A taxonomical and ecological study of nematodes from the Seekoeivlei Nature Reserve, Memel

[摘要] English: The Seekoeivlei Nature Reserve wetland is a designated Ramsar site, situated on the north-eastern boundary of the Free State Province. Field trips were made on three occasions between October 2011 and May 2012. A total of 43 genera belonging to 20 families and 7 orders were identified from the three localities. Of the three sites sampled, Bird Lookout point showed the highest species richness (S = 16) and species diversity in terms of the Shannon-Wiener diversity index (H' = 2.18) and Hills diversity index (Hills N1 = 8.78) during the summer survey. It was found that all localities were dominated by plant parasitic nematodes with the exception of Bird Lookout during the winter survey and Mamba Pool during the summer survey, which was dominated by predators and omnivores, respectively. The Maturity Index (MI) value was highest at the Hippo Pool during the preliminary collection (MI = 14.22) and lowest at the Mamba Pool on all three collections. Key genera found at the site included Tobrilus Andrássy, 1959, Eutobrilus Tsalolikhin, 1981; Brevitobrilus Andrássy, 1959 and Chronogaster Cobb, 1913. Tobrilus sp. 1 is characterised by a vulva at mid body (49%), the tail long and cylindrical (216-295 μm) with a spinneret present. Eutobrilus sp. 1 is characterised by labial sensillae papilli form, cephalic setae just over one third labial region diameter, vulva placement at midbody, tail elongate tapering, 6.5 anal body widths long. Brevitobrilus sp. 1 is characterised by body length (1019-1792 μm female; 1123-1526 μm male), labial sensillae papilliform, cephalic setae one third of labial region diameter, vulva at 46% body length, tail five anal body widths long and spinneret present. Males characterised by six supplements with largest distance between S5 and S6, spicule 21 μm, tail three anal body widths long and subterminal setae present. Chronogaster sp. 1. is recognised by female habitus being straight to completely ventrally curved and male habitus being ventrally curved, J-shaped, lip region not annulated, cephalic setae as long or longer than lip region diameter, cylindroid pharynx with denticulated valve in basal bulb, female reproductive system monodelphic-prodelphic, vulva at (45.3%) body lengths from anterior end, male tail conoid, spicule slender, with fifteen dissimilar supplements. Descriptions, measurements and illustrations including light microscope micrographs are provided for the four species.

[发布机构] University of the Free State