Rinus Knoetze, Antoinette Swart and Louwrens R. Tiedt
A new cyst nematode, herein described as Globodera capensis n. sp., was found on several farms in the Swartland and Sandveld areas in South Africa. As the host plant of G. capensis n. sp. is currently unknown, the species is represented by cysts and second-stage juveniles (J2) only. The cysts have a spherical form, are yellow to dark brown in colour and have bullae (vulval bodies) and subcuticular punctations. Six to 20 cuticular ridges/lines are present between the anus and vulval basin, Granek’s ratio is 0.7-4.0, the vulval basin diam. is 16-28.5 μm and vulval basin to anus distance is 19-60 μm. The J2 is 430-528 μm long and the stylet is 23-28 μm long with anteriorly flattened to rounded stylet knobs. These stages are morphologically and morphometrically very near to, or indistinguishable from PCN, G. artemisiae, G. millefolii and G. tabacum tabacum. It can be distinguished by the molecular characteristics of the ITS-region of the ribosomal DNA. Pairwise distances between closely related Globodera species show that G. capensis n. sp. differs the least in number of base differences per sequence from G. millefolii (63-64 bp) and most from an undescribed Globodera from Chile (72-73 bp). Phylogenetic relationships of G. capensis n. sp. with selected species of Punctoderinae, inferred from ITS-rRNA sequences by using the Maximum Likelihood method, indicate that G. capensis n. sp. occupies a basal position within a lineage of Globodera species from Europe, Asia and New Zealand that parasitises non-solanaceous plants. For diagnostic purposes, digestion of the ITS1 with AluI will distinguish G. capensis n. sp. from G. mexicana, G. pallida, G. rostochiensis and G. tabacum, but not from G. artemisiae, G. millefolii and G. zelandica, whilst FauI will distinguish G. capensis n. sp. from all the other Globodera species tested.
J. Heyns, Antoinette Swart and J.P. Furstenberg
Gerhard Du Preez, Antoinette Swart and Hendrika Fourie
Although the importance of nematodes, especially in soil ecosystems, is well appreciated, very little is known about the occurrence of and ecosystem services provided by cavernicolous nematodes. This study was undertaken to determine the nematode occurrence, density and distribution in the Wonderfontein Cave (South Africa), which is subjected to the influx of water from the Wonderfontein Spruit. Of the 53 nematode genera collected from the Wonderfontein Cave during the first (April 2013) and second (September 2013) sampling intervals, 22 have never been reported from a cave environment. Results indicated that many of the nematodes found may only be temporary residents introduced from the surface environment. This study reveals the necessity of further efforts to investigate the nematode communities associated with subterranean environments, which will provide a better understanding of the functioning of the associated ecosystems.
Rinus Knoetze, Antoinette Swart, Ria Wentzel and Lourens R. Tiedt
A new cyst nematode, herein described as Globodera agulhasensis n. sp., was found parasitising Senecio burchelli in the Western Cape Province, South Africa. Second-stage juveniles are characterised by a well developed stylet of 23.5 (22.5-24.8) μm with rounded to anteriorly flattened knobs. The dorsal pharyngeal gland outlet is 4.4 (3.5-6.5) μm posterior to the stylet knobs. The tail is 56 (49-64) μm long and the length of the hyaline region is 25 (19-29) μm. The cysts are characterised by their ovate to spherical shape, short neck, the presence of subcuticular punctations over the entire body and the absence of bullae or vulval bodies. Six to 12 cuticular ridges/lines are present on the outer surface of the cyst between the anus and vulval basin. Granek’s ratio is 1.7 (1.0-3.0), the vulval basin diam. 17.6 (11.7-26.1) μm and the distance between vulval basin and anus is 28.6 (19.1-47.0) μm. Males have a stylet length of 26.1 (24.4-27.7) μm and spicule length of 30.3 (27.2-33.8) μm with a rounded tip. Females have a stylet length of 22.1 (19.0-24.4) μm, a large median bulb almost filling the body diam., and a short vulval slit 4.2 (3.2-6.6) μm long. Phylogenetic relationships of G. agulhasensis n. sp. with other species of the genus, inferred from ITS-rRNA sequences by using the neighbour-joining (NJ), maximum likelihood (ML) and maximum parsimony method (MP), indicate that G. agulhasensis n. sp. is included in the clade of Globodera sp. that parasitise non-solanaceous plants, forming a monophyletic group with unidentified Globodera spp. from Portugal, G. millefolii and G. artemisiae. For diagnostic purposes, three restriction enzymes, Hpy8I, RsaI and XceI were selected as being able to discriminate between G. agulhasensis n. sp. and other Globodera spp. present in South Africa.
Rinus Knoetze, Antoinette Swart, Ria Wentzel and Lourens R. Tiedt
A new cyst nematode, herein described as Globodera sandveldensis n. sp., was found in the Sandveld, Western Cape Province, South Africa. As the host plant of G. sandveldensis n. sp. is currently unknown, the species is represented by cysts and second-stage juveniles (J2) only. The J2 are characterised by a well developed stylet of 26.4 (24.8-28.5) μm with rounded to anteriorly flattened knobs. The distance from the dorsal pharyngeal gland outlet to the stylet knobs is 4.5 (2.4-7.2) μm. The tail is 64 (56-77) μm long and the length of the hyaline region is 33 (22-39) μm. The cysts are characterised by their ovate to spherical shape, short neck, and the presence of subcuticular punctations and bullae or vulval bodies. Six to 14 cuticular ridges/lines are present on the outer surface of the cyst between the anus and vulval basin. Granek’s ratio is 1.7 (0.9-3.0), the vulval basin diam. is 20.4 (13.1-34.6) μm and the distance between vulval basin and anus is 33.5 (19.7-54.0) μm. Phylogenetic relationships with other species of the genus, inferred from ITS-rDNA sequences, indicate that G. sandveldensis n. sp. is included in the clade of Globodera sp. that parasitise non-solanaceous plants and is closely related to unidentified Globodera spp. from Portugal, G. millefolii, and G. artemisiae.
Sergei Subbotin, Antoinette Swart, Louwrens Tiedt and Ian Riley
Anguina woodi sp. n. was found in galls on dune grass, Ehrharta villosa var. villosa, on Milnerton Beach, South Africa. Mature galls varied in colour from purplish to brown and formed elongated to round elevations on the stems, leaf sheaths and, occasionally, the leaf blades. The adult females of Anguina woodi sp. n. are 1.6-2.7 mm long and coiled into a circle or spiral. Adult males were 1.4-2.1 mm long, straight or slightly curved ventrad or dorsad. Second-stage juveniles (J2) were more or less straight with a prominent mucro on the tail. A few larger juveniles, probably J3 and J4, with developing gonads were also found. Morphological, morphometric and molecular analyses showed that Anguina woodi sp. n. is closely related to A. australis Steiner, 1940 and, to a lesser extent, to A. microlaenae (Fawcett, 1938) Steiner, 1940. From A. australis it differs mainly in a slightly longer female stylet (9.5-15.5 vs 8.0-11.1 μm) and wider female head (8.6-11 vs 7.4 μm); a slightly longer male stylet (10.5-12.0 vs 10-11 μm) and longer spicule (33-36 vs 26.5-35.3 μm), and a longer tail (72-96 vs 49-68 μm) and slightly higher c-value (7.3-12 vs 6.1-8.1) in the J2. The mucro on the tail tip of the J2 of A. woodi sp. n. is also more prominent and, on average, longer than the mucro in A. australis (3.3 vs 1.5 μm). Anguina woodi sp. n. differs from A. microlaenae mainly in the appearance of the galls incited (roundish elevations attached to the substrate by a flattened base vs pedunculate galls attached to the substrate by a narrow base), a longer stylet in both females and males (8-9 μm long in females and males of A. microlaenae), body of male curved ventrad or dorsad in A. woodi sp. n. (dorsad in males of A. microlaenae) and female tail in A. woodi sp. n. tapering gradually to a sub-acute tip vs a prominent peg-like process in A. microlaenae. Phylogenetic analysis of the ITS1 sequences of 19 anguinid populations and species using maximum parsimony and maximum likelihood methods revealed that A. woodi sp. n. clustered with high bootstrap support with A. australis. The ITS1-5.8S-ITS2 fragment sequence differed between these species by 20 nucleotides (2.6%). The J2 of A. australis is herein described for the first time and is compared with the J2 of A. woodi sp. n. Phylogenetic relationships of A. woodi sp. n. with other anguinids parasitising grasses are presented.
Moses M. Lesufi, Antoinette Swart, Alex H. Mc Donald, Rinus Knoetze, Louwrens R. Tiedt and Mariette Truter
Aphelenchoides arachidis is reported for the first time from South Africa and for the fourth time outside Nigeria. The A. arachidis-infested pods from South Africa showed the following symptoms: small seeds with the testa wrinkled and darker in colour than that of non-infested seeds; the pods showed dark lesions and some seeds within the pods showed early germination. Differences between the two South African and the Nigerian populations of A. arachidis include more lateral lines in some specimens (2-4 vs 2) and, on average, longer post-uterine sac length (extending for 74 (41-96) and 62 (33-82) vs about 50% of vulva to anus distance). Scanning electron micrographs of this species are presented for the first time. The ITS regions of ribosomal DNA were amplified, sequenced, aligned and compared with other sequences of Aphelenchoides species. Two pathogenic fungi, Thielaviopsis basicola and Neocosmospora vasinfecta, were also isolated from this material.
Natsumi Kanzaki, Ebrahim Shokoohi, Hendrika Fourie, Antoinette Swart, Loureine Muller and Robin M. Giblin-Davis
In a survey of nematode damage in groundnut (Arachis hypogaea) (Fabaceae) production areas in the Vaalharts Irrigation Scheme in the Northern Cape Province of South Africa, a nematode was recovered and initially believed to be a member of the genus Robustodorus, i.e., the species has a characteristic robust stylet with very well-developed teardrop-shaped (garlic bulb-like) basal swellings. The specimens were recovered in large numbers from damaged hulls and kernels of field-collected groundnuts and, after thorough morphological and molecular studies, were subsequently identified as Aphelenchoides arachidis. Molecular analysis based on near-full-length small subunit (SSU), internal transcribed spacer (ITS) and D2-D3 expansion segments of the large subunit (LSU) rRNA genes supported the monophyly of A. arachidis, A. subtenuis and R. megadorus within the subfamily Aphelenchoidinae. Based on the typological characters observed in the present study compared with descriptions in the literature, these three species are considered as congeneric, i.e., they share very well-developed basal swellings of the stylet. Accordingly, these two Aphelenchoides species are transferred to Robustodorus as R. arachidis n. comb. and R. subtenuis n. comb. In addition, the male tail characters of Robustodorus and Aphelenchoides are discussed.
Gerhard Du Preez, Nabil Majdi, Antoinette Swart, Walter Traunspurger and Hendrika Fourie
Caves and cave-dwelling biota have fascinated scientists for centuries. Nevertheless, there is a considerable lack of information on subterranean realms and the ecosystems they host. Nematoda, for example, is a group of invertebrates that plays an important role in the functioning of epigean ecosystems, but whether or not the same is true for subterranean ecosystems remains unknown. For this reason it was decided to conduct an in-depth review of all reports related to cave-dwelling nematodes in order to provide a sound basis for future studies. A literature survey of 41 scientific works from over the last 138 years revealed 295 unique taxa reported from 78 different cave systems. The historical trends in cave nematology, peculiar findings from important studies and an ecological classification system are discussed. Lastly, the trophic distribution of the reported taxa is presented, whilst nematodes from other (non-cave) subterranean environments are also considered.