Revised 10/15/24
Lungworms
| Recent Clessification | Alternative Classification | Relationships among species, genera, and even families, within the Nematoda are becoming clearer as morphological, morphometric, and life history features are considered along with molecular-based phylogenies. However, there remain differences of opinion among experts regarding classifications above the family level. Such differences are apparent in the classification in the Order Strongylida or the consideration of suborders of the Strongylida as suborders of the Rhabditida. |
| Rhabditida | Strongylida | |
| Rhabditina | Trichostrongylina | |
| Rhabditomorpha | ||
| Trichostrongyloidea | Trichostrongyloidea | |
Trichostrongyloidea (Leiper, 1908) Chabaud, 1965
Many species of Trichostongyloidea are significant pathogens of humans, dometsic and wild mammals. They include nematodes in the families:
The pattern of longitudinal ridges (synlophe) on the external cuticular surface of trichostrongyloid nematodes is useful for distinguishing species and determining relationships among higher taxa. For example, synlophe patterns of Mecistocirrus digitatus, the large stomach worm of bovids, are very similary similar synlophe patterns to those described for some species of Haemonchus and of Ashworthius. In the three genera, the synlophe is absent from the posterior part of the body. extends beyond mid-body only in Haemonchus.
In these three genera, the synlophe consists of about 30 ridges in the region of the esophagus with variation among species in specific areas. The patterns are useful for identifying species and determining relationships among these large stomach worm parasites of cattle, sheep, goats, and cervids (Lichtenfels and Pilitt, 2000; Hoberg et al., 2009).
Many parasitic representatives of the superfamily Trichostrongyloidea have a
free-living stage in the life cycle with metamorphoses occur outside the host
(Connan & Wise, 1993; Sudhaus & Fitch, 2001).
Connan, R.M.,Wise, D.R. 1993. Development and survival at low temperature of the free living stages of Trichostrongylus tenuis. Research in Veterinary Science, 55:20-24.
Hoberg, E.P., Abrans, A., Pilitt, P.A. 2009. Synlophe structure for species of Longistrongylus (Nematoda: Trichostrongyloidea), abomasal parasites among ungulates from sub-Saharan Africa, with comparisons to the global ostertagiine fauna . J. Parasitology 95:1468-1478, doi: 10.1645/GE-2102.1.
Hoberg, E.P., Lloyd, S., Omar, H. 1995. Libyostrongylus dentatus n. sp. (Nematoda: Trichostrongylidae) from Ostriches in North America, with Comments on the Genera Libyostrongylus and Paralibyostrongylus. J. Parasitul. 81:85-93.
Lichtenfels, J.R., Pilitt, P.A. 2000. Synlophe patterns of the Haemonchinae of ruminants (Nematode: Trichostrongyloidea). J. Parasitology 86:1093-1098.
Sudhaus, W., Fitch, D. 2001. Comparative studies on the phylogeny and systematics of the Rhabditidae (Nematoda). Journal of Nematology, 33:1-70.