiostyle in females with triangular tip with bluntly rounded apex and strongly sclerotized dorsal edge, and subcylindrical body. Male onchiostyle less robust. Pharynx muscular in its anterior part and glandular in its posterior part, cylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Dorsal pharyngeal gland orifice opens at base of onchiostyle; orifices of subventral pharyngeal glands indistinct. Cardia short, embedded in intestine. Tail similar in shape in both sexes (longer and more curved ventrad in male), conoid, ventrally curved. Three caudal glands present, their nuclei are incaudal. Spinneret conoid, slightly curved dorsad, functional. Male. Reproductive system diorchic, both testes outstretched. Spicules paired, symmetrical, with arcuate subcylindrical shaft and small manubrium; manubrium is ventrally inclined. Gubernaculum present, plate-like, without apophysis. Alveolar supplements present along anterior body half, extending from anterior body end to anterior part of intestine, they are small and located at the bottom of a narrow ventral groove. Tubular supplements absent. Midventral precloacal sensilla absent. Single (?) postcloacal sensillum present, located subventrally at level of posterior one-third of tail length; sclerotized lamina absent. Tail with four pairs of papilliform sensilla (clearly observed in one male only): first (counting from cloaca) subventral pair located short distance posterior to cloacal opening, second subventral pair located about one body diameter posterior to cloacal opening, third subventral pair located at posterior two-fifth of tail length, and fourth sublateral pair located close to tail terminus. Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 72 ��m long (equal to 10 % of total body length), located on right-hand side of intestine (n = 3), posterior genital branch 45���79 ��m long (equal to 5.9���11 % of total body length), located on left-hand side of intestine (n = 3). Oviduct short. Spermathecae indistinct. Uterus voluminous. Vagina straight, 0.2���0.3 times vulval body diameter long. Epiptygmata, pars refringens vaginae and sensitive structures around vulva absent. Rectum 0.8���1.2 anal body diameters long. Diagnosis. Deontolaimus timmi sp. n. is characterized by having body 0.7���0.9 mm long; anterior-most somatic sensilla located at level with onchiostyle; cephalic sensilla equal to 0.2���0.3 labial region diameter in length; amphidial fovea ventrally-unispiral with one turn, located just in front of cephalic sensilla bases; excretory pore located just posterior to nerve ring level; onchiostyle with triangular tip with bluntly rounded apex and strongly sclerotized dorsal edge, and subcylindrical body; male with alveolar supplements extending from anterior end to anterior part of intestine, tubular supplements absent; spicules 28 ��m long; didelphic female reproductive system. Remarks. Timm (1963) described Camacolaimus tardus (now placed in the genus Deontolaimus) from the Arabian Sea, which was noticeably smaller than the specimens described by de Man (1889): 0.76���1.15 mm vs 2.1��� 2.5 mm. Upon re-examination of type material of de Man and recently collected specimens of D. tardus several other differences were noticed: onchiostyle length (15���16 ��m in Timm's specimens vs 20���23 ��m in D. tardus), spicule length (35 ��m in Timm's specimens vs 58���59 ��m in D. tardus), and shape of spinneret (narrow in Timm's specimens vs. broad in D. tardus), suggesting that the population from Arabian sea does not belong to D. tardus. One of the populations found in Swedish coastal waters closely resembles Timm's description in body size and major measurements, shape of anterior body end, gubernaculum and spinneret, differing only in slightly shorter onchiostyle (7���11 ��m in recent specimens vs 15���16 in specimens described by Timm), spicules (28 ��m in recent specimens vs 35 in specimens described by Timm) and gubernaculum (6���8 ��m in recent specimens vs 12 in specimens described by Timm). The new name, Deontolaimus timmi sp. n., is proposed to accommodate both populations and separate them from the other valid species of Deontolaimus. Another population originally described under the name C. tardus (now placed in the genus Deontolaimus) is from the North Sea (Lorenzen 1969; Platt & Warwick 1988). It is similar to Deontolaimus timmi sp. n. in body size and general measurements, but can easily be separated from D. timmi sp. n. in having no lateral alae (vs present in D. timmi sp. n.), longer cephalic setae (equal to 0.6 vs 0.2���0.3 labial region diameter in length), shorter spicules (20���21 ��m vs 28���35 ��m in D. timmi sp. n.), gubernaculum with strong dorsocaudal apophysis (vs without apophysis). The systematic position of the population described by Lorenzen (1969) under the name C. tardus will be discussed below. Deontolaimus timmi sp. n. is similar to D. papillatus in general body size and most measurements. These two species can be easily separated by the shape and size of alveolar supplements (small and hard to discern in D. timmi sp. n. vs distinct, obvious even under lower magnification in D. papillatus)., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on pages 19-25, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["de Bovee, F. (1977) Nematodes interstitiels des iles Kerguelen. Comite National Francais des Recherches Antarctiques, 42, 295 - 303.","Timm, R. W. (1963) Marine nematodes of the suborder Monhysterina from the Arabian Sea at Karachi. Proceedings of the Helminthological Society of Washington, 30, 34 - 49.","de Man, J. G. (1889) Especes et genres nouveaux de Nematodes libres de la mer du Nord et de la Manche. Memoires de la Societe zoolgique de France, 2, 1 - 10.","Lorenzen, S. (1969) Freilebende Meeresnematoden aus dem Schlickwatt und den Salzwiezen der Nordseekuste. Veroffentlichungen des Instituts fur Meeresforschung in Bremerhaven, 11, 195 - 238.","Platt, H. M. & Warwick, R. M. (1988) Free living marine nematodes. Part II. British chromadorids. Synopses of the British Fauna, 38, 1 - 502."]}

Deontolaimus catalinae sp. n. (Figs 7–8; Table 4) Type material examined. Holotype male (slide # Type- 8771), and ten male and eight female paratypes (slides # Type- 8771 —Type- 8775) deposited in the invertebrate type collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Type locality. Soft mud from 44 m deep, Gullmarn Fjord near Fiskebäckskil, Sweden (N 58 ° 15 ' 37 '', E 11 ° 27 ' 43 ''), 11 August 2011, legit O. Holovachov. Description. Adult. Body slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; weakly ventrally curved upon fixation, especially so in posterior part. Cuticle annulated; annules without ornamentation. Lateral field present, single cuticular ridge weakly demarcated by two lines extending from intestinal region to posterior part of tail. Crystalloids absent. Body pores and epidermal glands absent. Somatic sensilla present, equally distributed along entire body; anterior-most somatic sensilla are located short distance posterior to amphid, near onchiostyle base. Labial region truncate conoid, continuous with body contour; lips fused. There is a narrow slit-like structure on the dorsal side from the oral opening, which function and homology is unclear. Annulation along anterior-most part of body very weak; anterior-most annule appearing posterior to amphid and cephalic sensilla bases. Inner labial sensilla small papilliform, distinct, located on the anterior surface of labial region. Outer labial sensilla small pore-like, located on the outer surface of labial region. Cephalic sensilla setiform, equal to 0.2 labial region diameter in length, their bases are located at level with posterior margin of amphid. Subcephalic and cervical sensilla absent. Amphidial aperture circular, fovea ventrally-unispiral, making one turn, located in front of cephalic sensilla bases. Ocelli absent. Nerve ring surrounding pharynx just anterior to its middle. Hemizonid not seen. Secretory-excretory system present; renette cell located on left-hand side of body along anterior part of intestine; it extends anteriorly along ventral side of pharynx, excretory ampulla indistinct. Excretory canal weakly cuticularised, extends from renette cell for a short distance and opens to exterior on ventral side of anterior body end, short distance posterior to onchiostyle base, anterior to anterior-most alveolum in males. Oral opening terminal. Buccal cavity uniformly tubular: cheilostom barrel-shaped; stegostom tubular, with large dorsal onchiostyle. Onchiostyle with bluntly rounded tip and subcylindrical body. Pharynx muscular in its anterior part and glandular in its posterior part, cylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Dorsal pharyngeal gland orifice opens at base of onchiostyle; orifices of subventral pharyngeal glands indistinct. Cardia short, embedded in intestine. Tail similar in shape in both sexes (more curved ventrad in male) elongate-conoid, ventrally curved. Three caudal glands present, their nuclei are incaudal. Spinneret short, thornlike, unsclerotized, functional. Male. Reproductive system diorchic, both testes outstretched. Spicules paired, symmetrical, with arcuate subcylindrical shaft and small manubrium; manubrium is ventrally inclined. Gubernaculum present, plate-like, with paired dorsal apophysis. Alveolar supplements present along anterior half of body, extending from anterior body end to about middle of body, they are very small slit-like. Tubular supplements absent. Midventral precloacal sensilla absent. Two postcloacal sensilla present, located subventrally at level of posterior one-third of tail length; sclerotized lamina absent. Tail with two pairs of papilliform sensilla: first (counting from cloaca) subventral pair located short distance posterior to cloacal opening, second subventral pair located at posterior one third of tail length. Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 128–248 µm long (equal to 8.2–15.3 % of total body length), located on right-hand side of intestine (n = 5), posterior genital branch 155–272 µm long (equal to 10.0– 16.8 % of total body length), located on left-hand side of intestine (n = 5). Oviduct short. Spermathecae filled with sperm. Uterus voluminous. Vagina straight, 0.2– 0.4 times vulval body diameter long. Epiptygmata, pars refringens vaginae and sensitive structures around vulva absent. Rectum 0.9–1.1 anal body diameters long. Diagnosis. Deontolaimus catalinae sp. n. is characterized by having body 1.3–1.7 mm long; anterior-most somatic sensilla located short distance posterior to amphid; cephalic sensilla equal to 0.2 labial region diameter in length; amphidial fovea ventrally-unispiral with one turn, located in front of cephalic sensilla bases; excretory pore located short distance posterior to onchiostyle base; onchiostyle with bluntly rounded tip and subcylindrical body; male with alveolar supplements extending from anterior end to middle of body, tubular supplements absent; spicules 36–40 µm long; didelphic female reproductive system. Remarks. Our specimens are similar to Camacolaimus barbatus described by Pastor de Ward (1984) from Argentina in body measurements, shape of anterior body end, shape of spicules, gubernaculum and spinneret, and presence of fine slit-like supplements in male (C. Pastor, in litt. 3 June 2015). It differs in having shorter cephalic setae (1.5 µm in Swedish specimens vs 4 µm in specimens from Argentina) and shorter spicules (36–40 µm in Swedish specimens vs 45–50 µm in specimens from Argentina). The new species closely resembles Deontolaimus parvus (Timm, 1961) comb. n. in having the excretory pore located close to anterior body end. No other species of Deontolaimus is known to share this feature with D. catalinae sp. n. These two species, however, can be easily separated from each other based on the following characters: body size (1.28–1.66 mm in D. catalinae sp. n. vs 0.73–0.75 mm in D. parvus) and position of excretory pore (9–17 µm from cephalic setae bases in D. catalinae sp. n. vs at level with cephalic sensilla bases in D. parvus).

Camacolaimus propinquus Allg��n, 1929 (Fig. 19) Type material. Lectotype female (slide # Type- 3381) deposited in the invertebrate type collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Specimen is partly dried out and is in poor condition. Female. Body slender, fusiform over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation. Cuticle annulated. Lateral field, body pores, epidermal glands and subcephalic, cervical and somatic sensilla cannot be observed. Labial region rounded, continuous with body contour. Inner and outer labial, and cephalic sensilla indistinct. Amphid indistinct. Ocelli absent. Nerve ring, hemizonid and secretory-excretory system cannot be observed. Oral opening terminal. Onchiostyle relatively long and robust. Pharynx cylindrical anteriorly, expanding posteriorly; with strongly expanded dorsal glandular sector. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Vagina straight. Epiptygmata and pars refringens vaginae absent. Rectum short. Tail elongateconoid, ventrally curved. Spinneret acute, straight. Discussion. Description and illustrations of this species superficially match the diagnosis of the family Camacolaimidae (in particular the genera Deontolaimus and Procamacolaimus in having a single dorsal onchiostyle and a paired female reproductive system). Absence of males prevents from more precise identification of this species. It cannot be matched to any of the recently discovered Swedish populations of the genus Deontolaimus. It is considered species inquirenda et incerta sedis within the family Camacolaimidae., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on page 34, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["Allgen, C. (1929) Neue freilebende marine Nematoden von der Westkuste Schwedens. Zoologischer Jahrbucher, Abteilung fur Systematik, 57, 431 - 496."]}

Onchium parocellatum (Allg��n, 1940) Gerlach, 1962 (Figs 6���8; Table 3) Type material. Lectotype female (slide # Type ��� 8699) from the collection of C. Allg��n. Additional material. Four females (slides # 139325���139328) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Type locality. Norway, Vega. Additional localities. Sand and shells from 15���22 m deep, Bonden island in Skagerrak off the west coast of Sweden (N 58 12 ' 37 '', E 11 18 ' 53 ''), 0 9 August 2011, legit O. Holovachov (one female); gravel, mud and algae from 30���70 m deep, Skagerrak off the west coast of Sweden (N 58 �� 22 ' 14 '', E 11 �� 05' 00''), 0 9 August 2011, legit O. Holovachov (one female); coarse gravel from 30���50 m deep, Skagerrak off the west coast of Sweden (N 58 �� 17 ' 58 '', E 11 �� 10 ' 05''), 0 9 August 2011, legit O. Holovachov (two females). Description. Male. Not found. Female. Body slender, weakly fusiform or cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation, especially so along tail. Cuticle finely annulated; annules without ornamentation. Lateral field absent. Crystalloids absent. Body pores and epidermal glands absent. Somatic sensilla present, most prominent along pharyngeal region and on tail; anteriormost somatic sensilla are located anterior to ocelli. Labial region rounded, continuous with body contour; lips fused. Annulation along anteriormost part of body very weak; cuticle encircling labial region does not form "cephalic capsule". Inner and outer labial sensilla indistinct. Cephalic sensilla setiform. Subcephalic and cervical sensilla absent. Amphidial fovea ventrally-unispiral, located anterior to cephalic sensilla bases. Ocelli present, each ocellum consists of anteriorly located small opaque "lens" and posteriorly located large pigment body; two such bodies are present on left body side in lectotype specimen. Nerve ring surrounding pharynx at anterior third of its length. Hemizonid not seen. Secretory-excretory system present; renette cell visible only in some specimens, located on right-hand side of body, along anterior part of intestine; it extends anteriorly along ventral side of pharynx and forms an excretory ampulla just posterior to nerve ring level. Excretory canal weakly cuticularised, extends from excretory ampulla anteriorly towards lip region and opens to exterior on ventral side, at base of lips, anterior to cephalic sensilla. Oral opening terminal. Buccal cavity uniformly tubular: cheilostom barrel-shaped; stegostom tubular, with large dorsal onchiostyle. Onchiostyle uniformly cylindrical, bluntly rounded; connected to dorsal body side by oblique muscles. Pharynx glandular, cylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Dorsal pharyngeal sector strongly developed over entire pharynx length, more so in its posterior part. Subventral pharyngeal sectors weakly developed along anterior part (anterior to nerve ring) and indistinct posterior to nerve ring level. Dorsal pharyngeal gland orifice opens at base of onchiostyle; orifices of subventral pharyngeal glands indistinct. Cardia short, embedded in intestine. Several large coelomocytes are present on each body side along posterior part of pharynx and entire intestine, their cell bodies extend anteriorly into narrow ducts that are located laterally. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 183���224 ��m long (equal to 6.9���9.9 % of total body length), located on right-hand side of intestine (n = 4), posterior genital branch 179���335 ��m long (equal to 6.8���12.7 % of total body length), located on left-hand side of intestine (n = 4). Oviduct narrow, tubular. Spermathecae filled with sperm. Uterus composed of large cells. Vagina straight, 0.1���0.3 times vulval body diameters long. Epiptygmata, pars refringens vaginae and sensitive structures around vulva absent. Rectum 0.6���1.2 anal body diameters long. Tail elongate-conoid, ventrally curved. Three caudal glands present, their nuclei are incaudal. Spinneret broad conoid, functional. Diagnosis. Onchium parocellatum is particularly characterised by the 2.27���2.92 mm long body; anterior end without cephalic capsule; anteriormost somatic sensilla located anterior to ocelli; ocelli with small opaque "lens" and large pigment body; excretory pore located at base of lips, anterior to cephalic sensilla; onchiostyle uniformly cylindrical; male unknown. Remarks. Allg��n's slide includes two specimens, one complete female drawn by Allg��n (1940, Figs 4 a���b) here designated as lectotype of Onchium parocellatum, and one partial specimen belonging to Onchium robustum Gerlach, 1965. Although strongly flattened (Fig. 7), the lectotype still clearly shows major diagnostic features of this species, including the shape of the anterior end, shape and size of onchiostyle, size of ocelli and position of excretory pore. This species can be easily distinguished from closely related O. ocellatum by position of the excretory pore (at base of lips vs. at level of nerve ring in O. ocellatum) and from O. robustum by shape of the anterior body end (without cephalic capsule vs. with cephalic capsule in O. robustum), shape of onchiostyle (cylindrical vs. expanding posteriorly in O. robustum) and position of excretory pore (at base of lips vs. at level between onchiostyle base and ocellus in O. ocellatum)., Published as part of Holovachov, Oleksandr, 2015, Swedish Plectida (Nematoda). Part 8. The genus Onchium Cobb, 1920, pp. 521-546 in Zootaxa 3911 (4) on pages 531-536, DOI: 10.11646/zootaxa.3911.4.3, http://zenodo.org/record/242601, {"references":["Allgen, C. (1940). Uber einige neue freilebende Nematoden von der Nordwest - und Nordkuste Norwegens. Folia Zoologica et Hydrobiologica, 10, 443 - 449.","Gerlach, S. (1962) Freilebende Meeresnematoden von den Malediven. Kieler Meeresforschungen, 18, 81 - 108.","Gerlach, S. (1965) Freilebende Meersenematoden aus der Gezeitenzone von Spitzbergen. Veroffentlichungen des Instituts fur Meeresforschungen in Bremerhaven, 9, 109 - 172."]}

Camacolaimus austrogeorgiae Allg��n, 1959 Type material. Not found. Comments. Description and illustrations of this species match superficially the diagnosis of the family Camacolaimidae, in particular the genera Deontolaimus and Procamacolaimus in presence of single dorsal onchiostyle and paired female reproductive system (Allg��n 1959: 167, Fig. 172 a���b). Absence of males prevents from more precise identification of this species. It is considered species inquirenda et incerta sedis within the family Camacolaimidae., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on page 27, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["Allgen, C. A. (1959) Freeliving marine nematodes. Further Zoological Results of the Swedish Antarctic Expedition 1901 - 1903, 5, 1 - 293."]}

Camacolaimus macrocellatus Allg��n, 1959 (Fig. 16) Type material. Lectotype juvenile (slide # Type- 8739) deposited in the invertebrate type collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Specimen is completely dried out and is in poor condition. Juvenile. Body plump, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail. Cuticle annulated. Lateral field, body pores, epidermal glands and subcephalic, cervical and somatic sensilla cannot be observed. Anterior body end damaged. Ocelli present. Nerve ring, hemizonid and secretory-excretory system cannot be observed. Pharynx poorly preserved. Reproductive system absent. Tail short-conoid, ventrally curved. Spinneret present. Discussion. Available morphological data is not sufficient to identify this specimen with confidence. The species is considered species inquirenda et incerta sedis within Nematoda., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on page 31, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["Allgen, C. A. (1959) Freeliving marine nematodes. Further Zoological Results of the Swedish Antarctic Expedition 1901 - 1903, 5, 1 - 293."]}

Camacolaimus falklandiae Allg��n, 1959 (Fig. 14) Type material. Lectotype female (slide # Type- 8738) deposited in the invertebrate type collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Specimen is completely dried out and is in poor condition. Female. Body slender, fusiform; strongly ventrally curved upon fixation, especially so along tail. Cuticle, lateral field, body pores, epidermal glands and subcephalic, cervical and somatic sensilla cannot be observed. Anterior body end obscure. Nerve ring, hemizonid and secretory-excretory system cannot be observed. Posterior part of pharynx glandular. Reproductive system indistinct. Caudal glands indistinct. Spinneret acute. Discussion. Description and illustrations of this species match superficially the diagnosis of the family Camacolaimidae, in particular the genera Deontolaimus and Procamacolaimus in presence of single dorsal onchiostyle and paired female reproductive system (Allg��n 1959: 168, Fig. 174 a���b). Recent observations failed to add any more morphological data to the original description. Absence of males prevents from more precise identification of this species. It is considered species inquirenda et incerta sedis within the family Camacolaimidae., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on page 29, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["Allgen, C. A. (1959) Freeliving marine nematodes. Further Zoological Results of the Swedish Antarctic Expedition 1901 - 1903, 5, 1 - 293."]}

Onchium metocellatum (Wieser, 1956) Gerlach & Riemann, 1973 (Figs 3���5; Table 2) Material examined. Four males and ten females (slides # 139317 ���139324, 139331, 139335) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Habitat and locality. Sand and shells from 15���22 m deep, Bonden island in Skagerrak off the west coast of Sweden (N 58 12 ' 37 '', E 11 18 ' 53 ''), 0 9 August 2011, legit O. Holovachov (one female); gravel, mud and algae from 30���70 m deep, Skagerrak off the west coast of Sweden (N 58 �� 22 ' 14 '', E 11 �� 05' 00''), 0 9 August 2011, legit O. Holovachov (one female); algae from 20���40 m deep, Skagerrak off the west coast of Sweden (N 58 �� 21 ' 49 '', E 11 �� 04' 42 ''), 0 9 August 2011, legit O. Holovachov (one male), coarse gravel from 30���50 m deep, Skagerrak off the west coast of Sweden (N 58 �� 17 ' 58 '', E 11 �� 10 ' 05''), 0 9 August 2011, legit O. Holovachov (two females); algae from 15���55 m deep, Skagerrak off the west coast of Sweden (N 58 �� 17 ' 24 '', E 11 �� 10 ' 48 ''), 0 9 August 2011, legit O. Holovachov (one female); coarse sediment with algae from 45���55 m deep, Skagerrak off the west coast of Sweden (N 58 �� 17 ' 32 '', E 11 �� 11 ' 24 ''), 0 9 August 2011, legit O. Holovachov (three males and five females). Description. Male. Body slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation, especially so in posterior part. Cuticle finely annulated; annules without ornamentation. Lateral field absent. Crystalloids absent. Body pores and epidermal glands absent. Somatic sensilla present, most prominent along pharyngeal region and on tail; anteriormost somatic sensilla are located posterior to ocelli. Labial region rounded, continuous with body contour; lips fused. Annulation along anteriormost part of body very weak; cuticle encircling labial region does not form "cephalic capsule". Inner and outer labial sensilla indistinct. Cephalic sensilla setiform. Subcephalic and cervical sensilla absent. Amphidial fovea ventrally-unispiral, located anterior to cephalic sensilla bases. Ocelli present, each ocellum consists of two small opaque round bodies which are often more visible in males than in females. Nerve ring surrounding pharynx at anterior third of its length. Hemizonid not seen. Secretory-excretory system present; renette cell indistinct; excretory ampulla just posterior to nerve ring level. Excretory canal weakly cuticularised, extends from excretory ampulla anteriorly along ventral side of pharynx and opens to exterior at base of labial region. Oral opening terminal. Buccal cavity uniformly tubular: cheilostom barrel-shaped; stegostom tubular, with large dorsal onchiostyle. Onchiostyle with sharp anterior cone, cylindrical shaft and bifurcated base; connected to dorsal body side by oblique muscles. Pharynx glandular, cylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Dorsal pharyngeal sector strongly developed over entire pharynx length, more so in its posterior part. Subventral pharyngeal sectors weakly developed along anterior part (anterior to nerve ring) and indistinct posterior to nerve ring level. Dorsal pharyngeal gland orifice opens at base of onchiostyle; orifices of subventral pharyngeal glands indistinct. Cardia indistinct. A few coelomocytes present on each body side along the intestine. Reproductive system diorchic, both testes outstretched. Spicules paired, symmetrical, with weakly curved subcylindrical shaft and small manubrium; manubrium is ventrally inclined. Gubernaculum present, plate-like. Alveolar supplements recognizable in some specimens along pharyngeal region but their number can not be assessed with certainty. Tubular supplements absent. Midventral precloacal sensilla absent. Tail with two subventral pairs of papilliform sensilla. Tail elongate-conoid, ventrally curved. Three caudal glands present, their nuclei are incaudal. Spinneret conoid, functional. Female. Body slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation, especially so along tail. Cuticle finely annulated; annules without ornamentation. Lateral field absent. Crystalloids absent. Body pores and epidermal glands absent. Somatic sensilla present, most prominent along pharyngeal region; anteriormost somatic sensilla are located at level with or posterior to ocelli. Labial region truncated, continuous with body contour; lips fused. Annulation along anteriormost part of body very weak; cuticle encircling labial region does not form a "cephalic capsule". Inner and outer labial sensilla indistinct. Cephalic sensilla setiform. Subcephalic and cervical sensilla absent. Amphidial fovea ventrally-unispiral, located anterior to cephalic sensilla bases. Ocelli present, each ocellum consists of two small opaque round bodies. Nerve ring surrounding pharynx at anterior third of its length. Hemizonid not seen. Secretory-excretory system present; renette cell visible only in some specimens, located on the left-hand side of body, along anterior part of intestine; it extends anteriorly along ventral side of pharynx and forms an excretory ampulla just posterior to nerve ring level. Excretory canal weakly cuticularised, extends from excretory ampulla anteriorly along ventral side of pharynx and opens to exterior at base of labial region. Oral opening terminal. Buccal cavity uniformly tubular: cheilostom barrel-shaped; stegostom tubular, with large dorsal onchiostyle. Onchiostyle with sharp anterior cone, cylindrical shaft and bifurcated base; connected to the dorsal body side by oblique muscles. Pharynx glandular, cylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Dorsal pharyngeal sector strongly developed over entire pharynx length, more so in its posterior part. Subventral pharyngeal sectors weakly developed along anterior part (anterior to nerve ring) and usually becoming indistinct posterior to nerve ring level. Dorsal pharyngeal gland orifice opens at base of onchiostyle; orifices of subventral pharyngeal glands indistinct. In general, onchiostyle and pharynx are more strongly developed in females than in males. Cardia short, embedded in intestine. A few large coelomocytes are present on each body side along intestine. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 160���245 ��m long (equal to 8.8���13.2 % of total body length), located on right-hand side of intestine (n = 9), posterior genital branch 119���260 ��m long (equal to 6.2���14.1 % of total body length), located on left-hand side of intestine (n = 9). Oviduct narrow tubular. Spermathecae filled with spermatozoa. Uterus composed of large cells. Vagina straight, 0.2���0.4 times vulval body diameters long. Epiptygmata, pars refringens vaginae and sensory structures around vulva absent. Rectum 0.8���1.6 anal body diameters long. Tail elongate-conoid, ventrally curved. Three caudal glands present, their nuclei are incaudal. Spinneret conoid, functional. Diagnosis. Onchium metocellatum is particularly characterised by having 1.23���2.04 mm long body; anterior end without cephalic capsule; anteriormost somatic sensilla located at level with or posterior to ocelli; each ocellum consists of two small opaque round bodies; excretory pore located at base of lips, anterior to cephalic sensilla; onchiostyle with sharp anterior cone, cylindrical shaft and bifurcated base; male with alveolar supplements along pharyngeal region, tubular supplements absent; spicules arcuate and 17���24 ��m long. Remarks. We base our identification mainly on the size and shape of the onchiostyle and the position of ocelli relative to it: in both the recent population and in the original description provided by Cobb (1920) under the name Onchulella ocellata (later renamed to Onchium metocellatum Wieser, 1956) the onchiostyle is large and solid, and the ocelli are located at its base. Other characters mentioned in the original description of Onchulella ocellata are characteristic for the genus Onchium in general and can not be used for species identification. The only difference between the recent population and the female described by Cobb (1920) is the shape of the ocelli (consisting of two small opaque round bodies in recent specimens vs. yellowish with colourless lens in the original specimen). However, as shown in Onchium ocellatum, the shape of ocelli is variable within one species and can not be used as a sole distinguishing character in the genus Onchium. Camacolaimus conicaudatus Allg��n, 1935 is synonymized with Onchium metocellatum on the same basis���shape and size of onchiostyle and position of ocelli are identical in our specimens and in C. conicaudatus as described by Allg��n (1935)., Published as part of Holovachov, Oleksandr, 2015, Swedish Plectida (Nematoda). Part 8. The genus Onchium Cobb, 1920, pp. 521-546 in Zootaxa 3911 (4) on pages 527-531, DOI: 10.11646/zootaxa.3911.4.3, http://zenodo.org/record/242601, {"references":["Gerlach, S. A. & Riemann, F. (1973) The Bremerhaven Checklist of Aquatic Nematodes. A Catalogue of Nematoda Adenophorea excluding the Dorylaimida. Veroffentlichungen des Instituts fur Meeresforschung in Bremerhaven, Supplement Band, 4, 1 - 736.","Cobb, N. A. (1920) One hundred new nemas (type species of 100 new genera). Contribution to a science of Nematology, 9, 217 - 343.","Allgen, C. (1935) Die freilebenden Nematoden des Oresunds. Capita Zoologica, 6, 5 - 192."]}

Leptolaimoides filicaudatus sp. n. (Fig 3; Table 1) Type material. Holotype male (slide # Type- 8621) and two female paratypes (slides # Type- 8622 and Type- 8323) deposited in the type invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Additional material. One male and one female (slides # 140599 ��� 140600) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Type locality. Coarse sediment with algae from 45���55 m deep, Skagerrak off the coast of Sweden (N 58 �� 17 ' 32 '', E 11 �� 11 ' 24 ''), 0 9 August 2011, legit O. Holovachov (one male and two females). Additional localities. Mud and gravel from 40���60 m deep, Skagerrak off the coast of Sweden (N 58 �� 18 ' 06'', E 11 �� 05' 22 ''), 0 9 August 2011, legit O. Holovachov (one male); gravel, mud and algae from 30���70 m deep, Skagerrak off the coast of Sweden (N 58 �� 22 ' 14 '', E 11 �� 05' 00''), 0 9 August 2011, legit O. Holovachov (one female). Etymology. The specific epithet " filicaudatus " refers to very long filiform tail in this species. Description. Adult. Body tapering anteriorly in pharyngeal region and posteriorly on tail; straight or variously curved upon fixation, more strongly curved ventrad in posterior part in males. Maximum body diameter at vulva in female; male body more cylindrical. Cuticle finely annulated; annuli without ornamentation; annulation at level of amphid same as annulation along rest of body. Lateral field present, consists of single alae (two incisures), 1 ��m wide at mid-body; arising short distance posterior to amphid and extending posteriorly to proximal 1 / 5 th of tail. Posterior-most part of the lateral field (along tail) becomes areolated. Prominent body pores in sublateral position at both sides of lateral field present, arising from oval lateral epidermal gland cells; usually three pairs of body pores are present along pharyngeal region; several body pores scattered over rest of body. Anterior-most body pore located posterior to amphid, at level of procorpus. Labial region rounded, continuous with body contour, lips fused. Inner and outer labial sensilla indistinct. Cephalic sensilla papilliform. Subcephalic and cervical sensilla and ocelli absent. Amphidial fovea elongated; located at level of posterior part of stoma and anterior part of procorpus. Nerve ring surrounding pharynx at level of anterior part of isthmus. Hemizonid not seen. Secretory-excretory system indistinct. Buccal cavity uniformly tubular: cheilostom and gymnostom short, undifferentiated; stegostom tubular, with uniformly thickened lumen. Pharynx muscular, cylindrical anteriorly, with weakly developed pyriform basal bulb; valvular apparatus absent. Anterior cylindrical part of pharynx subdivided by breaks in muscular pharyngeal tissue into cylindrical procorpus, cylindrical metacorpus and narrow isthmus. Pharyngeal glands and their orifices indistinct. Cardia cylindrical, its posterior part embedded in intestine. Tail almost similar in shape in both sexes, elongate-conoid in its proximal part (equal to 18���21 % of total tail length), filiform in its distal part. Caudal glands indistinct. Spinneret absent. Male. Reproductive system diorchic; anterior testis outstretched, located on right hand side of intestine; posterior one reflexed. Spicules paired, symmetrical, with arcuate subcylindrical calamus and ovoid manubrium. Gubernaculum 5 ��m long, plate-like, with 10 ��m long caudal apophysis. Accessory apparatus composed of one midventral precloacal papilliform sensillum located at level with spicule manubrium; tubular and alveolar supplements absent. Sublateral precloacal sensilla absent, four caudal sensilla arranged in two subventral pairs. Four small papillae located at the posterior edge of lateral field, one subventral pair and one subdorsal pair. Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 50���65 ��m long (equal to 9���15 % of total body length), located on right-hand side of intestine (n= 3), posterior genital branch 28���56 ��m long (equal to 5���13 % of total body length), located on left-hand side of intestine (n= 3). Oviduct a narrow tube. Two offset, oval, sac-like spermathecae located on each (right and left) side of each (anterior and posterior) gonoduct. Spermathecae and oviducts filled with spermatozoa. Uterus a short tube. Vagina straight, 0.2���0.3 times vulval body diameters long; pars proximalis vaginae encircled by single sphincter muscle; pars refringens vaginae absent. Vulva midventral. Epiptygmata and sensory structures around vulva absent. Supplements absent. Rectum 0.9���1.3 anal body diameters long; surrounded by three gland-like cells at intestinerectum junction. Diagnosis. Leptolaimoides filicaudatus sp. n. is particularly characterised by the 431���543 ��m long body; cephalic sensilla papilliform; amphid 23���26 ��m long, located 9���10 ��m from anterior end; first body pore located 35���37 ��m from anterior end; lateral field simple along most of body, areolated on tail, originating 36���40 ��m from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male without tubular and without alveolar supplements; spicules arcuate and 16 ��m long. Relationships. The new species can be easily separated from all other species of the genus in having unusually long tail, simple lateral field that becomes areolated only along posterior part of tail, and midventral precloacal papilliform sensillum located at level with spicule manubrium. Additional characters separating new species from other members of Leptolaimoides are listed in Table 4., Published as part of Holovachov, Oleksandr, 2015, Swedish Plectida (Nematoda). Part 9. The genus Leptolaimoides Vitiello, 1971, pp. 83-100 in Zootaxa 3955 (1) on pages 87-88, DOI: 10.11646/zootaxa.3955.1.4, http://zenodo.org/record/241458

Deontolaimus longicauda (de Man, 1922) comb. n. (Fig. 6; Table 3) Material examined. One male and three females (slides # 145496���145497) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Habitat and locality. Sand and shells from 15���22 m deep, Bonden island in Skagerrak off the west coast of Sweden (N 58 12 ' 37 '', E 11 18 ' 53 ''), 0 9 August 2011, legit O. Holovachov (one male and three females). Description. Adult. Body slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation, especially so in posterior part. Cuticle annulated; annules without ornamentation. Lateral field present, single cuticular ridge demarcated by two lines extending from anterior part of intestine to posterior part of intestine. Crystalloids absent. Body pores and epidermal glands absent. Somatic sensilla present, equally distributed along entire body; anterior-most somatic sensilla are located 1���11 annules posterior to amphid. Labial region rounded, continuous with body contour; lips fused. Annulation along anterior-most part of body very weak; anterior-most annule appearing posterior to amphid and cephalic sensilla bases. One circle of labial sensilla visible on the anterior surface of labial region, they are small papilliform. Cephalic sensilla setiform, equal to 0.5���0.6 labial region diameter in length, their bases are located short distance posterior to amphid. Subcephalic and cervical sensilla absent. Amphidial fovea ventrallyunispiral, making one turn, located anterior to cephalic sensilla bases. Ocelli absent. Nerve ring surrounding pharynx anterior to its middle. Hemizonid not seen. Secretory-excretory system present; renette cell located on lefthand side of body along anterior part of intestine; it extends anteriorly along ventral side of pharynx and forms excretory ampulla just posterior to nerve ring level. Excretory canal weakly cuticularised, extends from excretory ampulla for a short distance and opens to exterior on ventral side, just posterior to nerve ring. Oral opening terminal. Buccal cavity uniformly tubular: cheilostom barrel-shaped; stegostom tubular, with large dorsal onchiostyle. Onchiostyle with bluntly rounded and strongly sclerotized tip and subcylindrical body. Pharynx muscular in its anterior part and partly glandular in its posterior part, more so in its dorsal sector, cylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Dorsal pharyngeal gland orifice opens at base of onchiostyle; orifices of subventral pharyngeal glands indistinct. Cardia short, embedded in intestine. Tail similar in shape in both sexes (shorter and more curved ventrad in male) elongate-conoid to subcylindrical, ventrally curved. Three caudal glands present, their nuclei are incaudal. Spinneret large conoid, functional. Male. Reproductive system diorchic, both testes outstretched. Spicules paired, symmetrical, with arcuate subcylindrical shaft and small manubrium; manubrium is ventrally inclined. Gubernaculum present, plate-like, with paired dorsal apophysis. Alveolar supplements present along most of the body, extending from anterior body end to posterior part of intestine, ending several body diameters anterior to cloaca, they are very small and located at the bottom of a narrow ventral groove, difficult to count. Tubular supplements absent. Midventral precloacal sensilla absent. Two postcloacal sensilla present, located subventrally at level of posterior third of tail; sclerotized lamina absent. Tail with three pairs of papilliform sensilla: first (counting from cloaca) subventral pair located less than one body diameter posterior to cloacal opening, second subventral pair located at posterior two-thirds of tail length, and third sublateral pair located at posterior one-fifth of tail length. Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 93���103 ��m long (equal to 7.0��� 7.9 % of total body length), located on right-hand side of intestine (n = 3), posterior genital branch 65���128 ��m long (equal to 5.5���8.6 % of total body length), located on left-hand side of intestine (n = 3). Oviduct short. Spermathecae filled with sperm. Uterus voluminous. Vagina straight, 0.3���0.4 times vulval body diameter long. Epiptygmata, pars refringens vaginae and sensitive structures around vulva absent. Rectum 1.0��� 1.1 anal body diameters long. Diagnosis. Deontolaimus longicauda is characterized by having body 1.0��� 1.5 mm long; anterior-most somatic sensilla located short distance posterior to amphid; cephalic sensilla equal to 0.5���0.6 labial region diameter in length; amphidial fovea ventrally-unispiral with one turn, located short distance anterior to cephalic sensilla bases; excretory pore located just posterior to nerve ring level; onchiostyle with bluntly rounded and strongly sclerotized tip and subcylindrical body; male with alveolar supplements extending from anterior end to several body diameters anterior to cloaca, tubular supplements absent; spicules 30 ��m long; didelphic female reproductive system. Remarks. Recent specimens agree well with the original description (de Man 1922) and subsequent redescriptions (De Coninck & Schuurmans Stekhoven 1933; Platt & Warwick 1988) in general body measurements, shape, size and location of amphid, length of cephalic setae, and shape of onchiostyle. The only difference is the shorter tail in our male, however, the specimen is not flat on the slide and cannot be measured with full confidence. V(%) or T(%)?? 49.3? 48���51? 48.4���50.1 Body diameter? 14 19 15���22 21 24���30 Pharynx length? 273 237 ?? 189 194���242 Tail length? 80 90 ?? 64 74���111 Anal or cloacal body diam.? 16 15 ?? 17 16���18, Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on pages 13-15, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["de Man, J. G. (1922) Vrij levende nematoden. Flora en Fauna der Zuiderzee, 1922, 214 - 261.","De Coninck, L. A. & Schuurmans Stekhoven, J. H. (1933) The freeliving marine nemas of the Belgian coast. II. Memoires du Musee Royal d'Histoire Naturelle de Belgique, 58, 1 - 163.","Platt, H. M. & Warwick, R. M. (1988) Free living marine nematodes. Part II. British chromadorids. Synopses of the British Fauna, 38, 1 - 502."]}

Leptolaimoides hexatubulosus Hoang Lai-Phu, Blome, Nguyen Vu Thanh & Saint-Paul, 2009 (Fig 5; Table 2) Material examined. Three males and one female (slides # 140612 ��� 140613) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Habitat and locality. Gravel, mud and algae from 30���70 m deep, Skagerrak off the coast of Sweden (N 58 �� 22 ' 14 '', E 11 �� 05' 00''), 0 9 August 2011, legit O. Holovachov (three males and one female). Description. Adult. Body tapering anteriorly in pharyngeal region and posteriorly on tail; straight or weakly ventrally curved upon fixation, more strongly curved ventrad in posterior part in males. Maximum body diameter at vulva in female; male body more cylindrical. Cuticle annulated; annuli 1.5���2 ��m wide at mid-body, without ornamentation; small region at level of amphid without annulation. Lateral field present, consists of three alae, middle ala smooth, outer alae areolated, 3.5���4 ��m wide at mid-body; originating at posterior end of amphid and extending posteriorly to anterior 2 / 5 th of tail. Prominent body pores in sublateral position at both sides of lateral field present, arising from oval lateral epidermal gland cells; usually three pairs of body pores are present along pharyngeal region; several body pores scattered over rest of body. Anterior-most body pore located posterior to amphid, at level of procorpus. Labial region rounded, continuous with body contour, lips fused. Inner and outer labial sensilla indistinct. Cephalic sensilla papilliform. Subcephalic and cervical sensilla and ocelli absent. Amphidial fovea elongated; located at level of posterior part of stoma. Nerve ring surrounding pharynx at level of anterior part of isthmus. Hemizonid not seen. Secretory-excretory system indistinct. Buccal cavity uniformly tubular: cheilostom and gymnostom short, undifferentiated; stegostom tubular, with uniformly thickened lumen. Pharynx muscular, cylindrical anteriorly, with weakly developed pyriform basal bulb; valvular apparatus absent. Anterior cylindrical part of pharynx subdivided by breaks in muscular pharyngeal tissue into cylindrical procorpus, cylindrical metacorpus and narrow isthmus. Pharyngeal glands and their orifices indistinct. Cardia cylindrical, its posterior part embedded in intestine. Tail almost similar in shape in both sexes (more curved ventrad in male), elongate-conoid in its proximal part (equal to 39���42 % of total tail length), subcylindrical in its distal part. Three caudal glands present, nuclei incaudal. Spinneret functional. Male. Reproductive system diorchic; anterior testis outstretched, located on right hand side of intestine; posterior one reflexed. Spicules paired, symmetrical, with arcuate conoid calamus and ovoid manubrium. Gubernaculum 4���5 ��m long, plate-like, with 8.5���11 ��m long caudal apophysis. Accessory apparatus composed of one midventral precloacal papilliform sensillum located on anterior cloacal lip, five evenly spaced midventral tubular supplements extending for 100���106 ��m from cloaca towards anterior end; alveolar supplements absent. Tubular supplements straight or weakly curved in shape, with blunt tips. Posterior-most tubular supplement 20���27 ��m anterior to cloaca, anterior to spicules. Sublateral precloacal sensilla absent, four caudal sensilla arranged in two subventral pairs. Four small papillae located at the posterior edge of lateral field, one subventral pair and one subdorsal pair. Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 67 ��m long (equal to 11 % of total body length), located on right-hand side of intestine (n= 1), posterior genital branch 79 ��m long (equal to 13 % of total body length), located on left-hand side of intestine (n= 1). Oviduct a narrow tube. Two offset, oval, sac-like spermathecae located on each (right and left) side of each (anterior and posterior) gonoduct. Spermathecae and oviducts filled with oval spermatozoa. Uterus a short tube. Vagina straight, 0.3 times vulval body diameters long; pars proximalis vaginae encircled by single sphincter muscle; pars refringens vaginae absent. Vulva midventral. Epiptygmata and sensory structures around vulva absent. Supplements absent. Rectum surrounded by three gland-like cells at intestine-rectum junction. Diagnosis (supplemented with literature data). Leptolaimoides hexatubulosus is particularly characterised by the 529���638 ��m long body; cephalic sensilla papilliform; amphid 11���16 ��m long, located 8���12 ��m from anterior end; first body pore located 30���35 ��m from anterior end; lateral field areolated, arising 23���24 ��m from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male with five���six tubular and without alveolar supplements; spicules arcuate and 20���21 ��m long. Remarks. Current specimens agree well with the type specimens in general morphology, shape of anterior end, amphids, lateral alae, spicules and gubernaculum. The only differences are longer body length (593���638 ��m vs. 529 ��m in holotype), fewer tubular supplements (five vs six in holotype), shorter amphid (11.0��� 13.5 ��m vs 16 ��m in holotype). Differences in spicule length between our male (20���21 ��m) and holotype male (12 ��m) are caused by different ways of measuring this character (along the arc vs along the chord)., Published as part of Holovachov, Oleksandr, 2015, Swedish Plectida (Nematoda). Part 9. The genus Leptolaimoides Vitiello, 1971, pp. 83-100 in Zootaxa 3955 (1) on pages 90-93, DOI: 10.11646/zootaxa.3955.1.4, http://zenodo.org/record/241458

Holovachov, Oleksandr (2015): Swedish Plectida (Nematoda). Part 9. The genus Leptolaimoides Vitiello, 1971. Zootaxa 3955 (1): 83-100, DOI: http://dx.doi.org/10.11646/zootaxa.3955.1.4

Holovachov, Oleksandr, Boström, Sven (2015): Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880. Zootaxa 4034 (1): 1-44, DOI: http://dx.doi.org/10.11646/zootaxa.4034.1.1

Onchium longispiculum sp. n. (Fig 11; Table 5) Type material. Holotype male (slide # Type ��� 8700) and three male and three female paratypes (slides # Type ��� 8700 ��� Type ��� 8705) deposited in the invertebrate type collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Additional material. One male (slide # 139335) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Type locality. Sand and shells from 15���22 m deep, Bonden island in Skagerrak off the west coast of Sweden (N 58 12 ' 37 '', E 11 18 ' 53 ''), 0 9 August 2011, legit O. Holovachov (four males and three females). Additional locality. Coarse sediment with algae from 45���55 m deep, Skagerrak off the west coast of Sweden (N 58 �� 17 ' 32 '', E 11 �� 11 ' 24 ''), 0 9 August 2011, legit O. Holovachov (one male). Etymology. The specific epithet " longispiculum " refers to the length of the spicules in males of this species, which is unusual for the genus. Description. Male. Body slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation, especially so in posterior part. Cuticle finely annulated; annules without ornamentation. Lateral field absent. Crystalloids absent. Body pores and epidermal glands absent. Somatic sensilla present, most prominent along pharyngeal region and on tail; anteriormost somatic sensilla are located far behind base of onchiostyle. Labial region conoid, continuous with body contour; lips fused; ventral side projects slightly more anteriorly than dorsal side. Annulation along anteriormost part of body very weak; cuticle encircling labial region does not form "cephalic capsule". Inner and outer labial sensilla indistinct. Cephalic sensilla setiform. Subcephalic and cervical sensilla absent. Amphidial fovea ventrally-unispiral, located anterior to cephalic sensilla bases. Ocelli absent. Nerve ring surrounding pharynx at anterior third of its length. Hemizonid not seen. Secretory-excretory system present; renette cell large, located on left-hand side of body along anterior part of intestine; it extends anteriorly along ventral side of pharynx and forms excretory ampulla just posterior to nerve ring level. Excretory canal weakly cuticularised, extends from excretory ampulla anteriorly towards lip region and opens to exterior on ventral side, at base of lips, anterior to cephalic sensilla. Oral opening subterminal. Buccal cavity uniformly tubular: cheilostom barrel-shaped; stegostom tubular, with dorsal onchiostyle. Onchiostyle cylindrical. Pharynx glandular, cylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Dorsal pharyngeal sector strongly developed over entire pharynx length, more so in its posterior part. Subventral pharyngeal sectors weakly developed along anterior part (anterior to nerve ring) and indistinct posterior to nerve ring level. Dorsal pharyngeal gland orifice opens at base of onchiostyle; orifices of subventral pharyngeal glands indistinct. Cardia indistinct. A few large coelomocytes are present on each body side along anterior part of intestine. Reproductive system diorchic, both testes outstretched. Spicules paired, usually asymmetrical, right spicule is often longer than left spicule, with arcuate cylindrical shaft and small manubrium; manubrium ventrally inclined. Gubernaculum present, platelike. Alveolar supplements indistinct. Tubular supplements absent. Midventral precloacal sensilla absent. Tail with three-four subventral papilliform sensilla. Tail elongate-conoid, ventrally curved. Three caudal glands present, their nuclei are incaudal. Spinneret conoid, functional. Female. Body slender, fusiform, tapering anteriorly along pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation, especially so along tail. Cuticle finely annulated; annules without ornamentation. Lateral field absent. Crystalloids absent. Body pores and epidermal glands absent. Somatic sensilla present, most prominent along pharyngeal region; anteriormost somatic sensilla is located far behind base of onchiostyle. Labial region conoid, continuous with body contour; lips fused; ventral side projects a bit more anterior than dorsal side. Annulation along anteriormost part of body very weak; cuticle encircling labial region does not form "cephalic capsule". Inner and outer labial sensilla indistinct. Cephalic sensilla setiform. Subcephalic and cervical sensilla absent. Amphidial fovea ventrally-unispiral, located anterior to cephalic sensilla bases. Ocelli absent. Nerve ring surrounding pharynx at anterior third of its length. Hemizonid not seen. Secretory-excretory system present; renette cell indistinct; excretory ampulla just posterior to nerve ring level. Excretory canal weakly cuticularised, extends from excretory ampulla anteriorly towards lip region and opens to exterior via a pore on ventral side, at basis of lips, anterior to cephalic sensilla. Oral opening subterminal. Buccal cavity uniformly tubular: cheilostom barrelshaped; stegostom tubular, with dorsal onchiostyle. Onchiostyle cylindrical. Pharynx glandular, subcylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Dorsal pharyngeal sector strongly developed over entire pharynx length, more so in its posterior part. Subventral pharyngeal sectors weakly developed along anterior part (anterior to nerve ring) and indistinct posterior to nerve ring level. Dorsal pharyngeal gland orifice opens at base of onchiostyle; orifices of subventral pharyngeal glands indistinct. Cardia indistinct. A few large coelomocytes present on each body side along anterior part of intestine. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 93���141 ��m long (equal to 7.0���9.0% of total body length), located on either right-hand side (n= 2) or left-hand side (n= 1) of intestine, posterior genital branch 131���152 ��m long (equal to 9.1���9.9 % of total body length), located on left-hand side (n= 2) or right-hand side (n= 1) of intestine. Oviduct short. Spermathecae filled with filamentous sperm. Uterus voluminous. Vagina straight, 0.1���0.2 times vulval body diameters long. Epiptygmata, pars refringens vaginae and sensory structures around vulva absent. Rectum 0.9���1.1 anal body diameters long. Tail elongate-conoid, ventrally curved. Three caudal glands present, their nuclei are incaudal. Spinneret conoid, functional. Diagnosis. Onchium longispiculum sp. n. is particularly characterised by 1.34���1.77 mm long body; anterior end without cephalic capsule; anteriormost somatic sensilla located posterior to onchiostyle base; ocelli absent; excretory pore located at basis of lips; onchiostyle uniformly cylindrical; alveolar supplements indistinct, tubular supplements absent; spicules arcuate and 44���65 ��m long. Relationships. Onchium longispiculum sp. n. can be separated from all other valid species of the genus Onchium by the absence of developed ocelli and very long somewhat asymmetrical spicules. Additional characters separating it from other species of the genus Onchium are summarised in the Table 6., Published as part of Holovachov, Oleksandr, 2015, Swedish Plectida (Nematoda). Part 8. The genus Onchium Cobb, 1920, pp. 521-546 in Zootaxa 3911 (4) on pages 540-542, DOI: 10.11646/zootaxa.3911.4.3, http://zenodo.org/record/242601

Leptolaimoides haploopis Jensen, 1978 (Fig 2; Table 1) Material examined. Seven males and seven females (slides # 140604 ��� 140607) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Habitat and locality. Gravel, mud and algae from 30���70 m deep, Skagerrak off the coast of Sweden (N 58 �� 22 ' 14 '', E 11 �� 05' 00''), 0 9 August 2011, legit O. Holovachov (seven males and seven females). Description. Adult. Body tapering anteriorly in pharyngeal region and posteriorly on tail; straight or ventrally curved upon fixation, more strongly curved ventrad in posterior part in males. Maximum body diameter at vulva in female; male body more cylindrical. Cuticle annulated; annuli 1���1.5 ��m wide at mid-body, without ornamentation; annulation at level of amphid same as annulation along rest of body. Lateral field present, consists of three alae, middle ala smooth, outer alae areolated, 3���4 ��m wide at mid-body; arising at the posterior end of amphid and extending posteriorly to mid-tail length. Prominent body pores in sublateral position at both sides of lateral field, arising from oval lateral epidermal gland cells; usually three-four pairs of body pores present along pharyngeal region; several body pores scattered over rest of body. Anterior-most body pore located posterior to amphid and stoma base, at level of procorpus. Labial region rounded, continuous with body contour, lips fused. Inner and outer labial sensilla indistinct. Cephalic sensilla short, setiform, 1���1.5 ��m long. Subcephalic and cervical sensilla and ocelli absent. Amphidial fovea elongated, an inverted U-shaped, inner borders sometimes visible; located at level of posterior part of stoma and anterior part of procorpus. Nerve ring surrounding pharynx at level of anterior part of isthmus. Hemizonid not seen. Secretory-excretory system indistinct. Buccal cavity uniformly tubular: cheilostom and gymnostom short, undifferentiated; stegostom tubular, with uniformly thickened lumen. Pharynx muscular, cylindrical anteriorly, with weakly developed pyriform basal bulb; valvular apparatus absent. Anterior cylindrical part of pharynx subdivided by breaks in muscular pharyngeal tissue into cylindrical procorpus, cylindrical metacorpus and narrow isthmus. Pharyngeal glands and their orifices indistinct. Cardia cylindrical, its posterior part embedded in intestine. Tail almost similar in shape in both sexes (more curved ventrad in male), elongateconoid in its proximal part (equal to 53���60 % of total tail length), subcylindrical in distal. Three caudal glands present, with nuclei incaudal. Spinneret functional. Male. Reproductive system diorchic; anterior testis outstretched, located on right hand side of intestine; posterior one reflexed. Spicules paired, symmetrical, with arcuate subcylindrical calamus and ovoid manubrium. Gubernaculum plate-like, 4���5 ��m long, with 4���6 ��m long double caudal apophysis. Accessory apparatus composed of one midventral precloacal papilliform sensillum located on anterior cloacal lip; tubular and alveolar supplements absent. Sublateral precloacal sensilla absent, four caudal sensilla arranged in two subventral pairs. Four small papillae located at the posterior edge of lateral field, one subventral pair and one subdorsal pair. Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 35���67 ��m long (equal to 7���14 % of total body length), located on right-hand side of intestine (n= 7), posterior genital branch 38���72 ��m long (equal to 8���14 % of total body length), located on left-hand side of intestine (n= 7). Oviduct a narrow tube. Two offset, oval, sac-like spermathecae located on each (right and left) side of each (anterior and posterior) gonoduct. Spermathecae and oviducts filled with oval spermatozoa. Uterus a short tube. Vagina straight, 0.3���0.4 times vulval body diameters long; pars proximalis vaginae encircled by single sphincter muscle; pars refringens vaginae absent. Vulva midventral. Epiptygmata and sensory structures around vulva absent. Supplements absent. Rectum 1.0��� 1.6 anal body diameters long; surrounded by three gland-like cells at intestine-rectum junction. Diagnosis (supplemented with literature data). Leptolaimoides haploopis is particularly characterised by the 455���766 ��m long body; cephalic sensilla 1���1.5 ��m long; amphid 12���30 ��m long, located 8���14 ��m from anterior end; first body pore located 25���32 ��m from anterior end; lateral field areolated, arising 22���29 ��m from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male without tubular and without alveolar supplements; spicules arcuate and 16���24 ��m long. Remarks. Current specimens agree well with the type specimens in general morphology, shape of anterior end, amphids, lateral alae, spicules and gubernaculum. The only differences are shorter body length (455���609 ��m vs. 766 ��m in holotype) and amphid (11.5���20 ��m vs. 30 ��m in holotype)., Published as part of Holovachov, Oleksandr, 2015, Swedish Plectida (Nematoda). Part 9. The genus Leptolaimoides Vitiello, 1971, pp. 83-100 in Zootaxa 3955 (1) on pages 84-85, DOI: 10.11646/zootaxa.3955.1.4, http://zenodo.org/record/241458, {"references":["Jensen, P. (1978) Four nematoda Araeolaimida from the Oresund, Denmark, with remarks on the oesophageal structures in Aegialolaimus. Cahiers de Biologie Marine, 19, 221 - 231."]}

Camacolaimus cylindricauda Allg��n, 1959 (Fig. 13) Type material. Lectotype juvenile (slide # Type- 8740) deposited in the invertebrate type collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. This specimen was described as male in the original publication. Specimen is broken, flattened and is in poor condition. Juvenile. Body slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation. Cuticle smooth. Lateral field, body pores, epidermal glands and subcephalic, cervical and somatic sensilla cannot be observed. Anterior body end obscure. Nerve ring, hemizonid and secretory-excretory system cannot be observed. Pharynx cylindrical anteriorly, expanding posteriorly into a weak basal bulb. Reproductive system indistinct. Structure drawn and described as spicule in the original publication is an artefact. Tail elongate-conoid, straight. Caudal glands and spinneret indistinct. Discussion. Available morphological data is not sufficient to identify this specimen with confidence. It is considered species inquirenda et incerta sedis within Nematoda., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on pages 27-29, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["Allgen, C. A. (1959) Freeliving marine nematodes. Further Zoological Results of the Swedish Antarctic Expedition 1901 - 1903, 5, 1 - 293."]}

Deontolaimus uniformis (Cobb, 1920) comb. n. (Fig. 5; Table 2) Material examined. Four males and one female (slides # 145492���145495) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Habitat and locality. Sand and shells from 15���22 m deep, Bonden island in Skagerrak off the west coast of Sweden (N 58 12 ' 37 '', E 11 18 ' 53 ''), 0 9 August 2011, legit O. Holovachov (two males); coarse gravel from 30���50 m deep, Skagerrak off the coast of Sweden (N 58 �� 17 ' 58 '', E 11 �� 10 ' 05''), 0 9 August 2011, legit O. Holovachov (three males and one female). Description. Adult. Body slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation, especially so in posterior part. Cuticle annulated; annules without ornamentation. Lateral field absent. Crystalloids absent. Body pores and epidermal glands absent. Somatic sensilla present, equally distributed along entire body; anterior-most somatic sensilla are located about two body diameters posterior to amphid. Labial region rounded, continuous with body contour; lips fused. Annulation along anterior-most part of body very weak; anterior-most annule appearing posterior to amphid and cephalic sensilla bases. One circle of labial sensilla visible on the anterior surface of labial region, they are small papilliform. Cephalic sensilla setiform, equal to 0.5���0.6 labial region diameter in length, their bases are located posterior to amphid. Subcephalic and cervical sensilla absent. Amphidial fovea ventrallyspiral, making at least two turns, located short distance anterior to cephalic sensilla bases. Ocelli absent. Nerve ring surrounding pharynx at anterior two-fifth of its length. Hemizonid not seen. Secretory-excretory system present; renette cell located on left-hand side of body along anterior part of intestine; it extends anteriorly along ventral side of pharynx and forms excretory ampulla just posterior to nerve ring level. Excretory canal weakly cuticularised, extends from excretory ampulla for a short distance and opens to exterior on ventral side, just posterior to nerve ring. Oral opening terminal. Buccal cavity uniformly tubular: cheilostom barrel-shaped; stegostom tubular, with large dorsal onchiostyle. Onchiostyle with bluntly rounded tip and subcylindrical body. Pharynx muscular in its anterior part and glandular in its posterior part, cylindrical anteriorly, expanding posteriorly; not subdivided into sections; without bulbs; valvular apparatus absent. Dorsal pharyngeal gland orifice opens at base of onchiostyle; orifices of subventral pharyngeal glands indistinct. Cardia short, embedded in intestine. Tail similar in shape in both sexes (more curved ventrad in male) elongate-conoid to subcylindrical, ventrally curved. Three caudal glands present, their nuclei are incaudal. Spinneret large conoid, with sclerotized distal part, functional. Male. Reproductive system diorchic, both testes outstretched. Spicules paired, symmetrical, with arcuate subcylindrical shaft and small manubrium; manubrium is ventrally inclined. Gubernaculum present, plate-like, with paired dorsal apophysis. Alveolar supplements present along the entire body length, extending from anterior body end to cloaca, they are very small and located at the bottom of a narrow ventral groove. Tubular supplements absent. Midventral precloacal sensilla absent. Single postcloacal sensillum present, located subventrally at level of anterior two-fifth of tail length; sclerotized lamina absent. Tail with three pairs of papilliform sensilla: first (counting from cloaca) subventral pair located about one body diameter posterior to cloacal opening, second subventral pair located at posterior two-fifth of tail length, and third sublateral pair located at posterior one-fifth of tail length. D. uniformis D. exilis Recent specimens Cobb, 1920 Cobb, 1920 Blome, 1982 Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 155 ��m long (equal to 8.2 % of total body length), located on right-hand side of intestine (n = 1), posterior genital branch 148 ��m long (equal to 7.8 % of total body length), located on left-hand side of intestine (n = 1). Oviduct short. Spermathecae indistinct. Uterus voluminous, filled with sperm. Vagina straight, 0.3 times vulval body diameter long. Epiptygmata, pars refringens vaginae and sensitive structures around vulva absent. Rectum 0.7 anal body diameter long. Diagnosis. Deontolaimus uniformis (Cobb, 1920) comb. n. is characterized by having body 1.8���2.4 mm long; anterior-most somatic sensilla located some distance posterior to amphid; cephalic sensilla equal to 0.5���0.6 labial region diameter in length; amphidial fovea ventrally-spiral with two turns, located short distance anterior to cephalic sensilla bases; excretory pore located just posterior to nerve ring level; onchiostyle with bluntly rounded tip and subcylindrical body; male with alveolar supplements extending from anterior end to cloaca, tubular supplements absent; spicules 43���46 ��m long; and didelphic female reproductive system. Relationships. Original description of this species is based on one female from the Atlantic coast of the USA. Swedish specimens agree with the original description in body size, shape of labial region, shape (with two turns) and position (anterior to cephalic sensilla bases) of amphid, relative length (equal to ��� 0.5���0.8 labial region diameters) and position (some distance posterior to amphid) of labial sensilla, shape of onchiostyle, and shape of spinneret. The only morphometric difference between recent specimens and the female described by Cobb (1920) is the relative length of the tail (c' = 4.5 in Swedish specimens vs c' = 3.3 in type female), while the absolute tail length is almost the same (124 ��m in Swedish female vs ��� 120 ��m in type female). The recently collected population also closely resembles Deontolaimus exilis (Cobb, 1920) comb. n. as described by Cobb (1920) in body size and other measurements, shape of labial region, and shape of amphid with two turns. Cobb described three minute supplementary organs located in front of cloaca. Males of recent specimens also have alveolar supplements in the same locations. The Swedish population differs from the original description of D. exilis in having shorter cephalic setae (equal to 0.5���0.6 labial region diameters in Swedish specimens vs equal to> 1 labial region diameter in D. exilis), shape of onchiostyle (without strongly sclerotized dorsal edge in Swedish specimens vs with strongly sclerotized dorsal edge in D. exilis), alveolar supplements extending from anterior end to cloaca (vs present in front of cloaca only in D. exilis), and longer tail (c' = 4.2���5.4 in Swedish specimens vs c' = 3.3 in D. exilis). From the single female of D. exilis described from Germany by Blome (1982), our specimens differ in having shorter cephalic setae (6.5���8.5 ��m Swedish specimens vs 18 ��m in female from Germany), shorter onchiostyle (12���13 ��m Swedish specimens vs 25 ��m in female from Germany), and longer tail (c' = 4.2���5.4 in Swedish specimens vs c' = 3.4 in female from Germany)., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on pages 10-13, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["Cobb, N. A. (1920) One hundred new nemas (type species of 100 new genera). Contribution to a science of Nematology, 9, 217 - 343.","Blome, D. (1982) Systematik der Nematoda eines Sandstrandes der Nordseeinsel Sylt. Mikrofauna Meeresbodens, 86, 1 - 194."]}

Camacolaimus roebergensis Allg��n, 1933 (Fig. 20) Type material. Lectotype juvenile (slide # Type- 8742) deposited in the invertebrate type collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Specimen is partly dried out and is in poor condition. Juvenile. Body slender, cylindrical over most of its length, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; ventrally curved upon fixation. Cuticle annulated. Lateral field present. Body pores, epidermal glands and subcephalic, cervical and somatic sensilla cannot be observed. Labial region rounded, continuous with body contour. Inner and outer labial, and cephalic sensilla indistinct. Amphid indistinct. Ocelli absent. Nerve ring, hemizonid and secretory-excretory system cannot be observed. Oral opening terminal. Onchiostyle relatively long and robust, with its tip strongly sclerotized. Pharynx cylindrical anteriorly, expanding posteriorly. Reproductive system undeveloped. Caudal glands indistinct. Spinneret sharply separated from the tail, acute and strongly sclerotized. Discussion. Studied specimen resembles Procamacolaimus profundus Vitiello, 1974 (species commonly found in our samples from Skagerrak) in the shape of onchiostyle and spinneret. However, it is impossible to be sure that both species are identical without having males of Camacolaimus roebergensis. It is considered species inquirenda et incerta sedis within the family Camacolaimidae., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on pages 34-35, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["Allgen, C. (1933) Freilebende Nematoden aus dem Trondhjemsfjord. Capita Zoologica, 4 (2), 1 - 162.","Vitiello, P. (1974) Considerations sur la systematique des nematodes Araeolaimida et description d'especes nouvelles ou peu connues. Archives de Zoologie experimentale & generale, 115, 651 - 669."]}

Camacolaimus spissus Allg��n, 1959 (Fig. 21) Type material. Lectotype female (slide # Type- 8737) deposited in the invertebrate type collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Specimen is flattened, but is still in relatively good condition with larger structures recognizable. Female. Body plump (flattened), fusiform, tapering anteriorly in anterior half of pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation, especially so along tail. Cuticle finely annulated. Lateral field, body pores, epidermal glands and subcephalic, cervical and somatic sensilla cannot be observed. Inner and outer labial, and cephalic sensilla indistinct. Amphid indistinct. Ocelli absent. Nerve ring, hemizonid and secretory-excretory system cannot be observed. Oral opening terminal. Onchiostyle relatively short and robust. Pharynx cylindrical anteriorly, expanding posteriorly; glandular; its posterior end indistinct. Nuclei of subventral pharyngeal glands distinct. Pharynx overall morphology is similar to that of Onchium Cobb, 1920 (see Holovachov, 2015). with strongly expanded dorsal glandular sector. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Vagina indistinct. Rectum short. Tail conoid, straight. Spinneret acute, straight. Discussion. Pharynx morphology in Camacolaimus spissus resembles that of the genus Onchium in having a distinct subventral pharyngeal gland cell located near half pharynx length, and with entire posterior part of pharynx being glandular with strongly granular content. It is considered species inquirenda et incerta sedis within the family Camacolaimidae., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2015, Swedish Plectida (Nematoda). Part 10. The genus Deontolaimus de Man, 1880, pp. 1-44 in Zootaxa 4034 (1) on pages 36-37, DOI: 10.11646/zootaxa.4034.1.1, http://zenodo.org/record/289820, {"references":["Allgen, C. A. (1959) Freeliving marine nematodes. Further Zoological Results of the Swedish Antarctic Expedition 1901 - 1903, 5, 1 - 293.","Cobb, N. A. (1920) One hundred new nemas (type species of 100 new genera). Contribution to a science of Nematology, 9, 217 - 343.","Holovachov, O. (2015) Swedish Plectida (Nematoda). Part 8. The genus Onchium Cobb, 1920. Zootaxa, 3911 (4), 521 - 546. http: // dx. doi. org / 10.11646 / zootaxa. 3911.4.3"]}

Leptolaimoides leptomicron sp. n. (Fig 6; Table 3) Type material. Holotype male (slide # Type- 8714) deposited in the type invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Additional material. One male and one female (slides # 140614 ��� 140615) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Type locality. Soft bottom 232���240 m deep, Skagerrak, Sweden (N 58 �� 27 ' 36.7 '' ��� 43.3 '', E 10 �� 32 ' 52.0'' - 59.4 ''), 12 September 2012, legit "Inventering Bratten" (one male). Additional localities. Soft bottom 248���316 m deep, Skagerrak, Sweden (N 58 �� 28 ' 22.1 '' - 19.2 '', E 10 �� 29 ' 35.6 '' - 43.6 ''), 11 September 2012, legit "Inventering Bratten" (one male); soft bottom 221���260 m deep, Skagerrak, Sweden (N 58 �� 28 ' 28.0'' ��� 31.1 '', E 10 �� 33 ' 19.1 '' ��� 23.80 ''), 11 September 2012, legit "Inventering Bratten" (one female). Etymology. The specific epithet " leptomicron " is a combination of generic names Lepto laimoides and Anto micron and refers to superficial similarity of this species to both genera. Description. Adult. Body tapering anteriorly in pharyngeal region and posteriorly on tail; strongly ventrally curved upon fixation, more strongly curved ventrad in posterior part in males. Maximum body diameter at vulva in female; male body more cylindrical. Cuticle annulated; annuli 2 ��m wide at mid-body, without ornamentation; small region at level of amphid without annulation. Lateral field present, consists of three alae, middle ala smooth, outer alae areolated, 6���6.5 ��m wide at mid-body; arising at posterior end of amphid and extending posteriorly to proximal third of tail. Prominent body pores in sublateral position at both sides of lateral field present, arising from oval lateral epidermal gland cells; usually four pairs of body pores are present along pharyngeal region; several body pores scattered over rest of body. Anterior-most body pore located posterior to amphid, at level of procorpus. Labial region rounded, continuous with body contour, lips fused. Inner and outer labial sensilla indistinct. Cephalic sensilla papilliform. Subcephalic and cervical sensilla and ocelli absent. Amphidial fovea elongated, an inverted Ushaped, inner borders strongly developed; located at level of posterior part of stoma. Nerve ring surrounding pharynx at level of anterior part of isthmus. Hemizonid not seen. Secretory-excretory system indistinct. Buccal cavity uniformly tubular: cheilostom and gymnostom short, undifferentiated; stegostom tubular, with uniformly thickened lumen. Pharynx muscular, cylindrical anteriorly, with weakly developed pyriform basal bulb; valvular apparatus absent. Anterior cylindrical part of pharynx subdivided by breaks in muscular pharyngeal tissue into cylindrical procorpus, cylindrical metacorpus and narrow isthmus. Pharyngeal glands and their orifices indistinct. Cardia cylindrical, its posterior part embedded in intestine. Tail almost similar in shape in both sexes (more curved ventrad in male), elongate-conoid in its proximal part (equal to 34���36 % of total tail length), subcylindrical in its distal part. Three caudal glands present, their nuclei are incaudal. Spinneret functional. Male. Reproductive system diorchic; anterior testis outstretched, located on right hand side of intestine; posterior one reflexed. Spicules paired, symmetrical, with arcuate cylindrical calamus and ovoid manubrium. Gubernaculum 6.5 ��m long, plate-like, with 12���13.5 ��m long caudal apophysis. Accessory apparatus composed of one midventral precloacal papilliform sensillum located on anterior cloacal lip, three evenly spaced midventral tubular supplements extending for 86���94 ��m from cloaca towards anterior end; alveolar supplements absent. Tubular supplements straight or weakly arcuate in shape, with blunt tips. Posterior-most tubular supplement 31���33 ��m anterior to cloaca, anterior to spicules. Sublateral precloacal sensilla absent, four caudal sensilla arranged in two subventral pairs. Four small papillae located at the posterior edge of lateral field, one subventral pair and one subdorsal pair. Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 112 ��m long (equal to 13 % of total body length), located on right-hand side of intestine (n= 1), posterior genital branch 78 ��m long (equal to 9 % of total body length), located on left-hand side of intestine (n= 1). Oviduct a narrow tube. Two offset, oval, sac-like spermathecae located on each (right and left) side of each (anterior and posterior) gonoduct. Spermathecae and oviducts filled with oval spermatozoa. Uterus a short tube. Vagina straight, 0.3 times vulval body diameters long; pars proximalis vaginae encircled by single sphincter muscle; pars refringens vaginae absent. Vulva midventral. Epiptygmata and sensory structures around vulva absent. Supplements absent. Rectum 1.2 anal body diameters long; surrounded by three gland-like cells at intestine-rectum junction. Diagnosis. Leptolaimoides leptomicron sp. n. is particularly characterised by the 776���847 ��m long body; cephalic sensilla papilliform; amphid 15���17 ��m long, located 9���13 ��m from anterior end; first body pore located 40���46 ��m from anterior end; lateral field areolated, originating 26���28 ��m from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male with three tubular and without alveolar supplements, spicules arcuate and 28���29 ��m long. Relationships. The new species can be easily separated from all other species of the genus in the combination of following characters: largest body size (0.77-0.85 mm) and spicule length (28���29 ��m) in the genus, strongly developed inner borders of amphidial fovea, making it almost an elongated 0-shape; distinct area of cuticle at level of amphid without annulation. Other characters separating new species from other members of Leptolaimoides are listed in Table 4., Published as part of Holovachov, Oleksandr, 2015, Swedish Plectida (Nematoda). Part 9. The genus Leptolaimoides Vitiello, 1971, pp. 83-100 in Zootaxa 3955 (1) on pages 93-96, DOI: 10.11646/zootaxa.3955.1.4, http://zenodo.org/record/241458

Leptolaimoides tubulosus Vitiello, 1971 (Fig 4; Table 2) Material examined. One male and four females (slides # 140616 ��� 140618) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Habitat and locality. Gravel, mud and algae from 30���70 m deep, Skagerrak off the coast of Sweden (N 58 �� 22 ' 14 '', E 11 �� 05' 00''), 0 9 August 2011, legit O. Holovachov (one male and four females). Description. Adult. Body tapering anteriorly in pharyngeal region and posteriorly on tail; straight upon fixation, curved ventrad only in posterior part in males. Maximum body diameter at vulva in female; male body more cylindrical. Cuticle annulated; annuli 1.4���2.1 ��m wide at mid-body, without ornamentation; annulation at level of amphid same as annulation along rest of body. Lateral field present, consists of single alae (two incisures), 1.5���2 ��m wide at mid-body; arising some distance posterior to amphid (metacorpus) and extending posteriorly to anterior 2 / 5 th of tail. Prominent body pores in sublateral position at both sides of lateral field present, arising from oval lateral epidermal gland cells; several pairs of body pores are present along pharyngeal region; several body pores scattered over rest of body. Anterior-most body pore located posterior to amphid, at level of procorpus. Labial region rounded, continuous with body contour, lips fused. Inner and outer labial sensilla indistinct. Cephalic sensilla papilliform. Subcephalic and cervical sensilla and ocelli absent. Amphidial fovea elongated, an inverted Ushaped, inner borders often visible; located at level of posterior part of stoma and anterior part of procorpus. Nerve ring surrounding pharynx at level of anterior part of isthmus. Hemizonid not seen. Secretory-excretory system indistinct. Buccal cavity uniformly tubular: cheilostom and gymnostom short, undifferentiated; stegostom tubular, with uniformly thickened lumen. Pharynx muscular, cylindrical anteriorly, with weakly developed pyriform basal bulb; valvular apparatus absent. Anterior cylindrical part of pharynx subdivided by breaks in muscular pharyngeal tissue into cylindrical procorpus, cylindrical metacorpus and narrow isthmus. Pharyngeal glands and their orifices indistinct. Cardia cylindrical, its posterior part embedded in intestine. Tail almost similar in shape in both sexes (more curved ventrad in male), elongate-conoid in its proximal part (equal to 38���41 % of total tail length in females and 29 % in male), subcylindrical in distal. Three caudal glands present, nuclei incaudal. Spinneret functional. Male. Reproductive system diorchic; anterior testis outstretched, located on right hand side of intestine; posterior one reflexed. Spicules paired, symmetrical, with arcuate cylindrical calamus and ovoid manubrium. Gubernaculum 6 ��m long, plate-like, with caudal apophysis 8 ��m long. Accessory apparatus composed of one midventral precloacal papilliform sensillum located at level with spicules, two midventral tubular supplements extending for 62 ��m from cloaca towards anterior end; alveolar supplements absent. Tubular supplements weakly arcuate in shape, with blunt tips. Posterior-most tubular supplement 40 ��m anterior to cloaca, anterior to spicules. Sublateral precloacal sensilla absent, four caudal sensilla arranged in two subventral pairs. Four small papillae located at the posterior edge of lateral field, one subventral pair and one subdorsal pair. Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 45���69 ��m long (equal to 6���9 % of total body length), located on right-hand side of intestine (n= 4), posterior genital branch 64���86 ��m long (equal to 9���12 % of total body length), located on left-hand side of intestine (n= 4). Oviduct a narrow tube. Two offset, oval, sac-like spermathecae located on each (right and left) side of each (anterior and posterior) gonoduct. Spermathecae and oviducts filled with oval spermatozoa. Uterus a short tube. Vagina straight, 0.3 times vulval body diameters long; pars proximalis vaginae encircled by single sphincter muscle; pars refringens vaginae absent. Vulva midventral. Epiptygmata and sensory structures around vulva absent. Supplements absent. Rectum 1.0��� 1.3 anal body diameters long; surrounded by three gland-like cells at intestine-rectum junction. Diagnosis (supplemented with literature data). Leptolaimoides tubulosus is particularly characterised by the 548���821 ��m long body; cephalic sensilla papilliform; amphid 21���32 ��m long, located 9���17 ��m from anterior end; first body pore located 45���50 ��m from anterior end; lateral field simple, originating 59���65 ��m from anterior end; female without supplements, vagina without pars refringens, vulva midventral; male with two���three tubular and without alveolar supplements; spicules arcuate and 25 ��m long. Remarks. Current specimens agree well with the type specimens in general morphology, shape of anterior end, amphids, lateral alae, spicules and gubernaculum. The only differences are longer body (679���821 ��m vs 548 ��m in holotype) and fever tubular supplements (two vs three in holotype). Differences in spicule length between our male (25 ��m) and holotype male (13 ��m) are caused by different ways of measuring this character (along the arch vs along the chord)., Published as part of Holovachov, Oleksandr, 2015, Swedish Plectida (Nematoda). Part 9. The genus Leptolaimoides Vitiello, 1971, pp. 83-100 in Zootaxa 3955 (1) on page 89, DOI: 10.11646/zootaxa.3955.1.4, http://zenodo.org/record/241458, {"references":["Vitiello, P. (1971) Especes nouvelles de Leptolaimidae (Nematoda) et description du genre Leptolaimoides n. gen. Cahiers de Biologie Marine, 12, 419 - 432."]}

The phylogeny and classification of the superfamily Plectoidea Örley, 1880 is revised on the basis of published and updated morphological data for 35 ingroup and 2 outgroup species. The following features are here considered to support the monophyletic origin of the superfamily: 1) stegostom developed and differentiated into two sections; 2) dorsal gland orifice opening into the second stegostom section; 3) pharynx cylindrical, with distinct subdivision into corpus and postcorpus by the orifices of the subventral pharyngeal glands and a discontinuity in the muscular pharyngeal tissue; 4) corpus cylindrical, with subdivision into procorpus and metacorpus homologues; 5) pharyngeal radii of the corpus with prominent pharyngeal tubes along the procorpus; 6) cuticular lumen of the basal part of postcorpus (within basal bulb if latter is present) is modified to form a valvular apparatus. In addition the inner labial sensilla open inside the cheilostom. New data on postembryonic development of Anaplectus grandepapillatus (Ditlevsen, 1928), Plectus parietinus Bastian, 1865, P. decens Andrássy, 1985 and P. communis Bütschli, 1873 are given and supplemented with a discussion of the phylogenetic significance of the ontogeny in Plectoidea. Following the proposal of a phylogeny, some key events in the evolution of Plectidae Örley, 1880 are discussed. It is suggested that the superfamily Plectoidea includes four families: Pakiridae Inglis, 1983, Chronogastridae Gagarin, 1975, Metateratocephalidae Eroshenko, 1973 and Plectidae. Plectolaimus supplementatus Keppner, 1988 is transferred to the genus Caribplectus Andrássy, 1973. The genus Keralanema Siddiqi, 2003 is considered a junior synonim of Chronogaster Cobb, 1913. The genus Chiloplectus Andrássy, 1984 is considered a junior synonim of Plectus Bastian, 1865. The family Anaplectidae Zell, 1993 is downgraded to the subfamily level

Rhadinema timmi (Vitiello, 1971) comb. n. (Figs 1 ���3, 4 A���E, 5 A & C; Tables 1 & 2) Material examined. 31 males and 25 females (slides # 128858 -128862, 133259- 133266) deposited in the general invertebrate collection of the Department of Zoology, Swedish Museum of Natural History, Stockholm, Sweden. Habitat and locality. Mud from 30���39 m deep, Gullmarn Fjord near Fiskeb��ckskil, Sweden (N 58 �� 15 ' 13 '', E 11 �� 27 ' 31 ''), 21 August 2010, legit M. Cl��ment (eight males and four females); muddy sediment from 53 m deep, Skagerrak, off the coast of Sweden (N 58 �� 20 ' 06'', E 11 �� 09' 24 ''), 0 9 August 2011, legit O. Holovachov (one female); muddy sand 8���15 m deep, Gullmarn Fjord near Fiskeb��ckskil, Sweden (N 58 �� 15 ' 09'', E 11 �� 27 ' 54 ''), 11 August 2011, legit O. Holovachov (11 males and 14 females); soft mud from 44 m deep, Gullmarn Fjord near Fiskeb��ckskil, Sweden (N 58 �� 15 ' 37 '', E 11 �� 27 ' 43 ''), 11 August 2011, legit O. Holovachov (one male); soft bottom 352���374 m deep, Skagerrak, Sweden (N 58 �� 19 ' 15.6 '' ��� 20.9 '', E 10 �� 29 ' 33.5 '' ���34.0''), 10 September 2012, legit "Inventering Bratten" expedition (4 females and 2 males); soft bottom 221���260 m deep, Skagerrak, Sweden (N 58 �� 28 ' 28.0'' ��� 31.1 '', E 10 �� 33 ' 19.1 '' ��� 23.80 ''), 11 September 2012, legit "Inventering Bratten" expedition (2 females and 4 males); soft bottom 232���240 m deep, Skagerrak, Sweden (N 58 �� 27 ' 36.7 '' ��� 43.3 '', E 10 �� 32 ' 52.0'' ��� 59.4 ''), 12 September 2012, legit "Inventering Bratten" expedition (5 males). Description. Adult. Body cylindrical over most of its length, tapering anteriorly in pharyngeal region and posteriorly on tail; straight or curved ventrad upon fixation, more strongly curved ventrad in posterior part in males. Maximum body diameter at vulva in female; male body more cylindrical, with cloacal body diameter the same or somewhat bigger than the diameter at midbody. Cuticle thin and weakly annulated; annuli poorly discernible under the light microscope, without ornamentation. Lateral field absent. Prominent body pores present, arranged in sublateral rows in close pairs on each body side; usually 6���7 body pores are present along each side of pharyngeal region; several body pores scattered over rest of the body. Anteriormost body pore located at level of stoma, just posterior to amphid. Labial region rounded, continuous with body contour, lips fused. Inner labial sensilla indistinct. Outer labial sensilla indistinct under the light microscope, small pore-like as seen under SEM; located on the anterior surface of lips. Cephalic sensilla setiform, equal to 0.3���0.6 of labial region diameter. Subcephalic and cervical sensilla, and ocelli absent. Amphidial fovea round, located at level of middle of stoma. One male specimen with two amphidial foveae on one body side (Fig. 4 D) and normal structure on the other side (Fig. 4 C). Nerve ring surrounding pharynx at level of anterior part of isthmus. Hemizonid not seen. Secretoryexcretory system present, excretory pore located just posterior to nerve ring, renette cell obscure. Buccal cavity uniformly tubular: cheilostom short, with six weakly cuticularised longitudinal rugae; gymnostom short, sclerotized, with bar-shaped rhabdia; stegostom long, tubular, with uniformly thickened lumen. Pharynx muscular, cylindrical anteriorly, with weak basal expansion; basal bulb and valvular apparatus absent. Anterior cylindrical part of pharynx subdivided by breaks in muscular pharyngeal tissue into cylindrical procorpus, cylindrical metacorpus and narrow isthmus. Pharyngeal glands and their orifices indistinct. Cardia short, cylindrical, its posterior part embedded in intestine. Tail almost similar in shape in both sexes (shorter and more curved ventrad in male), elongate-conoid, with subcylindrical distal portion. Three caudal glands present, their nuclei are incaudal. Spinneret functional. Male. Reproductive system diorchic; both testes outstretched. Spicules paired, symmetrical, with arcuate cylindrical calamus and ovoid manubrium; velum present, broad. Gubernaculum plate-like, with long caudal apophysis and short caudal projection located closer to the ventral body side. Accessory apparatus composed of one midventral precloacal papilliform sensillum located anterior to cloaca, at mid-distance between cloaca and posteriormost tubular supplement; 10���11 evenly spaced midventral tubular supplements extending for 300���353 ��m from cloaca towards anterior end; alveolar supplements absent. Tubular supplements straight, complex in shape, with blunt tips. Posteriormost tubular supplement 42���45 ��m anterior to cloaca, anterior to spicules. Precloacal subventral sensilla absent. Caudal setiform sensilla present, 6���8 pairs arranged as follows: 3���5 subventral pairs along the anterior to middle part of tail, one subdorsal, one subventral and another one subdorsal pair towards tail tip. One pair of subventral papilliform sensilla located at about anterior one-third of tail, posterior to the first or second (anteriormost) pair of caudal setiform sensilla. Female. Reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously. Anterior genital branch 197���307 ��m long (equal to 12.1���18.2 % of total body length), located on right-hand side of intestine (n= 6), posterior genital branch 183���335 ��m long (equal to 11.5���20.2 % of total body length), located on left-hand side of intestine (n= 6). Oviduct a narrow tube. Spermathecae as separate structures indistinct. Uterus a wide and long tube. Vagina straight, 0.3���0.5 times vulval body diameters long; pars proximalis vaginae encircled by single sphincter muscle; pars refringens vaginae absent. Vulva midventral, a transverse slit with small wrinkled lips as seen under SEM. Epiptygmata absent. Two small subventral sensillae are seen under SEM, one on each side of the vulva (Fig. 2 F), however, they are indistinct under the light microscope. Rectum 1.1���1.5 anal body diameters long; surrounded by gland-like cells at intestine-rectum junction. Diagnosis (supplemented with literature data). Rhadinema timmi is particularly characterised by the 1.3���1.8 mm long body; rounded labial region weakly offset from body contour; cephalic setae 2���4 ��m long; amphid located 12���19 ��m from anterior end; first body pore located 22���30 ��m from anterior end; lateral field absent; stoma tubular: cheilostom with six weakly cuticularised longitudinal rugae, gymnostom with sclerotized barshaped rhabdia, stegostom long, tubular; female without supplements, vagina without pars refringens, vulva midventral; male with 10���11 tubular and without alveolar supplements; spicules arcuate and 21���30 ��m long. Remarks. Current specimens agree well with the type specimens of R. timmi in general morphology, body size, measurements, shape of anterior end and amphids, number and shape of supplements, shape of spicules and gubernaculum. The only differences are a slightly longer and plumper body in females (L= 1534���1759 ��m vs. L= 1438���1595 ��m in type specimens; a= 55.1���70.4 vs. a= 71.9���88.6 in type specimens), somewhat longer tail in both males (135���148 ��m vs. 120���130 ��m in type specimens) and females (149���162 ��m vs. 145���151 ��m in type specimens), somewhat longer stoma (31���36 ��m vs. 27 ��m in type specimens) and slightly longer spicules (23.5 ��� 30.0 ��m vs. 21.0���23.0 ��m long in type specimens). Vitiello (1971) did not describe longitudinal rugae in the cheilostom in his specimens, but they are rather obvious in his drawings (Vitiello, 1971: Fig. 5 a���b). Unfortunately, the original description of this species is not complete enough to allow any further comparisons. Systematic position. This species fits within the diagnosis of the genus Rhadinema and of the family Rhadinematidae Lorenzen, 1981 but does not fit within the diagnosis of the genus Leptolaimus de Man, 1876 and of the family Leptolaimidae ��rley, 1880 based on the following features: cheilostom with six longitudinal rugae (vs. without rugae in Leptolaimus), lateral field absent (vs. present in Leptolaimus), precloacal sensilla located middistance between the posteriormost supplement and cloacal opening (vs. on the anterior cloacal lip in Leptolaimus); precloacal subventral setiform sensilla absent (vs. present in Leptolaimus). R. timmi can be easily distinguished from the type and only other known species of the genus Rhadinema, R. flexile (Figs 4 F���H, 5 B & D) in a number of morphological and morphometric characters (Cobb, 1920; Lorenzen, 1972; Holovachov & Bostr��m, 2004; Holovachov, 2006): narrower labial region (5.0���8.0 ��m vs. 10.0���13.0 ��m in R. flexile), smaller stoma (vs. stoma bigger and more spacious in R. flexile, see Fig. 4 F), absence of sublateral sensilla around the vulval region in females (vs. present in R. flexile, see Fig. 4 H), more anterior position of vulva (V= 47���50 % vs. V= 59 % in R. flexile), less arcuate spicules, different shape of gubernaculum (caudal apophyses cup-shaped in R. flexile), and longer tail (c'= 6.9���10.8 vs. c'= 5.1���7.2 in R. flexile)., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2014, Swedish Plectida (Nematoda). Part 5. Rhadinema timmi (Vitiello, 1971) comb. n., pp. 477-486 in Zootaxa 3779 (4) on pages 478-483, DOI: 10.11646/zootaxa.3779.4.6, http://zenodo.org/record/230518, {"references":["Vitiello, P. (1971) Especes nouvelles de Leptolaimidae (Nematoda) et description du genre Leptolaimoides n. gen. Cahiers de Biologie Marine, 12, 419 - 432.","Lorenzen, S. (1981) Entwurf eines phylogenetischen Systems der freilebenden Nematoden. Veroffentlichungen des Instituts fur Meeresforschung Bremerhaven, Supplement, 7, 1 - 472.","de Man, J. G. (1876) Onderzoekingen over vrij in de aarde levende Nematoden. Tijdschrift der Nederlandsche dierkundige Vereeniging, 2, 78 - 196.","Orley, L. (1880) Az anguillulidak maganrajza. Termeszetrajzi Fuzetek, 4, 1 - 165.","Cobb, N. A. (1920) One hundred new nemas (type species of 100 new genera). Contributions to a science of Nematology, 9, 217 - 343.","Lorenzen, S. (1972) Die Nematodenfauna im Verklappungsgebiet fur Industriaeabwasser nordwestlich von Helgoland. I. Araeolaimida und Monhysterida. Zoologischer Anzeiger, 187, 223 - 248.","Holovachov, O. & Bostrom, S. (2004) Morphology and systematics of the superfamilies Leptolaimoidea Orley, 1880 and Camacolaimoidea Micoletzky, 1924 (Nematoda: Plectida). Journal of Nematode Morphology and Systematics, 7, 1 - 49.","Holovachov, O. (2006) Morphology and systematics of the order Plectida Malakhov, 1982 (Nematoda). Wageningen University and Research Centre, the Netherlands, 244 pp. Available from: http: // edepot. wur. nl / 121751 (accessed 27 January 2014)"]}

Rhadinema Cobb, 1920 Diagnosis (emended after Holovachov & Bostr��m, 2010). Cuticle annulated, annules smooth, without ornamentation. Lateral alae absent. Epidermal glands present, opening through the distinct body pores. Somatic setae present only on tail, not connected to epidermal glands. Labial region rounded, continuous with body contour, lips fused. First annulus at level of cephalic setae bases, cephalic capsule absent. Inner labial sensilla indistinct. Outer labial sensilla papilliform, located on anterior surface of lips. Cephalic sensilla setiform; their bases located at base of labial region. Subcephalic and cervical sensilla, deirid and ocelli absent. Amphidial fovea round. Secretory-excretory system: renette cell located along the ventral side of intestine; excretory pore located posterior to nerve ring; excretory canal weakly cuticularised, extending from pore for a short distance to the excretory ampulla. Oral opening pore-like. Buccal cavity funnel-shaped or tubular: cheilostom consists of a sclerotised ring with six cuticularised longitudinal rugae: one dorsal, one ventral and four sublateral in position; gymnostom barrelshaped, with parallel, bar-shaped rhabdia; stegostom conoid or tubular, with uniformly thickened lumen, undifferentiated. Radial tubes absent. Arrangement of pharyngeal gland orifices unclear. Pharynx cylindrical anteriorly, gradually widening posteriorly; muscularised with uniformly thickened lumen throughout, lacking valves and bulbs. Anterior cylindrical part of pharynx subdivided by breaks in muscular pharyngeal tissue into cylindrical procorpus, cylindrical metacorpus and narrow isthmus. Cardia embedded in intestine. Female reproductive system didelphic, amphidelphic; ovary branches reflexed antidromously; spermathecae axial; vulva equatorial; vagina straight; pars proximalis vaginae encircled by a single sphincter muscle; pars refringens vaginae absent. Male reproductive system diorchic; testes outstretched; spicules arcuate, with ovoid manubrium, conoid shaft; gubernaculum plate-like with caudal apophysis. Copulatory apparatus: 7���11 tubular supplements, precloacal sensillum present; two postcloacal sensilla; several caudal setae arranged in subventral and dorsosublateral rows. Tail conoid. Three caudal glands present, their nuclei are incaudal. Spinneret functional, not cuticularised., Published as part of Holovachov, Oleksandr & Bostr��m, Sven, 2014, Swedish Plectida (Nematoda). Part 5. Rhadinema timmi (Vitiello, 1971) comb. n., pp. 477-486 in Zootaxa 3779 (4) on page 484, DOI: 10.11646/zootaxa.3779.4.6, http://zenodo.org/record/230518, {"references":["Cobb, N. A. (1920) One hundred new nemas (type species of 100 new genera). Contributions to a science of Nematology, 9, 217 - 343.","Holovachov, O. & Bostrom, S. (2010) Identification of Plectida (Nematoda). EUMAINE, Gent and Nematology, UC Riverside, 98 pp. Available from: http: // www. nrm. se / download / 18.9 ff 3752132 fdaeccb 6800015609 / PLECTIDA % 5 B 1 % 5 D. pdf (accessed 27 January 2014)"]}

Holovachov, Oleksandr, Boström, Sven (2014): Swedish Plectida (Nematoda). Part 5. Rhadinema timmi (Vitiello, 1971) comb. n. Zootaxa 3779 (4): 477-486, DOI: http://dx.doi.org/10.11646/zootaxa.3779.4.6

Halaphanolaimus Southern, 1914 Diagnosis. Halaphanolaimus is a genus of the family Leptolaimidae that belongs to the Chromadorida. It was described by Southern (1914) as ��� Anguillulidae as small size with coarsely striated cuticle. Head small, with posterior circular groove, and single ring of four submedian hairs. Lateral sense-organs are simple spirals. Pharynx narrow with posterior bulb. Lateral line linear, without structure. Spicules paired, with simple accessory pieces. A variable number of ventral tubular chitinous gland-ducts present in both sexes, some on the neck, others in front of the anus.��� Type species. Halaphanolaimus pellucidus Southern, 1914 Relationships. Halaphanolaimus resembles Leptolaimus in general appearance, males always having tubular precloacal supplements, elongated and cuticularised stoma, and circular amphids with a posterior break. Halaphanolaimus can be distinguished from Leptolaimus by having tubular precloacal supplements extending to the neck or pharyngeal region (Platt & Warwick, 1988)., Published as part of ��rkmez, Derya & Brennan, Michael L., 2013, A new species of Halaphanolaimus (Nematoda: Leptolaimidae) from the southern Black Sea (Turkey) with a modified key for species identification, pp. 220-228 in Zootaxa 3691 (2) on page 221, DOI: 10.11646/zootaxa.3691.2.2, http://zenodo.org/record/216947

Ürkmez, Derya, Brennan, Michael L. (2013): A new species of Halaphanolaimus (Nematoda: Leptolaimidae) from the southern Black Sea (Turkey) with a modified key for species identification. Zootaxa 3691 (2): 220-228, DOI: http://dx.doi.org/10.11646/zootaxa.3691.2.2