Michel Luc

Usefulness of morphological data for the study of nematode biodiversity

Public interest in biodiversity has never been so high, but the necessary inventory of existing species is hindered by the scarcity of taxonomists able to characterise and describe new species (α-taxonomy). This situation is particularly worrisome in nematology where only a small fraction of the estimated 105 to 108 existing species has been described and where experienced taxonomists are fast disappearing while the few that are still active find it increasingly difficult to publish morphological descriptions and to get financial support for biodiversity studies. The present disregard for α-taxonomy is said to originate from the excessive reliance by funding agencies and academic authorities on the Impact Factors attributed to scientific journals by ISI (Institute for Scientific Information). Molecular studies gave back some support and prestige to taxonomy, but that approach suffers from some limitations and it cannot be used alone for reaching taxonomic conclusions. In addition, any described DNA sequence should always be linked to a named species whose morphology has been correctly described by a trained taxonomist. The authors call for a renewed interest in α-taxonomy. Electronic publication according to the Code of Zoological Nomenclature would be one solution, but journals and authors seem reluctant to accept it. A variant would be to publish on paper only the diagnosis of the new species. The complete descriptions could be deposited in an Internet database but the setting-up of such a database would be a costly enterprise that would require several years of work by a team composed of morphological and molecular taxonomists and computer scientists.

On five species of the genus Xiphinema Cobb, 1913 (Nematoda: Longidoridae) recently described from India

Examination of paratypes of five species of Xiphinema from India described by Singh and Khan (1998) led to the following conclusions: X. larliani Khan & Singh, 1998 appears a valid species close to X. simillimum Loof & Yassin, 1971. The other four species are considered junior synonyms, X. digicaudatum of X. brasiliense Lordello, 1951; X. gracilicaudatum of X. radicicola Goodey, 1936; X. arunachalense of X. brevicollum Lordello & Da Costa, 1961; X. pruni of X. basiri Siddiqi, 1959. Complementary morphological data, measurements and illustrations based on the paratypes are given for the five species.

Morphometrics of Juvenile Stages of Some Xiphlnema Species (Nematoda: Longidoridae)

Information is supplied on the juvenile stages of Xiphinema bergeri Luc, 1973, X. filicaudatum Loof & Maas, 1972, X. longicaudatum Luc, 1961, X. parasetariae Luc, 1958, X. spaulli Heyns & Vermeulen, 1982 and X. vitis Heyns, 1974. Measurements including length of odontostyle and replacement odontostyle are tabulated, and illustrations are given of the tail shapes of the four juvenile stages, plus that of the adult female for comparison.

On Macroposthonia de Man, 1880 (Nematoda: Criconematidae)

Macroposthonia napoensis Talavera & Hunt, 1997 and M. planilobata Talavera & Hunt, 1997 are transferred to the genus Mesocriconema Andrássy, 1965, taking into account the action of Geraert & Luc (1994), which demonstrated that the description of the so-called population of M. annulata de Man, 1880 from Spain could not represent that type-species. Consequently, Macroposthonia de Man, 1880 and M. annulata are confirmed as genus et species dubia. Moreover, Macroposthonia surinamensis (De Grisse & Maas, 1970) Loof & De Grisse, 1974 is returned to Mesocriconema surinamensis (De Grisse & Maas, 1970) Loof & De Grisse, 1989.