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

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Date
2014-02
Authors
Mobara, Ayesha
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University of the Free State
Abstract
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.
Afrikaans: Die Seekoei-Natuurreservaat Vleiland is ʼn Ramsargebied wat aan die noord-oostelike grens van die Vrystaat geleë is. Veldwerkbesoeke is op drie geleenthede tussen Oktober 2011 en Mei 2012 na hierdie gebied onderneem. ʼn Totaal van 43 genera in 20 families en sewe ordes wat voorkom, is vanaf drie spesifieke areas geïdentifiseer. Een van hierdie areas, die Voëluitkykpunt het die grootste spesieverskeidenheid (S = 16) asook spesiediversiteit in terme van die Shannon-Weiner diversiteitsindeks (H’ = 2.18) opgelewer en gedurende die somer was die Hill’s diversiteitsindeks (Hills N1 = 8.78) die grootste. Die algemene bevinding was dat die gebied deur plant-parasitiese nematode oorheers word, behalwe die Voëluitkykpunt in die winter en die Mambapoel in die somer, wat onderskeidelik deur predatore en omnivore oorheers was. Gedurende die aanvanklikeondersoek, was die volwassenheidindeks (VI) die hoogste by die Seekoeipoel (VI = 14.22) en ten tye van al drie besoeke die laagste by die Mambapoel. Sleutelgenera wat hier aangetref was, sluit Tobrilus Andrássy, 1959, Eutobrilus Tsalolikhin, 1981, Brevitobrilus Andrássy, 1959 en Chronogaster Cobb, 1913 in. Tobrilus sp. 1 word gekenmerk deur ʼn vulvaplasing by die middellyf, ‘n stertlengte van 216-295 μm en ‘n silindriese spineret. Eutobrilus sp. 1 word gekenmerk deur labiale sensiliums wat papillivormig is, sefaliese setas wat een derde van die labiale-area deursnee is, asook ‘n vulvaplasing by die middellyf, ‘n verlengde vernouende stert wat 6.5 anale liggaamsbreedtes lank is. Brevitobrilus sp. 1 word gekenmerk deur ‘n liggaamslengte van 1019-1792 μm by die wyfie en 1123-1526 μm by die mannetjie, asook labiale sensiliums wat papillivormig is, sefaliese setas een derde van die labiale areadeursnit, vulva 46% van die liggaamslengte, die stert vyf anale liggaamsbreedtes lank, asook ‘n spineret wat teenwoordig is. Mannetjies word gekenmerk deur ses byvoegsels met die grootste afstand tussen S5 en S6, spikulums 21 μm lank, stert drie anale liggaamsbreedtes lank en subterminale setas wat teenwoordig is. Chronogaster sp. 1 is uitkenbaar aan die habitus wat reguit of ventraal gebuig is vir wyfies terwyl dié van die mannetjies ventraal gebuig en J-vormig is, die liparea is nie verwyd nie, sefaliese setas is lank, of langer as die liparea-omtrek, silindervormige farinks bevat ‘n getande klep in die basale knop, wyfie se voortplantingstelsel is monodelfies-prodelfies, vulva (45.3%) van liggaamslengte, manlike stert konies verleng, spikulums skraal asook vyftien verskillende byvoegsels. Beskrywings, afmetings en illustrasies insluitende ligmikroskoopmikrograwe van die vier spesies word voorsien.
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Dissertation (M.Sc. (Zoology and Entomology))--University of the Free State, 2014, Nematodes -- Ecology, Parasites, Wetland ecology -- South Africa -- Free State, Natural areas -- South Africa -- Free State, Nature conservation -- South Africa -- Free State, Taxonomy, Nematode, Morphology, Freshwater, Ecology, Tobrilus sp. 1, Eutobrilus sp. 1, Chronogaster sp. 1, Brevitobrilus sp. 1
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