Axonolaimus de Man 1889
Creators: name: Liang, Huixin
name: Guo, Wen
name: Wang, Chunming
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Nematoda
Chromadorea
Araeolaimida
Axonolaimidae
Axonolaimus

description: Genus Axonolaimus de Man, 1889
Diagnosis. (based on Leduc & Zhao 2023) Cuticle finely striated or smooth. Anterior end with four cephalic setae. Cervical setae present, posterior to the amphidial fovea. Amphidial fovea loop-shaped, longitudinally elongated or with rounded outline, at level of buccal cavity. Buccal cavity funnel-shaped, without odontia. Females with two opposed, outstretched ovaries; males with one outstretched testis, sometimes two testes present. Spicules arcuated. Gubernaculum apophysis oriented dorso-caudally. Small tubular or pitlike precloacal supplements sometimes present. Males tail with subventral rows of setae.
Remarks. de Man (1889) erected Axonolaimus with the type species A. spinosus transferred from Anoplostoma, described A. filiformis de Man, 1889 and defined the genus characters as cuticle smooth, head with four cephalic setae, amphidial fovea oval shaped divided by a longitudinal crest, anterior buccal cavity widened and posterior restricted, spicules arcuated and gubernaculum with apophysis, precloacal supplements absent and tail with caudal setae. After de Man (1889), A. limalis Ssaweljev, 1912, A. impar Ssaweljev, 1912 and A. polaris Cobb, 1914 were described. Filipjev (1918) described A. ponticus Filipjev, 1918 and A. setosus Filipjev, 1918 and revised genus characters of amphidial fovea shape, buccal cavity shape and reproduction systems. Afterwards, A. villosus Skwarra, 1922, A. typicus de Man, 1922 and A. antarcticus Cobb, 1930 were described. Schuurmans Stekhoven & Adam (1931) redescribed Anoplostoma spinosus found by de Man (1889) from Walcheren and gave the new name Axonolaimus paraspinosus Schuurmans Stekhoven & Adam, 1931. Axonolaimus similis Schulz, 1932, A. tenuis Schulz, 1932 and A. elegans Schulz, 1932 were later described. De Coninck & Schuurmans Stekhoven (1933) reviewed the unidentified species of Axonolaimus reported by de Man (1928) and named it as A. demani De Coninck & Schuurmans Stekhoven, 1933. Later, eleven species (A. schuurmansstekhoveni Allgén, 1935, A. odontophoroides Chitwood, 1936, A. subsimilis Chitwood, 1936, A. mediterraneus Brunetti, 1941, A. tirrenicus Brunetti, 1941, A. versiliensis Brunetti, 1941, A. longisetosus Allgén, 1947a, A. tenuicollis Allgén, 1947b, A. diegoensis Allgén, 1947b, A. arcuatus Schuurmans Stekhoven, 1950 and A. leptosoma Allgén, 1951) have been described. Timm (1954) described A. filipjevi Timm, 1954 and A. steineri Timm, 1954, and redescribed A. demani and A. spinosus. Afterwards, A. tenuicaudatus Allgén, 1959, A. austrogeorgiae Allgén, 1959, A. drachi Luc & De Coninck, 1959, A. interrogativus Wieser, 1959 and A. stomamilivus Crites, 1961 were described. Hopper (1963) described A. paraponticus Hopper, 1963, provided a pictorial key to 21 species and considered A. austrogeorgiae, A. diegoensis, A. filiformis, A. leptosoma, A. limalis, A. longisetosus, A. tenuicollis as species inquirenda. After Hopper (1963), A. hexapilus Wieser & Hopper, 1967, A. orcombensis Warwick, 1970, A. seticaudatus Platonova, 1971, A. helgolandicus Lorenzen, 1971, A. caudostriatus Boucher, 1973, A. geminus Belogurov & Koroleva, 1975, A. orus Belogurov & Koroleva, 1975 and A. deconincki Vincx & Furstenberg, 1989 were described. More recently, Leduc & Zhao (2023) described A. glandifer Leduc & Zhao, 2023 and revised genus characters. There have been many transferences from the genus Axonolaimus mainly based on buccal cavity (Table 2). Axonolaimus versiliensis should be considered as species inquirenda for the description based on a juvenile specimen. Before the description in the present work 33 species were considered as valid.
List of valid Axonolaimus species
A. anellifer (Wieser, 1956) Lorenzen, 1994
A. antarcticus Cobb, 1930
A. arcuatus Schuurmans Stekhoven, 1950
A. caudostriatus Boucher, 1973
A. deconincki Vincx & Furtenberg, 1989
A. demani De Coninck & Schuurmans Stekhoven, 1933
A. dimorphous sp. nov.
A. drachi Luc & De Coninck, 1959
A. filipjevi Timm, 1954
A. geminus Belogurov & Koroleva, 1975
A. glandifer Leduc & Zhao, 2023
A. helgolandicus Lorenzen, 1971
A. hexapilus Wieser & Hopper, 1967
A. interrogativus Wieser, 1959
A. mediterraneus Brunetti, 1941
A. odontophoroides Chitwood, 1936
A. orcombensis Warwick, 1970
A. orus Belogurov & Koroleva, 1975
A. paraponticus Hopper, 1963
A. paraspinosus Schuurmans Stekhoven & Adam, 1931
A. ponticus Filipjev, 1918
A. schuurmansstekhoveni Allgén, 1935
A. seticaudatus Platonova, 1971
A. setosus Filipjev, 1918
A. similis Schulz, 1932
A. spinosus (Bütschli, 1874) de Man, 1889
A. steineri Timm, 1954
A. stomamilivus Crites, 1961
A. subsimilis Chitwood, 1936
A. tenuicaudatus Allgén, 1959
A. tenuis Schulz, 1932
A. tirrenicus Brunetti, 1941
A. typicus de Man, 1922
A. villosus Skwarra, 1922
List of species inquirenda
A. austrogeorgiae Allgén, 1959
A. diegoensis Allgén, 1947b
A. filiformis de Man, 1889
A. leptosoma Allgén, 1951
A. limalis Ssaweljev, 1912
A. longisetosus Allgén, 1947a
A. tenuicollis Allgén, 1947b
A. versiliensis Brunetti, 1941
Identification key to valid species of the genus Axonolaimus
1 Tail conico-cylindrical................................................................................. 2
- Tail conical........................................................................................ 18
2 Subcephalic setae absent............................................................................... 3
- Subcephalic setae present.............................................................................. 7
3. Body length> 2mm ............................................................................ A. drachi
- Body length <2 mm ................................................................................... 4
4. Amphidial fovea roundish, only slightly longer than wide............................................. A. filipjevi
- Amphidial fovea elongated, at least 2 times as long as wide................................................... 5
5. Cephalic setae shorter than 0.5 head diameter...................................................... A. geminus
- Cephalic setae longer than 0.5 head diameter............................................................... 6
6. Spicules length> 35 μm................................................................... A. paraponticus
- Spicules length <35μm....................................................................... A. spinosus
7. Amphidial fovea roundish, only slightly longer than wide..................................................... 8
- Amphidial fovea elongated, at least 2 times as long as wide................................................... 9
8. Precloacal supplements present..................................................................... A. orus
- Precloacal supplements absent................................................................... A. typicus
9. Subcephalic setae situated at middle portion of buccal cavity................................................. 10
- Subcephalic setae situated at posterior portion of buccal cavity................................................ 11
10. Body length> 2.2 mm .......................................................................... A. similis
- Body length <2.2 mm ..................................................................... A. paraspinosus
11. Ten subcephalic setae present................................................................... A. ponticus
- Six to eight subcephalic setae present.................................................................... 12
12. Precloacal supplements present......................................................................... 13
- Precloacal supplements absent......................................................................... 16
13. Precloacal supplements> 35................................................................... A. glandifer
- Precloacal supplements <35........................................................................... 14
14. Spicules slightly curved...................................................................... A. deconincki
- Spicules strongly curved.............................................................................. 15
15. Body length> 2 mm ....................................................................... A. antarcticus
- Body length <2 mm ......................................................................... A. arcuatus
16. de Man ratio a> 50............................................................................ A. setosus
- de Man ratio a <50.................................................................................. 17
17. Caudal setae present...................................................................... A. seticaudatus
- Caudal setae absent...................................................................... A. tenuicaudatus
18. Amphidial fovea shape different in males and females...................................... A. dimorphous sp. nov.
- Amphidial fovea same shape in males and females......................................................... 19
19. Amphidial fovea dorsal and ventral branch equal in length................................................... 20
- Amphidial fovea shepherd’s crook...................................................................... 29
20. Amphidial fovea elongated, at least 2 times as long as wide.................................................. 21
- Amphidial fovea roundish, only slightly longer than wide.................................................... 25
21. Precloacal supplements present......................................................................... 22
- Precloacal supplements absent......................................................................... 23
22. Tail end bluntly conical....................................................................... A. hexapilus
- Tail elongated conical.................................................................... A. helgolandicus
23. Tail elongated conical.................................................................... A. caudostriatus
- Tail end bluntly conical............................................................................... 24
24. Spicules proximal end not tapered............................................................. A. tirrenicus *
- Spicules proximal end tapered.............................................................. A. mediterraneus
25. Precloacal supplements present.............................................................. A. orcombensis
- Precloacal supplements absent......................................................................... 26
26. Subcephalic setae present...................................................................... A. demani
- Subcephalic setae absent.............................................................................. 27
27. Body length> 3 mm ............................................................................ A. tenuis
- Body length <3 mm ................................................................................. 28
28. Tail length shorter than 5 anal body diameter................................................... A. stomamilivus
- Tail length longer than 5 anal body diameter....................................................... A. anellifer
29. Subcephalic setae absent....................................................................... A. villosus
- Subcephalic setae present............................................................................. 30
30. Cephalic setae shorter than 1.2 head diameter............................................................. 31
- Cephalic setae longer than 1.2 head diameter.............................................................. 32
31. Subcephalic setae in two circles............................................................... A. subsimilis
- Subcephalic setae in one circle........................................................... A. odontophoroides
32. de Man a ratio <35............................................................... A. schuurmansstekhoveni
- de Man a ratio> 35.................................................................................. 33
33. de Man c ratio> 20...................................................................... A. interrogativus
- de Man c ratio <20........................................................................... A. steineri *(based on Gerlach 1953)
description: Published as part of Liang, Huixin, Guo, Wen & Wang, Chunming, 2024, Two new species of Nematoda: Gairleanema pulchra sp. nov. (Tripyloididae) and Axonolaimus dimorphous sp. nov. (Axonolaimidae) from the Yellow Sea, China, pp. 547-561 in Zootaxa 5447 (4) on pages 552-559, DOI: 10.11646/zootaxa.5447.4.6, http://zenodo.org/record/11150576