Revised 02/10/22
Craeagrocercidae Baylis, 1943
A rare family of nematodes that includes (so far, exclusively) parasites of earthworms (Ivanova and Spiridonov, 2011).
Classified by some authorities in the Drilonematoidea of the Rhabditida however, molecular analyses suggest relatedness to Leptolaimoidea.
The original represnetives of the family were described by Baylis (1943) from the coelom of the moniligastrid earthworm Moniligaster gravelyi.
Baylis erected the family Creagocercidae to accommodate the new genus and species, Creagrocercus barbatus Baylis, 1943.
The family was placed in the Drilonematoidea based solely on its inhabiting the body-cavity of earthworms. The only morphological character uniting the Creagrocercidae and the Drilonematoidea Pierantoni, 1916 was the lack of valves in the pharynx.
The type- and only species of the Creagrocercidae was characterised by females being didlephic and males diorchic, filiform sperm, two spicules which were dissimilar in shape and size, the lack of a gubernaculum and the presence of a tiny, cuticularised hook on the tip of the tail.
Despite extensive studies on nematodes parasitic in earthworms from South-East Asia, representatives of the family Creagrocercidae were not seen again for more than 50 years when Spiridonov (2001) described two females Creagrocercidae species from the body-cavity of an unidentified African acanthodrilid earthworm in the collection of the Royal Museum of Central Africa in Tervuren, Belgium, and fragments of yet another creagrocercid female from an African octochaetid oligochaete, Dichogaster itoliensis. These creagrocercid females possessed distinct caudal hooks but were monodelphic.
The non-relatedness of Creagrocercus (Creagrocercidae) to the rest of Drilonematoidea was confirmed by LSU and SSU rDNA analyses which demonstrated its close affinity with Domorganus (Ohridiidae, Plectida) (Ivanova & Spiridonov 2011).
Ref: Ivanova and Spiridonov,
2011.
References
Baylis, H.A. 1943. Some nematode parasites of earthworms from the Indo-Malay region. Parasitology 35:112-127.
Ivanova, E.S. and Spiridonov, S.E. 2011. Two new species of creagrocercid nematodes parasitic in earthworms, with comments on the phylogenetic affiliations of the Creagrocercidae Baylis, 1943. Syatematic Parsitology 78:81-94.
Spiridonov, S. E. 2001.. Parasitic organisms from tropical earthworms deposited in the Royal Museum of Central Africa. Annales. Musée Royal de l’Afrique Centrale. Tervuren. Sciences Zoologiques, 285:19-27.
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