Xennella Cobb 1920
- 1. National Institute of Water and Atmospheric Research, Wellington, 14 - 901, New Zealand.
- 2. Landcare Research, Private Bag 92170, Auckland Mail Centre, Auckland 1142, New Zealand.
- 3. Tropical Biosphere Research Centre, University of the Ryukyus, Motobu, Okinawa, Japan.
Description
Genus Xennella Cobb, 1920 Diagnosis
Xennellidae. Cuticle annulated or smooth; longitudinal ridges on cuticle present or absent. Tapering cephalic capsule offset from rest of body by constriction, cuticular discontinuity and/or thickened cuticle. Female reproductive system with reflexed anterior ovary and rudiment of posterior genital branch. Male reproductive system monorchic (at least in X. suecica Allgén, 1935). Spicules short, arcuate; gubernaculum present or absent, precloacal supplements present or absent. Four species.
Type speciesXennella cephalata Cobb, 1920.
Other valid speciesX. filicaudata Allgén, 1954.
X. metallica Tchesunov, 1988.
X. suecica Allgén, 1935.
RemarksIn the classification of Filipjev (1925; 1934), Xennella was placed together with the genus Tycnodora Cobb, 1920, which has since been synonymized with Halalaimus de Man, 1888 by Lorenzen (1981), and Schistodera Cobb, 1920, which has since been synonymized with Oxystomina Filipjev, 1918 (family Oxystominidae Chitwood, 1935) by Hope & Murphy (1972). This placement reflected the apparently smooth cuticle of X. cephalata, although the cuticle of X. suecica and X. metallica is clearly annulated. De Coninck (1937) later provided a detailed description of the males of X. suecica, and indicated close similarities between Xennella and Dasynemoides Chitwood, 1936 based on the annulated cuticle with longitudinal ridges, structure of the cephalic capsule and arrangement of anterior sensilla.
The changing classification of Xennella partly stems from uncertainty regarding the structure of the amphids. While Cobb (1920) shows a pocket-shaped amphideal fovea in his original description of X. cephalata (which indicates relationships with the Enoplida), De Coninck (1965) shows a rounded amphideal fovea in X. suecica (which, together with other features, could indicate relationships with either the Desmodoridae Filipjev, 1922, Ceramonematidae Cobb, 1933 or Monoposthiidae Filipjev, 1934). Other authors only show an almond-shaped amphideal aperture without showing the structure of the amphideal fovea (Allgén 1935; Tchesunov 1988), which may have been obscured by the thick cuticle of the cephalic capsule (De Coninck 1937).
Notes
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Linked records
Additional details
Identifiers
Biodiversity
- Family
- Xennellidae
- Genus
- Xennella
- Kingdom
- Animalia
- Order
- Desmodorida
- Phylum
- Nematoda
- Scientific name authorship
- Cobb
- Taxon rank
- genus
- Taxonomic concept label
- Xennella Cobb, 1920 sec. Leduc, Zhao & Sinniger, 2020
References
- Cobb N. A. 1920. One hundred new nemas (type species of 100 new genera). Contributions to a Science of Nematology 9: 217 - 343.
- Allgen C. A. 1935. Die freilebenden Nematoden des Oresunds. Capita Zoologica 6: 1 - 192.
- Allgen C. A. 1954. Uber eine neue Art der Gattung Xennella Cobb 1920, Xennella filicaudata n. sp. aus Sudgeorgien. Zoologischer Anzeiger 152: 93 - 94.
- Tchesunov A. V. 1988. New species of nematodes from the White Sea. Proceedings of the Zoological Institute of the USSR Academy of Science (Leningrad) 180: 68 - 76.
- Filipjev I. N. 1925. Les nematodes libres des mers septentrionales appartenant a la famille des Enoplidae. Archiv fur Naturgeschichte 91: 1 - 216.
- Filipjev I. N. 1934. The classification of the free-living nematodes and their relation to the parasitic nematodes. Smithsonian Miscellaneous Collections 89 (6): 1 - 63.
- de Man J. G. 1888. Sur quelques nematodes libres de la Mer du Nord, nouveaux ou peu connus. Memoires de la Societe zoologique de France 1: 1 - 51.
- Lorenzen S. 1981. Entwurf eines phylogenetischen Systems der freilebenden Nematoden. Veroffentlichungen des Instituts fur Meeresforschung in Bremerhaven 7: 1 - 472.
- Filipjev I. N. 1918. Free-living marine nematodes of the Sevastopol area. Transactions of the Zoological Laboratory and the Sevastopol Biological Station of the Russian Academy of Sciences 4: 1 - 350.
- Chitwood B. G. 1935. Nomenclatorial notes, I. Proceedings of the Helminthological Society of Washington 2: 51 - 54.
- Hope W. D. & Murphy D. G. 1972. A taxonomic hierarchy and checklist of the genera and higher taxa of marine nematodes. Smithsonian Contributions to Zoology 137: 1 - 101.
- De Coninck L. A. 1937. Sur le male de Xennella suecica Allgen 1935 (Nematodes), ainsi que sur la position systematique du genre Xennella Cobb, 1920. Biologisch Jaarboek (Dodonaea) 4: 378 - 387.
- Chitwood B. G. 1936. Some marine nematodes from North Carolina. Proceedings of the Helminthological Society of Washington 3: 1 - 16.
- De Coninck L. A. 1965. Systematique des nematodes. In: Grasse P. P. (ed.) Traite de Zoologie: Anatomie, Systematique, Biologie. Nemathelminthes (Nematodes): 586 - 731. Masson et Cie, Paris.
- Filipjev I. N. 1922. Encore sur les nematodes libres de la Mer Noire. Acta Instituti Agronomomici Stavropol 1: 83 - 184.
- Cobb N. A. 1933. New nemic genera and species, with taxonomic notes. Journal of Parasitology 20: 81 - 94.