Crassolabium		Contents		Rev 06/09/2023
		Classification		Biology and Ecology
		Morphology and Anatomy		Life Cycle
Return to Crassolabium Menu				Ecosystem Functions and Services
		Distribution		Management
Return to Dorylaimidae Menu		Feeding		References
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Classification:

Synonym:

Allodorylaimus Thorne, 1974

Thonus Thorne, 1974

Note:Athough Thonus is considered a synonym of Crassolobium and, based on dates of publication, would be the junior synonym, Pena-Santiago and Ciobanu (2007) suggest a reversal of the precedence condition because (i) The name Thonus identifies a highly diversified taxon (more than 40 species are currently named with this generic substantive while Crassolabium is a poorly known and seldom used name, with only two species; (ii) Thonus is a name that identifies a worldwide-distributed taxon, recorded in many (50) bibliographic references on taxonomical, faunistical and ecological subjects, whereas by contrast only a few (10) references are available on Crassolabium, mostly discussing its taxonomy and status; (iii) Thonus is a name that identifies a rather well-defined morphological pattern among dorylaimid nematodes, and relevant morphological (and also biogeographical and ecological information) is associated with it, obviously, that is not at all the case of Crassolabium; (iv) the etymology of Crassolabium, meaning thick or fat lip, refers to a peculiar morphological feature that does not fit the Thonus pattern and whose taxonomical value has been demonstrated to be of minor significance and interest.

However, despite those arguments, Pena-Santiago and Alvarez-Ortega (2014) listed Thonus as a junior synonym of Crassolobium!  In the same paper, the rounded tail members of the subfamily Qudsianematinae of the family Qudsianematidae were transferred to a new subfamily (Labronematinae) of the family Dorylaimidae.  In his recent book, Dorylaimida Mundi (Nematoda) 2021, Pena-Santiago, ever and appropriately an advocate for the Rules of Zoological Nomenclature, listed the current species of Thonus under the genus name Crassolobium.

Crassolabium was moved to Dorylaimidae: Labronematinae from Qudsianematidae with other round-tailed genera, by Pena-Santiago and Alvarez-Ortega (2014).

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Morphology and Anatomy:

• Body length ranging from 0.6-2.1 mm.
• Cuticle smooth, rarely finely striated.
• Lip region slightly offset from body contour; lips somewhat separate.
• Odontostyle about as long as labial diameter, aperture 1/3 its length.
• Esophagus enlargement starts at about 50% of esophageal length.
• Female genital system diovarial, amphidelphic; vulva usually transverse with sclerotized lips.
• Males common; spicules dorylaimoid; 3-18 ventromedian supplements.
• Tail in both sexes short, rounded or convex-conoid.
• Similar appearing to Eudorylaimus except for the rounded tail; considered identical to, and synonymizad with, the genus described as Allodorylaimus, Thorne, 1974..But, Pena-Satiago and Ciobanu T2007) consider Crassolobium identical to Thonus and suggest a reversal of the precedence condition to maintain the use of Thonus as the genus name.

Ref. Andrássy, 2009.

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Distribution:

Members of this genus, designated either Crassolobium or Thonus, occur throughotu the world/

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Feeding:

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Biology and Ecology:

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Life Cycle:

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Ecosystem Functions and Services:

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Management:

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References:

Andrassy, I. 2009. Free-living Nematodes of Hungary III.  Hungarian Natural History Museum, Budapest. 608p.

Pena-Santiago, R. and Ciobanu, M. 2007. On the Identity of the Genus Crassolabium Yeates, 1967 (Dorylaimida: Qudsianematidae). J. Nematology 39:231-236.

Pena-Santiago, R. 2021. Dorylaimida Mundi (Nematoda); checklist of genera and species, with their records. UJA Editorial. 957p.

Yeates, G.W., T. Bongers, R. G. M. De Goede, D. W. Freckman, and S. S. Georgieva. 1993. Feeding habits in soil nematode families and genera—An outline for soil ecologists. Journal of Nematology 25:315-331.

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Copyright © 1999 by Howard Ferris.
Revised: June 09, 2023.