Taxonomic review of the genus Histotylenchus Siddiqi, 1971 (Nematoda: Belonolaimidae) in South Africa

[摘要] English: A diverse and abundant nematode fauna is known to exist in South Africa with plant parasitic nematodes being the most representative. Seven genera belonging to the family Belonolaimidae Whitehead, 1960 are known to occur in South Africa, including Histotylenchus Siddiqi, 1971, a small genus only found in Africa and India. Nematodes belonging to the family Belonolaimidae are obligatory, primarily migratory ectoparasites of roots. These nematodes are found in cultivated soils and natural veld and are usually seen as mild plant parasites. Histotylenchus is represented by three species from South Africa, namely Histotylenchus hedys Kleynhans, 1975, Histotylenchus histoides Siddiqi, 1971 and Histotylenchus mohalei Kleynhans, 1992. Diagnostic characters of Histotylenchus include a lip region confluent with body contour or offset, asymmetrical stylet conus with an angular lumen, a large metacorpus valve, genital tracts about equal, lateral fields with four lines usually areolated, spicules tapering distally with distinct vela and gubernaculum proximally recurved with titillae. The aim of this study was to review all existing literature concerning the genus Histotylenchus in Africa, and to examine and describe the species from this genus collected in South Africa, which are deposited in the National Collection of Nematodes, Biosystematics Programme, Agricultural Research Council, Plant Protection Research Institute, Pretoria, South Africa. Results showed that a total of 44% of the fixed material examined was not suitable for this morphological study as a result of the separation of the cuticle from the body. This phenomenon is reported from this genus for the first time. Histotylenchus hedys and Histotylenchus mohalei were re-described from material of the National Collection of Nematodes, while Histotylenchus histoides was re-described from type material of the Rothamsted Nematode Collection housed at the Food and Environment Research Agency (Fera), York, United Kingdom; and CABI Bioscience, Egham, United Kingdom. A new species, Histotylenchus niveus sp. n., was described from material collected in the Witsand Nature Reserve, Northern Cape, South Africa. Additionally, two species Histotylenchus sp. 1 and Histotylenchus sp. 2 were described during this study and could possibly be new to science. However, additional material needs to be collected to verify these results. The present study revealed that further research into the genus is necessary, especially since the current information is limited and incomplete.

[发布机构] University of the Free State