Family: Diplogastridae

 Rev: 08/09/2023




A note on nomenclature of the order, suborder, superfamily, family and subfamily:

Schultz (in Carus, 1857) erected and described the genus Diplogaster.  Through various taxonomic revisions and classification schemes, names at different levels of resolution were derived from the genus name.  Hence, Diplogasterida, Diplogasterina, Diplogasteroidea, Diplogasteridae and Diplogasterinae appear in the earlier (and some recent literature) as, respectively, names for order, suborder, superfamily, family and subfamily.  Baker and Sanwal (1969) pointed out that the possesive case for the word ending "gaster" would be "gastros", so that the latinized family name would have the ending "gastridae", not "gasteridae" and likewise for the names of the other taxonomic categories.  Hence, in concordance with the International Code of Zoological Nomenclature, the correct usage of the names is Diplogastrida, Diplogastrina, Diplogastroidea, Diplogastridae and Diplogastrinae.

Interestingly, the family and subfamily names Diplogasteroididae and Diplogasteroidinae, derived from the genus name Diplogasteroides are unchanged, presumably because the possessive case is based on the word ending "oid" rather than "er".

Modern Phylogenies:

The Order Diplogastrida is considered a suborder (Diplogastrina) of the Rhabditida by Andrassy (2005) and as the superfamily Diplogastroidea within the suborder Rhabditina of the order Rhabditida by DeLey and Blaxter (2002, 2004) and DeLey et al. (2006).

A taxonomic note:

In species descriptions of plant and soil nematodes, it is usual to designate a female nematode as the holotype for the species;  Males, if present, are included in the descriptions as paratypes and (quite rarely) one of those may be designated an allotype.

In insect associated nematodes of the Aphelenchoididae and Diplogastridae it has become standard to designate a male as the holotype and list the morphometric charaxcteristics of males before those of females.  The reason for using male holotypes is that females of these groups are typically not topologically very informative at the species level.  Actually, given the number of cryptic species that are being revealed by use of  molecular markers and mating studies, the anatomicakl and morphometric characteristics of males may not be very useful in species designations either (Robin Giblin-Davis, pers. com. November 2018).


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Morphology and Anatomy:



Diplogastridae are considered free-living nematode with aither predatory or bacterivorous feeding habits.  Most genera are associlated with invertebrates, often with a free-living stage in soil.  Hugotdiplogaster infects terrestrial molluscs while in the adult stage; juveniles of come species of Diplogaster are parasites of molluscs (Pieterse et al., 2017).


Andassy, I. (2005) Free-living Nematodes of Hungary, Part I. (Nematoda errantia). Hungarian Natural History Museum 518p.

Baker, A.D. and Sanwal, K.C. 1969. Some notes on nomenclature (Nematoda).  Journal of Helminthology 18:363-366.

Carus, J.V. 1857. Icones zootomicae. Rste Halfte: Die wirbellosen Thiere 1pp.

De Ley, P. and Blaxter. M. 2002.  Systematic position and phylogeny.  In:  D. L. Lee (ed) The Biology of Nematodes.

De Ley, P. and Blaxter. M. 2004.  A new system for Nematoda: combining morphological characters with molecular trees, and translating clades into ranks and taxa.  Nematology Monographs and Perspectives, 2004: 633-653.

De Ley, P., Decraemer, W. & Eyualem-Abebe. (2006). Introduction, summary of present knowledge and research addressing the ecology and taxonomy of freshwater nematodes. Pp 3-30 in Eyualem-Abebe, Andrássy, I. & Traunspurger, W. (Eds). Freshwater Nematodes, Ecology and Taxonomy. CABI Publishing, Wallingford, UK.

Pieterse, A., Malan, A.P., Ross, J.L. 2017. Nematodes that associate with terrestrial molluscs as definitive hosts, including Phasmarhabditis hermaphrodita (Rhabditida: Rhabditidae) and its development as a biological molluscicide. J. Helminthol. 91:517-527.

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