Rev 05/28/2024
Chromadorea Rhabditida Rhabditia Chambersiellidae
Macrolaimus montrealensis Cid del Prado-Vera, Ferris & Subbotin 2020
Body an open C shape, curved ventrad after fixation;
Cuticle with very fine striations.
Head truncate, continuous with the body contour.
Stoma surrounded by six triangular-shaped lips which are not fused;
Inner labial sensilla not visible, six conoid outer labial setae 2.0 - 3.0 (2.5 +/- 0.5) um long, and four small cephalic sensilla situated slightly posterior to the outer labial setae.
Amphid apertures small, oval shape, located two cuticular striations posterior to the cephalic setae.
Stoma heavily sclerotized, subdivided into cheilostom 4.0 - 7.0 (5.5 +/- 0.9) um long and gymnostom 3.0 - 6.0 (4.6 +/- 1.0) um long; the stegostom is funnel-shaped but not clearly visible.
Lateral field with three incisures, the external incisures evident throughout the body length and the middle incisure most visible in the region of the vulva and at the posterior end of body
A single longitudinal line along the dorsal side of the body.
Esophagus cephaloboid: corpus cylindrical 75.0 - 112.0 (99.7 +/- 12.6) um long and 1.5 times longer than the isthmus; isthmus narrower 49.0 - 76.0 (63.0 +/- 9.7) um long; metacorpus nearly pyriform 20.0 - 27.0 (23.4 +/- 2.4) um long and 17.0 - 22.0 (19.0 +/- 1.6) um wide. Cardia conoid.
Nerve ring in the first third of the isthmus at 85.0 - 145.0 (121.0 +/- 20.6) um from the anterior end.
Excretory pore posterior to the nerve ring and anterior to the deirid.
Deirid slightly posterior to excretory pore at 104.0 - 178.0 (158.0 +/- 23.1) um from the anterior end.
Anterior and posterior regions of female of Macrolaimus montrealensis
(drawings adapted from Cid del Prado et al., 2019)
Female:
Reproductive system monodelphic-prodelphic with the ovary reflexed, the germinal area at 83.0 - 229.0 (142.0 +/- 50.2) um from the anus, with a short postuterine sac, 5.0 - 12.0 (8.8 +/- 2.3) um long.
Vulva with protruding lips oriented posteriad, anterior lip the larger.
Two gland cells, 8 um long by 4 um wide with conspicuous nuclei, are located one anterior and the other posterior to the vagina.
Vagina length 8.0 - 15.0 (11.0 +/- 1.9) um.
Rectum length 1.1 - 2.3 (1.6 +/- 0.3) times anal body diameter with two gland-like cells at its anterior end.
Tail elongate conoid, curved ventrally and ending in an acute tip with a dorsally-curved mucro.
Anal lips slightly protruding, mainly the posterior lip.
Phasmids located in the posterior end of the tail 35.0 - 45.0 (41.0 +/- 3.7) um and 51.0 - 61.0 (56.2 +/- 3.8) % of tail length from anus.
Male:
Reproductive system monarchic reflexed ventrad.
Spicules paired and symmetrical, curved ventrad; manubrium with rounded proximal end, short calamus and curved lamina.
Gubernaculum arc-shaped. Three gland-like cells are present anterior to the spicules.
Two pairs of subventral precloacal genital papillae; one pair is 6.0 - 10.0 (8.3 +/- 2.1) um and the second 31.0 - 45.0 (38.0 +/- 6.6) um from cloacal aperture.
Five postcloacal pairs of papillae.
Phasmids are located in the posterior half of the tail at 53.8 - 61.0% (57.3 +/- 3.1) of tail length from anus.
Tail curved more ventrad than in females, ending in an acute tip with a dorsally- curved mucro.
Characteristics from Cid del Prado-Vera et al. 2020.
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
The type specimens of M. montrealensis were collected on July 22, 2016 from lichen on the trunk of a maple tree, Acer sp. in the Montreal Botanical Garden, Montreal, Quebec, Canada,
N 45+/- 55' 94.9 ", W 73+/- 56' 27. 2", 40 m above sea level,
Macrolaimus spp. are assumed to be bacterivores based on the unarmed stoma and the cephaloboid oesophagus. Given their frequent association with insects, besides the advantage of transportation to new resources by phoresy, some species may acquire resources through necromeny, that is, by feeding on bacteria that are exploiting the bodies of dead insects.
Like Macrolaimus montrealensis, some species of the genus have been described from above-ground habiats associated with lichen, moss and insect galleries in tree trunks (Thorne, 1937; Sanwal, 1960) while others have been described from soil samples (Abolafia et al., 2019; Swart and Heyns, 1992; Timm, 1960; Andrassy, 1984).
Species of Macrolaimus may be carried among above-ground habitats by insects (Massey, 1974).
Azizoglu et al. (2016) noted that Macrolaimus species are commonly recovered from bark infested with beetles; M. canadensis was isolated from the frass of the bark beetle Phloeosinus canadensis (Sanwal, 1960), M. crucis was isolated from the pine - top weevil gallery Pissodes piniphilus (Poinar, 1975), and M. taurus, was isolated from gallery of Ips confusus on Pinus edulis (Thorne, 1937).
Ecophysiological Parameters:
Abolafia, J., A. N. Ruiz-Cuenca, J. Foit, and V. Čermak. 2019. Redescription of Macrolaimus canadensis Sanwal, 1960 and M. ruehmi Andrássy, 1966 (Nematoda, Rhabditida, Chambersiellidae), and new data on M. crucis Maupas, 1900. Journal of Helminthology 93:109-125.
Andrássy, I. 1984. Klasse Nematoda (Ordnungen Monhysterida, Desmocolecida, Araeolaimida, Chromadorida, Rhabditida) Bestimmungsbűcher zur Bodenfauna Europas, No.9. Berlin (Deutschland): Akademie Verlag.
Azizoglu, U., S. Karaborklu, A. Ayvaz, and S. Yilmaz. 2016. Phylogenetic relationships of insect-associated free-living rhabditid nematodes from eastern Mediterranean region of Turkey. Applied Ecology and Environmental Research 14:93-103.
Cid del Prado-Vera, I. Ferris, H., Subbotin, S.A. 2020. Two new species of Macrolaimus (Nematoda: Chambersiellidae) with comments on diagnostic characters for distinguishing species. Nematropica 50:170-185.
Massey, C. L. 1974. Biology and taxonomy of nematode parasites and associates of bark beetles in the United States. Agriculture Handbook no. 446. Washington: USDA Forest Service.
Maupas, E. F. 1900. Modes et formes de reproduction des nématodes. Archives de Zoologie Experimentale et Générale 8:463-624.
Poinar, G. O. 1975. Entomogenous nematodes: A manual and host list of insect-nematode associations. Leiden, The Netherleands: Brill.
Sanwal, K. C. 1960. Macrolaimus canadensis n. sp. (Nematoda: Panagrolaiminae), from the frass of the bark beetle Phloeosinus canadensis Swaine, 1917, with remarks on other species of the genus Macrolaimus Maupas, 1900. Canadian Journal of Zoology 38:1127-1131.
Swart, A., and J. Heyns. 1992. Macrolaimus richteri spec. nov. (Nematoda: Chambersiellidae) from the Richtersveld, South Africa. Koedoe 35:19-23.
Thorne, G. 1937. A revision of the nematode family Cephalobidae Chitwood and Chitwood, 1934. Proceedings of the Helminthological Society of Washington 4:1-16.
Timm, R.W. 1960. Brevibucca punctata, n.sp. and Macrolaimus natator, n.sp., new soil nematodes from East Pakistan. Biologia 6:252-256