Hostname: page-component-788cddb947-pt5lt Total loading time: 0 Render date: 2024-10-09T00:29:15.596Z Has data issue: false hasContentIssue false
  • English
  • Français

Description of two new species, Microlaimus paraaffinis sp. nov. and Pseudomicrolaimus major sp. nov. (Nematoda: Microlaimidae), from Yangma Island, the Yellow Sea, China

Published online by Cambridge University Press:  18 September 2023

Wen Guo ,
Mengna Wang  and
Chunming Wang Open the ORCID record for Chunming Wang [Opens in a new window]
Wen Guo
Affiliation:
College of Life Sciences, Liaocheng University, Liaocheng, 252059, P.R. China
Mengna Wang
Affiliation:
College of Life Sciences, Liaocheng University, Liaocheng, 252059, P.R. China
Chunming Wang*
Affiliation:
College of Life Sciences, Liaocheng University, Liaocheng, 252059, P.R. China
*
Corresponding author: Chunming Wang; Email: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Two new species of Microlaimidae: Microlaimus paraaffinis sp. nov. and Pseudomicrolaimus major sp. nov. are described from Yangma Island, the Yellow Sea. M. paraaffinis sp. nov. is characterized by body length 662–785 μm, six inner and six outer labial sensilla papilliform, four short cephalic setae 3–4 μm in length, amphidial fovea cryptocircular at level of buccal cavity, spicules L-shaped with equal thickness, gubernaculum boat shaped, tail conico-cylindrical with short cylindrical portion. P. major sp. nov. is characterized by large body size, six inner labial sensilla papilliform, six outer labial sensilla and four cephalic sensilla setiform, eight subcephalic setae present, amphidial fovea cryptospiral, anterior pharynx region at the buccal cavity widened, posterior pharynx region with oval-shaped bulb, spicules curved with proximal portion enlarged, gubernaculum boat shaped, tail short and conical. Pictorial key to genus Pseudomicrolaimus is given.

Keywords

Free-living marine nematodeNematodataxonomy
Type
Research Article
Information
Journal of the Marine Biological Association of the United Kingdom , Volume 103 , 2023 , e74
Copyright
Copyright © The Author(s), 2023. Published by Cambridge University Press on behalf of Marine Biological Association of the United Kingdom

Introduction

To study the diversity and taxonomy of free-living marine nematodes in Yangma Island, undisturbed sediments were acquired along the coast of the Yellow Sea in July, 2019. Marine nematodes are the dominant meiofauna group.

The genus Microlaimus was erected by de Man in Reference de Man1880 with the type species of M. globiceps de Man, Reference de Man1880 and was the most diverse group in the family Microlaimidae Micoletzky, Reference Micoletzky1922. Gerlach (Reference Gerlach1950) first reviewed the genus, described three new species, redescribed 16 reported species, provided two new names, and subdivided the valid species into six groups mainly based on buccal cavity structure, cuticle, and tail shape. Wieser (Reference Wieser1954) described five new species of Microlaimus and erected the genus Paramicrolaimus Wieser, Reference Wieser1954 in Microlaimidae. Jensen (Reference Jensen1978) reviewed Microlaimidae with more differentiating characters, erected Molgolaimidae Jensen, Reference Jensen1978 to accommodate species with reflexed ovaries and one testis from Microlaimus and transferred eight Microlaimus species to Molgolaimus Ditlevsen, Reference Ditlevsen1921 and regarded M. labradorensis Allgén, Reference Allgén1957, M. tenuicaudatus Allgén, Reference Allgén and Odhner1959 and M. tenuilaimus Allgén, Reference Allgén1932 as species inquirendae for poor description, erected the genus Aponema Jensen, Reference Jensen1978 with type species of A. torosum (Lorenzen, Reference Lorenzen1973) Jensen, Reference Jensen1978 transferred from Microlaimus, four species to Bolbolaimus Cobb, Reference Cobb1920 based on buccal cavity and pharynx structure, three species from Paramicrolaimus. Taxonomic relationships of Microlaimus with the genus Molgolaimus (ovaries reflexed vs ovaries outstretched in Microlaimus) and other genera in Microlaimidae have been deeply discussed. Lorenzen (Reference Lorenzen1981, Reference Lorenzen1994) discussed the phylogenetic position of Microlaimidae and considered Jensen's taxonomic characters variable, downgraded Molgolaimidae as Molgolaiminae Jensen, Reference Jensen1978 in Desmodoridae Filipjev, Reference Filipjev1922 and erected the family Paramicrolaimidae Lorenzen, Reference Lorenzen1981 to accommodate Paramicrolaimus. Kovalyev and Tchesunov (Reference Kovalyev and Tchesunov2005) discussed taxonomic problems of Microlaimus with Molgolaimus, Aponema, and Pseudomicrolaimus Sergeeva, Reference Sergeeva1976 based on characters of ovary structure, tail shape, stoma and copulatory apparatus, described one new species of M. paraconothelis Kovalyev and Tchesunov, Reference Kovalyev and Tchesunov2005, and placed Microlaimus citrus as incertae sedis. Tchesunov (Reference Tchesunov and Schmidt-Rhaesa2014) transferred M. bathyalis (Kovalyev and Miljutina, Reference Kovalyev and Miljutina2009) Tchesunov, Reference Tchesunov and Schmidt-Rhaesa2014, M. martinezi (Miljutin and Miljutina, Reference Miljutin and Miljutina2009) Tchesunov, Reference Tchesunov and Schmidt-Rhaesa2014, M. minutissimus (Kovalyev and Miljutina, Reference Kovalyev and Miljutina2009) Tchesunov, Reference Tchesunov and Schmidt-Rhaesa2014, M. nanus Blome, Reference Blome1982, M. nympha (Bussau and Vopel, Reference Bussau and Vopel1999) Tchesunov, Reference Tchesunov and Schmidt-Rhaesa2014, M. westindicus (Kovalyev and Miljutina, Reference Kovalyev and Miljutina2009) Tchesunov, Reference Tchesunov and Schmidt-Rhaesa2014 from Aponema with absence of gubernaculum apophysis. Leduc (Reference Leduc2016) discussed the differentiation between Microlaimus and Bolbolaimus with the character of a constriction setting off the head from the rest of the body, resurrected M. wieseri (Hopper, Reference Hopper1961) from Bolbolaimus by the presence of set off head, described one new species of M. korari Leduc, Reference Leduc2016, and listed 83 valid species. After Leduc (Reference Leduc2016), M. pecticauda Murphy, Reference Murphy1966 and M. spirifer Warwick, Reference Warwick1970 were transferred to Molgolaimus (Shi and Xu, Reference Shi and Xu2017), by now 87 valid species have been listed in Nemys (Bezerra et al., Reference Bezerra, Decraemer, Eisendle-Flöckner, Hodda, Holovachov, Leduc, Miljutin, Mokievsky, Peña Santiago, Sharma, Smol, Tchesunov, Venekey, Zhao and Vanreusel2023).

The genus Pseudomicrolaimus was first erected by Sergeeva in 1976 with the description of P. murinae Sergeeva, Reference Sergeeva1976 with the character of wide and funnel-shaped buccal cavity with numerous denticles on the subventral side, dorsal tooth much larger than others. Jensen (Reference Jensen1978) regarded Pseudomicrolaimus as a junior synonym of Bolbolaimus for most characters of these two genera agreed well. Genus Pseudomicrolaimus was reconsidered as a valid genus by Kovalyev and Tchesunov (Reference Kovalyev and Tchesunov2005) with presence of numerous denticles on the left subventral side of stoma. By now, three species, P. murinae, P. dentatus (Allgén, Reference Allgén1935) Sergeeva, Reference Sergeeva1976 and P. denticulatus (Gerlach, Reference Gerlach1953) Kovalyev and Tchesunov, Reference Kovalyev and Tchesunov2005 are considered valid.

Materials and methods

In July 2019, undisturbed sediment samples were collected using a syringe (2.6 cm internal diameter) to a depth of 8 cm at the intertidal mud flats of Yangma Island and were vertically subdivided into 0–2 and 2–8 cm depth and fixed with 10% formalin in seawater. In laboratory, samples were stained with rose Bengal for more than 24 h and washed with tap water. Meiofauna was separated from heavier sediment particles by centrifugation in Ludox-TM (Sigma-Aldrich Co., USA) (de Jonge and Bouwman, Reference de Jonge and Bouwman1977), transferred into grid-lined Petri dish and sorted under stereoscopic microscope. Nematodes were transferred into mixture of ethanol (50%) and glycerine (1:9 in volume ratio) with ethanol slowly evaporated, and mounted in glycerine on permanent slides. Descriptions were made using a differential interference contrast microscope (Axiscope-5, Zeiss, Germany). Line drawings were made through an iPad (Apple, USA) and photos were taken with the aid of ZEN software (provided by Zeiss corporation). Type specimens were deposited in the Institute of Oceanology, Chinese Academy of Sciences, Qingdao.

Abbreviations are as follows: a, body length/maximum body diameter; b, body length/pharynx length; c, body length/tail length; c’, tail length/anal body diameter; V%, position of vulva from anterior body end expressed as a percentage of total body length.

Description of new species

Order MICROLAIMIDA Leduc, Verdon and Zhao, Reference Leduc, Verdon and Zhao2017
Superfamily MICROLAIMOIDEA Micoletzky, Reference Micoletzky1922
Family MICROLAIMIDAE Micoletzky, Reference Micoletzky1922
Genus Microlaimus de Man, Reference de Man1880

Diagnosis

Cuticle annulated, in some species also showing punctations or longitudinal bars. Head slightly set off. Spicules usually short and arcuate, seldom long and slender; gubernaculum present, often bent distally but without dorso-caudal apophyses. Papilloid precloacal supplements may be present (based on Leduc, Reference Leduc2016).

Type species

Microlaimus globiceps de Man, Reference de Man1880
Microlaimus paraaffinis sp. nov.
(Figures 1–2, Table 1)

Type material

Four males and three females were measured and studied. Holotype: m#1 on slide 19YMD2-2-65; paratypes: m#2, m#3, m#4 on slides 19YMD2-2-65,19YMD2-2-26, 19YMD2-4-5; f#1 f#2, f#3 on slides 19YMD2-2-46.

Figure 1. Microlaimus paraaffinis sp. nov. (A) Lateral view of male anterior portion, showing buccal cavity and pharynx region (holotype); (B) Lateral view of male anterior end, showing amphids (holotype); (C) Lateral view of female anterior end (19YMD2-2-46); (D) Lateral view of male posterior portion (holotype); (E) Lateral view of spicules and gubernaculum (holotype); (F) Lateral view of female posterior portion (19YMD2-2-46); (G) Lateral view of female body, showing female reproductive structure (19YMD2-2-46). Scale bars: A, B, C = 20 μm; D, F = 30 μm; G = 50 μm.

Figure 2. Microlaimus paraaffinis sp. nov. (A) Lateral view of male body, showing buccal cavity (holotype); (B) Lateral view of male anterior end, showing amphidial fovea (holotype); (C) Lateral view of male posterior region, showing spicules (holotype); (D) Lateral view of male posterior body, showing gubernaculum (holotype); (E) Lateral view of male posterior end, showing male tail (holotype). Scale bars: 20 μm.

Table 1. Individual measurements of Microlaimus paraaffinis sp. nov. (in μm except for ratios)

Type locality and habitat

Specimens were collected from intertidal muddy sediment at Yangma Island, Shandong Province. 37°26´N, 121°36΄E.

Etymology

The species name refers to similarity with species M. affinis.

Measurements

All measurement data are given in Table 1.

Description

Males. Body spindle shaped, 714–785 μm in length. Anterior body end slightly truncated, posterior body end elongated conical. Cuticle striated without dots or punctuations. Cuticle striation from posterior to cephalic setae to tail tip. Head smooth and slightly set off at the cephalic setae region. Six inner labial sensilla and six outer labial sensilla papilliform. Four cephalic setae short, 4 μm in length. Somatic setae absent. Amphidial fovea cryptocircular, 4–6 μm in diameter (33–42% corresponding body diameter), 9–11 μm from anterior body end. Buccal cavity wide, 3 μm in width and 13–16 μm in depth with a large dorsal tooth and two small ventrosublateral teeth, right ventrosublateral tooth situated approximately 3–4 μm anteriorly relative to left one, small longitudinal cuticularized folds present in cheilostoma. Pharynx muscular, 126–140 μm in length, anterior part slightly widened at the buccal cavity region, posterior part widened into bulb (24–32 μm in length). Nerve ring situated 73–80 μm from anterior end. Ventral gland immediately posterior to pharyngeal bulb and excretory pore situated just anterior to nerve ring. Cardia not observed. Tail conico-cylindrical, 95–108 μm (3.7–3.9 cloacal body diameter) in length, with cylindrical portion short (18–19% of tail length). Three caudal glands present and spinneret absent.

Testes outstretched and opposed, anterior and posterior testis to the right of intestine. Spicules paired and L-shaped, slender with equal thickness and distal end tapered, 31–35 μm in length (1.1–1.3 cloacal body diameter). Gubernaculum simple, boat-shaped, 19–21 μm in length and parallel to distal end of spicules. Precloacal supplements absent.

Females. Similar to males in most characters. Reproductive system didelphic-amphidelphic with two ovaries outstretched. Anterior ovary to the left of the intestine (112–122 μm in length), posterior ovary to the right (120–124 μm in length). Vulva located slightly posterior to the mid-body, 393–431 μm from the anterior end. Vagina short and sclerotized.

Differentiation diagnosis and discussion

The new species presents as main characteristics: cuticle striated, four short cephalic setae, buccal cavity with one large dorsal tooth and two small ventrosublateral teeth, amphidial fovea cryptocircular at level of posterior buccal cavity, somatic setae absent, spicules L-shaped and 31–35 μm in length, gubernaculum simple and boat-shaped, precloacal supplements absent, tail conico-cylindrical with cylindrical portion short.

M. paraaffinis sp. nov. similar to M. arenicola Schulz, Reference Schulz1938, M. affinis Gerlach, Reference Gerlach1958, M. borealis Steiner, Reference Steiner1916, M. campiensis Lima, Neres and Esteves, Reference Lima, Neres and Esteves2022, M. papillatus Gerlach, Reference Gerlach1956, M. pinguis Wieser, Reference Wieser1954, M. undulatus Gerlach, Reference Gerlach1953 in body length and amphidial fovea position. M. paraaffinis sp. nov. differs from M. arenicola in the testis number (two testes vs one testis), spicules shape (L-shaped, slender with equal thickness vs crescentic shaped, with proximal end knobbed), and tail shape (conico-cylindrical vs conical). M. paraaffinis sp. nov. differs from M. affinis in de Man c value (6.7–7.5 vs 9.5–10), spicules length and shape (31–35 μm, L-shaped vs 24 μm, slightly curved), gubernaculum length (19–21 μm vs 11 μm), absence of precloacal supplements (6–7 supplements present, redescribed by Kovalyev and Tchesunov, Reference Kovalyev and Tchesunov2005) and tail length and shape (conico-cylindrical, 92–111 μm vs conical, 77 μm). M. paraaffinis sp. nov. differs from M. borealis in the smaller amphidial fovea (33–42% vs 50%, measured according to Steiner, Reference Steiner1916), shorter cephalic setae (0.3 head diameter vs 0.75 head diameter, measured according to Steiner, Reference Steiner1916), and tail length (92–111 μm vs 66–68 μm). M. paraaffinis sp. nov. differs from M. campiensis in the shorter cephalic setae (3–4 μm vs 5–12 μm), spicules shape and length (slender with equal thickness, 31–35 μm vs slender with proximal end enlarged, 38–43μm), absence of precloacal supplements (7 papilliform supplements in M. campiensis) and tail length (3.7–4.4 anal body diameter vs 2.6–3.2 anal body diameter). M. paraaffinis sp. nov. differs from M. papillatus in outer labial sensilla and cephalic setae length (papilliform, 3–4 μm vs 5 μm, 8.5 μm), amphidial fovea diameter (4–5 μm vs 8 μm), spicules length and shape (31–35 μm, equal thickness vs 26 μm, proximal end offset), and absence of precloacal supplements (six precloacal supplements present in M. papillatus). M. paraaffinis sp. nov. differs from M. pinguis in amphidial fovea diameter (4–5 μm vs 10–10.5 μm), spicules shape (L-shaped vs slightly curved), and tail length (3.7–4.4 anal body diameter vs 2.25–2.6 anal body diameter). M. paraaffinis sp. nov. differs from M. undulatus in shorter cephalic setae length (3–4 μm vs 7 μm), amphidial fovea diameter (33–42% vs 53%), spicules length and shape (31–35 μm, L-shaped vs 27 μm, slightly knee-shaped), gubernaculum shape (boat-shaped vs twisted), and shorter tail length (92–111 μm vs 72–83 μm).

Order MICROLAIMIDA Leduc, Verdon and Zhao, Reference Leduc, Verdon and Zhao2017
Superfamily MICROLAIMOIDEA Micoletzky, Reference Micoletzky1922
Family MICROLAIMIDAE Micoletzky, Reference Micoletzky1922
Genus Pseudomicrolaimus Sergeeva, Reference Sergeeva1976

Diagnosis

Cuticle strongly annulated, head truncated and not set off, cephalic setae close to the front end, amphidial fovea unispiral or circular, buccal cavity rather wide and strongly sclerotized, with a large dorsal tooth, and transversal rows of denticles, pharyngeal tissue inflated around the buccal cavity, posterior oval bulb present, copulatory apparatus strongly sclerotized, no dorso-caudal gubernaculum apophyses (based on Tchesunov, Reference Tchesunov and Schmidt-Rhaesa2014).

Type species

Pseudomicrolaimus murinae Sergeeva, Reference Sergeeva1976

Pseudomicrolaimus major sp. nov.
(Figures 3–4, Table 2)

Type material

Three males and three females were measured and studied. Holotype: m#1 on slide 19YMD1-1-4; paratypes: m#2, m#3 on slides 19YMD1-1-9, 19YMD1-1-4; f#1 on slides 19YMD1-1-9; f#2, f#3 on slides 19YMD1-1-4.

Figure 3. Pseudomicrolaimus major sp. nov. (A) Lateral view of male anterior portion, showing buccal cavity and pharynx region (holotype); (B) Lateral view of male anterior end, showing amphids and buccal cavity (holotype); (C) Lateral view of male anterior portion, showing cuticle and amphids (holotype); (D) Lateral view of male posterior portion, showing tail (holotype); (E) Spicules and gubernaculum (holotype); (F) Lateral view of female anterior end (19YMD1-1-9); (G) Lateral view of female posterior portion (19YMD1-1-9); (H) Lateral view of female middle portion, showing female reproductive structure (19YMD1-1-9). Scale bars: A, B, C, D, F = 20 μm; G = 50 μm.

Figure 4. Pseudomicrolaimus major sp. nov. (A) Lateral view of male anterior end, showing buccal cavity (holotype); (B) Lateral view of male anterior end, showing amphidial fovea (holotype); (C) Lateral view of male anterior region, showing denticles and inner labial setae (arrows) (19YMD1-1-9); (D) Lateral view of male pharynx region (19YMD1-1-9); (E) Lateral view of male posterior body, showing spicules and gubernaculum (holotype); (F) Lateral view of female showing vulva (19YMD1-1-9). Scale bars: A, B, C, D, E = 20 μm, F = 50 μm.

Table 2. Individual measurements of Pseudomicrolaimus major sp. nov. (in μm except for ratios)

Type locality and habitat.

Specimens were collected from intertidal muddy sediment at Yangma Island, Shandong Province. 37°26´N, 121°36΄E.

Etymology

The species name refers to large body size of the nematode.

Measurements

All measurement data are given in Table 2.

Description

Males. Body yellow brownish, long, stout and cylindrical, 2586–3258 μm in length. Anterior body end truncated, posterior body end conical. Cuticle annulated. Anterior sensilla in three crowns, six inner labial sensilla papilliform (2 μm in length), six outer labial setae 5–6 μm in length, and four cephalic setae 7–10 μm in length. Eight subcephalic setae present (8–9 μm in length, 11–13 μm from posterior amphidial fovea end). Somatic setae absent. Amphidial fovea cryptospiral at level of buccal cavity, 7–10 μm in diameter (36%–38% corresponding body diameter), 9–12 μm from anterior body end. Buccal cavity wide, 7 μm in width and 16–20 μm in depth with a large cuticularized dorsal tooth and two small ventrosublateral teeth at the same level, small denticles present at left ventrosublateral side of buccal cavity. Pharynx muscular, 188–196 μm in length, anterior part widened at the buccal cavity region, posterior part widened into long oval-shaped bulb. Nerve ring situated 100–115 μm from anterior end. Excretory-secretory system not observed. Cardia not observed. Tail short and conical, 80–95 μm (2.4–2.9 cloacal body diameter) in length. Three caudal glands present and spinneret absent.

Testes outstretched and opposed, the anterior testis to the right and the posterior one to the left of intestine. Spicules paired, curved, 62–65 μm in length (1.9 cloacal body diameter). Proximal third of spicules widened (oval or rectangular-shaped) and the rest portion slender. Gubernaculum simple, boat-shaped, and parallel to distal end of spicules.

Females. Similar to males in most characters. Reproductive system didelphic-amphidelphic with two ovaries outstretched. Anterior ovary to the left of the intestine (279–342 μm in length), posterior ovary to the right (313–336 μm in length). Vulva located slightly posterior to the mid-body, 1779–2236 μm from the anterior end. Vagina short and sclerotized.

Differentiational diagnosis and discussion

The new species presents as main characteristics: body size relatively large, cuticle striated, buccal cavity with one large dorsal tooth and two small subventral teeth at the same level, small denticles present at left subventral side of buccal cavity, amphidial fovea cryptospiral, eight subcephalic setae present, somatic setae absent, spicules curved 62–65 μm in length with proximal portion widened and other portion slender, gubernaculum simple and boat-shaped, tail conical with three caudal glands.

P. major sp. nov. differs from P. denticulatus (Cobb, Reference Cobb1920; Gerlach, Reference Gerlach1953) in the longer body (2586–3403 μm vs 2025–2139 μm), subcephalic setae position (11–14 μm from posterior end of amphidial fovea vs level with posterior end of amphidial fovea), and spicules length and shape (62–65 μm, proximal portion widened vs 33 μm, proximal end offset). P. major sp. nov. differs from P. murinae (Sergeeva, Reference Sergeeva1976) in the longer body (2586–3403 μm vs 841–1167 μm), buccal cavity tooth number (one dorsal tooth vs two dorsal teeth), presence of subcephalic setae (absence in P. murinae), spicules length and shape (62–65 μm, proximal portion widened vs 32.5–37.5 μm, proximal portion slightly cephalated). P. major sp.nov. differs from P. dentatus (Allgén, Reference Allgén1935) in the longer body (2586–3403 μm vs 950 μm), presence of subcephalic setae (absence in P. dentatus), spicules length and shape (62–65 μm, proximal portion widened vs 30 μm, proximal end cephalated).

Dichotomous key for species of genus Pseudomicrolaimus Sergeeva, Reference Sergeeva1976

  1. 1. subcephalic setae present2

    • • subcephalic setae absent3

  2. 2. Spicules proximal portion widened, subcephalic setae posterior to posterior amphidial endP. major sp. nov.

    • – Spicules proximal end offset, subcephalic setae level with posterior amphidial endP. denticulatus

  3. 3. Two dorsal teeth presentP. murinae

    • – One dorsal tooth presentP. dentatus

Acknowledgements

We are greatly thankful to two anonymous reviewers for their kind reviews and valuable suggestions, and Dr Huang Yong for sample collecting.

Authors’ contributions

Wen Guo: sample collection, preparation of Microlaimus paraaffinis sp. nov. and draft preparation; Mengna Wang: preparation of pseduomicrolaimus major sp. nov.; Chunming Wang: picture drawing, manuscript editing.

Financial support

This work was supported by A Project of Shandong Province Higher Educational Science and Technology Program (No. J18KA152) and Open Project of Liaocheng University Animal Husbandry Discipline (Grant no. 319312101).

Competing interest

None.

Data availability statements

The authors confirm that the data supporting the findings of this study are available within the article.

References

Allgén, CA (1932) Weitere Beiträge zur Kenntnis der marinen Nematodenfauna der Campbellinsel. Nyt Magazin for. Naturvidenskaberne 70, 97–198.Google Scholar
Allgén, CA (1935) Die freilebenden Nematoden des Öresunds. Capita Zoologica 6, 1–192.Google Scholar
Allgén, CA (1957) On a small collection of free living marine nematodes from Greenland and some other arctic regions with reviews and analyses of the compositions of all hitherto known arctic nematode faunas. Meddelelser om Gronland 159, 1–42.Google Scholar
Allgén, CA (1959) Freeliving marine nematodes. In Odhner, NH (ed.), Further Zoological Results of the Swedish Antarctic Expedition, 1901–1903 Under the Direction of Dr Otto Nordenskjold. Stockholm: P.A. Norstedt & Söner, pp. 1–293.Google Scholar
Bezerra, TN, Decraemer, W, Eisendle-Flöckner, U, Hodda, M, Holovachov, O, Leduc, D, Miljutin, D, Mokievsky, V, Peña Santiago, R, Sharma, J, Smol, N, Tchesunov, A, Venekey, V, Zhao, Z and Vanreusel, A (2023) Nemys: World Database of Nematodes. Accessed at http://nemys.ugent.be on 2023-07-19.Google Scholar
Blome, D (1982) Systematik der Nematoda eines Sandstrandes der Nordseeinsel Sylt. Mikrofauna des Meeresbodens 86, 1–194.Google Scholar
Bussau, C and Vopel, K (1999) New nematode species and genera (Chromadorida, Microlaimidae) from the deep sea of eastern South Pacific (Peru Basin). Annalen des Naturhistorichen Museums in Wien 101B, 405–421.Google Scholar
Cobb, NA (1920) One hundred new nemas (type species of 100 new genera). Contributions to a Science of Nematology 9, 217–343.Google Scholar
de Jonge, VN and Bouwman, LA (1977) A simple density separation technique for quantitative isolation of meiobenthos using the colloidal silica Ludox-TM. Marine Biology 42, 143–148.CrossRefGoogle Scholar
de Man, JG (1880) Die einheimischen, frei in der reinen Erde und im süßen Wasser lebende Nematoden monographisch bearbeitet. Vorläufiger Bericht und descriptiv–systematischer Theil. Tijdschrift der Nederlandische Dierkundige Vereeniging 5, 1–104.Google Scholar
Ditlevsen, H (1921) Papers from Dr Th. Mortensens Pacific expedition 1914–16. III marine free-living nematodes from the Auckland and Campbell Islands. Videnskabelige Meddelelser fra Dansk naturhistorisk Forening i Kjøbenhavn 73, 1–39.Google Scholar
Filipjev, IN (1922) New data about free-living nematodes of the Black Sea. Transactions of Stavropol Agricultural Institute 1, 83–184.Google Scholar
Gerlach, SA (1950) Die nematoden-gattung microlaimus. Zoologische Jahrbücher, Abteilung fur Systematik, Ökologie und Geographie der Tiere 79, 188–208.Google Scholar
Gerlach, SA (1953) Die Nematodenbesiedlung des Sandstrandes und des Küstengrundwassers an der italienischen Küste I. Systematischer Teil. Archo zool. ital 37, 517–640.Google Scholar
Gerlach, SA (1956) Brasilianische Meeres-Nematoden I. Boletim do Instituto Oceanográfico, S. Paulo Tomo 5, 3–69.CrossRefGoogle Scholar
Gerlach, SA (1958) Freilebende Nematoden von den Korallenriffen des Roten Meeres. Kieler Meeresforsch 14, 241–246.Google Scholar
Hopper, BE (1961) Marine nematodes from the coast line of the Gulf of Mexico. Canadian Journal of Zoology 39, 183–199.CrossRefGoogle Scholar
Jensen, P (1978) Revision of microlaimidae, erection of molgolaimidae fam.n., and remarks on the systematic position of Paramicrolaimus (Nematoda, Desmodorida). Zoologica Scripta 7, 159–173.CrossRefGoogle Scholar
Kovalyev, SV and Miljutina, MA (2009) A review of the genus Aponema Jensen, 1978 (Nematoda: Microlaimidae) with description of three new species. Zootaxa 2077, 56–68.CrossRefGoogle Scholar
Kovalyev, V and Tchesunov, AV (2005) Taxonomic review of microlaimids with description of five species from the White Sea (Nematoda: Chromadoria). Zoosystematica Rossica 14, 1–16.CrossRefGoogle Scholar
Leduc, D (2016) One new genus and three new species of deep-sea nematodes (Nematoda: Microlaimidae) from the Southwest Pacific Ocean and Ross Sea. Zootaxa 4079, 255–271.CrossRefGoogle ScholarPubMed
Leduc, D, Verdon, V and Zhao, ZQ (2017) Phylogenetic position of the Paramicrolaimidae, description of a new Paramicrolaimus species and erection of a new order to accommodate the Microlaimoidea (Nematoda: Chromadorea). Zoological Journal of the Linnean Society 183, 52–69.CrossRefGoogle Scholar
Lima, RC, Neres, PF and Esteves, AM (2022) Three new species of Microlaimus (Nematoda: Microlaimidae) from the South Atlantic. Peer J 10, 12734.CrossRefGoogle ScholarPubMed
Lorenzen, S (1973) Freilebende Meersenematoden aus dem Sublitoral der Nordsee und der Kieler Bucht. Veröff. Inst. Meeresforsch. Bremerh 14, 103–130.Google Scholar
Lorenzen, S (1981) Entwurf eines phylogenetischen Systems der freilebenden Nematoden. Veröffentlichugen de Institut für Meeresforschung in Bremerhaven 7.Google Scholar
Lorenzen, S (1994) The phylogenetic systematics of freeliving nematodes. London: The Ray Society, pp. 1–383.Google Scholar
Micoletzky, H (1922) Zur Nematodenfauna des Bodensees. Internationale Revue der Gesamten Hydrobiologie und Hydrographie 10, 491–512.CrossRefGoogle Scholar
Miljutin, DM and Miljutina, MA (2009) Deep-sea nematodes of the family microlaimidae from the Clarion-Clipperton fracture zone (North-Eastern Tropic Pacific), with the descriptions of three new species. Zootaxa 2096, 137–172.CrossRefGoogle Scholar
Murphy, DG (1966) An initial report on a collection of Chilean marine nematodes. Mitteilungen aus dem Hamburgischen Zoologischen Museum und Institut 63, 29–50.Google Scholar
Schulz, E (1938) Beiträge zur Morphologie und Systematik freilebender mariner Nematoden I. Kieler Meeresforschungen 3, 114–121.Google Scholar
Sergeeva, NG (1976) New data on taxonomy of the subfamily Microlaiminae (Nematoda). Zoologichesky Zhurnal 55, 1090–1094.Google Scholar
Shi, BZ and Xu, KD (2017) Spirobolbolaimus undulatus sp. nov. in intertidal sediment from the East China Sea, with transfer of two Microlaimus species to Molgolaimus (Nematoda, Desmodorida). Journal of the Marine Biological Association of the United Kingdom 97, 1335–1342.CrossRefGoogle Scholar
Steiner, G (1916) Freilebende Nematoden aus der Barentssee. Zoologische Jahrbücher 39, 511–664.Google Scholar
Tchesunov, AV (2014) Order desmodorida. In Schmidt-Rhaesa, A (Ed.), Handbook of Zoology, Gastrotricha, Cycloneuralia and Gnathifera, vol. 2. Berlin/Boston: Nematoda. De Gruyter, pp. 424–425.Google Scholar
Warwick, RM (1970) Fourteen new species of free-living marine nematodes from the Exe estuary. Bulletin of the British Museum Natural History (Zoology) 19, 137–177.Google Scholar
Wieser, W (1954) Free-living marine nematodes II. Chromadoroidea. Acta Univ. Lund (N.F.2) 50, 1–148.Google Scholar
Figure 0

Figure 1. Microlaimus paraaffinis sp. nov. (A) Lateral view of male anterior portion, showing buccal cavity and pharynx region (holotype); (B) Lateral view of male anterior end, showing amphids (holotype); (C) Lateral view of female anterior end (19YMD2-2-46); (D) Lateral view of male posterior portion (holotype); (E) Lateral view of spicules and gubernaculum (holotype); (F) Lateral view of female posterior portion (19YMD2-2-46); (G) Lateral view of female body, showing female reproductive structure (19YMD2-2-46). Scale bars: A, B, C = 20 μm; D, F = 30 μm; G = 50 μm.

Figure 1

Figure 2. Microlaimus paraaffinis sp. nov. (A) Lateral view of male body, showing buccal cavity (holotype); (B) Lateral view of male anterior end, showing amphidial fovea (holotype); (C) Lateral view of male posterior region, showing spicules (holotype); (D) Lateral view of male posterior body, showing gubernaculum (holotype); (E) Lateral view of male posterior end, showing male tail (holotype). Scale bars: 20 μm.

Figure 2

Table 1. Individual measurements of Microlaimus paraaffinis sp. nov. (in μm except for ratios)

Figure 3

Figure 3. Pseudomicrolaimus major sp. nov. (A) Lateral view of male anterior portion, showing buccal cavity and pharynx region (holotype); (B) Lateral view of male anterior end, showing amphids and buccal cavity (holotype); (C) Lateral view of male anterior portion, showing cuticle and amphids (holotype); (D) Lateral view of male posterior portion, showing tail (holotype); (E) Spicules and gubernaculum (holotype); (F) Lateral view of female anterior end (19YMD1-1-9); (G) Lateral view of female posterior portion (19YMD1-1-9); (H) Lateral view of female middle portion, showing female reproductive structure (19YMD1-1-9). Scale bars: A, B, C, D, F = 20 μm; G = 50 μm.

Figure 4

Figure 4. Pseudomicrolaimus major sp. nov. (A) Lateral view of male anterior end, showing buccal cavity (holotype); (B) Lateral view of male anterior end, showing amphidial fovea (holotype); (C) Lateral view of male anterior region, showing denticles and inner labial setae (arrows) (19YMD1-1-9); (D) Lateral view of male pharynx region (19YMD1-1-9); (E) Lateral view of male posterior body, showing spicules and gubernaculum (holotype); (F) Lateral view of female showing vulva (19YMD1-1-9). Scale bars: A, B, C, D, E = 20 μm, F = 50 μm.

Figure 5

Table 2. Individual measurements of Pseudomicrolaimus major sp. nov. (in μm except for ratios)